Trajectory control system for multiple vertical takeoff and landing aircraft configurations

Abstract

A control system for controlling various configurations of aircraft includes a first module that receives pilot inceptor input and maps input to an input command, a second module that controls a longitudinal trajectory of an aircraft and is configured to receive the input command and generate a normalized vertical thrust command or a normalized horizontal thrust command derived from the input command, and a third module that generates a control state for one or more control effectors of the aircraft based on one or both of the normalized vertical and horizontal thrust commands. The normalized vertical and horizontal thrust commands are configuration-invariant so as to be applicable to any aircraft having one of the various configurations.

Description

55879-427819 TRAJECTORY CONTROL SYSTEM FOR MULTIPLE VERTICAL TAKEOFF AND LANDING AIRCRAFT CONFIGURATIONS CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present disclosure claims priority to and the benefit of U.S. Provisional Patent Application No.63 / 677,689, entitled “Inceptors-to-Effectors Flight Control System Architecture for Multiple Vertical Takeoff and Landing Configurations,” filed July 31, 2024, and U.S. Provisional Patent Application No.63 / 687,469, entitled “Trajectory Control System,” filed August 27, 2024, the disclosures of which are incorporated by reference herein in their entirety. FIELD

[0002] The present disclosure relates to systems, devices, and methods for controlling propulsors of aircraft, and in particular, controlling propulsors of vertical takeoff and landing aircraft. BACKGROUND

[0003] Vertical takeoff and landing (VTOL) aircraft that are being developed for the Urban Air Mobility (UAM) and / or Advanced Air Mobility (AAM) concept of operations show great diversity with respect to their configurations, in particular the arrangement of lifting surfaces, distributed propulsors, and control effectors. Regardless, the majority of concepts transition between a thrust-borne vertical flight mode (VFM) for takeoff and landing and a wing-borne forward flight mode (FFM) for more efficient cruise. The multiplicity of propulsors and control effectors yields over-actuated dynamical systems. These present additional challenges for the design of a flight control system (FCS).

[0004] If such complex vehicles are to be operated safely and proficiently by UAM pilots who will almost certainly lack the training and experience of airline pilots, the FCS must be designed for Simplified Vehicle Operations (SVO), which involves integrated design of flight control laws, control inceptors, and cockpit displays. In particular, the pilot’s trajectory commands should be translated into coordinated control of propulsor thrust and vehicle attitude. For fixed-wing aircraft, an exemplary control system of these aircraft may include the Total Energy Control System (TECS), a multi-input-multi-output (MIMO) control scheme aimed at replacing traditional single-input-single output autopilot and autothrottle controllers. In pursuit55879-427819 of the SVO paradigm, certain aspects of the TECS may be applicable to lift-plus-cruise and tilt- wing configurations. TECS, however, only considers forward flight based on horizontal thrust and aerodynamic lift-based flight, as fixed-wing aircraft do not have a vertical thrust component. As such, TECS, which adjusts throttle to increase or decrease energy and pitch to affect airspeed and altitude, does not consider or generate vertical thrust commands.

[0005] Prior devices and methods have not addressed, at least, simplifying flight control systems that provide standardized, configuration-agnostic responses to pilot inceptor inputs. In this way, pilots will be able to seamlessly transition between controlling various configurations of aircraft, such as, for example lift-plus-cruise, tilt-wing, vectored thrust, and other configurations, by utilizing the same or substantially similar pilot inputs that produce the same or substantially similar responses (i.e., operation of control effectors) in an aircraft regardless of the particular configuration of aircraft being flown. This ensures pilot proficiency with substantially reduced training time and cost. Accordingly, development of a flight control system that provides standardized, configuration-agnostic responses to pilot inceptor inputs would be desirable. SUMMARY

[0006] According to the present disclosure, a control system for controlling a plurality of configurations of aircraft includes a first module including a processor and configured to receive at least one pilot inceptor input and map the at least one pilot inceptor input to at least one input command, the at least one input command being representative of a desired dynamic aircraft state responsive to the at least one pilot inceptor input, a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to receive the at least one input command from the first module and generate at least one of a normalized vertical thrust command or a normalized horizontal thrust command derived from the at least one input command, and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the at least one of the normalized vertical thrust command or the normalized horizontal thrust command. The at least one of the normalized vertical thrust command or the normalized horizontal thrust command is configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.55879-427819

[0007] In some embodiments, the second module is further configured to generate a normalized vertical thrust command and a horizontal thrust command based on the at least one input command so as to generate the at least one control state of the at least one control effector of the aircraft.

[0008] In some embodiments, the at least one pilot inceptor input includes at least one of lateral input, heave input, directional input, or acceleration input.

[0009] In some embodiments, the at least one input command that is mapped from the at least one pilot inceptor input includes at least one of normalized acceleration and climb rate.

[0010] In some embodiments, the second module is further configured to determine a normalized acceleration in a horizontal direction based on the normalized acceleration and a normalized acceleration in a vertical direction based on the climb rate, and the normalized acceleration in the horizontal direction and the normalized acceleration in the vertical direction include a desired horizontal movement command value and a desired vertical movement command value.

[0011] In some embodiments, the second module is further configured to receive an actual horizontal movement value and an actual vertical movement value based on a current state of operation of the aircraft, and configured to determine a horizontal error based on a difference between the actual horizontal movement value and the desired horizontal movement command value and a vertical error based on a difference between the actual vertical movement value and the desired vertical movement command value.

[0012] In some embodiments, the second module is further configured to determine the normalized horizontal thrust command via driving the horizontal error to zero via integrating the horizontal error and determine the normalized vertical thrust command via driving the vertical error to zero via integrating the vertical error.

[0013] In some embodiments, the integration of the horizontal and vertical errors is controlled, via the second module, by: ^^= ^ ^^^^ −55879-427819 ^^(^^)^^ௗ,^ = ^^ூ^ ^ ^^^ೇ ^^^^ − ^^^^^^where ^^ூு, ^^ூ^, ^^^ு,and nHand nVare an actual normalized horizontal acceleration value and an actual vertical acceleration value.

[0014] In some embodiments, the second module is further configured to determine a thrust- axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

[0015] In some embodiments, the normalized vertical thrust command includes a vertical component in a vertical direction and the normalized horizontal thrust command includes a horizontal component in a horizontal direction.

[0016] In some embodiments, the second module is further configured to determine a thrust- axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

[0017] In some embodiments, the second module is further configured to determine a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand.

[0018] In some embodiments, the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

[0019] In some embodiments, the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^55879-427819 ^ି^^^( ( )) ^^^^ ^^௧^ ≠ 0^^^^^^ = ^^ି^^^ ^ିୡ୭^ థ^^ ^^^^ 0where ^^௧^and ^^^^

[0020] In some embodiments, the second module is further configured to determine a flight mode in which the aircraft is operating, and the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

[0021] In some embodiments, the second module is further configured to generate a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

[0022] In some embodiments, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

[0023] In some embodiments, the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: (^^ / ^^) = ^(^^ / ^^)ଶ + ^^^^^(^^ / ^^) ଶ.

[0024] In somepropulsors in hybrid flight mode is generated, via the second module, by: ^మ మ^^ ^ ^^ ^. ழ^55879-427819

[0025] In some embodiments, the second module is further configured to generate a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

[0026] In some embodiments, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion, and, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

[0027] In some embodiments, the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: (^^ / ^^) = ^(^^ / ^^)ଶ + ^^ (^^ / ^ ) ଶ^^ௗ,^^ ^^ௗ,ு ^ ^^ ^ ^^ௗ,^^ .

[0028] In somein hybrid flight mode is generated, via the second module, by: ଶ^ ^^^^ ^ ^

[0029] In some embodiments,to determine that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

[0030] In some embodiments, the second module is further configured to transition from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.

[0031] In some embodiments, the second module is further configured to transition from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one55879-427819 command, which includes a speed command, increases beyond a first speed command threshold.

[0032] In some embodiments, the second module is further configured to transition from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

[0033] In some embodiments, the second nacelle angle is less than the first nacelle angle.

[0034] In some embodiments, the second module is further configured to transition from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

[0035] In some embodiments, the second module is further configured to transition from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

[0036] In some embodiments, the second module is further configured to transition from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

[0037] In some embodiments, the plurality of configurations of aircraft includes lift-plus- cruise aircraft, tilt-wing aircraft, and vectored thrust aircraft.

[0038] According to a further aspect of the present disclosure, a method includes receiving, via a first module, at least one pilot inceptor input, mapping, via the first module, the at least one pilot inceptor input to at least one command, the at least one command being representative of a desired dynamic aircraft state responsive to the at least one pilot inceptor input, controlling, via a second module, a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the controlling including, receiving the at least one input command55879-427819 from the first module, and generating at least one of a normalized vertical thrust command or a normalized horizontal thrust command derived from the at least one input command. The method can further include generating, via a third module, at least one control state for at least one control effector of the aircraft based on the at least one of the normalized vertical thrust command or the normalized horizontal thrust command. The at least one of the normalized vertical thrust command or the normalized horizontal thrust command is configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

[0039] In some embodiments, the method further includes generating, via the second module, a normalized vertical thrust command and a horizontal thrust command based on the at least one input command so as to generate the at least one control state of the at least one control effector of the aircraft.

[0040] In some embodiments, the at least one pilot inceptor input includes at least one of lateral input, heave input, directional input, or acceleration input.

[0041] In some embodiments, the at least one input command that is mapped from the at least one pilot inceptor input includes at least one of normalized acceleration and climb rate.

[0042] In some embodiments, the method further includes determining, via the second module, a normalized acceleration in a horizontal direction based on the normalized acceleration and a normalized acceleration in a vertical direction based on the climb rate, and the normalized acceleration in the horizontal direction and the normalized acceleration in the vertical direction include a desired horizontal movement command value and a desired vertical movement command value.

[0043] In some embodiments, the method further includes receiving, via the second module, an actual horizontal movement value and an actual vertical movement value based on a current state of operation of the aircraft, and determining, via the second module, a horizontal error based on a difference between the actual horizontal movement value and the desired horizontal movement command value and a vertical error based on a difference between the actual vertical movement value and the desired vertical movement command value.

[0044] In some embodiments, the method further includes determining, via the second module, the normalized horizontal thrust command via driving the horizontal error to zero via55879-427819 integrating the horizontal error and determine the normalized vertical thrust command via driving the vertical error to zero via integrating the vertical error.

[0045] In some embodiments, the integration of the horizontal and vertical errors is controlled, via the second module, by: ^^(^^)^^ௗ,ு = ^^ூு ^ ^^^ಹ ^^^^ − ^^^ு^ுwhere ^^ூு, ^^ூ^, ^^^ு,and nHand nVare an actual normalized horizontal acceleration value and an actual vertical acceleration value.

[0046] In some embodiments, the method further includes determining, via the second module, a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

[0047] In some embodiments, the normalized vertical thrust command includes a vertical component in a vertical direction and the normalized horizontal thrust command includes a horizontal component in a horizontal direction.

[0048] In some embodiments, the method further includes determining, via the second module, a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

[0049] In some embodiments, the method further includes determining, via the second module, a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand.

[0050] In some embodiments, the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a55879-427819 lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

[0051] In some embodiments, the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^^^^ା^^^00where ^^௧^and ^^^^

[0052] In some embodiments, the method further includes determining, via the second module, a flight mode in which the aircraft is operating, and the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

[0053] In some embodiments, the method further includes generating, via the second module, a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

[0054] In some embodiments, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

[0055] In some embodiments, the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: =^ ଶ ^^^^^ .

[0056] In some propulsors in hybrid flight mode is generated, via the second module, by:55879-427819 ^మ మ^ ^ ^ೈ^^^,ಹ ା^^^^^ೈ^ ൠ ^^ ^ೈ^ ஹ^= ^^^,ೇ ^^^,ಹ.

[0057] In somesecond module, a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

[0058] In some embodiments, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion, and, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

[0059] In some embodiments, the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: (^^ / ^^) = ^(^^ / ^^)ଶ + ^^ (^ ) ଶ^^ௗ,^^ ^^ௗ,ு ^ ^^ ^ / ^^ ^^ௗ,^^ .

[0060] In somein hybrid flight mode is generated, via the second module, by: ଶ.

[0061] In some embodiments, via the second module, that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

[0062] In some embodiments, the method further includes transitioning, via the second module, from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.55879-427819

[0063] In some embodiments, the method further includes transitioning, via the second module, from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one command, which includes a speed command, increases beyond a first speed command threshold.

[0064] In some embodiments, the method further includes transitioning, via the second module, from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

[0065] In some embodiments, the second nacelle angle is less than the first nacelle angle.

[0066] In some embodiments, the method further includes transitioning, via the second module, from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

[0067] In some embodiments, the method further includes transitioning, via the second module, from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

[0068] In some embodiments, the method further includes transitioning, via the second module, from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

[0069] According to a further aspect of the present disclosure, a control system for controlling a plurality of configurations of aircraft includes a first module including a processor and configured to receive at least two pilot inceptor inputs and map the at least two pilot inceptor inputs to at least two input commands, the at least two input commands being representative of55879-427819 a desired dynamic aircraft state responsive to the at least two pilot inceptor inputs, a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to receive the at least two input commands from the first module, and generate a normalized vertical thrust command and a normalized horizontal thrust command derived from the at least one input command, and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the normalized vertical thrust command and the normalized horizontal thrust command. The normalized vertical thrust command and the normalized horizontal thrust command are configuration- invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

[0070] According to a further aspect of the present disclosure, a control system for controlling a plurality of configurations of aircraft includes a first module including a processor and configured to receive at least two pilot inceptor inputs and map the at least two pilot inceptor inputs to at least two input commands, the at least two input commands being representative of a desired dynamic aircraft state responsive to the at least two pilot inceptor inputs, a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to receive the at least two input commands from the first module, generate a normalized vertical thrust command and a normalized horizontal thrust command derived from the at least one input command, determine a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command, and determine a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand, and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the normalized vertical thrust command and the normalized horizontal thrust command. The normalized vertical thrust command and the normalized horizontal thrust command are configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft, and the the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a55879-427819 lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

[0071] In some embodiments, the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^^^^ା^^^00where ^^௧^and ^^^^

[0072] In some embodiments, the second module is further configured to determine a flight mode in which the aircraft is operating, and the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

[0073] In some embodiments, the second module is further configured to generate a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

[0074] In some embodiments, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

[0075] In some embodiments, the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: =^ ଶ ^^^^^ .

[0076] In some propulsors in hybrid flight mode is generated, via the second module, by:55879-427819 ^^ మ ^ మ ^ೈ^^^,ಹ ା^^^^^ೈ^ ൠ ^^ ^ೈ^ ஹ^= ^^^,ೇ ^^^,ಹ.

[0077] In somea normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

[0078] In some embodiments, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion, and, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

[0079] In some embodiments, the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: (^^ / ^^) = ^(^^ / ଶ ( ) ଶ^^ௗ,^^ ^^)^^ௗ,ு + ^^^^^ ^^ / ^^ ^^ௗ,^^ .

[0080] In somein hybrid flight mode is generated, via the second module, by: ଶ.

[0081] In some embodiments, to determine that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

[0082] In some embodiments, the second module is further configured to transition from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.55879-427819

[0083] In some embodiments, the second module is further configured to transition from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one command, which includes a speed command, increases beyond a first speed command threshold.

[0084] In some embodiments, the second module is further configured to transition from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

[0085] In some embodiments, the second nacelle angle is less than the first nacelle angle.

[0086] In some embodiments, the second module is further configured to transition from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

[0087] In some embodiments, the second module is further configured to transition from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

[0088] In some embodiments, the second module is further configured to transition from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

[0089] In some embodiments, the plurality of configurations of aircraft includes lift-plus- cruise aircraft, tilt-wing aircraft, and vectored thrust aircraft.55879-427819

[0090] Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] The following Detailed Description references the accompanying drawings which form a part this application, and which show, by way of illustration, specific example implementations, in which:

[0092] FIG.1A is a schematic view of a flight control system (FCS) according to the present disclosure, showing that the system includes a pilot inceptor input module, an inceptor to command mapping module, a trajectory control system (TCS) module, an inverse propulsor model module, an inner-loop controller module, a control allocation module, and a control effector module, the TCS module being configured to generate normalized vertical and horizontal thrust commands for any configuration of aircraft including at least aircraft that include a vertical thrust component;

[0093] FIG.1B is a schematic view of a TCS algorithm of the TCS module, the algorithm including, among other steps, receiving input commands, generating normalized vertical and horizontal thrust commands, determining a TAI value, determining a share of thrust for main and lift propulsors, determining TCS outputs, and determining a mode in which the aircraft is operating to dictate particulars of the thrust commands;

[0094] FIG.2A is a perspective view of a lift-plus-cruise aircraft configured to utilize the FCS and TCS of FIGS.1A and 1B;

[0095] FIG.2B is a front perspective view of the lift-plus-cruise aircraft of FIG.2A;

[0096] FIG.3A is a perspective view of a tilt-wing aircraft configured to utilize the FCS and TCS of FIGS.1A and 1B;

[0097] FIG.4A is a perspective view of a vectored-thrust aircraft configured to utilize the FCS and TCS of FIGS.1A and 1B;

[0098] FIG.4B is a front perspective view of the vectored-thrust aircraft of FIG.4A;

[0099] FIG.5 is a diagram of flight modes of the aircraft of FIGS.2A-4B;55879-427819

[0100] FIG.6 is a schematic view of time-domain simulations of the FCS of FIG.1A;

[0101] FIG.7 is a view of example pilot inceptor input devices that can provide the inputs to the TCS of FIG.1A;

[0102] FIG.8 is a view of further example pilot inceptor input devices that can provide the inputs to the TCS of FIG.1A;

[0103] FIG.9 is a graphical view of the normalized horizontal and vertical thrust commands and the horizontal and vertical components thereof of the TCS of FIG.1B, showing that a TAI value can be determined based on the horizontal and vertical components;

[0104] FIG.10A is a diagram view of transition thresholds between flight modes of the lift- plus-cruise aircraft of FIG.2A;

[0105] FIG.10B is a diagram view of transition thresholds between flight modes of the tilt- wing aircraft of FIG.3A;

[0106] FIG.10C is a diagram view of transition thresholds between flight modes of the vectored thrust aircraft of FIG.4A;

[0107] FIG.11 is a diagram view of thrust share between main and lift propulsors of an aircraft having main tilt propulsors and lift propulsors;

[0108] FIG.12 is a schematic view of a control architecture is implemented for roll, pitch, and yaw axes of the inner-loop controller module of FIG.1A;

[0109] FIG.13A is a graphical view of simulations of vertical velocity response of the LPC, TW, and VT aircraft in vertical flight mode, the command of which including a 200 ft / min vertical velocity step command;

[0110] FIG.13B is a graphical view of velocity deviations of the simulations of the LPC, TW, and VT aircraft shown in FIG.15A;

[0111] FIG.13C is a graphical view of simulations of vertical velocity response of the LPC, TW, and VT aircraft in hybrid flight mode, the command of which including a 200 ft / min vertical velocity step command;55879-427819

[0112] FIG.13D is a graphical view of velocity deviations of the simulations of the LPC, TW, and VT aircraft shown in FIG.15C;

[0113] FIG.13E is a graphical view of simulations of vertical velocity response of the LPC, TW, and VT aircraft in transition flight mode, the command of which including a 200 ft / min vertical velocity step command;

[0114] FIG.13F is a graphical view of velocity deviations of the simulations of the LPC, TW, and VT aircraft shown in FIG.15E;

[0115] FIG.14A is a graphical view of simulations of vertical velocity response of the LPC, TW, and VT aircraft in vertical flight mode, the command of which including a 5 knot step command in velocity;

[0116] FIG.14B is a graphical view of velocity deviations of the simulations of the LPC, TW, and VT aircraft shown in FIG.16A;

[0117] FIG.14C is a graphical view of simulations of vertical velocity response of the LPC, TW, and VT aircraft in hybrid flight mode, the command of which including a 5 knot step command in velocity;

[0118] FIG.14D is a graphical view of velocity deviations of the simulations of the LPC, TW, and VT aircraft shown in FIG.16C;

[0119] FIG.14E is a graphical view of simulations of vertical velocity response of the LPC, TW, and VT aircraft in transition flight mode, the command of which including a 5 knot step command in velocity;

[0120] FIG.14F is a graphical view of velocity deviations of the simulations of the LPC, TW, and VT aircraft shown in FIG.16E;

[0121] FIG.15A is a graphical view of a departure transition of the LPC showing altitude and altitude command on a graph of altitude versus time;

[0122] FIG.15B is a graphical view of a departure transition of the LPC showing velocity and velocity command on a graph of velocity versus time;55879-427819

[0123] FIG.15C is a graphical view of a departure transition of the LPC showing TAI and flight mode on a graph of TAI versus time, where each flight mode is shown with each step of the flight mode line, showing a step for VFM, a step for HFM, a step for TFM, and a step for FFM;

[0124] FIG.15D is a graphical view of a departure transition of the LPC showing lift and main propulsors (CP) on a graph of RPM versus time;

[0125] FIG.15E is a graphical view of a departure transition of the LPC showing pitch and pitch command on a graph of pitch versus time;

[0126] FIG.15F is a graphical view of a departure transition of the LPC showing bank angle and bank angle command on a graph of bank angle versus time;

[0127] FIG.15G is a graphical view of a departure transition of the LPC showing yaw rate and yaw rate command on a graph of yaw rate versus time;

[0128] FIG.15H is a graphical view of a departure transition of the LPC showing control commands on a graph of control commands versus time;

[0129] FIG.16A is a graphical view of a departure transition of the TW showing altitude and altitude command on a graph of altitude versus time;

[0130] FIG.16B is a graphical view of a departure transition of the TW showing velocity and velocity command on a graph of velocity versus time;

[0131] FIG.16C is a graphical view of a departure transition of the TW showing wing tilt and flight mode on a graph of wing tilt versus time, where each flight mode is shown with each step of the flight mode line, showing a step for VFM, a step for HFM, a step for TFM, and a step for FFM;

[0132] FIG.16D is a graphical view of a departure transition of the TW showing propulsor RPM versus time;

[0133] FIG.16E is a graphical view of a departure transition of the TW showing pitch and pitch command on a graph of pitch versus time;55879-427819

[0134] FIG.16F is a graphical view of a departure transition of the TW showing bank angle and bank angle command on a graph of bank angle versus time;

[0135] FIG.16G is a graphical view of a departure transition of the TW showing yaw rate and yaw rate command on a graph of yaw rate versus time;

[0136] FIG.16H is a graphical view of a departure transition of the TW showing control commands on a graph of control commands versus time;

[0137] FIG.17A is a graphical view of a departure transition of the VT showing altitude and altitude command on a graph of altitude versus time;

[0138] FIG.17B is a graphical view of a departure transition of the VT showing velocity and velocity command on a graph of velocity versus time;

[0139] FIG.17C is a graphical view of a departure transition of the VT showing nacelle tilt and flight mode on a graph of wing tilt versus time, where each flight mode is shown with each step of the flight mode line, showing a step for VFM, a step for HFM, a step for TFM, and a step for FFM;

[0140] FIG.17D is a graphical view of a departure transition of the VT showing lift and main propulsors on a graph of RPM versus time;

[0141] FIG.17E is a graphical view of a departure transition of the VT showing pitch and pitch command on a graph of pitch versus time;

[0142] FIG.17F is a graphical view of a departure transition of the VT showing bank angle and bank angle command on a graph of bank angle versus time;

[0143] FIG.17G is a graphical view of a departure transition of the VT showing yaw rate and yaw rate command on a graph of yaw rate versus time;

[0144] FIG.17H is a graphical view of a departure transition of the VT showing control commands on a graph of control commands versus time;

[0145] FIG.18A is a graphical view of an arrival transition of the LPC showing altitude and altitude command on a graph of altitude versus time;55879-427819

[0146] FIG.18B is a graphical view of an arrival transition of the LPC showing velocity and velocity command on a graph of velocity versus time;

[0147] FIG.18C is a graphical view of an arrival transition of the LPC showing TAI and flight mode on a graph of TAI versus time, where each flight mode is shown with each step of the flight mode line, showing a step for VFM, a step for HFM, a step for TFM, and a step for FFM;

[0148] FIG.18D is a graphical view of an arrival transition of the LPC showing lift and main propulsors (CP) on a graph of RPM versus time;

[0149] FIG.18E is a graphical view of an arrival transition of the LPC showing pitch and pitch command on a graph of pitch versus time;

[0150] FIG.18F is a graphical view of an arrival transition of the LPC showing bank angle and bank angle command on a graph of bank angle versus time;

[0151] FIG.18G is a graphical view of an arrival transition of the LPC showing yaw rate and yaw rate command on a graph of yaw rate versus time;

[0152] FIG.18H is a graphical view of an arrival transition of the LPC showing control commands on a graph of control commands versus time;

[0153] FIG.19A is a graphical view of an arrival transition of the TW showing altitude and altitude command on a graph of altitude versus time;

[0154] FIG.19B is a graphical view of an arrival transition of the TW showing velocity and velocity command on a graph of velocity versus time;

[0155] FIG.19C is a graphical view of an arrival transition of the TW showing wing tilt and flight mode on a graph of wing tilt versus time, where each flight mode is shown with each step of the flight mode line, showing a step for VFM, a step for HFM, a step for TFM, and a step for FFM;

[0156] FIG.19D is a graphical view of an arrival transition of the TW showing propulsor RPM versus time;55879-427819

[0157] FIG.19E is a graphical view of an arrival transition of the TW showing pitch and pitch command on a graph of pitch versus time;

[0158] FIG.19F is a graphical view of an arrival transition of the TW showing bank angle and bank angle command on a graph of bank angle versus time;

[0159] FIG.19G is a graphical view of an arrival transition of the TW showing yaw rate and yaw rate command on a graph of yaw rate versus time;

[0160] FIG.19H is a graphical view of an arrival transition of the TW showing control commands on a graph of control commands versus time;

[0161] FIG.20A is a graphical view of an arrival transition of the VT showing altitude and altitude command on a graph of altitude versus time;

[0162] FIG.20B is a graphical view of an arrival transition of the VT showing velocity and velocity command on a graph of velocity versus time;

[0163] FIG.20C is a graphical view of an arrival transition of the VT showing nacelle tilt and flight mode on a graph of wing tilt versus time, where each flight mode is shown with each step of the flight mode line, showing a step for VFM, a step for HFM, a step for TFM, and a step for FFM;

[0164] FIG.20D is a graphical view of an arrival transition of the VT showing lift and main propulsors on a graph of RPM versus time;

[0165] FIG.20E is a graphical view of an arrival transition of the VT showing pitch and pitch command on a graph of pitch versus time;

[0166] FIG.20F is a graphical view of an arrival transition of the VT showing bank angle and bank angle command on a graph of bank angle versus time;

[0167] FIG.20G is a graphical view of an arrival transition of the VT showing yaw rate and yaw rate command on a graph of yaw rate versus time;

[0168] FIG.20H is a graphical view of an arrival transition of the VT showing control commands on a graph of control commands versus time; and55879-427819

[0169] FIG.21 is a schematic diagram that shows a non-limiting example of a computing system that can be used to implement the techniques described herein such as the FCS and TCS algorithm of FIGS.1A and 1B. DETAILED DESCRIPTION

[0170] Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non- limiting exemplary embodiments and that the scope of the present disclosure is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure. Further, the present disclosure provides some illustrations and descriptions that include prototypes, lab models, experimental setups, and / or schematic illustrations of setups. A person skilled in the art will recognize how to rely upon the present disclosure to integrate the techniques, systems, devices, and methods provided for herein into a product and / or a system provided to customers, such customers including but not limited to individuals in the public or a company that will utilize the same within manufacturing facilities or the like. To the extent features are described as being disposed on top of, below, next to, etc. such descriptions are typically provided for convenience of description, and a person skilled in the art will recognize that, unless stated or understood otherwise, other locations and positions are possible without departing from the spirit of the present disclosure.

[0171] The control system 10, also referred to herein as a flight control system (FCS) 10, and related methods described herein includes a Trajectory Control System (TCS) 32 (also referred to herein as a TCS module 32) that includes features that facilitate vertical takeoff and landing (VTOL) operations and standardize responses to pilot inputs across VTOL configurations. The TCS 32 may also be applicable to fixed-wing and wingless multi-rotor aircraft. The TCS 32 can be paired with explicit model following (EMF) inner-loop control 62 (also referred to herein as inner-loop module 62, EMF 62, or EMF module 62), or other inner-loop controls as described in detail herein, whose architecture is “configuration-invariant” and a control allocation logic that is “configuration-specific.” It is demonstrated that the core FCS 10 architecture remains55879-427819 largely unaltered for the three dissimilar aircraft described herein, in particular three dissimilar aircraft each having a different configuration of propulsors for VTOL. The exemplary applications of the FCS 10 and TCS 32 described herein include lift-plus-cruise (LPC), tilt- wing (TW), and vectored thrust (VT) configurations. The FCS 10 gains for the three aircraft are optimized identically using a genetic algorithm constrained optimization setup to yield consistent responses for each vehicle to pilot control inputs. This is demonstrated through simulations of UAM / AAM-relevant maneuvering scenarios, as described in detail herein, including single-axis maneuvering as well as departure and arrival transitions. The simulations described herein, in at least some embodiments, utilize a Modular Aircraft Dynamics and Control Algorithm Simulation Platform (MADCASP), a MATLAB / Simulink-based framework developed with Explicit Model Following Trajectory Control System For Multiple Vertical Takeoff and Landing Configurations funding from NASA Langley Research Center to facilitate stability and control analysis and flight control law development for novel air vehicle configurations.

[0172] An exemplary implementation of the FCS 10 of the present disclosure is shown in FIG.1A. As will be described in greater detail below, the FCS 10 includes a plurality of modules 12, 22, 32, 52, 62, 82, 92 that are configured to take a pilot’s input and translate the input into control of the aircraft utilizing the FCS 10. Specifically, the FCS 10 can include a pilot inceptor input module 12, an inceptor-to-command mapping module 22, the TCS module 32, an inverse propulsor model module 52, the inner-loop module 62, a control allocation module 82, and a control effector module 92.

[0173] Details regarding the FCS 10 and its modules 12, 22, 32, 52, 62, 82, 92, in particular the TCS module 32, are described in greater detail after the following description of the exemplary aircraft configurations, namely LPC, TW, and VT, that are considered, simulated, and tested in the present disclosure. The modeling and simulation approach to testing the FCS 10 and the TCS 32 are also described below and prior to the description of the FCS 10 and the TCS 32. EXAMPLE AIRCRAFT CONFIGURATIONS CONFIGURED TO UTILIZE TCS

[0174] The aircraft classifications utilizing the TCS 32 described herein include LPC, TW, and VT aircraft, examples of which can be seen in FIGS.2A-4B. A lift-plus-cruise (LPC) configuration (LPC aircraft 200), which is shown in FIG.2A and FIG.2B, is an aircraft with completely independent thrusters used for cruise versus for lift without any thrust vectoring. A55879-427819 vectored thrust (VT) configuration (VT aircraft 400), which is shown in FIG.4A and FIG.4B, is defined as an aircraft that uses any of its thrusters for lift and cruise. A tilt-wing (TW) configuration (TW aircraft 300), in which one or more wings with wing-mounted propulsors tilt between vertical flight mode (VFM) and forward flight mode (FFM), falls with the VT category.

[0175] The three VTOL aircraft 200, 300, 400 configurations utilizing the TCS 32 as described herein include the following specific configurations. The LPC aircraft 200 shown in FIG.2A and FIG.2B includes eight lift propulsors 204, 206, 208, 210, 212, 214, 216, 218 and a single cruise propulsor 220. The TW aircraft 300 shown in FIG.3A includes a single tiling wing 303 and two tip-mounted propulsors 304, 306 on opposing ends of the wing 303. The VT aircraft 400 includes six lift propulsors 404, 406, 408, 410, 412, 414 and two tilting propulsors 416, 418. Each aircraft 200, 300, 400 will be described in greater detail below.

[0176] Although the present disclosure makes specific reference to these three configurations, the TCS 32 and the FCS 10 are applicable to any other similar configurations of aircraft. For example, LPC aircraft that include a greater or fewer number of lift and main propulsors, TW aircraft that include a greater or fewer number of tip-mounted propulsors, and VT aircraft that include a greater or fewer number of tilting propulsors and lift propulsors may utilize the TCS 32 and the FCS 10 described herein. Moreover, the TCS 32 and FCS 10 may be applicable to both fixed-wing aircraft as well as wingless multi-rotor aircraft. Even further, although the present disclosure describes types of UAV’s and small, unmanned aircraft, the TCS 32 and FCS 10 are applicable and usable in other types of aircraft as well, including manned VTOL aircraft of varying sizes including full-size passenger / cargo aircraft.

[0177] As shown in FIG.2A and FIG.2B, the LPC aircraft 200 (also referred to as an “LCP- 03-s subscale vehicle”) includes a fuselage 202, a main wing 203A, and eight identical lift propulsors 204, 206, 208, 210, 212, 214, 216, 218 fixedly coupled to the wing 203A via plurality of support rods 203B (also referred to as inboard and outboard booms) on which the lift propulsors 204, 206, 208, 210, 212, 214, 216, 218 are mounted. Two lift propulsors may be mounted on each boom 203B. Although the exemplary embodiment includes eight identical lift propulsors 204, 206, 208, 210, 212, 214, 216, 218, a person skilled in the art would understand that the propulsors 204, 206, 208, 210, 212, 214, 216, 218 need not be identical.

[0178] The LPC aircraft 200 further includes one pusher cruise propulsor 220, also referred to as a main propulsor 220 arranged on an aft end of the fuselage 202. Each of the lift and main55879-427819 propulsors 204, 206, 208, 210, 212, 214, 216, 218, 220 is a fixed-pitch propeller driven by an electric motor. The main wing 203A includes an inboard flaperon 224, 226 (inboard of the inboard boom 203B) and an outboard flaperon 222, 228 (between the two booms 203B), as shown in FIG.2A and FIG.2B. An empennage 230 includes twin vertical stabilizers 232, 234 and a horizontal stabilizer 233 extending between upper ends of the vertical stabilizers 232, 234. Each vertical stabilizer includes a rudder 236, 238, and the horizontal stabilizer includes two elevators 237A, 237B. The vertical stabilizers 232, 234 are mounted at the aft ends of the inboard booms 203B.

[0179] The LPC aircraft 200 control effectors (i.e., propulsors 204, 206, 208, 210, 212, 214, 216, 218, 220 and control surfaces 222, 224, 226, 228, 236, 237A, 237B, 238) are listed in Table 1. The flaperons 222, 224, 226, 228, elevators 237A, 237B, and rudders 236, 238 are used to control roll, pitch, and yaw respectively in FFM. In VFM, roll is controlled through differential thrust between the left-side propulsors 204, 206, 212, 214 and right-side lift propulsors 208, 210, 216, 218. Pitch control is achieved by differential thrust between fore propulsors 204, 206, 208, 210 and aft lift propulsors 212, 214, 216, 218. The lift propeller 204, 206, 208, 210, 212, 214, 216, 218 spin directions and thrust axis lateral tilt are as shown in FIG. 2B. In addition to balancing out moments in hover, this arrangement ensures that for each lift propeller 204, 206, 208, 210, 212, 214, 216, 218, the yawing moment due to lateral tilt is in the same direction as that due to aerodynamic reaction torque, which enhances yaw control authority. To yaw nose-right, for example, thrust is increased on lift propellers 206, 210, 214, 218 and simultaneously reduced on lift propellers 204, 208, 212, 216. Some characteristics of the an exemplary LPC aircraft 200 utilizing the FCS 10 and TCS 32 are summarized in Table 2. A person skilled in the art will understand that any references to specific data, dimensions, and the like with regard to the LPC aircraft 200 are merely exemplary and non-limiting, and are described for the purposes of illustrating the usage of the FCS 10, including the TCS 32. A person skilled in the art will understand that the FCS 10, including the TCS 32, can be utilized in any style, design, and size of LPC aircraft, as noted above. It is noted that the propulsors and control surface are also defined by N and δ, as can be seen in FIG.2A and Table 1. # Symbol Description Unit 1-2δf 1, δf 2 Flaperon, left wing, out / inboard deg3-4δf 3, δf 4 Flaperon, right wing, in / outboard deg5 δeElevator deg 6-7δr1, δr2Left, right rudder deg8Ncp Cruise propeller RPM RPM9-16 N1−N8Lift propeller RPMs RPM55879-427819 Table 1 Parameter Metric Imperial Max takeoff mass (MTOM) 8.30 kg 18.3 lb Empty mass 7.20 kg 15.87 lb Battery mass 1.10 kg 2.40 MOI, roll (Ixx) 7 kg.m2lb 0.9 23.01 lb.ft2MOI, pitch (Iyy) 0.62 kg.m214.71 lb.ft2MOI, yaw (Izz) 1.57 kg.m2 2ia (Ixz) -0.02 kg.m237.25 lb.ftProduct of inert -0.47 lb.ft2Main wing area 0.42 m24.52 ft2Main wing span 1.50 m 4.92 izontal tail area 0.13 m2ft Hor 1.39 ft2Horizontal tail span 0.70 m 2.29 ft Fuselage length 0.82 m 2.69 ft Lift propeller diameter 0.30 m 12.0 in Lift motor rated power 8 x 950 W 8 x 0.47 hp Cruise propeller diameter 0.43 m 17.0 in Cruise motor rated power 2200 W 2 2.95 hp Wing loading (MTOM) 19.8 kg / m 4.02Disc loading (MTOM)g / m25 lb / ft14.22 k 2.91 lb / ft2Table 2

[0180] As shown in FIG.3A, the TW aircraft 300 includes a fuselage 302, a main wing 303, and two tip-mounted propulsors 304, 306 on opposing ends of the wing 303. In the TW aircraft 300 shown in FIG.3A, the propellers 304, 306 are fixed-pitch propellers, each driven by an electric motor. The wing 303 is configured to tilt between a generally vertical position for VFM and a generally horizontal position for FFM (see also FIG.5). The wing 303 has trailing-edge flaperons 308, 309 (two ganged together per side in the TW aircraft 300).

[0181] The tailfan array 310 located in the tail section is used for pitch control in VFM the array 310 consists of two fixed-pitch propellers 312, 314 mounted on the same vertical axis but thrusting in opposite directions. A single horizontal stabilizer 316, containing two elevators 318, 320, is mounted aft of the fuselage 302, as shown in FIG.3A. Twin vertical stabilizers 322, 324, each containing a rudder 326, 328, are mounted at the tips of the horizontal stabilizer 316, as also shown in FIG.3A.

[0182] The tiltwing aircraft 300 control effectors (i.e., propulsors 304, 306, 312, 314 and control surfaces 303, 308, 309, 318, 320, 326, 328) are listed in Table 3, which include the tip- mounting propulsors 304, 306 (N1−2), the rear propulsors 312, 314 (Nt f,1−2), the wing 303 (δw) itself which can tilt between and including vertical and horizontal, flaperons 308, 309 (δf), elevators 318, 320 (δe), and rudders 326, 328 (δr). The flaperons 308, 309, elevators 318, 320,55879-427819 and rudders 326, 328 are used to control roll, pitch, and yaw respectively in FFM. In VFM, roll is controlled using differential thrust between left and right side wingtip propulsors 304, 306. Pitch is controlled through the thrust of the tailfans 312, 314. Yaw is controlled by opposite deflection of the wing flaperons 308, 309, which are blown by the propeller 304, 306 slipstream. Some characteristics of the tiltwing aircraft 300 are summarized in Table 4. A person skilled in the art will understand that any references to specific data, dimensions, and the like with regard to the TW aircraft 300 are merely exemplary and non-limiting, and are described for the purposes of illustrating the usage of the FCS 10, including the TCS 32. A person skilled in the art will understand that the FCS 10, including the TCS 32, can be utilized in any style, design, and size of TW aircraft, as noted above. # Symbol Description Unit 1-2δf 1, δf 2 Flaperon, left wing, out / inboard deg3-4δf 3, δf 4 Flaperon, right wing, in / outboard deg5-6 δe1, δe2Left / right elevator deg 7-8 δr1, δr2 Left, right rudder deg 9 δwWing actuator deg 10-11 N1−2Left, right propeller RPM RPM 12-13 Nt f,1−2Upward-, downward-facing fan RPM RPM Table 3 Parameter Metric Imperial 255879-427819 Product of inertia (Ixz) -0.01 kg.2 2nwing area 0.36 m2m -0.24 lb.ftMai 3.87 ft2Main wing span 1.36 m 4.46 ft Horizontal tail area0.14 m2 1.51 ft2Horizontal tail span 0.71 m 2.33 ft Fuselage length 1.69 m 5.54 ft Lift propeller diameter 0.51 m 20.0 in Lift motor rated power 2 x 2000 W 2 x 2.68 hp Tail propeller diameter 0.28 m 11.0 in Tail motor rated power 210 W 0.28 hp Wing loading (MTOM) 22.3 kg / m24.56 lb / ft2Disc loading (MTOM) 19.8 kg / m2 4.05lb / ft2Table 4

[0183] As shown in FIG.4A and FIG.4B, the VT aircraft 400 includes a fuselage 402, a canard wing 403A, and six identical lift propulsors 404, 406, 408, 410, 412, 414 fixedly coupled to the canard wing 403A via plurality of support rods 403B (also referred to as booms) on which the lift propulsors 404, 406, 408, 410, 412, 414 are mounted. Each of the propulsors 404, 406, 408, 410, 412, 414 may be a fixed-pitch propeller driven by an electric motor. Although the exemplary embodiment includes six identical lift propulsors 404, 406, 408, 410, 412, 414, a person skilled in the art would understand that the propulsors 404, 406, 408, 410, 412, 414 need not be identical.

[0184] The VT aircraft 400 further includes two main propulsors 416, 418 that are mounted on a tilting boom 403C that extends between outer booms 403B, one of which supports the lefthand lift propulsors 404, 408, 412 and the other of which supports the righthand lift propulsors 406, 410, 414. The tilting boom 403C rotates about its central axis and relative to the outer booms 403B in order to allow the main propulsors 416, 418 to tilt between and including a generally vertical position in VFM and a generally horizontal position in FFM (see also FIG. 5).

[0185] The VT aircraft 400 further includes two canardvators 422, 424 on the canard wing 403A. The VT aircraft 400 also includes an empennage 430 that includes a horizontal stabilizer 432 having two elevons 433, 434, and vertical stabilizers 436, 437 arranged on the ends of the horizontal stabilizer 432 and coupled to the outer booms 403B. The vertical stabilizers 436, 437 each include a rudder 438, 439.

[0186] The VT aircraft 400 control effectors (propulsors 404, 406, 408, 410, 412, 414, tiling main propulsors 416, 418, and control surfaces 422, 424, 433, 434, 438, 439) are summarized in55879-427819 Table 5. In FFM, the MPs are tilted to their forward flight position (δnac= 0°) and the LPs are inactive. Pitch and roll control is executed through the manipulation of the elevons 433, 434 and canardvators 422, 424, while rudders 438, 439 are used to control yaw. In VFM, the lift propulsors 404, 406, 408, 410, 412, 414 are active and the main propulsors 416, 418 are tilted to their vertical position (δnac= 90°). Roll is controlled through differential thrust between propulsors 404, 408, 412, 416 and propulsors 406, 410, 414, 418. Pitch control is achieved through differential thrust between propulsors 404, 406 and propulsors 412, 414. The lift propulsors 404, 406, 408, 410, 412, 414 spin directions and thrust axis lateral tilt are as illustrated in FIG.4A. Yaw control involves differential thrust on the canted lift propulsors 404, 406 and 412, 414. Some characteristics of the VT aircraft 400 are summarized in Table 6. It is noted that the propulsors and control surface are also defined by N and δ, as can be seen in FIG. 4A and Table 5. A person skilled in the art will understand that any references to specific data, dimensions, and the like with regard to the VT aircraft 400 are merely exemplary and non- limiting, and are described for the purposes of illustrating the usage of the FCS 10, including the TCS 32. A person skilled in the art will understand that the FCS 10, including the TCS 32, can be utilized in any style, design, and size of VT aircraft, as noted above. # Symbol Description Unit 1-2 δc1, δc2Canardvator deflections degf2Flaperon deflections degRudder deflections degNacelle tilt angle degPropeller RPMs RPMTable 5 Parameter Metric Imperial Max takeoff mass (MTOM) 7.63 kg 16.8 lb Empty mass 6.54 kg 14.4 lb Battery mass 1.09 kg 2.40 lb MOI, roll (Ixx) 1.50 kg.m235.7 lb.2MOI, pitch (Iyy) 1.08 kg.m2ft25.5 lb.ft255879-427819 MOI, yaw (Izz) 1.86 kg.m244.2 lb.ft2Product of inertia (Ixz) -0.09 kg.m2-2.14 lb.ft2Canard area 0.15 m21.61 ft2Canard span 1.33 m 4.37 ft Main wing area 0.35 m23.76 ft2Main wing span 1.33 m 4.37 ft Fuselage length 0.95 m 3.12 ft Lift propeller diameter 0.31 m 12.0 in Lift motor rated power 6 x 950 W 6 x 0.47 hp Main propeller diameter 0.38 m 15.0 in Main motor rated power 2 x 1250 W 2 x 1.68 hp Wing loading (MTOM) 15.3 kg / m23.13 lb / ft2Canard Area Ratio 0.30 - Disc loading (MTOM)11.2 kg / m2 2.30 lb / ft2Table 6

[0187] FIG.5 illustrates the various aircraft configurations described above, as well as wingless multi-rotor, in conceptual diagrams showing FFM, HF (hybrid flight, which is an intermediate mode between vertical and forward flight modes), and VFM. Although not illustrated here, an additional mode, TFM (transition flight mode) may exist between HFM and FFM, during which the aircraft transitions from HFM to FFM. It is noted that the conceptual images shown here do not mirror the actual aircraft structures of the aircraft 200, 300, 400 described above, and as such, the prime symbol (′) is used in the figure to indicate this difference.

[0188] In some embodiments, the TCS 32 is configured to output specific commands based on the flight mode in which the aircraft is currently operating. Each mode may have specific thrust requirements, in particular in the vertical and horizontal directions. For example, VFM corresponds to hovering flight and flight at low speeds where the vehicle is entirely thrust- borne, with insufficient airspeed for aerodynamic lifting surfaces to generate any appreciable lift or for un-energized / unblown aerodynamic control effectors to be effective. Attitude control is achieved through the modulation of propulsor thrust or the action of control surfaces that are energized (blown over) by propulsor slipstream. The vehicle is accelerated in any desired direction by tilting the net thrust vector in that direction by adjusting the pitch and roll attitudes of the entire vehicle. For the LPC, the cruise propulsors are inactive. For vectored thrust configurations, tilting elements (wings, nacelles) are oriented vertically.

[0189] HFM comprises the speed range where the aerodynamic lifting surfaces generate progressively more lift, but not an amount sufficient to completely support the weight of the55879-427819 vehicle. The weight of the vehicle is borne by a combination of vertical thrust and aerodynamic lift, with the former reducing and the latter increasing as speed increases. Aerodynamic control surfaces also become progressively more effective, and contribute towards attitude control. The net thrust vector is angled forward by a magnitude that cannot be practically achieved by pitching the entire airframe. Therefore, the airframe pitch attitude is maintained at an acceptable, pre-defined setting, while the required thrust axis inclination is achieved in LPC designs by a combination of lift propulsor vertical thrust and cruise propulsor forward thrust, and in vectored thrust designs by the inclination angle of tilting elements (wings, rotors).

[0190] TFM is a transitory mode that occurs between HFM and forward flight mode during acceleration, and between forward flight mode and HFM during deceleration. Unlike the other modes, it is a transient mode that is not intended to be flown in for an extended period of time. However, this should not be taken to mean that the vehicle is unstable during TFM. Rather, the intent of TFM is to smoothly and deliberately complete the conversion between hybrid and forward flight modes. While accelerating through TFM, any lift propulsors smoothly shut down. Tilting elements (wings, nacelles) tilt forward to their forward flight position. The reverse occurs during deceleration through TFM. This mode typically begins at the edges of HFM and FFM, where the vehicle is nearly at stall conditions.

[0191] In forward flight, the weight of the vehicle is borne entirely by aerodynamic lift generated by its lifting surfaces, and control moments required for attitude control are generated entirely by aerodynamic control effectors. Any lift propulsors are inactive. Any tilting elements (wings or rotors) are locked in their forward flight position. Thrust generated by the propulsors is aligned with the vehicle’s longitudinal axis. All transitioning VTOLs behave like conventional fixed-wing aircraft when in FFM. The efficiency of flight is typically higher in FFM, which is therefore the preferred flight mode for traveling longer distances or achieving higher airspeeds. MODELING AND SIMULATION APPROACH FOR TESTING TCS

[0192] The aero-propulsive model of the aircraft described herein employs strip theory to represent the loads acting on the lifting surfaces. These surfaces are discretized into spanwise strips. The computation of local geometric angles of attack (AOA) at each strip is based on their quarter-chord locations and the translational and angular velocity components of the aircraft in the body-fixed frame. The modeling of control surface deflections involves representing them as alterations in the angle of attack (AOA) for the corresponding strips. To account for the55879-427819 three-dimensional flow over the finite lifting surfaces, a reduced-order downwash model is employed. This model calculates induced AOA and induced drag. The induced AOA is then subtracted from the geometric AOA, resulting in the effective strip AOA. This effective AOA is utilized to query strip sectional aerodynamics (lift, drag, and pitching moment), producing strip loads. These loads are transferred from strip quarter-chord points to the aircraft moment reference center based on the strip quarter-chord locations and orientations. Finally, they are summed to determine the overall aerodynamic loads attributable to the lifting surfaces.

[0193] Loads on non-strip components, including fuselages, booms, and landing gear, are computed lookup tables. These tables express body-fixed forces and moments (in coefficient form) as functions of angle of attack (AOA) and sideslip. During the evaluation of the model, these lookup tables are queried using the instantaneous AOA and sideslip to obtain the relevant values.

[0194] Propulsor loads are computed using a blade element momentum theory propeller model integrated with a 7-state Pitt-Peters dynamic inflow model that accounts for wake distortion effects. The inflow dynamics are characterized by three states representing mean induced inflow, longitudinal inflow gradient, and lateral inflow gradient. Additionally, wake distortion is incorporated through four additional states representing wake skew, wake spacing, longitudinal wake curvature, and lateral wake curvature. As all propellers are treated as rigid with collective control, there are no extra states to account for cyclic pitch, flapping, and lead- lag dynamics.

[0195] Where applicable, the interaction between lift propellers and their underlying booms is expressed through a thrust reduction factor, determined by an empirical model that considers boom geometry and propeller diameter. The impact of propeller slipstream is confined to the wing sections immediately downstream of the propellers. The slipstream model calculates alterations in slipstream velocity and orientation following the passage through each propeller disc.

[0196] Control surface and blade pitch actuator dynamics are represented by second-order dynamics relating actual position δ to commanded position δcmd, characterized by a natural frequency ωn and a damping ratio ζ, as follows: ఋ(^) ఠ^మ(^^) = = (1)55879-427819

[0197] For control effector dynamics, rate limits are selected assuming full range traversal in one second. The assumed control effector characteristics are summarized in Table 7. Effector Symbol Posn. Limits Rate limits Nat. freq. Damp. Ratio [-] [-] ωn[rad / s] ζ [-] Control surfaceδ1 −δn ±30◦±200◦ / s 30 0.95Butterworth filters with a specified natural frequency ωn,s of 10 Hz with an assumed 0.707 damping ratio ζs, as follows: ௫ᇲ(^ ఠమ^^ (^ ) ) ^,ೞ^^^^ ^ = ௫(^) = ^మାଶ^ೞఠ^,ೞ^ାఠ^మ,ೞ (2)

[0199] where x′ representsof the roll rate p, and the two are related by Equation 2), and x represents the true state. Velocity, position estimates, and altitude sensors were modeled as first-order transfer functions with specified time constants τ of 0.1 (with the exception of airspeed, using τ = 0.25), as follows: ^^^^^^(^^) = ௫ᇲ(^)௫(^) = ^ఛ^ା^ (3)

[0200] The characteristics of theflight testing.

[0201] The aircraft model was implemented within the Modular Aircraft Dynamics and Control Algorithm Simulation Platform (MADCASP), a MATLAB / Simulink-based framework developed with funding from NASA Langley Research Center. In MADCASP, conventional control surfaces and propulsors are treated as generalized control effectors. Aircraft trim is achieved by solving a constrained optimization problem where a specified cost function (e.g., control effort or propulsive power) is minimized. Subsequently, the nonlinear vehicle model is55879-427819 linearized around the established trim points to generate linear models. These linear models are then employed to determine dynamic stability characteristics through eigenvalue problem solutions and to assist in the design of the control system.

[0202] The aircraft dynamics and FCS architecture were implemented in two models: The nonlinear simulation (NLS) model and the linear time-invariant model with actuator and sensor dynamics (LTI-ASD). Both models were time-marched using a fourth-order Runge-Kutta integration scheme with a fixed time-step of 1 / 120 sec. As shown in Table 8, the models differed in the states used to model the aircraft dynamics as well as the inclusion of states for propeller inflow. The LTI-ASD was used for FCS optimization, following which the closed- loop time responses of the LTI-ASD and NLS were cross-checked for consistency. States NLS LTIwAD Comments Velocities u, v, w u, v, w Sec.3.3 Angular rates p, q, r p, q, r Sec.3.3 Attitude Quaternions e0, e1, e2, e3Euler angles φ, θ, ψ Sec.3.3 Position λ, µ, Rgeo flat-Earth x, y, z Sec.3.3 Propeller inflow 7-state Pitt-Peters Not modeled Sec.3.1 Control effectors 2nd-order 2nd-order Sec.3.2 Sensors 1st- and 2nd-order 1st- and 2nd- order Sec.3.2 Table 8

[0203] Time-domain simulations are executed within MADCASP, utilizing a Simulink model 500 whose top-level is depicted in FIG.6. The Flight Control System (FCS) architecture is implemented in the Flight Controls block 504, generating commands for control effectors. The aero-propulsive model of the aircraft and control effector dynamics are captured within the Flight Mechanics & Systems Models block 508, producing net external forces, moments, and net angular momenta of rotating propellers / rotors. These outputs feed into the Vehicle Equations of Motion Integration block 512, which calculates the motion states using the six- degree-of-freedom rigid body equations of motion. Velocity is represented by body-axis components u, v, w, and angular velocity is expressed through roll rate p, pitch rate q, and yaw rate r. Aircraft position is defined by latitude λ, longitude μ, and geocentric radius Rgeo, while attitude is represented by quaternions. Flat-Earth coordinates x, y, z and a 3-2-1 Euler angle sequence comprising heading ψ, pitch θ, and bank φ are post-processed based on the position and attitude descriptors. The Mass Properties block 516 monitors any variations in mass properties resulting from fuel consumption or configuration changes. Finally, the Communication Interface block 520 facilitates the connection between MADCASP and flight simulators, as well as external controls for real-time piloted simulations.55879-427819

[0204] A person skilled in the art will understand that the simulations and testing approaches described above and further herein are merely exemplary and non-limiting, and are described for the purposes of illustrating the usage of the FCS 10, including the TCS 32. A person skilled in the art will understand that the FCS 10, including the TCS 32, can be utilized in any style, design, and size of VT aircraft, as noted above, including not only experimental and simulated setups but also in real-world aircraft capable of utilizing the FCS 10 and TCS 32, including, as non-limiting examples, UAV’s, drones, general aviation aircraft, cargo aircraft, military aircraft, commercial aircraft, and the like. FCS AND TCS

[0205] As described above, the FCS 10, as shown in FIG.1A, includes a pilot inceptor input module 12, an inceptor-to-command mapping module 22, the TCS module 32, an inverse propulsor model module 52, the inner-loop module 62, a control allocation module 82, and a control effector module 92. At a high level, these modules 12, 22, 32, 52, 62, 82, 92 include the following operations.

[0206] In the pilot inceptor input module 12, the aircraft pilot inceptors (i.e., pilot controls and input, such as via a yoke, joystick, throttle, etc.) provide lateral, heave, directional, and fore-aft acceleration inputs. In some embodiments, the pilot inceptor input module 12 may be referred to as a “first module.” The inceptor-to-command mapping module 22 maps the inputs received from the pilot inceptor input module 12 to commands that can be sent to the TCS module 32 and the inner-loop module 62, as shown in FIG.1A. These commands can include normalized acceleration, vertical velocity, bank angle, and yaw rate commands. The TCS module 32 manages the longitudinal trajectory by generating commands for propulsor thrust, thrust axis inclination (TAI), and pitch attitude, which are derived from the commanded acceleration and vertical velocity received from the inceptor-to-command mapping module 22. In some embodiments, the TCS module 32 may be referred to as a “second module.”

[0207] The inner-loop module 62 produces normalized control efforts ulat, ulon, udir ∈ [−1,+1] about the roll, pitch, and yaw axes, respectively. These are determined based on the commanded bank angle and yaw rate, which are received from the inceptor-to-command mapping module 22, and the pitch angle command received from the TCS module 32, as shown in FIG.1A. The TCS module 32 also sends horizontal and vertical thrust commands to the inverse propulsor model module 52 (also referred to as a “third module” herein), as well as sending a TAI determination to the control allocation module 82. Thrust commands for the55879-427819 propulsors of the aircraft are converted to corresponding RPM commands based on the flight and inflow conditions, in particular those received from the TCS module 32. The control allocation logic of the control allocation module 82 generates the commanded states (also referred to as a “control state” herein) of all control effectors for each configuration of aircraft. The control effector module 92 may include the aircraft control surfaces and propulsors, in which the aircraft is controlled based on the operation of these surfaces and propulsors.

[0208] A more detailed description of the modules 12, 22, 32, 52, 62, 82, 92 is presented here. In the pilot inceptor input module 12, the inceptors (i.e., pilot controls and input, such as via a yoke, joystick, throttle, etc.) provide lateral (δlat), heave (δver), directional (δdir), and fore- aft acceleration (δacc) inputs. Each of these is a normalized signal in the [−1, +1] range. The FCS 10 architecture is applicable to any physical inceptor setup that can generate these inputs. FIG.7 and FIG.8 show example pilot inceptor input devices that can provide the inputs (lateral (δlat), heave (δver), directional (δdir), and fore-aft acceleration (δacc) inputs) described above.

[0209] Table 9 summarizes exemplary response types (listed under “Vertical Flight” and “Forward Flight”), or “command,” based on the inputs from the pilot inceptor input module 12 (lateral (δlat), heave (δver), directional (δdir), and fore-aft acceleration (δacc) inputs) that are considered in the inceptor-to-command mapping module 22. Blends between VFM and FFM response types are scheduled with respect to speed. These commands may also be referred to herein as “dynamic aircraft states” of the aircraft such that the commands are “representative of a desired dynamic aircraft state responsive to the at least one pilot inceptor input.” In VFM, the pilot lateral inceptor input δlatcommands lateral velocity vcmd, which blends to the direct command of bank angle φcmd in FFM. The pilots heave input δver commands vertical velocity (or height rate) ḣcmdover the entire flight envelope. The directional input δdirgenerates a direct yaw rate command rcmd in VFM, and an incremental Δrcmd (over that required for a coordinated turn) in FFM. The acceleration input δaccgenerates a normalized forward acceleration command (V / ̇g)cmd in VFM. In FFM, it simply controls the rate of change of the commanded velocity, Vcmd, (i.e., Vċmd).55879-427819 Input Symbol Vertical Flight Forward Flight +ve convention LateralδlatLateral velocityBank angle Sidestep / bank right (vcmd) (φcmd) Heave δverVertical velocityVertical velocity Climb ḣ cmd ḣ cmdDirectional δdirYaw rate∆ Yaw rate Nose right (rcmd) (∆rcmd) Acceleration δaccAcceleration (inCmd velocity rate Accelerate

[0210] The TCS module 32, also simply referred to the TCS 32 or TCS algorithm 32, is configured to generate commands for propulsor thrust, in particular normalized vertical thrust command ((T / W)cmd,V) and a normalized horizontal thrust command ((T / W)cmd,H), a thrust axis inclination (TAI) value (θTAI), and pitch attitude (θcmd). As will be described in detail below, the TCS algorithm 32 produces standardized, configuration-invariant vertical andhorizontal thrust that are applicable to, at least, all of the VTOL aircraft configurations described herein (i.e., configurations including and similar to the LCS aircraft 200, configurations including and similar to the TW aircraft 300, and configurations including and similar to the VT aircraft 400), as well as wingless multi-rotor and fixed-wing aircraft. These thrust commands can then be applied to the specific aircraft configuration with very minimal modifications.

[0211] The TCS 32 thus provides numerous benefits in its standardizing of and generation of thrust commands, TAI values, and pitch attitudes, including but not limited to (i) calculation of separate normalized thrust-to-weight commands to satisfy trajectory commands along horizontal and vertical axes, as will be described below, (ii) regardless of the configuration of aircraft, the speed envelope is broken down into four distinct modes, with configuration- specific triggers governing the transitions between the modes, as will be described below, (iii) the governing equations are configuration-independent, allowing for use in VTOL, fixed-wing, and multi-rotor applications without requiring extensive modifications, as will be described below, and (iv) the inputs to TCS require outer-level trajectory commands from the pilot, reducing piloting complexity.

[0212] The TCS algorithm 32 is shown in detail in FIG.1B. A person skilled in the art will understand that many of the steps shown in FIG.1B do not need to be performed in the sequence shown in FIG.1B. For example, steps such as determining the mode that the aircraft55879-427819 is flying in (i.e. step 46) and determining the specific thrust commands in each mode (i.e. steps 48, 49, 50, 51) do not have to be performed in the order shown in FIG.1B. A person skilled in the art will understand that the order shown in FIG.1B is not limiting, and that any other possible sequence of steps may be utilized based on the requirements of the system and the system resources.

[0213] The TCS algorithm 32 takes inputs of climb rate command ḣcmdand normalized acceleration command (V / ̇g)cmd. The normalized acceleration (V / ̇g)cmd, for the purposes of control law development, the control laws being, at least the Equations 4-10, is assumed to represent horizontal acceleration. The normalized acceleration command (V / ̇g)cmd is considered “normalized” in that the time derivative of velocity V̇ (i.e., acceleration) is divided by acceleration due to gravity g to produce an expression of acceleration in terms of units of gravity. The fundamental equations for TCS 32 as described below are founded on a force balance in the vertical and horizontal axes, as shown in FIG.9 and as described in detail below. The resulting commands from TCS 32 are a horizontal and vertical thrust-to-weight command, (T / W)cmd,Hand (T / W)cmd,V, respectively. These commands are also “normalized” in that the thrust T is divided by the weight W of the aircraft to produce an expression for thrust-to-weight ratio of the aircraft. The normalized vertical and horizontal thrust commands (T / W)cmd,H, (T / W)cmd,V can then be utilized in any of the configurations of aircraft contemplated by the present disclosure in order to control the velocity and horizontal components of the movement of the aircraft.

[0214] In order to determine the normalized vertical and horizontal thrust commands (T / W)cmd,H, (T / W)cmd,V, the following governing equations are utilized. First, considering the aircraft as a point mass, applying Newton’s second law (F = ma) along the horizontal axis (in the inertial frame) yields incremental thrust in the horizontal axis, as shown in Equation 4: ^^^^ = ^ ^^ ^ ^^ு ^ , ^^( )ு = ^ = ^^ு (4)

[0215] where nH represents 32 automatically receives at step 34. Similarly, in the vertical axis, the incremental thrust can be formulated according to Equation 5: ^^^^ = ^ ^ ^^^ ^ ℎ , ^^ ^ = ^ = ^^^ (5)55879-427819

[0216] where nVrepresents the normalized acceleration in the vertical axis. Incremental thrust is essentially a change in thrust value over the current value that the controller (TCS 32) will command or output to the aircraft propulsors in order to ultimately reach a target aircraft behavior or state (i.e., to reach a commanded vertical speed or climb rate, or a commanded horizontal acceleration).

[0217] TCS 32 expects to receive climb rate commands ḣcmd(i.e. at step 34), so a modifier term τV (similar to a time constant) is used to relate incoming climb rate commands ḣcmd to vertical acceleration commands. The time constant can be chosen based on the desired aggressiveness of the vertical axis response of the aircraft (a smaller value will yield a more aggressive response). The incremental vertical thrust-to-weight (“normalized” incremental thrust) can be formed according to Equation 6: ^^( h^ h^ ^^^்)^ = gτ = ^^^ , =⇒ (6)V gτV ^

[0218] where (ḧ / g) is

[0219] Based on Equations 4-6, the command and error terms are automatically determined at step 36, as shown in FIG.1B, and can be defined as shown in Equations 7 and 8: ^^^^ௗ,ு = (^^^)^^ௗ , ^^^ಹ = ^^^^ௗ,ு − ^^ு (7)(8)

[0220] The commandaccelerations, while, as described above with regard to Equations 4 and 5, nHand nVare the actual normalized horizontal acceleration value and the actual vertical acceleration value. In other words, the commanded normalized vertical acceleration and the commanded normalized horizontal acceleration are determined from the pilot’s input for the desired climb rate and horizontal acceleration (ḣcmd, (V / ̇g)cmd) (i.e. the desired state of the aircraft), while the actual normalized horizontal acceleration value and the actual normalized vertical acceleration value (nH, nV) are the horizontal and vertical accelerations that the aircraft is actually experiencing (i.e. the actual state of the aircraft). As such, in some embodiments, the normalized acceleration in the horizontal direction and the normalized acceleration in the vertical direction may be considered to include a desired horizontal movement command value and a desired vertical movement command value.55879-427819

[0221] In both axes, the command errors are automatically driven to zero using integral action with proportional damping, as shown in step 38 in FIG.1B. The integral action and proportional damping is shown in Equations 9 and 10: () = ^^ ^^ ^^^^ − ^ ^^் ^^ௗ,ு ூு ^ ^ಹ ^^ு ு (9)

[0222] where KIH, KIV, KPH,integral action and the proportional damping that controls how aggressively the system will respond.

[0223] Integral action is the process of integrating the error signal (e.g., enHdt) over time (i.e. calculating the area under the error curve). For each time step, the control loop (which includes the TCS 32 as well as modules 52, 62, and 82) will produce outputs that ultimately control the aircraft in order to attempt to reach the commanded (desired) values that were input by the pilot. If an error remains after each attempt, the integration of the error signal over time will recognize this persistent error (by calculating the area under the error curve), and thus cause the control loop to continuously make adjustments such that the error eventually reaches zero (0). In addition to the integral action, a proportional action (KPHnH, KPVnV) is applied as well, which helps to damp the transition to zero error (i.e. softens the arrival to the target aircraft state as opposed to a hard stop once the target is reached). The proportional action is applied only to the fed back state (and not the error) to avoid creating an undesirable zero in the system transfer function and its associated overshoot.

[0224] In other words, the integral action in Equation 9 and Equation 10 achieves the command with zero steady-state error, while the proportional action provides damping. The integral gain and associated integral control action will continuously increase or decrease the thrust command until zero steady-state error exists between the commanded and actual values of the relevant states. The proportional gain and associated proportional control action oppose the change in the thrust command, thus providing damping to the system. The relative magnitudes of the integral and proportional gains can be selected based on the desired balance between aggressive versus damped response.

[0225] Taking these orthogonal commands in the horizontal and vertical axes, a thrust-axis- inclination (TAI) can be automatically and geometrically computed at step 40 of FIG.1B,55879-427819 representing the angle between the horizontal axis and the resultant thrust (T / W)cmd, which is the vector summation of (T / W)cmd,H and (T / W)cmd,V (Equation 11). A visual representation of the determination of TAI is also shown in FIG.9. Equation 12 is the calculation of TAI: TT2T2 ( W )= ^(W)+ (W) (11) cmd cmd,H cmd,V

[0226] For reference, for a= 90°. As can be seen in FIG.9, the normalized vertical thrust command includes a vertical component (i.e., vertical vector shown in FIG.9) in a vertical direction and the normalized horizontal thrust command includes a horizontal component (i.e., horizontal vector shown in FIG.9) in a horizontal direction.

[0227] To generalize the TCS algorithm 32 between aircraft configurations, the following definitions can be made: (i) a main propulsor (MP) is defined as any propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, (ii) a lift propulsor (LP) is defined as any propulsor fixed in a vertical orientation and incapable of tilt. The total thrust requirements of the vehicle are split between the main and lift propulsors, resulting in a “share” of vertical thrust requirements for the main propulsors ζmp and lift propulsors ζlp. FIG.1B shows this at step 42 in which the share of vertical thrust requirements for the main propulsors ζmpand lift propulsors ζlpis determined automatically. An exemplary representation of this share can be computed asfunction of the number of each type of propulsor as shown in Equations 13 and 14: ^^^^^^ = ^^^^^^ା^^^ (13)

[0228] where ntpis the number of main propulsors that can tilt (such as the propulsors 304, 306 of the TW aircraft 300, and the propulsors 416, 418 of the VT aircraft 400), nlp is the55879-427819 number of lift propulsors (such as the lift propulsors 204, 206, 208, 210, 212, 214, 216, 218 of the LPC aircraft 200 and the lift propulsors 404, 406, 408, 410, 412, 414 of the VT aircraft 400), and φcis the cant angle (the lateral inclination of the axes of the propulsors to the vertical) of the lift propulsors (if applicable). If desired, share terms can be set directly. In some embodiments, the share of vertical thrust requirements may be referred to herein as a main propulsor portion of vertical thrust demand, the vertical thrust demand being based on the command mapped from the pilot inceptor input, and a lift propulsor portion of the vertical thrust demand.

[0229] Using the method from Equation 14, each propulsor will get an equal share of the thrust (whether LP or MP) in hover conditions. The cosine correction accounts for the loss of vertical thrust when the axis of a propulsor is canted laterally. Using Equations 13 and 14 on, for example, the configurations described above (LPC aircraft 200, TW aircraft 300, VT aircraft 400), the shares of each configuration can be computed as shown in Table 10. Example configurations for fixed-wing and multi-rotor vehicles are also shown for completeness. Variable Configuration φc[deg] ζmpζlpLPC Aircraft 200 5 0 1.00 LPC Aircraft 200 (“Lite” 15 0 1.04 Version) TW Aircraft 300 0 1 0 VT Aircraft 400 0 6 / 8 2 / 8 Fixed-Wing 0 1 0 Wingless Multi-Rotor φc 0 1 / φc Table 10

[0230] The thrust control laws of Equation 9 and Equation 10 and the TAI calculation of Equation 12 are “configuration-invariant” and apply to, at least, all transitioning VTOL configurations, such as, but not limited to, those described herein (LPC aircraft 200, TW aircraft 300, VT aircraft 400).

[0231] The TCS algorithm 32 divides the speed envelope of the vehicle into four distinct modes: (i) vertical flight mode (VFM), (ii) hybrid flight mode (HFM), (iii) transition flight mode (TFM), and (iv) forward flight mode (FFM). The two “configuration-dependent” aspects of the TCS 32 are the outputs from the TCS algorithm 32 and the manner in which these are controlled over the four modes VFM, HFM, TFM, and FFM. These aspects are determined based on the share values ζmp and ζlp as well as (T / W)cmd,H and (T / W)cmd,V , and if necessary, TAI. This is done automatically at step 44 by the TCP 32. For all aircraft configurations, as can55879-427819 be seen in FIG.1A and FIG.1B, the TCS 32 outputs are (i) MP thrust command (T / W)cmd,mp(common to all MP’s), (ii) LP thrust command (T / W)cmd,lp (common to all LP’s), (iii) pitch command θcmd, and (iv) thrust axis inclination θTAI. LPC configurations do not make use of the θTAI value other than for mode transition logic, as described below, and TW and VT configurations assign this directly to wing δwor nacelle δnacangle commands, respectively (see Tables 3 and 5 for examples of the wing δw and nacelle δnac angle commands).

[0232] The TCS 32 may first determine which mode (VFM, HFM, TFM, and FFM) the aircraft is operating in and when to transition from one mode to the next mode. The conditions that govern TCS 32 transitioning between VFM, HFM, TFM, and FFM are visualized in a general form for the LPC, VT, and TW configurations in FIGS.10A-10C, respectively. FIGS. 10A-10C refer to the modes VFM, HFM, TFM, and FFM as “1, 2, 3, 4” in some areas, which are included as subscripts with regard to certain variables (i.e., subscript “23” refers to HFM→TFM, subscript “34” refers to TFM→FFM, etc.). The criteria for transitioning between modes, in terms of a set of inequality constraints on certain specific variables that must each be satisfied, are standardized across all vehicles. Only the numerical thresholds associated with these inequality constraints are, in certain cases, vehicle-specific.

[0233] During acceleration (departure transition), the VFM→HFM transition occurs when (i) the speed of the aircraft rises above a specified speed Vm,1 and (ii) the commanded speed Vcmd is above the minimum VFM speed Vm,1. During deceleration, the HFM→VFM transition occurs when (i) the speed of the aircraft drops below a specified speed Vm,2, (ii) the commanded speed Vcmdfalls below a specified speed Vm,2, and (iii) the TAI command θTAIfor LPC aircraft 200 (δnac or δW in VFM in VT aircraft 400 and TW aircraft 300, respectively) rises above a specified angle (e.g., 85°), shown as θTAI,21in FIGS.10A-10C. In some embodiments, this angle may be in a range of 80 degrees to 90 degrees. In some embodiments, the angle may be in a range of 75 to 95 degrees. The hysteresis band in speeds ensures that the TCS algorithm 32 does not fall into a repeating cycle between VFM and HFM. The extra requirement for TAI from HFM→VFM minimizes any transients induced when the deck leveling deactivates.

[0234] The HFM→TFM transition occurs when (i) the speed of the aircraft rises above Vh,1(typically set to stall speed), (ii) the nacelle angle θTAI for LPC aircraft 200 (δnac or δW in VFM in VT aircraft 400 and TW aircraft 300, respectively) falls below a specifiedθTAI,HT, shown as θTAI,23in FIGS.10A-10C, and (iii) the speed command Vcmdis above the minimum safe forward flight speed Vh,2, indicating pilot intent to transition. In some embodiments, the55879-427819 nacelle angle (i.e., the angle of the tilt of the wing in a TW configuration or the angle of the tilt of the propulsors in the VT configuration) being below a specified angle may include an angle of 20 degrees relative to horizontal. In some embodiments, the angle may be in a range of 18 and 22 degrees, and in some embodiments, may be in a range of 15 to 25 degrees.

[0235] During deceleration, the TFM→HFM transition occurs when (i) the speed of the aircraft is below the minimum safe FFM speed Vh,2, ensuring the vehicle is still decelerating and (ii) the nacelle angle θTAI for LPC aircraft 200 (δnac or δW in VFM in VT aircraft 400 and TW aircraft 300, respectively) climbs above a specified angle θTAI,HT, shown as θTAI,32 in FIGS.10A- 10C, ensuring the nacelles are at a sufficient angle to transition into HFM. In some embodiments, the nacelle angle for a TW configuration being above a specified angle may include an angle of 20 degrees relative to horizontal. In some embodiments, the angle may be in a range of 18 and 22 degrees, and in some embodiments, may be in a range of 15 to 25 degrees. In some embodiments, the nacelle angle for a VT configuration being above a specified angle may include an angle of 10 degrees relative to horizontal. In some embodiments, the angle may be in a range of 8 and 12 degrees, and in some embodiments, may be in a range of 5 to 15 degrees.

[0236] During acceleration, the TFM→FFM transition occurs when (i) the speed command Vcmd rises above the minimum safe FFM speed Vh,2, showing pilot intent to transition, (ii) the nacelle angle θTAIfor LPC aircraft 200 (δnacor δWin VFM in VT aircraft 400 and TW aircraft 300, respectively) falls below the FFM threshold θTAI,HF, shown as θTAI,34 in FIGS.10A-10C, indicating the vehicle is fully wing-borne, and (iii) the speed of the aircraft rises above the minimum safe FFM speed Vh,2, indicating that the vehicle is within the safe FFM envelope. In some embodiments, the nacelle angle for a TW configuration being above a specified angle may include an angle of 7 degrees relative to horizontal. In some embodiments, the angle may be in a range of 5 and 9 degrees, and in some embodiments, may be in a range of 3 to 11 degrees. In some embodiments, the nacelle angle for a VT configuration being above a specified angle may include an angle of 2 degrees relative to horizontal. In some embodiments, the angle may be in a range of 1 and 3 degrees, and in some embodiments, may be in a range of 0 to 4 degrees.

[0237] During deceleration, the FFM→TFM transition occurs when (i) the speed of the aircraft falls below the minimum safe FFM speed Vh,2and (ii) the speed command Vcmdfalls below the safe FFM speed Vh,2, indicating pilot intent to transition from FFM. The magnitudes55879-427819 of speeds Vh,1and Vh,2depend on the wing loading of the aircraft and its maximum usable lift coefficient, which determines the minimum speed at which it can remain wing-borne.

[0238] A person skilled in the art will understand that the numerical values described above regarding the various angle ranges and thresholds are only exemplary, and can apply to the LPC aircraft 200, TW aircraft 300, and VT aircraft 400 vehicles that were tested and simulated as described herein. For other vehicles of LPC, TW, and VT types that utilize the FCS 10 and TCS 32 described herein, these values may be used as starting values that are then refined based on simulation or flight-testing of those LPC, TW, and VT type aircraft.

[0239] As such, during operation of the aircraft, at step 46 shown in FIG.1B, the TCS 32 is configured to automatically determine which mode (VFM, HFM, TFM, and FFM) the aircraft is operating in and when to transition from one mode to the next mode based on the thresholds described above. From this step 46, the TCS 32 can then transition to determining the normalized thrust commands for the MP’s and LP’s (i.e. the algorithm 32 proceeds to one of steps 48, 49, 50, 51, as described below), and then may also transition to sub-steps of each of steps 48, 49, 50, 51 based on the specific configuration of aircraft that is utilizing the TCS 32 (i.e. sub-steps 48A, 48B, 48C, 49A, 49B, 49C, 50A, 50B, 50C, 51A, 51B, 51C).

[0240] For simplicity, tilting components (i.e. tilting wings and tiling propulsors) will be referred to broadly as “nacelles.” The general TCS 32 control outputs for each of the four modes are described first at a general level, and then with specificity for each aircraft configuration.

[0241] For general VFM, in step 48, the pitch attitude command θcmd is automatically generated as θcmd= θTAI− 90°. The nacelle tilt command δnacremains at its vertical setting, butresponds to sustained pitch commands based on Equation 15:^^ ^^^^^^ = ,^^^^ ∈

[0242] This more horizontal thrust requirements. The net thrust command (T / W)cmdis split among the MP’s and LP’s to give them equal share of the net thrust, as shown in Equations 16 and 17:55879-427819 (^^ / ^^) = ^( ଶ^^ௗ,ு ( ) ଶ^^ௗ,^^ ^^ / ^^) + ^^^^^ ^^ / ^^ ^^ௗ,^^

[0243] For LPCHowever, since the horizontal thrust requirement is met by the LP’s in Equation 16, (T / W)cmd,mp = 0 is set to keep the cruise propulsor(s) inactive. Moreover, thrust addition from a horizontally- mounted propulsor would act to thrust the vehicle downward in situations where θcmd < 0 during acceleration in VFM.

[0244] In at least some embodiments, after the TCS 32 determines that the aircraft is in or has transitioned to VFM in step 46, at step 48, the TCS 32 automatically determines in step 48 the MP thrust command (T / W)cmd,mpand the LP thrust command (T / W)cmd,lpand sends these commands to the inverse propulsor module 52 so as to ultimately control the aircraft based on the MP and LP thrust commands (T / W)cmd,mp, (T / W)cmd,lp. At least one control effector of the aircraft is thus controlled based at least on the MP and LP thrust commands (T / W)cmd,mp, (T / W)cmd,lp determined in VFM. The TCS 32 is also configured to automatically execute other operations and equations described above at this step in order to determine other commands such as pitch command and TAI, and the same commands as described with regard to the specific aircraft configurations described in sub-steps 48A, 48B, 48C, in order to ultimately control the aircraft.

[0245] For general HFM, in step 49, the aircraft weight is supported by a combination of propulsor thrust and aerodynamic lift, while a level pitch attitude θcmd= θref(reference pitch angle that the aircraft should maintain) is maintained through first-order dynamics at a specific aggressiveness Klvl (gain) as shown in Equation 18 below. As the vehicle speeds up and aerodynamic lift builds up progressively, a compensatory pitch attitude command θcmdis incorporated to compensate for the loss in vertical thrust due to turn commands (φcmd) through increased aerodynamic lift. This term θtc(the subscript tc stands for turn compensation) is computed analytically as follows in Equation 18:55879-427819 ௧^ୀ ^^ ୡ୭^థ^^^ ( ^^ௗ ) ^^^^^ ^^ ି^ ^^^^^^ sec^^ − 1 ^^^^,^^ఈ = −൬^^^^^^^ =^^^^௭

[0246] Thisnoseup pitch attitude in proportion to the vertical load factor reduction due to the thrust angle during a turn (change in pitch attitude per unit change in vertical thrust-to-weight). This term washes in linearly with airspeed through the term ζa, acting through Equation 18 with θref = θtc. During deceleration, the computed TAI can exceed 90° if (T / W)cmd,Hfalls below 0. In this case, the deck is allowed to pitch up by a desiredThe pitch attitude command θcmd in HFM is synthesized as follows in Equation 19: ^^^ ି^^ೡ^൫ఏ^^^ି ఏ^^^൯ , ^^ఏ^ಲ^ஸଽ^^^ௗ = {^^ೡ^൫^ఏ^ಲ^ିଽ^^ା ఏ^^^ିఏ^^^൯ , ^^ఏ^ಲ^ வଽ^

[0247] The pitch-upaft. This pitch-up magnitude is limited by a specified value θHFMsuch that θcmd≤ θHFMduring HFM. The value θHFM is an angle that may be, in some embodiments, less than or equal to 5 degrees.

[0248] The nacelle command δnac is set equal to the computed TAI, (i.e., δnac = θTAI). In HFM, the TAI is computed as a geometric share of the thrust given a level deck, where the main propulsors (MP’s) are responsible for the horizontal thrust requirements, as expressed visually in FIG.11 and shown in Equation 20: ^ୟ୬షభ^അ^^ (^ / ೈ)^^^,ೇ(^ ൠ , ^^ ^^^ஷ^^^ = / ೈ)^^^,ಹ

[0249] LPC configurations (which have no tilting propulsors, so ζmp = 0) retain the classical calculation of TAI from Equation 12.

[0250] For tilting propulsors (such as the TW aircraft 300 propulsors 304, 306 and the VT aircraft 400 propulsors 416, 418), to ensure that the correct thrust magnitude is applied at the correct thrust inclination, the thrust magnitude and inclination are synchronized to change at the same rate as shown in Equations 21 and 22:55879-427819 ^^^^^^ ^(^^ / ^^)^^^,^^൧ = 1τ ൫(^^ / ^^)^^^^^,^^ − (^^ / ^^)^^ௗ,^^൯

[0251] The LP(T / W)cmd,V. The MP thrust command is set based on the horizontal thrust command (T / W)cmd,H and the MP share of the vertical thrust command (T / W)cmd,Vas shown in Equation 23: మమ^^^^்^^^,ಹା^^^^^^்^^^^,ೇൠ ^^ ^^்^^^^,ಹஹ^^

[0252] The controlmodels module 52 as shown in FIG.1B) of Equation 22 ensures that acceleration commands are reflected in increased main propulsor thrust. However, if a sharp deceleration command causes (T / W)cmd,H < 0, no corresponding MP thrust increase occurs, as this would tend to accelerate the vehicle.

[0253] In at least some embodiments, after the TCS 32 determines that the aircraft is in or has transitioned to HFM in step 46, at step 49, the TCS 32 automatically determines the MP thrust command (T / W)cmd,mp and the LP thrust command (T / W)cmd,lp and sends these commands to the inverse propulsor module 52 so as to ultimately control the aircraft based on the MP and LP thrust commands (T / W)cmd,mp, (T / W)cmd,lp. At least one control effector of the aircraft is thus controlled based at least on the MP and LP thrust commands (T / W)cmd,mp, (T / W)cmd,lpdetermined in HFM. The TCS 32 is also configured to automatically execute other operations and equations described above at this step in order to determine other commands such as pitch command and TAI, and the same commands as described with regard to the specific aircraft configurations described in sub-steps 49A, 49B, 49C, in order to ultimately control the aircraft.55879-427819

[0254] The TFM is the transition phase between HFM and FFM, as indicated in step 50 of FIG.1B. The actions of the LP’s and nacelles are governed by the transition direction (HFM→FFM or FFM→HFM).

[0255] During departure transition (HFM→FFM), the LP thrust command (T / W)cmd,lpisreduced at a specified rate (T / W^) lp,HF as Equation 24:^^ ^^ ^^^^^^ ^൬^^^ ^ = ^^ுி ൬ ^ , ^^ுி < 0^^ௗ,^^ ^^ ^^ௗ,^^

[0256] Similarly, thethe MP’s for forward flight mode, as shown in Equation 25:^^ ^^^^^^ ^൬^^^ ^ = ^^ ^^ுி ൬^^^ , ^^ுி < 0

[0257] The nacelleaspecified rate ^^^nac,HF which is shown in Equation 26:^^ 1 ^^^^^^ ^^^^^^,^ெ^൧ =^^ ൫^^^^^,ிிெ − ^^^^^,^^ௗ൯,^^ ^^^^^^,^^ௗ൧ ∈ ^^^^^^^,ுி , +^^^^^^,ுி൧

[0258] , (increased), responding to changes in (T / W)cmd,V unless otherwise commanded by a specific rateKFH as shown in Equation 27:^^( ) ^^^^^(் / ^)^^^,ೇି(^்)^^^,^^^ , ^^ ^ಷಹୀ^^ ^^ / ^^ = ^^

[0259] Therate ^^^nac,FH as shown in Equation 28:^^ 1 ^^^^^ = − ^^ ^^^ ^−^^^ +^^^55879-427819

[0260] In both scenarios (departure and arrival), MP thrust (T / W)cmd,mpresponds the same as HFM and pitch attitude command θcmd is generated in the same manner as in FFM (described below) in Equation 29: (^^ / ^^) ^( )ଶ^^ௗ,ு ^^( ) ଶ^^ௗ,^^ = ^^ / ^^ + ^^^ ^^ / ^^ ^^ௗ,^^

[0261] In at leasttransitioned to TFM in step 46, at step 50, the TCS 32 automatically determines the MP thrust command (T / W)cmd,mp and sends the command to the inverse propulsor module 52 so as to ultimately control the aircraft based on the MP thrust command (T / W)cmd,mp. At least one control effector of the aircraft is thus controlled based at least on the MP thrust command (T / W)cmd,mp determined in TFM. The TCS 32 is also configured to automatically execute other operations and equations described above at this step in order to determine other commands such as pitch command, and the same commands as described with regard to the specific aircraft configurations described in sub-steps 50A, 50B, 50C, in order to ultimately control the aircraft.

[0262] In FFM, all LPs are inactive (i.e., (T / W)cmd,lp = 0 and (T / W)cmd,V = 0) and the nacelles are in their forward position, i.e., δnac= δnac,FFM. The MP thrust command (T / W)cmd,mpis generated as shown in Equation 30: (^^ / ^^)^^ௗ,^^ = ^^ூு ^^^^^^ + ^^൫ℎ^ ^^ௗ − ℎ^ ൯^^^^^ − ^^^^^^^ு + ^^ℎ^ ^

[0263] Thisacceleration and vertical velocity errors. The integral component of the thrust control action attempts to achieve the commanded acceleration and height rate by driving the acceleration and height rate errors to zero, while the proportional term adds damping. The pitch control action is synthesized as shown in Equation 31 (six commands): ^55879-427819 ^^^^ௗ,ଷ = −^(^^௧^^^^^ு)^^^^(31)

[0264] ^^^^^^^^,^: This is a pitch command component based on ℎ^ ^^ௗ and ℎ^ feedback usingintegral proportional damping. The factor ℱ has the value ℱ = ^^^. Using therelationship ℎ^ = ^^sin γ between height rate ℎ^ and flightpath angle γ, with γ assumed to besmall, this yields ^^ℎ^ ^^ௗ = ^^^^^^ఊ^^ௗ ≈ ^^^^^^^^ and ^^ℎ^ = sin ^^ ≈ ^^. Thus, this term effectivelytracks flightpath angle like the classical TECS algorithm. When speed priority is active൫^^^^ = 1൯, the integral term is nullified while the proportional term remains to providedamping.

[0265] ^^^^^^^^,ଶ: If speed priority is inactive ^^^^ = 0, the acceleration command ^^^^ௗ,ு anderror ^^^^do not influence the pitch attitude command. If it is active, the accelerationcommands is synthesized as ൫^^^ / ^^൯^^ௗ = ^^௩൫^^௧^^^^௧ − ^^൯, where ^^௧^^^^௧is the target airspeedthat the speed priority logic is protecting. The integral component modulates the pitch attitude to maintain ^^௧^^^^௧, while the second term adds damping.

[0266] ^^^^^^^^,ଷ: Similar to the updated TECS architecture, this term maintains the balance between aerodynamic lift and weight as airspeed varies. Considering this equilibrium, whichrequires a nose-down pitch attitude change to reduce the AOA as airspeed increases, the gain^^௧^^^can be derived as ^^௧^^^(^^) = ସ^(௪ / ^)^^య^^ where W / S is the wing loading, p is the density, and∝^^ is the lift-cu^∝ rve slope.

[0267] ^^^^^^^^,ସ: This component changes the pitch command at a specified rate ^^^^∗^ௗas desired to aid in transition. This can be used during TFM to balance the changes in aerodynamic lift and propulsor-borne thrust. Though this component is not used the results shown in this dissertation, it is nevertheless available to the control designer, and is therefore shown for completeness.55879-427819

[0268] ^^^^^^^^,ହ: This is a feed-forward control component proportional to the normalized vertical acceleration command. Its function is to quicken the net pitch response of the aircraft,similar to the feed-forward gain, and the gain ^^^^ ^^ఏ can be derived as ^^ఏ (^^) = ଶ(^ / ௌ)^^మ^^ .^

[0269] ^^^^^^^^,^: Provides turn compensation directly to the pitch axis from the analytical expression in Equation 18. This provides a direct pitch attitude as a function of the reduction of vertical lift due to a turn.

[0270] As described above, components ^^^^ௗ,^and ^^^^ௗ,ଶaffected by speed priority logic. Under nominal conditions, when the propulsion system is not at an upper or lower power limit, the TCS logic tracks both commanded acceleration and vertical velocity simultaneously. However, if either limit is reached through aggressive acceleration and / or height rate commands, it is necessary to prioritize the tracking of either the acceleration command (speedpriority, with ^^^^ = 1 or the height rate command (path priority, with ^^^^ = 0.

[0271] In at least some embodiments, after the TCS 32 determines that the aircraft is in or has transitioned to FFM in step 46, at step 51, the TCS 32 automatically determines the MP thrust command (T / W)cmd,mpand sends the command to the inverse propulsor module 52 so as to ultimately control the aircraft based on the MP thrust commands (T / W)cmd,mp. At least one control effector of the aircraft is thus controlled based at least on the MP thrust command (T / W)cmd,mp, (T / W)cmd,lp determined in FFM. The TCS 32 is also configured to automatically execute other operations and equations described above at this step in order to determine other commands such as pitch command and TAI, and the same commands as described with regard to the specific aircraft configurations described in sub-steps 51A, 51B, 51C, in order to ultimately control the aircraft.

[0272] The determinations of each of the thrust, TAI, and pitch commands described above for the specific modes (VFM, HFM, TFM, FFM) will now be described for each configuration of aircraft described herein (LPC, TW, VT).

[0273] If the aircraft is an LPC aircraft similar to the LPC aircraft 200 described herein, the TCS 32 can be configured to, in addition or alternative to the steps 48, 49, 50, 51 described above, proceed to sub-steps 48A, 49A, 50A, 51A in which the TCS 32 automatically determines the same commands as in steps 48, 49, 50, 51 based on the equations in described55879-427819 with regard to each of those steps. The commands are specific to the LPC configuration based on the characteristics of an LPC aircraft (as described with regard to the LPC aircraft 200).

[0274] For example, in step 48A in VFM for LPC, the MP is inactive (i.e., (T / W)cmd,mp = 0). The thrust requirements are therefore met entirely by LP thrust (i.e., (T / W)cmd,lp= (T / W)cmd). Fore-aft accelerations are achieved by varying the commanded pitch attitude as θcmd = θTAI − 90°.

[0275] In step 49A in HFM for LPC, the MP and LP thrust commands are obtained from the horizontal and vertical thrust commands respectively (i.e., (T / W)cmd,mp= (T / W)cmd,Hand (T / W)cmd,lp = (T / W)cmd,V. If θTAI < 90°, a level-deck condition is maintained by discharging thepitch command as θ^ cmd = − Klvl θcmd. However, if, during deceleration, θTAI > 90°, the MP is setto idle (i.e., (T / W)cmd,mp= 0), and the LP thrust vector is inclined aft by generating a nose-uppitch command at the rate θ^ cmd = Klvl (θTAI − 90°), limited to a maximum attitude θcmd ≤ θlim. Thegain Klvl> 0 controls the aggressiveness of the pitch command change.

[0276] In step 50A in TFM for LPC, the MP thrust command (T / W)cmd,mptracks the horizontal thrust command (i.e., (T / W)cmd,mp = (T / W)cmd,H). The pitch attitude command θcmd is generated in the same manner as in FFM (described below). When accelerating from HFM to FFM (departure transition), the LP thrust command (T / W)cmd,lp is reduced at a specified rate, and when decelerating from FFM to HFM (arrival transition), it is increased at a specified rate.

[0277] In step 51B in FFM for LPC, the LPs are inactive (i.e., (T / W)cmd,lp = 0). The MP thrust (T / W)cmd,mpand pitch attitude θcmdcontrol laws are similar in form to those described above in step 51.

[0278] In similar embodiments, if the aircraft is an TW aircraft similar to the TW aircraft 300 described herein, the TCS 32 can be configured to, in addition or alternative to the steps 48, 49, 50, 51 described above, proceed to sub-steps 48B, 49B, 50B, 51B in which the TCS 32 automatically determines the same commands as in steps 48, 49, 50, 51 based on the equations in described with regard to each of those steps. The commands are specific to the TW configuration based on the characteristics of an TW aircraft (as described with regard to the TW aircraft 300).

[0279] For example, in step 48B in VFM for TW, the wing propulsor thrust command is set to the net thrust command, i.e., (T / W)cmd,mp = (T / W)cmd. The pitch command is generated as θcmd55879-427819 = θTAI− 90°. The wing, nominally vertical, can move slowly to offset any long-term pitch command back to zero through the simple proportional rate control law ^^^w= Kθcmd, with a ±3° / s rate limit.

[0280] In step 49B in HFM for TW, the wing propulsor thrust command is generated as (T / W)cmd,mp= (T / W)cmd. The wing command is set to the computed TAI (i.e., δw,cmd= θTAI). If θTAI < 90°, a level deck condition is maintained by discharging the pitch command at therate θ^ cmd = − Klvl θcmd. However, if, during deceleration, θTAI > 90°, the wing is set to verticalposition (i.e., δw = 90°), and the net thrust vector is inclined aft by generating a nose-up pitchcommand at the rate θ^ cmd = Klvl (θTAI − 90°), limited to a maximum attitude θcmd ≤ θlim.

[0281] In step 50B in TFM for TW, the wing propulsor thrust command (T / W)cmd,mp is set to the horizontal thrust command (T / W)cmd,H. The pitch attitude command θcmdis generated in the same manner as in FFM. Depending on the transition direction (HFM to FFM or FFM to HFM), the wing δw,cmd is moved forward / aft at a specified rate.

[0282] In step 51B in FFM for TW, the wing is in its forward position. Thrust command (T / W)cmd,mpand pitch command θcmdare generated in a manner identical to that for the LPC configuration.

[0283] In similar embodiments, if the aircraft is an VT aircraft similar to the VT aircraft 400 described herein, the TCS 32 can be configured to, in addition or alternative to the steps 48, 49, 50, 51 described above, proceed to sub-steps 48C, 49C, 50C, 51C in which the TCS 32 automatically determines the same commands as in steps 48, 49, 50, 51 based on the equations in described with regard to each of those steps. The commands are specific to the VT configuration based on the characteristics of an VT aircraft (as described with regard to the VT aircraft 400).

[0284] For example, in step 48C in VFM for VT, the pitch command is generated as θcmd= θTAI − 90°. The nacelles, nominally vertical, move slowly to offset any long-term pitch command back to zero through the simple proportional rate control law ^^^w= Kθcmd, with a ±3° / s rate limit. The net thrust command (T / W)cmd,is split among the twoand six LP’s to give them equal share of the net thrust (i.e., (T / W)cmd,mp = (2 / 8) (T / W)cmd and (T / W)cmd,lp = (6 / 8) (T / W)cmd).55879-427819

[0285] In step 49C in HFM for VT, the nacelle command is set equal to the computed TAI, (i.e., δnac,cmd = θTAI). TAI is computed to account for the vertical thrust share in this mode as Equation 32: ^మ^ ^^ ^ೈ^^^ = tanି^{ ^^^,ೇ்^ூ ^^ } (32)

[0286] The LP thrust command is(T / W)cmd,lp= (6 / 8) (T / W)cmd,V. The MP thrust command is set based on the horizontal thrust command and the MP share of (T / W)cmd,V as (T / W)cmd,mp, as shown in Equation 33: 22( T)= ^( T ) + (2 / 8 TWcmd, mp W cmd,H )(W )cmd,V (33)

[0287] The MP(T / W)cmd,Hand pitch command θcmdis generated in the same manner as in FFM. Depending on the transition direction (HFM to FFM or FFM to HFM), the LP thrust command (T / W)cmd,lp is reduced / increased at a specified rate, while the nacelle angle δnac,cmd is moved forward / aft at a specified rate.

[0288] In FFM, the LPs are inactive (i.e., (T / W)cmd,lp= 0) and the nacelles are in their forward position, i.e., δnac = 0. The MP thrust command (T / W)cmd,mp and pitch command θcmd control laws are identical to the LPC and TW configurations.

[0289] After the normalized thrust commands, TAI, and pitch commands θcmd are determined in the various ways described above, the pitch command(s) θcmdare sent to the inner-loop module 62, the thrust commands are sent to the inverse propulsor model module 52, and the TAI value is sent to the control allocation module 82, as shown in FIG.1A. In an inner-loop controller or module, the controller loop typically generates commands for roll, pitch, and yaw of the aircraft. Although the following inner-loop described herein is an Explicit Model- Following (EMF) inner-loop, other types of inner-loops may be utilized for the purposes of generating these commands, such as, for example, classical proportional-integral-derivative, linear quadratic regulator (LQR), and linear quadratic integral (LQI) control schemes.

[0290] The inner-loop EMF module 62 control architecture is implemented for roll, pitch, and yaw axes, as shown in FIG.12. This system generates normalized roll, pitch, and yaw commands ulat, ulon, udir ∈ [−1,+1]. In the feed-forward path, the command model and inverse55879-427819 plant model, incorporating first- or second-order transfer functions to yield a lower-order equivalent system (LOES) representation of the aircraft dynamics, produce a feed-forward control component whose goal is to approximately track the command. The feedback path involves a classical proportional-integral-derivative (PID) control action, the goal of which is to ensure stability, robustness, and disturbance rejection. The net command is the sum of the feed- forward and feedback components, as shown in Equation 34: ^^lat(t) = ^^lfaft (t) + ^^lfabt (t) (34)

[0291] This two-degree-of-control designer to simultaneously meet stability and controllability requirements and accommodate various response types. Its performance was found to be comparable to dynamic inversion controllers in single-input-single-output implementations.

[0292] The pitch axis employs an attitude-command / attitude-hold (ACAH) implementation, with the pitch attitude command θcmd generated by the TCS algorithm 32 serving as the input to the command model. The second-order pitch axis command model transfer function (CMTF) is shown in Equation 35: ఏ^ಾ ఠమ^ಾఏ^^^ (^^) = ^మାଶ^^ಾఠ^ಾ^ାఠమ^ಾ (35)

[0293] In FFM, the feed-forward component ^^lfofn is computed using a second order LOES as shown in Equation 36: ^ெ భೠ (^ା )= ^^^ ^ഇమ ⇒ ^^^^^ ^^^^ = + +

[0294] where ζ sp aircraft short period mode. In VFM, ^^lfofn (t) is computed using a first-order LOES as shown in Equation 37: ^(^^) = ெೠ^^^ ,⇒ ^^^^ (^^) = ^ {^^^ (^^) − ^^^^^ (^^)} (37)55879-427819

[0295] The feedback component ^^lfobn (t) is generated based on errors of pitch attitude, eθ (t) = θ′CM(t)−θ′(t), and pitch rate, eq(t) = q′CM(t) − q′(t), through PID control action, as shown in Equation 38:^^^^^^^ (^^) = ^^ఏ^^ఏ(^^) + ^^^^^^(^^) + ^^ூఏ ^ ^^ఏ(^^) · ^^^^ (38)

[0296] The roll axis,response type. The output φCM from the command model, associated with the bank command φcmdgenerated upstream, is connected through a second-order CMTF, as shown in Equation 39: ఝ^ಾ (^^) = ఠమ^ಾఝ^^^ ^మାଶ^^ಾఠ^ಾ^ାఠమ^ಾ (39)

[0297] The feedforward controlinverse plant for both VFM and FFM as Equation 40:^^ ^^^^ (^^) = ௨^ೌ^^^ − ^^ ^ ^^^^^^௧ (^^) = 1^^^^^^^^(^^) − ^^^^^^^^^(^^)^^ ^^

[0298] Theerrors of bank, e (t) = φ′CM(t) − φ′(t), and rate, ep(t) = p′CM(t) − p′(t), as shown in41:^^^^^^௧ (^^) = ^^ఝ^^ఝ(^^) + ^^^^^^(^^) + ^^^ఝ ^^^ఝ(^^) ∙ ^^^^

[0299] The yaw axisfrom the command model is linked to the upstream yaw rate command rcmdthrough a first-order CMTF, as shown in Equation 42:^^^ெ 1^^ =^^

[0300] In VFM, the feed-forward component ^^diris found using a first-order LOES representation of the inverse plant as shown in Equation 43:55879-427819 ^^ ^^^^ (^^) = ௨^^^^^ − ^^ ^ ^^^^ௗ^^ (^^) = 1{^^^^ெ(^^) − ^^^^^^ெ(^^)}ௗ^^ ^ ^^௨^^^

[0301] In FFM,solely from the feedback component. The feedback component ^^dfbiris generated through PI control action on yaw rate error, er(t) = r′CM(t) − r′(t), as shown in Equation 44: ^^^^ௗ^^ (^^) = ^^^^^^(^^) + ^^ூ^ ^ ^^^(^^) ∙ ^^^^

[0302] Similar to the EMFcommands from the TCS module 32, in particular (T / W)cmd,mp and (T / W)cmd,lp. Thrust commands for the main propulsors (T / W)cmd,mpand lift propulsors (T / W)cmd,lpare converted into equivalent RPM commands (Nmp and Nlp) or blade pitch commands (βmp and βlp) based on inverse propulsor models (IPPMs) for each respective propulsor group. The IPPM for each propulsor group is determined in one of the following ways.

[0303] Fixed-pitch propellers are used on subscale vehicles, and the IPPM is generated using known databases. The databases include propeller performance characteristics at different inflow velocities and RPMs, providing a mapping of RPM based on different flight conditionsas shown in Equation 45:^^^^ௗ = ^^(^^^^ௗ / ^^,^^^ைூ ,^^^,^^^)

[0304] where T is thethrust is split among, θAOI is the angle of incidence of the free-stream velocity, V∞ is the vehicle airspeed, and ρ∞is the air density. This formulation assumes vertically oriented propulsors (θAOI= 90°) see static conditions.

[0305] For constant speed propellers, the IPPMs map thrust commands into equivalent blade pitch commands based on 2-dimensional gridded interpolants (GIs). The GIs are developed from blade-element momentum theory (BEMT) blade pitch models based on a design-point RPM. The GIs follow a similar form of the constant-pitch IPPMs employed on the subscale vehicles, as shown in Equation 46:55879-427819 ^^^^ௗୀ^^(^^^^ௗ , ^^)(46)

[0306] where Tcmd is the commanded thrust (per-propeller) and J is the advance ratio of the propeller, computed based on Equation 47: 60 ^^^^ = ^ cos^^^ைூ^^ ^^ ,

[0307] where V∞is the airspeed, θAOIfor MP’s and θAOI = 90° for LP’s), N is the propeller RPM, and D is the propeller diameter.

[0308] From these equations and methods, the inverse propulsor model module 52 is configured to automatically generate RPM values Nmp and Nlp and send these values to the control allocation module 82.

[0309] After these commands are generated by the EMF module 62 and the inverse propulsor model module 52, the commands (Nmp, Nlp, ulat, ulon, udir) are sent to the control allocation module 82. This module 82 creates at least one command Ucmd that is then sent to the aircraft control effectors (control surfaces and propulsors, such as those described with regard to the LPC aircraft 200, TW aircraft 300, VT aircraft 400) in order to effect the alteration to the aircraft operating state in order to attempt to achieve the original pilot inceptor input that was input in the pilot inceptor input module 12. As a non-limiting, an operating state may include an aircraft climbing at 500 feet per second. In order to alter this operating state, the pilot causes an input, as described above, which may be, for example, a climb at 1000 feet per second. The received pilot input then proceeds through the various steps and modules described above (i.e. the modules 22, 32, 52, 62) until the outputs of these modules of the flight control system 10 are sent to the control allocation module 82, which will then set the control state of at least one aircraft control effector (control surfaces or propulsors, or a combination thereof), so as to control these control effectors so as to achieve a vertical climb rate of 1000 feet per second. A person skilled in the art will understand the vast number of possible similar scenarios in which the flight control system 10 may operate utilizing the modules described herein.

[0310] After the aircraft attempts to alter its operating state based on these commands, the control system 10 will then measure the actual operating conditions of the aircraft (such as the actual climb rate ḣ, the actual velocity change rate (acceleration) V,̇ and the actual roll, pitch,55879-427819 and yaw values (φ, θ, r)) and then feed these actual values back into the control loops (i.e., the TCS module 32 and the EMF module 62, as shown in FIG.1A), and the TCS module 32 and the EMF module 62 can compute the error and repeat the algorithms described above (the TCS algorithm 32 and the EMF module 62 calculations and determinations) in order to attempt to reduce the error to zero (0) and move the aircraft to the desired operating state (based on the pilot input).The details of the control allocation module 82 for each aircraft configuration described herein (LPC, TW, VT) are as follows.

[0311] For LPC such as the LPC aircraft 200, the commanded positions of the control effectors (i.e., servos) are obtained through the allocation of the normalized control inputs ulat,ulon, udir as shown in Equation 48:^^ , ^^ = ^^^^௫^ ^^ ^^௫ ^^௫ ^^௫^^ ^ଶ ^^௧, ^^^ଷ,^^^ସ = −^^^ ^^^^௧, ^^^ = −^^^ ^^^^^, ^^^^, ^^^ଶ = ^^^ ^^ௗ^^(48)

[0312] with maximum deflections on each axis δm()axof 30° for all control surfaces.

[0313] The LP RPM commands area common component N0,lp and three incremental quantities Nφ, Nθ, and Nψ(for roll, pitch, and yaw control), computed from ulat, ulon,udir as shown in Equation 49:^^ఝ = Δ^^^^ே^^^^௧,^^ఏ = Δ^^^^ே^^^^^,^^ట = Δ^^^^ே^^ௗ^^(49)

[0314] where ΔN represents the differential RPM authority of each axis (ΔN = 2000 for the LPC), and the wash-out variable KN washes out the use of LP’s for attitude control as the vehicle is in the final stages of transition (35-40 KEAS on the LPC aircraft 200). The LP RPM commands N1−8 are generated as Equation 50: (50) ^^é ^ù 1.001.000.43 − 0.54é ùê^^ଶú ê 1.000.54 1.00ê^^ଷú^^^^^úସ ê1.00 − 0.541.00 −1.00 − 1.000.430.54ú é ,^^^^ఝù ê ^^ú ê úê1.001.00 − 0.43 − ^^úêହú ê úê^^^úê1.000.54 − 1.001.00 ûê^^^úê1.00 − 0.54 − 1.00 −ë^^û ë 1.0^0 − 1.00 − 0.4355879-427819

[0315] The numerical elements of the matrix shown in Equation 49 are determined based on the relative roll, pitch, and yaw axis moment arms of each lift propulsor.

[0316] For TW such as the TW aircraft 300, the commanded positions of the control effectors for the TW configuration are obtained through the allocation of ulat, ulon, udiras shown inEquations 51, 52, 53, 54:^^ , ^^ = ^^^^௫^^ ^^ ^^௫^^ ^ଶ ^ ^^௧ ^ക − ^^^ ^^ௗ^^^^^ഗ

[0317] with maximum deflections on each axis δm()axof 30° for all control surfaces, and elevon deflections ^^^^_^^௨௫^_థof 15° for roll control. The use of flaperon deflections for yaw control ζf_sub_ψ washes out linearly in the wing angle interval [60°, 50°]. The use of flaperons for roll control ζf_sub_φwashes in linearly in the wing angle interval [50°, 40°].

[0318] The main propulsor RPM commands are synthesized through a common component N0and one incremental quantity Nφ(for roll control), computed from ulatas shown in Equation55:^^ఝ = ^^^^ ^^ே ^^^^௧

[0319] where ΔN represents the = TW), and the wash-out variable KNwashes out the use of differential RPM for roll control as wing comes forward. This wash-out occurs linearly in the [70°, 40°] wing interval. The MP RPM commands are generated as N1= N0+ Nφand N2= N0− Nφ.

[0320] The upper and lower tail fans are mounted to provide outward thrust (i.e., the upper tail fan produces a nose-up pitching moment and the lower tail fan produces a nose-down55879-427819 pitching moment) and are synthesized through a common “idle” component Nt f,0and an incremental quantity ΔNt f (for pitch control), computed from ulon as shown in Equations 56 and57:^^௧^,^ = ^^௧^,^ + ^^^^^Δ^^௧^, ^^^^^ > 0(56)^^௧^,ଶ = ^^௧^,^ + ^^^^^Δ^^௧^, ^^^^^ < 0(57)

[0321] where ΔNt f = 7500 for the TW aircraft 300. The tail fans are active throughout the entire flight envelope to aid in pitch control.

[0322] For VT such as the VT aircraft 400, the commanded positions of the control effectors for the VT configuration are obtained through the allocation ulat, ulon, udiras shown in Equations58-60:^^ , ^^௫ ^^௫^^ ^^^ଶ = ±^^^ക ^^^^௧ + ^^^ ^^^^^(60)

[0323] with maximum deflections on each axis δm()axof 30° for all control surfaces, and canardvator deflections δm(ca_sxub_^^)and elevon deflections δm(ea_sxub_^^)of 20° for roll control.

[0324] The LP RPM commands are synthesized through a common component N0,l p and three incremental quantities Nφ,lp, Nθ,lp, and Nψ,lp(for roll, pitch, and yaw control), computedfrom ulat, ulon, udir as shown in Equation 61:^^ఝ = Δ^^ ^^ே ^^^^௧ ,^^ఏ = Δ^^ ^^ே ^^^^^,^^ట = Δ^^ ^^ே ^^ௗ^^

[0325] where ΔN VT), and the washout variable KN washes out the use of lift propulsors for attitude control as the55879-427819 vehicle is in the final stages of transition (30-35 KEAS for the VT configuration). The LP RPM commands are generated as shown in Equation 62: ^^é ^ê^^ଶùúêଷé 1.00 0.25 1.00 − 1.00^^1.00 − 0.25 1.00 1.00 ù^^^,^^^^ úê 1.00 1.00 0. úé ^^ù êସú 00 0.00ఝê^^ହ = êúê1.00 − 1.00 0.000.00 ú êú ê ^^úఏúê^^^úê1.00 0.25 − 1.00 1.00 ú ë ^^ట ûê^^^ú ë1.00 − 0.25 − 1.00 − 1.00ûë^^^û(62)

[0326] The numerical elements of the matrix shown in Equation 61 were determined heuristically and the authors do not claim any associated optimality. The main (tilting) propulsor RPM commands are synthesized through a common component N0,mpand one incremental quantity Nφ,mp (for roll control), computed from ulat as shown in Equation 63: ^^ఝ = Δ^^^^ ^^ே,^^ ^^^^௧

[0327] where ΔN represents thethe VT), and the wash-out variable KN,mp washes out the use of differential RPM for roll control as wing comes forward. This wash-out occurs linearly in the nacelle interval [85°, 80°]. The MP RPM commands are generated as N4 = N0,mp + Nφ,mp and N5 = N0,mp − Nφ,mp.

[0328] A person skilled in the art will understand how certain control allocation actions, such as, for example, the wash-out actions described above, can utilize the value of TAI directly received from the TCS module 32 for calculation of these actions. As non-limiting examples, TAI can be used directly for (i) pitch control in VFM, as described above, and (ii) wing angle control for tiltwing vehicles in HFM, as also described above. A modified version of TAI (with thrust share values) can be used for any other tilt-type vehicles.55879-427819 MANEUVER SIMULATIONS

[0329] To compare vehicle responses with optimized gains, the nonlinear simulation models for the LPC, TW, and VT were subjected to identical step commands for vertical velocity (ḣcmd) and velocity ((V / ̇g)cmd) step responses at airspeeds of 0 KEAS (VFM), 20 KEAS (HFM), and 45 KEAS (FFM). These airspeeds were chosen to span the vehicle speed envelopes.

[0330] FIGS 13A-13F show the responses of the LPC, TW, and VT configurations to a 200 ft / min vertical velocity step command in VFM, HFM, and FFM. During the pulses, velocity was maintained through a speed hold. The plots in FIGS.13A, 13C, 13E show the vertical velocity response, while those in FIGS.13B, 13D, 13F show the corresponding velocity deviations.

[0331] In VFM, all configurations exhibited favorable performance with minimal overshoot and quick settling times. However, the TW configuration displayed a slightly faster response time compared to the LPC and VT configurations. The velocity deviations were negligible, indicating effective control in maintaining a stationary position.

[0332] During HFM, all configurations experienced a minor increase in oscillations and deviations. The TW configuration showed the most significant oscillations and overshoot, suggesting that the hybrid phase (HFM) introduces greater control challenges due to on account of no thrust-splitting capabilities. The LPC and VT configurations also exhibited oscillations, but to a lesser extent. Velocity deviations for all configurations were less than 1 kt.

[0333] In FFM, all configurations follow the same control laws and show similar, favorable response characteristics. Velocity deviations were minor across all configurations, indicating robust control in FFM.

[0334] The velocity step responses of the three VTOL configurations were analyzed in VFM, HFM, and FFM conditions, each subjected to a 5 knot step command in velocity, as shown in FIGS.14A-14F. In VFM, all configurations demonstrated acceptable performance with minimal overshoot and comparable settling times. The TW configuration exhibited the largest vertical velocity deviations indicating increased coupling.

[0335] During HFM, all configurations experienced increased oscillations and deviations. The TW configuration showed the largest overshoot and oscillations, highlighting the control55879-427819 challenges during this phase. LPC and VT configurations tracked the command with reduced vertical velocity deviations.

[0336] In FFM, all configurations showed similar velocity responses, although the TW showed larger vertical velocity deviations, a potential need for increased vertical velocity damping KTP,V. However, the total altitude deviations for all configurations were less than 5 ft. TRANSITION SIMULATIONS

[0337] Representative UAM transition profiles, including a climbing departure transition and a descending arrival transition, were performed in severe turbulence conditions on all three configurations to test the performance of the optimized FCS 10 architecture over the speed envelope. The Von Karmen Wind Turbulence Model in Simulink was used for turbulence simulation. The low-altitude intensity was set to 7 m / s with a turbulence frequency of 6 Hz. These settings were found to closely resemble flight test data.

[0338] The departure transition profile is meant to simulate a representative UAM departure from a vertiport (scaled appropriately for the subscale vehicle). It begins with a vertical takeoff to 15 ft, followed by a velocity command of 20 kts while maintaining altitude. A climb to 50 ft is commanded while at this speed, followed by a speed command of 45 kts after reaching the target altitude.

[0339] The arrival transition profile is meant to simulate a representative UAM arrival and landing at a vertiport. The profile begins with the vehicle in FFM, followed by a velocity command of 20 kts while maintaining altitude. The vehicle then descends to an approach altitude while in HFM. A position hold is enabled once the vehicle is above the landing zone, following which it descends to a landing.

[0340] FIGS.15A-15H show the departure transition of the LPC. At around t =10s, the velocity command is set to 20 kts and is met at around t = 20s. The altitude command increases to 50 ft at around t = 27s and is met around t =36s with very minor velocity excursions. At around t =44s, the velocity command is set to 45 kts, and this is met at around t = 56s. The altitude excursions during the transition are minimal, and the vehicle maintains the velocity and altitude during the severe turbulence. The equivalent thrust axis inclination θTAI (not directly used in the LPC configuration) is shown along with the TCS mode. Common RPM time histories are also shown for the lift and cruise propulsors (LP and MP).55879-427819

[0341] The departure transition for the TW configuration is shown in FIGS.16A-16H. Following takeoff, the velocity command of 20 kts is set at around t = 5s and is met around 10 seconds after. This is achieved while maintaining a commanded altitude of 20 ft through a combination of wing angle δw and modulating thrust while in TFM (Flight Mode 2). Both trajectory commands are met with minimal deviations. At around t = 20s, the altitude command is increased to 50 ft while in TFM. The velocity command is then set to 45 kts at around t = 36s and is met with some overshoot. This overshoot is attributable to the inverse propulsor modeling being less accurate at reduced thrust conditions on account of the reduced (T / W)cmd commanded by the TCS algorithm coupled with a potentially under-predicted drag at this airspeed. The FFM airspeed is met around t = 55s.

[0342] The departure transition of the VT configuration is shown in FIGS.17A-17H. The vehicle begins the velocity command at t = 10s, meeting it at around t = 20s while climbing to 20 ft. During this flight phase, the nacelles are positioned around δnac= 50°, aiding to meet the required vertical and horizontal thrust requirements. A climb to 50 ft is initiated at around t = 27s and is met at around t = 35s, after which the velocity is commanded to 45 KEAS, initiating the departure transition. The lift propulsors begin to shut down smoothly from t = 45s while the nacelles reach their FFM position of δnac= 0°.

[0343] Across all configurations, the response times to the commanded altitudes and velocities are similar. The consistency in altitude, velocity, and inner-loop attitudes highlights the adaptability of the TCS 32 architecture with EMF inner-loop controllers 62. Variations in RPM and control commands reflect the inherent differences in each configuration’s propulsion and control effectors. The inner-loop EMF controllers 62 also performed well in the turbulence, maintaining the attitude and rate commands with reduced control activity across all configurations.

[0344] The response of the LPC configuration to the arrival transition profile is shown in FIGS.18A-18H. The velocity command of 20 kts is input at around t = 19s and is met at around t = 36s, during which time the arrival transition is performed with adequate altitude tracking. The arrival transition is shown as the flight mode drops from 4-3-2 around t = 22s. The altitude command changes to 20 ft at around t = 45s and is met with minimal velocity deviations at around t = 54s. The pitch attitude is set to 3° during TFM to aid in deceleration via thrust vectoring of the lift propulsors. The velocity command reduces further to an approach speed of 5 kts at t = 60s until the vehicle approaches the landing zone (shown by the command changing55879-427819 at around t = 107s. At this point, the vehicle positions itself around the landing point before descending to a landing at t = 124s.

[0345] The TW configuration’s response to the arrival transition profile is shown in FIGS. 19A-19H. The velocity command drops to 20 kts at around t = 18s, and is met with negligible oscillations at around t = 25s. During this arrival transition, the altitude briefly drops by around 7 ft before the commanded altitude of 50 ft is reestablished. At t = 47s, the altitude command reduces to 20 ft and is met through a combination of wing angle reduction and thrust reduction. The deck also attains a level attitude at this speed (seen as θcmd = 0°). When the velocity command reduces further to 5 kts, the deck rises slightly to θcmd = 3° to aid in the deceleration in TFM. From t = 20s to t = 65s, the wing angle δw is around 55°, a region where roll-yaw coupling could cause potential control challenges.

[0346] The VT configuration performing the arrival transition maneuver is shown in FIGS. 20A-20H. The vehicle begins the arrival transition following the velocity command reduction to 20 kts at t = 20s. The lift propulsors begin to re-activate to aid in vertical thrust requirements while the pitch attitude begins to level θcmd = 0°. The velocity stabilizes at 20 kts at around t = 38s, followed by a altitude command reduction as the vehicle approaches the final waypoint to 20 ft. The velocity command drops again to 5 kts, indicating the final approach of the maneuver. During this velocity reduction, the main propulsors (MP) reduce thrust in an attempt to slow the vehicle which results in a minor altitude deviation. The vehicle reestablishes the commanded altitude until reaching the final waypoint, at which point the landing commences.

[0347] The arrival transition results once again show similar performance across the three configurations. The altitude and velocity traces are similar, with key differences stemming from the different drag characteristics of the vehicles. This results in slightly different deceleration profiles, but the overall performance in recapturing the commanded velocity is similar. On the LPC and VT configurations, the LPs spool up quickly before steadying out during the initial transition from wing-borne to rotor-borne flight. The EMF inner-loop controllers perform well, maintaining the desired pitch attitudes during the deceleration and transition phases. Once again, the control activity is seen to be very minor throughout the turbulence. The overall time to perform the arrival transition and landing is within seconds for each configuration despite the differing characteristics.

[0348] FIG.21 is a schematic diagram that shows a non-limiting example of a computing system 900 that can be used to implement the techniques described herein. The computing55879-427819 system 900 includes one or more computing devices (e.g., controller 910), which can be the equivalent of any of the modules described herein, such as the modules 12, 22, 32, 52, 62, 82, 92. The modules 12, 22, 32, 52, 62, 82, 92 can each be one of the “controllers” (i.e., controller 910) described below, or each module 12, 22, 32, 52, 62, 82, 92 can include multiple controllers as necessary. As such, these controllers / modules 12, 22, 32, 52, 62, 82, 92 can execute the steps of the various algorithms (i.e., TCS algorithm) described herein.

[0349] The controller 910 can be in wired and / or wireless communication with various peripheral device(s) 980, data source(s) 990, and / or other computing devices (e.g., over network(s) 970). The controller 910 can represent various forms of stationary computers 912 (e.g., workstations, kiosks, servers, mainframes, edge computing devices, quantum computers, etc.) and mobile computers 914 (e.g., laptops, tablets, mobile phones, personal digital assistants, wearable devices, etc.). In some implementations, the controller 910 can be included in (and / or in communication with) various other sorts of devices, such as data collection devices (e.g., devices that are configured to collect data from a physical environment, such as microphones, cameras, scanners, sensors, etc., which can include the cameras, load sensors, motors, and other devices described herein), robotic devices (e.g., devices that are configured to physically interact with objects in a physical environment, such as manufacturing devices, maintenance devices, object handling devices, etc.), vehicles (e.g., devices that are configured to move throughout a physical environment, such as automated guided vehicles, manually operated vehicles, etc.), or other such devices. Each of the devices (e.g., stationary computers, mobile computers, and / or other devices) can include components of the controller 910, and an entire system can be made up of multiple devices communicating with each other. For example, the controller 910 can be part of a computing system that includes a network of computing devices, such as a cloud-based computing system, a computing system in an internal network, or a computing system in another sort of shared network. Processors of the computing device controller 910 and other computing devices of a computing system can be optimized for different types of operations, secure computing tasks, etc. The components shown herein, and their functions, are meant to be examples, and are not meant to limit implementations of the technology described and / or claimed in this document.

[0350] The controller 910 can include processor(s) 920, memory device(s) 930, storage device(s) 940, and interface(s) 950. Each of the processor(s) 920, the memory device(s) 930, the storage device(s) 940, and the interface(s) 950 can be interconnected using a system bus 360. The processor(s) 920 are capable of processing instructions for execution within the55879-427819 controller 910, which can include the algorithms described herein such as the TCS algorithm, and can include one or more single-threaded and / or multi-threaded processors. The processor(s) 920 are capable of processing instructions stored in the memory device(s) 930 and / or on the storage device(s) 940. The memory device(s) 930 can store data within the controller 910, and can include one or more computer-readable media, volatile memory units, and / or non-volatile memory units. The storage device(s) 940 can provide mass storage for the controller 910, can include various computer-readable media (e.g., a floppy disk device, a hard disk device, a tape device, an optical disk device, a flash memory or other similar solid state memory device, or an array of devices, including devices in a storage area network or other configurations), and can provide date security / encryption capabilities.

[0351] The interface(s) 950 can include various communications interfaces (e.g., USB, Near- Field Communication (NFC), Bluetooth, WiFi, Ethernet, wireless Ethernet, etc.) that can be coupled to the network(s) 970, peripheral device(s) 980, and / or data source(s) 990 (e.g., through a communications port, a network adapter, etc.). Communication can be provided under various modes or protocols for wired and / or wireless communication. Such communication can occur, for example, through a transceiver using a radio-frequency. As another example, communication can occur using light (e.g., laser, infrared, etc.) to transmit data. As another example, short-range communication can occur, such as using Bluetooth, WiFi, or other such transceiver. In addition, a GPS (Global Positioning System) receiver module can provide location-related wireless data, which can be used as appropriate by device applications. The interface(s) 950 can include a control interface that receives commands from an input device (e.g., operated by a user) and converts the commands for submission to the processors 920. The interface(s) 950 can include a display interface that includes circuitry for driving a display to present visual information to a user. The interface(s) 950 can include an audio codec which can receive sound signals (e.g., spoken information from a user) and convert it to usable digital data. The audio codec can likewise generate audible sound, such as through an audio speaker. Such sound can include real-time voice communications, recorded sound (e.g., voice messages, music files, etc.), and / or sound generated by device applications.

[0352] The network(s) 970 can include one or more wired and / or wireless communications networks, including various public and / or private networks. Examples of communication networks include a LAN (local area network), a WAN (wide area network), and / or the Internet. The communication networks can include a group of nodes (e.g., computing devices) that are configured to exchange data (e.g., analog messages, digital messages, etc.), through55879-427819 telecommunications links. The telecommunications links can use various techniques (e.g., circuit switching, message switching, packet switching, etc.) to send the data and other signals from an originating node to a destination node. In some implementations, the controller 910 can communicate with the peripheral device(s) 980, the data source(s) 990, and / or other computing devices over the network(s) 970. In some implementations, the controller 910 can directly communicate with the peripheral device(s) 980, the data source(s), and / or other computing devices.

[0353] The peripheral device(s) 980 can provide input / output operations for the controller 910. Input devices (e.g., keyboards, pointing devices, touchscreens, microphones, cameras, scanners, sensors, etc.) can provide input to the controller 910 (e.g., user input and / or other input from a physical environment). Output devices (e.g., display units such as display screens or projection devices for displaying graphical user interfaces (GUIs)), audio speakers for generating sound, tactile feedback devices, printers, motors, hardware control devices, etc.) can provide output from the controller 910 (e.g., user-directed output and / or other output that results in actions being performed in a physical environment, such as, for example, controlling the rotation of the motors 22, 26 and propellers 14, 18). Other kinds of devices can be used to provide for interactions between users and devices. For example, input from a user can be received in any form, including visual, auditory, or tactile input, and feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback).

[0354] The data source(s) 990 can provide data for use by the controller 910, and / or can maintain data that has been generated by the controller 910 and / or other devices (e.g., data collected from sensor devices, data aggregated from various different data repositories, etc.). Data including the angular speed data (target angular speed, adjusted angular speed, user- defined maximum angular speed change, aircraft data related to these angular speed data, and any other data or information described herein) can be provided to the controller 910, and the controller 910 can relay and store data regarding the same to and from the various storage and processing devices of the system 900. This data can be the data sent between the modules 12, 22, 32, 52, 62, 82, 92 described herein. In some implementations, one or more data sources can be hosted by the controller 910 (e.g., using the storage device(s) 940). In some implementations, one or more data sources can be hosted by a different computing device. Data can be provided by the data source(s) 990 in response to a request for data from the controller 910 and / or can be provided without such a request. For example, a pull technology can be used55879-427819 in which the provision of data is driven by device requests, and / or a push technology can be used in which the provision of data occurs as the data becomes available (e.g., real-time data streaming and / or notifications). Various sorts of data sources can be used to implement the techniques described herein, alone or in combination.

[0355] In some implementations, a data source can include one or more data store(s) 990a. The database(s) can be provided by a single computing device or network (e.g., on a file system of a server device) or provided by multiple distributed computing devices or networks (e.g., hosted by a computer cluster, hosted in cloud storage, etc.). In some implementations, a database management system (DBMS) can be included to provide access to data contained in the database(s) (e.g., through the use of a query language and / or application programming interfaces (APIs)). The database(s), for example, can include relational databases, object databases, structured document databases, unstructured document databases, graph databases, and other appropriate types of databases.

[0356] Various implementations of the systems and techniques described herein can be realized in digital electronic circuitry, integrated circuitry, specially designed ASICs (application specific integrated circuits), computer hardware, firmware, software, and / or combinations thereof. A computer program product can be tangibly embodied in an information carrier (e.g., in a machine-readable storage device), for execution by a programmable processor. Various computer operations (e.g., methods described in this document) can be performed by a programmable processor executing a program of instructions to perform functions of the described implementations by operating on input data and generating output. The described features can be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. A computer program is a set of instructions that can be used, directly or indirectly, by a computer to perform a certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program product can be a computer- or machine-readable medium, such as a storage device or memory device. As used herein, the terms machine-readable medium and computer-readable medium refer to any computer program product, apparatus and / or device (e.g., magnetic discs, optical disks, memory, etc.)55879-427819 used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term machine-readable signal refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0357] As a non-limiting example, a non-transitory computer-readable storage medium with instructions which, when executed by a computer, which may include the modules 12, 22, 32, 52, 62, 82, 92 and their respective controllers described herein, may be configured to execute the algorithms (i.e., TCS algorithm and others described herein) or any other programmed steps, calculations, determinations, settings (i.e., setting of the angular speeds), and the like included in this disclosure. Such computers, controllers, or modules, may communicate with and be in operable connection with any of the other devices, controllers, or modules configured to operate with, share data with, or be operated by or with each other. Communication between these device may occur by any known means, and in some embodiments, via the networks 970, as described above.

[0358] Suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and can be a single processor or one of multiple processors of any kind of computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer can also include, or can be operatively coupled to communicate with, one or more mass storage devices for storing data files. Such devices can include magnetic disks (e.g., internal hard disks and / or removable disks), magneto-optical disks, and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data can include all forms of non-volatile memory, including by way of example semiconductor memory devices, flash memory devices, magnetic disks (e.g., internal hard disks and removable disks), magneto-optical disks, and optical disks. The processor and the memory can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits).

[0359] The systems and techniques described herein can be implemented in a computing system that includes a back end component (e.g., a data server), or that includes a middleware component (e.g., an application server), or that includes a front end component (e.g., a client computer having a graphical user interface or a Web browser through which a user can interact55879-427819 with an implementation of the systems and techniques described here), or any combination of such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). The computer system can include clients and servers, which can be generally remote from each other and typically interact through a network, such as the described one. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

[0360] It is to be understood that while the invention has been described in this document with respect to a specific but illustrative embodiment, various configurational and size changes may be made within the scope of the invention described and claimed herein.

[0361] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

[0362] There are a plurality of advantages of the present disclosure arising from the various features of the method, apparatus, and system described herein. It will be noted that alternative embodiments of the method, apparatus, and system of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the method, apparatus, and system that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present disclosure as defined by the appended claims.

[0363] The features illustrated or described in connection with one exemplary embodiment may be combined with any other feature or element of any other embodiment described herein. Such modifications and variations are intended to be included within the scope of the present disclosure. Further, a person skilled in the art will recognize that terms commonly known to those skilled in the art may be used interchangeably herein.

[0364] As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the presently described subject matter are not intended to be interpreted as excluding the existence of55879-427819 additional embodiments that also incorporate the recited features. Specified numerical ranges of units, measurements, and / or values comprise, consist essentially or, or consist of all the numerical values, units, measurements, and / or ranges including or within those ranges and / or endpoints, whether those numerical values, units, measurements, and / or ranges are explicitly specified in the present disclosure or not.

[0365] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms “first,” “second,” “third” and the like, as used herein do not denote any order or importance, but rather are used to distinguish one element from another. The term “or” is meant to be inclusive and mean either or all of the listed items. In addition, the terms “connected” and “coupled” are not restricted to physical or mechanical connections or couplings, and can include electrical connections or couplings, whether direct or indirect.

[0366] Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. The term “comprising” or “comprises” refers to a composition, compound, formulation, or method that is inclusive and does not exclude additional elements, components, and / or method steps. The term “comprising” also refers to a composition, compound, formulation, or method embodiment of the present disclosure that is inclusive and does not exclude additional elements, components, or method steps.

[0367] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,” “about,” “approximately,” and “substantially” is not to be limited to the precise value specified, but in some embodiments, may refer to within 2% of a specified value or range of values. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and / or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.

[0368] As used herein, the terms “may” and “may be” indicate a possibility of an occurrence within a set of circumstances in a particular embodiment; a possession of a specified property,55879-427819 characteristic or function; and / or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of “may” and “may be” indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances, the modified term may sometimes not be appropriate, capable, or suitable.

[0369] It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and / or aspects thereof) may be used individually, together, or in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the subject matter set forth herein without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the disclosed subject matter, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the subject matter described herein should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0370] This written description uses examples to disclose several embodiments of the subject matter set forth herein, including the best mode, and also to enable a person of ordinary skill in the art to practice the embodiments of disclosed subject matter, including making and using the devices or systems and performing the methods. The patentable scope of the subject matter described herein is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0371] The following numbered clauses include embodiments that are contemplated and non- limiting:

[0372] Clause 1. A control system for controlling a plurality of configurations of aircraft includes a first module including a processor and configured to receive at least one pilot inceptor input and map the at least one pilot inceptor input to at least one input command, the at least one input command being representative of a desired dynamic aircraft state responsive to the at least one pilot inceptor input, a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of55879-427819 configurations of aircraft, the second module configured to receive the at least one input command from the first module, and generate at least one of a normalized vertical thrust command or a normalized horizontal thrust command derived from the at least one input command, and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the at least one of the normalized vertical thrust command or the normalized horizontal thrust command. The at least one of the normalized vertical thrust command or the normalized horizontal thrust command is configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

[0373] Clause 2. The control system of clause 1, any other clause, or combination of clauses, wherein the second module is further configured to generate a normalized vertical thrust command and a horizontal thrust command based on the at least one input command so as to generate the at least one control state of the at least one control effector of the aircraft.

[0374] Clause 3. The control system of clause 2, any other clause, or combination of clauses, wherein the at least one pilot inceptor input includes at least one of lateral input, heave input, directional input, or acceleration input.

[0375] Clause 4. The control system of clause 3, any other clause, or combination of clauses, wherein the at least one input command that is mapped from the at least one pilot inceptor input includes at least one of normalized acceleration and climb rate.

[0376] Clause 5. The control system of clause 4, any other clause, or combination of clauses, wherein the second module is further configured to determine a normalized acceleration in a horizontal direction based on the normalized acceleration and a normalized acceleration in a vertical direction based on the climb rate.

[0377] Clause 6. The control system of clause 5, any other clause, or combination of clauses, wherein the normalized acceleration in the horizontal direction and the normalized acceleration in the vertical direction include a desired horizontal movement command value and a desired vertical movement command value.

[0378] Clause 7. The control system of clause 6, any other clause, or combination of clauses, wherein the second module is further configured to receive an actual horizontal movement value and an actual vertical movement value based on a current state of operation of55879-427819 the aircraft, and configured to determine a horizontal error based on a difference between the actual horizontal movement value and the desired horizontal movement command value and a vertical error based on a difference between the actual vertical movement value and the desired vertical movement command value.

[0379] Clause 8. The control system of clause 7, any other clause, or combination of clauses, wherein the second module is further configured to determine the normalized horizontal thrust command via driving the horizontal error to zero via integrating the horizontal error and determine the normalized vertical thrust command via driving the vertical error to zero via integrating the vertical error.

[0380] Clause 9. The control system of clause 8, any other clause, or combination of clauses, wherein the integration of the horizontal and vertical errors is controlled, via the second module, by: (^^^^)^^ௗ,ு = ^^ூு ^ ^^^ಹ ^^^^ − ^^^ு^ுwherein ^^ூு, ^^ூ^, ^^^ு,and nH and nV are an actual normalized horizontal acceleration value and an actual vertical acceleration value.

[0381] Clause 10. The control system of clause 9, any other clause, or combination of clauses, wherein the second module is further configured to determine a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command.

[0382] Clause 11. The control system of clause 10, any other clause, or combination of clauses, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

[0383] Clause 12. The control system of clause 2, any other clause, or combination of clauses, wherein the normalized vertical thrust command includes a vertical component in a vertical direction and the normalized horizontal thrust command includes a horizontal component in a horizontal direction.55879-427819

[0384] Clause 13. The control system of clause 12, any other clause, or combination of clauses, wherein the second module is further configured to determine a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command,

[0385] Clause 14. The control system of clause 13, any other clause, or combination of clauses, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

[0386] Clause 15. The control system of clause 14, any other clause, or combination of clauses, wherein the second module is further configured to determine a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand.

[0387] Clause 16. The control system of clause 15, any other clause, or combination of clauses, wherein the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and

[0388] Clause 17. The control system of clause 16, any other clause, or combination of clauses, wherein the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

[0389] Clause 18. The control system of clause 17, any other clause, or combination of clauses, wherein the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^^^^ା^^^0wherein ^^௧^and55879-427819

[0390] Clause 19. The control system of clause 17, any other clause, or combination of clauses, wherein the second module is further configured to determine a flight mode in which the aircraft is operating.

[0391] Clause 20. The control system of clause 19, any other clause, or combination of clauses, wherein the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

[0392] Clause 21. The control system of clause 20, any other clause, or combination of clauses, wherein the second module is further configured to generate a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

[0393] Clause 22. The control system of clause 21, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

[0394] Clause 23. The control system of clause 22, any other clause, or combination of clauses, wherein the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: (^^ / ^^)^^ௗ,^^ = ^(^^ / ^^)ଶ + ^^^^^(^^ / ^^)^^ௗ,^^ଶ.

[0395] Clause 24.of clauses, wherein the normalized thrust command for the main propulsors in hybrid flight mode is generated, via the second module, by: ^మ మ^ ା^^ ^^^ ൠ ^^ ^ ^^.

[0396] Clause 25. any or of clauses, wherein the second module is further configured to generate a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.55879-427819

[0397] Clause 26. The control system of clause 25, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion.

[0398] Clause 27. The control system of clause 26, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

[0399] Clause 28. The control system of clause 27, any other clause, or combination of clauses, wherein the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: (^^ / ^^)^^ௗ,^^ = ^(^^ / ^^)ଶ^^ௗ,ு + ^^^^^(^^ / ^^) ଶ^^ௗ,^^ .

[0400] Clause 29.of clauses, wherein the normalized thrust command for the lift propulsors in hybrid flight mode is generated, via the second module, by: ଶ^^^^^^ ^ ൠ .

[0401] Clause 30. Theor combination of clauses, wherein the second module is further configured to determine that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

[0402] Clause 31. The control system of clause 30, any other clause, or combination of clauses, wherein the second module is further configured to transition from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.

[0403] Clause 32. The control system of clause 31, any other clause, or combination of clauses, wherein the second module is further configured to transition from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a55879-427819 second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one command, which includes a speed command, increases beyond a first speed command threshold.

[0404] Clause 32. The control system of clause 31, any other clause, or combination of clauses, wherein the second module is further configured to transition from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

[0405] Clause 33. The control system of clause 32, any other clause, or combination of clauses, wherein the second nacelle angle is less than the first nacelle angle.

[0406] Clause 34. The control system of clause 30, any other clause, or combination of clauses, wherein the second module is further configured to transition from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

[0407] Clause 35. The control system of clause 34, any other clause, or combination of clauses, wherein the second module is further configured to transition from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

[0408] Clause 36. The control system of clause 35, any other clause, or combination of clauses, wherein the second module is further configured to transition from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

[0409] Clause 37. The control system of clause 2, any other clause, or combination of clauses, wherein the plurality of configurations of aircraft includes lift-plus-cruise aircraft, tilt- wing aircraft, and vectored thrust aircraft.55879-427819 Clause 38. A method for controlling a plurality of configurations of aircraft includes receiving, via a first module, at least one pilot inceptor input, mapping, via the first module, the at least one pilot inceptor input to at least one command, the at least one command being representative of a desired dynamic aircraft state responsive to the at least one pilot inceptor input, controlling, via a second module, a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the controlling including receiving the at least one input command from the first module, and generating at least one of a normalized vertical thrust command or a normalized horizontal thrust command derived from the at least one input command. The method further includes generating, via a third module, at least one control state for at least one control effector of the aircraft based on the at least one of the normalized vertical thrust command or the normalized horizontal thrust command. The at least one of the normalized vertical thrust command or the normalized horizontal thrust command is configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

[0410] Clause 39. The control system of clause 38, any other clause, or combination of clauses, wherein the method further includes generating, via the second module, a normalized vertical thrust command and a horizontal thrust command based on the at least one input command so as to generate the at least one control state of the at least one control effector of the aircraft.

[0411] Clause 40. The control system of clause 39, any other clause, or combination of clauses, wherein the at least one pilot inceptor input includes at least one of lateral input, heave input, directional input, or acceleration input.

[0412] Clause 41. The control system of clause 40, any other clause, or combination of clauses, wherein the at least one input command that is mapped from the at least one pilot inceptor input includes at least one of normalized acceleration and climb rate.

[0413] Clause 42. The control system of clause 41, any other clause, or combination of clauses, wherein the method further includes determining, via the second module, a normalized acceleration in a horizontal direction based on the normalized acceleration and a normalized acceleration in a vertical direction based on the climb rate.

[0414] Clause 43. The control system of clause 42, any other clause, or combination of clauses, wherein the normalized acceleration in the horizontal direction and the normalized55879-427819 acceleration in the vertical direction include a desired horizontal movement command value and a desired vertical movement command value.

[0415] Clause 44. The control system of clause 43, any other clause, or combination of clauses, wherein the method further includes receiving, via the second module, an actual horizontal movement value and an actual vertical movement value based on a current state of operation of the aircraft, and determining, via the second module, a horizontal error based on a difference between the actual horizontal movement value and the desired horizontal movement command value and a vertical error based on a difference between the actual vertical movement value and the desired vertical movement command value.

[0416] Clause 45. The control system of clause 44, any other clause, or combination of clauses, wherein the method further includes determining, via the second module, the normalized horizontal thrust command via driving the horizontal error to zero via integrating the horizontal error and determine the normalized vertical thrust command via driving the vertical error to zero via integrating the vertical error.

[0417] Clause 46. The control system of clause 45, any other clause, or combination of clauses, wherein the integration of the horizontal and vertical errors is controlled, via the second module, by: (^^^^)^^ௗ,ு = ^^ூு ^ ^^^ಹ ^^^^ − ^^^ு^ுwherein ^^ூு, ^^ூ^, ^^^ு, and nH and nV are an actual normalized horizontal acceleration value and an actual vertical acceleration value.

[0418] Clause 47. The control system of clause 46, any other clause, or combination of clauses, wherein the method further includes determining, via the second module, a thrust-axis- inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command,

[0419] Clause 48. The control system of clause 47, any other clause, or combination of clauses, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.55879-427819

[0420] Clause 49. The control system of clause 39, any other clause, or combination of clauses, wherein the normalized vertical thrust command includes a vertical component in a vertical direction and the normalized horizontal thrust command includes a horizontal component in a horizontal direction.

[0421] Clause 50. The control system of clause 49, any other clause, or combination of clauses, wherein the method further includes determining, via the second module, a thrust-axis- inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command,

[0422] Clause 51. The control system of clause 50, any other clause, or combination of clauses, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

[0423] Clause 52. The control system of clause 51, any other clause, or combination of clauses, wherein the method further includes determining, via the second module, a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand.

[0424] Clause 53. The control system of clause 52, any other clause, or combination of clauses, wherein the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt.

[0425] Clause 54. The control system of clause 53, any other clause, or combination of clauses, wherein the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

[0426] Clause 55. The control system of clause 54, any other clause, or combination of clauses, wherein the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^55879-427819 ^ି^^^^ି^^^ (^ିୡ୭^(థ^)) ^^^^ ^^௧^ ≠ 0^^^^^^ = ^ ^ ^^^^ 0wherein ^^௧^and ^^^^

[0427] Clause 56. The control system of clause 54, any other clause, or combination of clauses, wherein the method further includes determining, via the second module, a flight mode in which the aircraft is operating.

[0428] Clause 57. The control system of clause 56, any other clause, or combination of clauses, wherein the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

[0429] Clause 58. The control system of clause 57, any other clause, or combination of clauses, wherein the method further includes generating, via the second module, a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

[0430] Clause 59. The control system of clause 58, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

[0431] Clause 60. The control system of clause 59, any other clause, or combination of clauses, wherein the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: =^ ଶ + ^^^ ଶ^^ .

[0432] Clause 61. of clauses, wherein the normalized thrust command for the main propulsors in hybrid flight mode is generated, via the second module, by:55879-427819 ^మ మ^ ା ^ ^ ^ ^ೈ^^^,ಹ ^ ^^^ೈ^^^ ൠ ^ ^ೈ^ ஹ^= ^,ೇ ^^^,ಹ.

[0433] Clause 62.of clauses, wherein the method further includes generating, via the second module, a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

[0434] Clause 63. The control system of clause 62, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion.

[0435] Clause 64. The control system of clause 63, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

[0436] Clause 65. The control system of clause 64, any other clause, or combination of clauses, wherein the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: (^^ / ^^) = ^(^^ / ^^)ଶ + ^^^^^(^^ / ^^) ଶ.

[0437] Clause 66.of clauses, wherein the normalized thrust command for the lift propulsors in hybrid flight mode is generated, via the second module, by: ଶ^

[0438] Clause 67. The any or combination of clauses, wherein the method further includes determining, via the second module, that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.55879-427819

[0439] Clause 68. The control system of clause 67, any other clause, or combination of clauses, wherein the method further includes transitioning, via the second module, from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.

[0440] Clause 69. The control system of clause 68, any other clause, or combination of clauses, wherein the method further includes transitioning, via the second module, from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one command, which includes a speed command, increases beyond a first speed command threshold.

[0441] Clause 70. The control system of clause 69, any other clause, or combination of clauses, wherein the method further includes transitioning, via the second module, from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

[0442] Clause 71. The control system of clause 69, any other clause, or combination of clauses, wherein the second nacelle angle is less than the first nacelle angle.

[0443] Clause 72. The control system of clause 67, any other clause, or combination of clauses, wherein the method further includes transitioning, via the second module, from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

[0444] Clause 73. The control system of clause 72, any other clause, or combination of clauses, wherein the method further includes transitioning, via the second module, from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.55879-427819

[0445] Clause 74. The control system of clause 73, any other clause, or combination of clauses, wherein the method further includes transitioning, via the second module, from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

[0446] Clause 75. A control system for controlling a plurality of configurations of aircraft includes a first module including a processor and configured to receive at least two pilot inceptor inputs and map the at least two pilot inceptor inputs to at least two input commands, the at least two input commands being representative of a desired dynamic aircraft state responsive to the at least two pilot inceptor inputs, a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to receive the at least two input commands from the first module, and generate a normalized vertical thrust command and a normalized horizontal thrust command derived from the at least one input command, and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the normalized vertical thrust command and the normalized horizontal thrust command. The normalized vertical thrust command and the normalized horizontal thrust command are configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

[0447] Clause 76. A control system for controlling a plurality of configurations of aircraft includes a first module including a processor and configured to receive at least two pilot inceptor inputs and map the at least two pilot inceptor inputs to at least two input commands, the at least two input commands being representative of a desired dynamic aircraft state responsive to the at least two pilot inceptor inputs, a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to receive the at least two input commands from the first module, generate a normalized vertical thrust command and a normalized horizontal thrust command derived from the at least one input command, determine a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command, and determine a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift55879-427819 propulsor portion of the vertical thrust demand, and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the normalized vertical thrust command and the normalized horizontal thrust command. The normalized vertical thrust command and the normalized horizontal thrust command are configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft, and the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

[0448] Clause 77. The control system of clause 76, any other clause, or combination of clauses, wherein the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^^^^ା^^^00wherein ^^௧^and ^^^^are total propulsors and lift propulsors.

[0449] Clause 78. The control system of clause 76, any other clause, or combination of clauses, wherein the second module is further configured to determine a flight mode in which the aircraft is operating.

[0450] Clause 79. The control system of clause 78, any other clause, or combination of clauses, wherein the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

[0451] Clause 80. The control system of clause 79, any other clause, or combination of clauses, wherein the second module is further configured to generate a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

[0452] Clause 81. The control system of clause 80, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the vertical, hybrid, and transition55879-427819 flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

[0453] Clause 82. The control system of clause 81, any other clause, or combination of clauses, wherein the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: (^^ / ^^) = ^(^^ / ^^)ଶௗ,ு + ^ ( ) ଶ^^ௗ,^^ ^^ ^ ^^^ ^^ / ^^ ^^ௗ,^^ .

[0454] Clause 83.of clauses, wherein the normalized thrust command for the main propulsors in hybrid flight mode is generated, via the second module, by: ^మ మ^ ା ^ ^ೈ^^^,ಹ ^^^^^ೈ^^^^,ೇൠ ^^ ^ೈ^^^^,ಹ ஹ^

[0455] Clause 84.of clauses, wherein the second module is further configured to generate a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

[0456] Clause 85. The control system of clause 84, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion.

[0457] Clause 86. The control system of clause 85, any other clause, or combination of clauses, wherein, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

[0458] Clause 87. The control system of clause 86, any other clause, or combination of clauses, wherein the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by:55879-427819 (^^ / ^^) = ^( ଶ^^ௗ,ு ( ) ଶ^^ௗ,^^ ^^ / ^^) + ^^^^^ ^^ / ^^ ^^ௗ,^^ .

[0459] Clause 88.of clauses, wherein the normalized thrust command for the lift propulsors in hybrid flight mode is generated, via the second module, by: ଶ(^^ / ^^)^^ௗ,^^ = ^^^^^^ .

[0460] Clause 89. Theor combination of clauses, wherein the second module is further configured to determine that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

[0461] Clause 90. The control system of clause 89, any other clause, or combination of clauses, wherein the second module is further configured to transition from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.

[0462] Clause 91. The control system of clause 90, any other clause, or combination of clauses, wherein the second module is further configured to transition from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one command, which includes a speed command, increases beyond a first speed command threshold.

[0463] Clause 92. The control system of clause 91, any other clause, or combination of clauses, wherein the second module is further configured to transition from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

[0464] Clause 93. The control system of clause 92, any other clause, or combination of clauses, wherein the second nacelle angle is less than the first nacelle angle.55879-427819

[0465] Clause 94. The control system of clause 89, any other clause, or combination of clauses, wherein the second module is further configured to transition from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

[0466] Clause 95. The control system of clause 94, any other clause, or combination of clauses, wherein the second module is further configured to transition from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

[0467] Clause 96. The control system of clause 95, any other clause, or combination of clauses, wherein the second module is further configured to transition from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

[0468] Clause 97. The control system of clause 77, any other clause, or combination of clauses, wherein the plurality of configurations of aircraft includes lift-plus-cruise aircraft, tilt- wing aircraft, and vectored thrust aircraft.

Claims

55879-427819 WHAT IS CLAIMED IS:

1. A control system for controlling a plurality of configurations of aircraft, comprising: a first module including a processor and configured to receive at least one pilot inceptor input and map the at least one pilot inceptor input to at least one input command, the at least one input command being representative of a desired dynamic aircraft state responsive to the at least one pilot inceptor input; a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to: receive the at least one input command from the first module; and generate at least one of a normalized vertical thrust command or a normalized horizontal thrust command derived from the at least one input command; and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the at least one of the normalized vertical thrust command or the normalized horizontal thrust command, wherein the at least one of the normalized vertical thrust command or the normalized horizontal thrust command is configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

2. The control system of claim 1, wherein the second module is further configured to generate a normalized vertical thrust command and a horizontal thrust command based on the at least one input command so as to generate the at least one control state of the at least one control effector of the aircraft.

3. The control system of claim 2, wherein the at least one pilot inceptor input includes at least one of lateral input, heave input, directional input, or acceleration input.

4. The control system of claim 3, wherein the at least one input command that is mapped from the at least one pilot inceptor input includes at least one of normalized acceleration and climb rate.

5. The control system of claim 4, wherein the second module is further configured to determine a normalized acceleration in a horizontal direction based on the normalized55879-427819 acceleration and a normalized acceleration in a vertical direction based on the climb rate, and wherein the normalized acceleration in the horizontal direction and the normalized acceleration in the vertical direction include a desired horizontal movement command value and a desired vertical movement command value.

6. The control system of claim 5, wherein the second module is further configured to receive an actual horizontal movement value and an actual vertical movement value based on a current state of operation of the aircraft, and configured to determine a horizontal error based on a difference between the actual horizontal movement value and the desired horizontal movement command value and a vertical error based on a difference between the actual vertical movement value and the desired vertical movement command value.

7. The control system of claim 6, wherein the second module is further configured to determine the normalized horizontal thrust command via driving the horizontal error to zero via integrating the horizontal error and determine the normalized vertical thrust command via driving the vertical error to zero via integrating the vertical error.

8. The control system of claim 7, wherein the integration of the horizontal and vertical errors is controlled, via the second module, by: (^^^^)^^ௗ,ு = ^^ூு ^ ^^^ಹ ^^^^ − ^^^ு^ுwherein ^^ூு, ^^ூ^, ^^^ு,and nH and nV are an actual normalized horizontal acceleration value and an actual vertical acceleration value.

9. The control system of claim 8, wherein the second module is further configured to determine a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.55879-427819 10. The control system of claim 2, wherein the normalized vertical thrust command includes a vertical component in a vertical direction and the normalized horizontal thrust command includes a horizontal component in a horizontal direction.

11. The control system of claim 10, wherein the second module is further configured to determine a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

12. The control system of claim 11, wherein the second module is further configured to determine a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand.

13. The control system of claim 12, wherein the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and wherein the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

14. The control system of claim 13, wherein the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^^^^ା^^^00wherein ^^௧^and ^^^^are total propulsors and lift propulsors.

15. The control system of claim 13, wherein the second module is further configured to determine a flight mode in which the aircraft is operating, and wherein the flight mode includes55879-427819 one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

16. The control system of claim 15, wherein the second module is further configured to generate a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

17. The control system of claim 16, wherein, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

18. The control system of claim 17, wherein the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: (^^ / ^^) = ^(^^ / ଶ^^ௗ,ு ( ) ଶ^^ௗ,^^ ^^) + ^^^^^ ^^ / ^^ ^^ௗ,^^ .

19. The controlfor the main propulsors in hybrid flight mode is generated, via the second module, by: ^మ ^ మ^ ା^^ ^ ^ ൠ ^^ ^ ^ ஹ^.

20. The controlconfigured to generate a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

21. The control system of claim 20, wherein, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion, and wherein, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.55879-427819 22. The control system of claim 21, wherein the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: (^^ / ^^)^^ௗ,^^ = ^(^^ / ^^)ଶ^^ௗ,ு + ^^^^^(^^ / ^^)^^ௗ,^^ଶ.

23. The controlfor the lift propulsors in hybrid flight mode is generated, via the second module, by: ଶ(^^ / ^^) = ^^^^^^ ^ ^ .

24. The control system ofis further configured to determine that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

25. The control system of claim 24, wherein the second module is further configured to transition from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.

26. The control system of claim 25, wherein the second module is further configured to transition from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one command, which includes a speed command, increases beyond a first speed command threshold.

27. The control system of claim 26, wherein the second module is further configured to transition from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.55879-427819 28. The control system of claim 27, wherein the second nacelle angle is less than the first nacelle angle.

29. The control system of claim 24, wherein the second module is further configured to transition from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

30. The control system of claim 29, wherein the second module is further configured to transition from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

31. The control system of claim 30, wherein the second module is further configured to transition from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

32. The control system of claim 2, wherein the plurality of configurations of aircraft includes lift-plus-cruise aircraft, tilt-wing aircraft, and vectored thrust aircraft.

33. A method for controlling a plurality of configurations of aircraft, comprising: receiving, via a first module, at least one pilot inceptor input; mapping, via the first module, the at least one pilot inceptor input to at least one command, the at least one command being representative of a desired dynamic aircraft state responsive to the at least one pilot inceptor input; controlling, via a second module, a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the controlling including: receiving the at least one input command from the first module; and generating at least one of a normalized vertical thrust command or a normalized horizontal thrust command derived from the at least one input command; and55879-427819 generating, via a third module, at least one control state for at least one control effector of the aircraft based on the at least one of the normalized vertical thrust command or the normalized horizontal thrust command, wherein the at least one of the normalized vertical thrust command or the normalized horizontal thrust command is configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

34. The method of claim 33, further comprising: generating, via the second module, a normalized vertical thrust command and a horizontal thrust command based on the at least one input command so as to generate the at least one control state of the at least one control effector of the aircraft.

35. The method of claim 34, wherein the at least one pilot inceptor input includes at least one of lateral input, heave input, directional input, or acceleration input.

36. The method of claim 35, wherein the at least one input command that is mapped from the at least one pilot inceptor input includes at least one of normalized acceleration and climb rate.

37. The method of claim 36, further comprising: determining, via the second module, a normalized acceleration in a horizontal direction based on the normalized acceleration and a normalized acceleration in a vertical direction based on the climb rate, and wherein the normalized acceleration in the horizontal direction and the normalized acceleration in the vertical direction include a desired horizontal movement command value and a desired vertical movement command value.

38. The method of claim 37, further comprising: receiving, via the second module, an actual horizontal movement value and an actual vertical movement value based on a current state of operation of the aircraft; and determining, via the second module, a horizontal error based on a difference between the actual horizontal movement value and the desired horizontal movement command value and a vertical error based on a difference between the actual vertical movement value and the desired vertical movement command value.55879-427819 39. The method of claim 38, further comprising: determining, via the second module, the normalized horizontal thrust command via driving the horizontal error to zero via integrating the horizontal error and determine the normalized vertical thrust command via driving the vertical error to zero via integrating the vertical error.

40. The method of claim 39, wherein the integration of the horizontal and vertical errors is controlled, via the second module, by: (^^^^)^^ௗ,ு = ^^ூு ^ ^^^ಹ ^^^^ − ^^^ு^ுwherein ^^ூு, ^^ூ^, ^^^ு,and nH and nV are an actual normalized horizontal acceleration value and an actual vertical acceleration value.

41. The method of claim 40, further comprising: determining, via the second module, a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

42. The method of claim 34, wherein the normalized vertical thrust command includes a vertical component in a vertical direction and the normalized horizontal thrust command includes a horizontal component in a horizontal direction.

43. The method of claim 42, further comprising: determining, via the second module, a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command.

44. The method of claim 43, further comprising:55879-427819 determining, via the second module, a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand.

45. The method of claim 44, wherein the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and wherein the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

46. The method of claim 45, wherein the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^^^^ା^^^^ି^^^^ି^ (^ିୡ୭^(థ^)) ^^^^ ^^௧^ ≠ 0^^^^^^ = ^ ^^0wherein ^^௧^and ^^^^are total propulsors and lift propulsors.

47. The method of claim 45, further comprising: determining, via the second module, a flight mode in which the aircraft is operating, and wherein the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

48. The method of claim 47, further comprising: generating, via the second module, a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

49. The method of claim 48, wherein, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is55879-427819 based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

50. The method of claim 49, wherein the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: (^^ / ^^)^^ௗ,^^ = ^(^^ / ^^)ଶ^^ௗ,ு + ^^^ ଶ^^(^^ / ^^)^^ௗ,^^ .

51. The method ofthe main propulsors in hybrid flight mode is generated, via the second module, by: ^^ మ ^ మ ^ೈ^^^,ಹ ା^^^^^ೈ^^^^,ೇൠ ^^ ^ೈ^^^^,ಹ ஹ^.

52. The method ofgenerating, via the second module, a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

53. The method of claim 52, wherein, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion, and wherein, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

54. The method of claim 53, wherein the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: =^ ଶ ^^^ ଶ^^ .

55. The method of the lift propulsors in hybrid flight mode is generated, via the second module, by:55879-427819 ଶ(^^ / ^^)^^ௗ,^^ = ^^^^^^ ^^்^ .

56. The method of claim 47,determining, via the second module, that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

57. The method of claim 56, further comprising: transitioning, via the second module, from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.

58. The method of claim 57, further comprising: transitioning, via the second module, from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at least one command, which includes a speed command, increases beyond a first speed command threshold.

59. The method of claim 58, further comprising: transitioning, via the second module, from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

60. The method of claim 59, wherein the second nacelle angle is less than the first nacelle angle.

61. The method of claim 56, further comprising: transitioning, via the second module, from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.55879-427819 62. The method of claim 61, further comprising: transitioning, via the second module, from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

63. The method of claim 62, further comprising: transitioning, via the second module, from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

64. A control system for controlling a plurality of configurations of aircraft, comprising: a first module including a processor and configured to receive at least two pilot inceptor inputs and map the at least two pilot inceptor inputs to at least two input commands, the at least two input commands being representative of a desired dynamic aircraft state responsive to the at least two pilot inceptor inputs; a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to: receive the at least two input commands from the first module; and generate a normalized vertical thrust command and a normalized horizontal thrust command derived from the at least one input command; and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the normalized vertical thrust command and the normalized horizontal thrust command, wherein the normalized vertical thrust command and the normalized horizontal thrust command are configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft.

65. A control system for controlling a plurality of configurations of aircraft, comprising: a first module including a processor and configured to receive at least two pilot inceptor inputs and map the at least two pilot inceptor inputs to at least two input commands, the at least55879-427819 two input commands being representative of a desired dynamic aircraft state responsive to the at least two pilot inceptor inputs; a second module including a processor and configured to control a longitudinal trajectory of an aircraft having a configuration of a plurality of configurations of aircraft, the second module configured to: receive the at least two input commands from the first module; generate a normalized vertical thrust command and a normalized horizontal thrust command derived from the at least one input command; determine a thrust-axis-inclination (TAI) based on the normalized horizontal thrust command and the normalized vertical thrust command, wherein the TAI is a vector summation of the normalized horizontal thrust command and the normalized vertical thrust command; and determine a main propulsor portion of vertical thrust demand of the aircraft, the vertical thrust demand being based on the at least one command mapped from the at least one pilot inceptor input, and a lift propulsor portion of the vertical thrust demand; and a third module including a processor and configured to generate at least one control state for at least one control effector of the aircraft based on the normalized vertical thrust command and the normalized horizontal thrust command, wherein the normalized vertical thrust command and the normalized horizontal thrust command are configuration-invariant so as to be applicable to any aircraft having the plurality of configurations of aircraft, and wherein the main propulsor portion is a portion of the vertical thrust demand configured to be carried out via a main propulsor of the aircraft, the main propulsor being a propulsor capable of tilt or fixed in a horizontal orientation and incapable of tilt, and wherein the lift propulsor portion is a portion of the vertical thrust demand configured to be carried out via a lift propulsor of the aircraft, the lift propulsor being a propulsor fixed in a vertical orientation and incapable of tilt.

66. The control system of claim 65, wherein the main and lift propulsor portions are determined, via the second module, by: ^^^^^^ = ^^^^^^ା^^^55879-427819 ^ି^^^^ି ( ( )) ^^^^ ^^௧^ ≠ 0^^^^^^ = ^ ^^^ ^ିୡ୭^ థ^^ ^^^^ 0wherein ^^௧^and ^^^^67. The control system of claim 65, wherein the second module is further configured to determine a flight mode in which the aircraft is operating, and wherein the flight mode includes one of a plurality of flight modes including vertical flight mode, hybrid flight mode, transition flight mode, or forward flight mode.

68. The control system of claim 67, wherein the second module is further configured to generate a normalized thrust command for the main propulsors based on the flight mode in which the aircraft is operating.

69. The control system of claim 68, wherein, in response to the aircraft operating in the vertical, hybrid, and transition flight modes, the normalized thrust command for the main propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the main propulsor portion.

70. The control system of claim 69, wherein the normalized thrust command for the main propulsors in vertical and transition flight modes is generated, via the second module, by: (^^ / ^^) = ^(^^ / ^^)ଶ + ^^^^^(^^ / ^^) ଶ.

71. The controlfor the main propulsors in hybrid flight mode is generated, via the second module, by: మమ^^ ^^ ^ ^^ ^.55879-427819 72. The control system of claim 68, wherein the second module is further configured to generate a normalized thrust command for the lift propulsors based on the flight mode in which the aircraft is operating.

73. The control system of claim 72, wherein, in response to the aircraft operating in the vertical flight mode, the normalized thrust command for the lift propulsors is based on the normalized horizontal thrust command, the normalized vertical thrust command, and the lift propulsor portion, and wherein, in response to the aircraft operating in the hybrid flight mode, the normalized thrust command for the lift propulsors is based on the normalized vertical thrust command and the lift propulsor portion.

74. The control system of claim 73, wherein the normalized thrust command for the lift propulsors in vertical flight mode is generated, via the second module, by: (^^ / ^^)^^ௗ,^^ = ^(^^ / ^^)ଶ^^ௗ,ு + ^^^^^(^^ / ^^) ଶ^^ௗ,^^ .

75. The controlfor the lift propulsors in hybrid flight mode is generated, via the second module, by: ଶ^ ^^ ^ ^76. The control system ofis further configured to determine that the aircraft has transitioned from one of the plurality of flight modes to a different one of the plurality of flight modes.

77. The control system of claim 76, wherein the second module is further configured to transition from the vertical flight mode to the hybrid flight mode in response to a speed of the aircraft increasing beyond a first speed threshold.

78. The control system of claim 77, wherein the second module is further configured to transition from the hybrid flight mode to the transition flight mode in response to the speed of the aircraft increasing beyond a second speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a first nacelle angle threshold, and the at55879-427819 least one command, which includes a speed command, increases beyond a first speed command threshold.

79. The control system of claim 78, wherein the second module is further configured to transition from the transition flight mode to the forward flight mode in response to the speed of the aircraft increasing beyond a third speed threshold, a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft decreasing below a second nacelle angle threshold, and the at least one command, which includes the speed command, increase beyond a second speed command threshold.

80. The control system of claim 79, wherein the second nacelle angle is less than the first nacelle angle.

81. The control system of claim 76, wherein the second module is further configured to transition from the hybrid flight mode to the vertical flight mode in response to a speed of the aircraft decreasing beyond a first speed threshold, the TAI increasing above a first nacelle angle threshold, and the at least one command, which includes a speed command, decreases below a first speed command threshold.

82. The control system of claim 81, wherein the second module is further configured to transition from the transition flight mode to the hybrid flight mode in response to the speed of the aircraft decreasing beyond a second vertical threshold and a nacelle angle of one of a wing of the aircraft or a propulsor of the aircraft increasing beyond a first nacelle angle threshold.

83. The control system of claim 82, wherein the second module is further configured to transition from the forward flight mode to the transition flight mode in response to the speed of the aircraft decreasing beyond a third speed threshold and the at least one command, which includes the speed command, decreases below a second speed command threshold.

84. The control system of claim 65, wherein the plurality of configurations of aircraft includes lift-plus-cruise aircraft, tilt-wing aircraft, and vectored thrust aircraft.

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