Roll-biased skid-to-turn end guidance with rudder integrator feedback

Abstract

Systems, devices and methods for an aircraft autopilot guidance and control system (100, 300) for guiding an aircraft having an airframe, the system comprising: a processor (101) configured to determine whether a yaw angle difference and a pitch angle difference meet corresponding angle thresholds; a skid-to-turn module (105) configured to generate a skid-to-turn signal if the corresponding angle thresholds are met; a bank-to-turn module (102) configured to generate a bank-to-turn signal having a lower bandwidth than the generated skid-to-turn signal; a rudder integrator module (104) configured to add a rudder integrator feedback signal to the bank-to-turn signal, the rudder integrator feedback signal being proportional to a rudder integrator; and a filter module (103) configured to filter the generated bank-to-turn signal, the filter module (103) comprising a low pass filter configured with a set of gains to pass the bank-to-turn signal if a lateral force acting on the airframe meets a lateral force threshold (111).

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 194,762, filed May 28, 2021, and claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 314,597, filed February 28, 2022, all of which are incorporated by reference in their entirety herein.

[0002]

[0002] The present invention relates to autopilot control systems, and more particularly to autopilot control systems for terminally guided munitions. [Background technology]

[0003]

[0003] One type of aircraft autopilot guidance includes a control system that enables an aircraft to perform a series of maneuvers and turns to close in and engage a target. The control system operates on the aircraft's control surfaces, such as the ailerons, elevators, and rudder, to guide the aircraft in a desired direction. Summary of the Invention

[0004]

[0004] An aircraft autopilot guidance and control system may include a processor having addressable memory configured to calculate a line-of-sight angle and line-of-sight velocity from the aircraft to a target; determine whether a yaw angle difference and a pitch angle difference meet corresponding angle thresholds; generate a skid-to-turn signal if the corresponding angle thresholds are met; generate a bank-to-turn signal having a lower bandwidth than the skid-to-turn signal if the corresponding angle thresholds are met; add rudder integrator feedback to the bank-to-turn signal proportional to a rudder integrator used in the skid-to-turn signal; and filter the bank-to-turn signal using a low-pass filter configured with a series of gains that passes the bank-to-turn signal if the lateral force of the aircraft meets a lateral force threshold.

[0005]

[0005] One embodiment of an aircraft autopilot guidance control system for guiding an aircraft having an airframe may include a processor configured to determine whether a yaw angle difference and a pitch angle difference meet corresponding angle thresholds; a skid-to-turn module configured to generate a skid-to-turn signal if the corresponding angle thresholds are met; a bank-to-turn module configured to generate a bank-to-turn signal having a lower bandwidth than the generated skid-to-turn signal; a rudder integrator module configured to add a rudder integrator feedback signal to the bank-to-turn signal, the rudder integrator feedback signal may be proportional to a rudder integrator module; and a filter module configured to filter the generated bank-to-turn signal, the filter module comprising a low pass filter configured with a set of gains that pass the bank-to-turn signal if a lateral force acting on the airframe meets a lateral force threshold.

[0006]

[0006] In additional system embodiments, the processor may be further configured to receive a line-of-sight signal from the aircraft to a target, receive a line-of-sight velocity signal, and determine the yaw angle difference and the pitch angle difference based on the line-of-sight signal from the aircraft to the target and the line-of-sight velocity signal. In additional system embodiments, the skid-to-turn module further comprises a loop for implementing the skid-to-turn signal; the rudder integrator module further comprises a rudder integrator feedback gain configured to receive an output from the loop for implementing the skid-to-turn signal; and the bank-to-turn module further comprises a loop for implementing the bank-to-turn signal configured to receive an output from the rudder integrator feedback gain.

[0007]

[0007] In an additional system embodiment, the loop for implementing the skid-to-turn signal includes: an aircraft lateral ratio force command module; a skid-to-turn steady-state gain configured to receive a signal from the aircraft lateral ratio force command module; a skid-to-turn acceleration error summation junction configured to receive a signal from the skid-to-turn steady-state gain; the skid-to-turn acceleration error gain configured to receive a signal from the skid-to-turn acceleration error junction; a skid-to-turn velocity error command summation junction configured to receive a signal from the skid-to-turn acceleration error gain; a skid-to-turn speed error integrator gain configured to receive a signal from a skid-to-turn speed error command summation junction; a rudder integrator module configured to receive a signal from the skid-to-turn speed error integrator gain; a skid-to-turn speed error summation block configured to receive a signal from the rudder integrator module; a skid-to-turn rudder command control gain configured to receive a signal from the skid-to-turn speed error summation block; and a skid-to-turn rudder command dynamic pressure scaling gain configured to receive a signal from the skid-to-turn rudder command control gain.

[0008]

[0008] In an additional system embodiment, the ladder integrator feedback gain may be configured to receive a signal from the ladder integrator module, and the ladder integrator feedback gain may be configured to generate a ladder integrator signal. In an additional system embodiment, the loop for implementing the bank-to-turn signal further comprises: a roll angle command module; an extended bank-to-turn signal generated based on a signal from the roll angle command module and the generated rudder integrator signal; a main filter module configured to receive the extended bank-to-turn signal; a roll angle error summation junction configured to receive a signal from the main filter module; a roll angle error proportional gain configured to receive a signal from the roll angle error summation junction; a roll rate command proportional integral summation junction configured to receive a signal from the roll angle error proportional gain; a roll angle error integral gain configured to receive a signal from the roll angle error summation junction; a roll angle error integrator configured to receive a signal from the roll angle error integral gain; a roll rate error summation junction configured to receive a signal from the roll angle error integrator, a signal from the roll rate command proportional integral summation junction, and a signal from a roll rate feedback gain; and a roll aileron command dynamic pressure scaling gain configured to receive a signal from the roll rate error summation junction.

[0009]

[0009] In additional system embodiments, the roll angle command module further comprises the low pass filter. In additional system embodiments, the roll angle command module may be configured to set a non-zero value to generate the bank to turn signal with a lower bandwidth than the skid to turn signal generated by the aircraft lateral ratio force command module. In additional system embodiments, the main filter module may be configured to decouple the loop for implementing the bank to turn signal from the loop for implementing the skid to turn signal. In additional system embodiments, a low pass filter of the main filter module may be configured to ensure that the bank to turn signal has a lower bandwidth than the skid to turn signal.

[0010]

[0010] In additional system embodiments, the processor may be further configured to: generate one or more actuator commands; and output the one or more actuator commands to vehicle plant dynamics. In additional system embodiments, the vehicle plant dynamics comprises: a skid-to-turn rudder actuator transfer function model configured to receive a signal from the skid-to-turn rudder command dynamic pressure scaling gain; a roll aileron actuator transfer function model configured to receive a signal from the roll aileron command dynamic pressure scaling gain; and a vehicle lateral dynamics state space model configured to receive a signal from the skid-to-turn rudder actuator transfer function model and a signal from the roll aileron actuator transfer function model.

[0011]

[0011] In additional system embodiments, the system may further comprise one or more optical sensors, the one or more optical sensors configured to generate a line of sight from the vehicle to a target. In additional system embodiments, the system may further comprise one or more differentiators, the one or more differentiators configured to generate the line of sight velocity. In additional system embodiments, the generated line of sight velocity includes a derivative of a line of sight vector expressed in an inertial frame.

[0012] In additional system embodiments, the system may further include one or more side force optimizers configured to provide the side force threshold to the processor. In additional system embodiments, the side force threshold may be selected through optimization and set pre-flight.

[0013] In additional system embodiments, the system may further include one or more angle threshold optimizers configured to provide the angle thresholds to the processor. In additional system embodiments, the angle thresholds may be selected through optimization and set prior to the flight.

[0014]

[0014] The components in the drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the present invention. Like reference characters indicate corresponding parts throughout the different views. Embodiments are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. [Brief description of the drawings]

[0015] [Figure 1]

[0015] Figure 1 illustrates normal forces in the pitch plane acting on an aircraft having a control surface, such as a missile, according to one embodiment of the present disclosure. [Figure 2A]

[0016] 1 illustrates an exemplary missile performing a skidding turn in accordance with one embodiment of the present disclosure. [Figure 2B]

[0017] 1 illustrates an exemplary missile performing a banking turn, according to one embodiment of the present disclosure. [Diagram 3]

[0018] FIG. 1 illustrates a high-level block diagram of an embodiment of an aircraft autopilot guidance and control system in accordance with an embodiment of the present disclosure. [Figure 4A]

[0019] FIG. 1 illustrates a block diagram of a combined bank-to-turn / skid-to-turn guidance system according to one embodiment of the present disclosure. [Figure 4B]

[0020] FIG. 1 illustrates a block diagram of an embodiment of a guidance and control method and system in accordance with an embodiment of the present disclosure. [Figure 4C]

[0021] FIG. 1 illustrates a block diagram of an embodiment of a guidance and control method and system in accordance with an embodiment of the present disclosure. [Figure 4D]

[0022] FIG. 1 illustrates a block diagram of an embodiment of a guidance and control method and system in accordance with an embodiment of the present disclosure. [Diagram 5]

[0023] FIG. 2 illustrates a block diagram of one implementation of a main filter module in accordance with an embodiment of the present disclosure. [Figure 6]

[0024] 1 shows the overall configuration of a main filter module according to one embodiment of the present invention. [Figure 7]

[0025] 1 illustrates contributions from skid-to-turn induction and bank-to-turn induction that vary over time according to one embodiment of the present disclosure. [Figure 8]

[0026] 1 illustrates an exemplary aircraft model in simulation and testing according to one embodiment of the present disclosure. [Figure 9A]

[0027] 1 illustrates a step response from an exemplary skid-to-turn guidance system in accordance with one embodiment of the present disclosure. [Figure 9B]

[0028] 1 illustrates a step response based on roll bias skid-to-turn guidance according to one embodiment of the present disclosure. [Figure 10A]

[0029] 1 shows a table containing time domain response data. [Figure 10B]

[0030] 1 shows a table containing the results of the mean error radius. [Figure 11A]

[0031] 1 illustrates a terminal miss distance for a stationary target according to one embodiment of the present disclosure. [Figure 11B]

[0032] 1 illustrates a terminal guidance miss distance for a moving target according to one embodiment of the present disclosure. [Figure 12]

[0033] 1 illustrates a moving target according to one embodiment of the present disclosure. [Figure 13]

[0034] 1 illustrates a method embodiment for guiding a missile using bank-to-turn and skid-to-turn signals. [Figure 14]

[0035] 1 illustrates a high-level block diagram and process of a computing system for implementing one embodiment of the present systems and processes. [Figure 15]

[0036] 1 illustrates a block diagram and process of an exemplary system in which an embodiment may be implemented. [Figure 16]

[0037] 1 illustrates a cloud computing environment for implementing one embodiment of the systems and processes disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016]

[0038] The following description is provided for the purpose of illustrating the general principles of the embodiments disclosed herein and is not intended to limit the concepts disclosed herein. Moreover, specific features described herein may be used in combination with other described features in each of the various possible combinations and permutations. Unless otherwise specifically defined herein, all terms are to be given the broadest possible interpretation, including the meanings suggested by the description and the meanings understood by those skilled in the art and / or defined in dictionaries, treatises, etc.

[0017]

[0039] Disclosed herein are embodiments of methods and systems for aircraft guidance. One embodiment provides a method and system for aircraft autopilot guidance. In one embodiment, bank-to-turn aircraft guidance control includes a control system implementing a method for manipulating aircraft control surfaces such that the aircraft executes a bank turn, thereby rotating the aircraft about its roll axis. During a bank turn, the aircraft is controlled such that the centripetal force experienced by the aircraft is equal to the horizontal component of the vertical lift force. This may be achieved by adjusting the aircraft's ailerons to rotate the aircraft to a desired roll angle. In one example, bank-to-turn guidance is suitable for turns that require large lateral forces. Bank-to-turn (BTT) has the advantage of generating larger lateral forces than skid-to-turn (STT), which may be achieved by commanding a relatively large roll angle (>30 degrees). At these angles, a large pitch normal force is required, which in turn requires a large lateral force.

[0018]

[0040] An aircraft guidance system is disclosed herein that implements a guidance method for guiding an aircraft to a target. In one embodiment, the guidance includes calculating a line-of-sight angle and a line-of-sight velocity from the airframe of the aircraft to the target. The target line-of-sight angle and the line-of-sight velocity are determined using an in-vehicle camera-based target tracker. The camera tracker may be always active when the vehicle is tracking the target. In certain embodiments, the yaw angle and pitch angle thresholds are not related to the camera tracker and may be used only to turn on the roll bias STT algorithm when it is time to engage the target.

[0019]

[0041] The parameters used to determine the yaw angle difference and the pitch angle difference may be Psi, Psi_tgt, and Psi_threshold_for_arcover. Psi is the yaw angle of the aircraft. Psi_tgt is the yaw angle between the yaw angle of the aircraft and the target line-of-sight angle, i.e., the yaw command error or the yaw angle difference. Psi_threshold_for_arcover is whether the absolute value of psi_tgt is less than this threshold, after which the fused STT / BTT guidance is initiated.

[0020]

[0042] Theta is the pitch angle of the aircraft. Theta_tgt is the pitch angle between the pitch angle of the aircraft and the target line-of-sight pitch angle. Theta_threshold_for_arcover is whether theta_tgt is less than (more negative than) theta_tgt, after which the fused STT / BTT guidance is initiated.

[0021]

[0043] The selected angle thresholds may be greater than or less than the comparison. In the case of (abs(psi_tgt)<psi_threshold_for_arcover). In the case of (theta_tgt<theta_threshold_for_arcover). Both thresholds may be selected through optimization.

[0022]

[0044] If a selected angle threshold is met, a skid-to-turn signal is generated, and a bank-to-turn signal having a lower bandwidth than the skid-to-turn signal is generated. After both the bank-to-turn signal and the skid-to-turn signal are generated, a ladder integrator feedback signal is added to the bank-to-turn signal, where the ladder integrator feedback signal is proportional to the ladder integrator.

[0023]

[0045] In one embodiment, the bank-to-turn signal is filtered using a low pass filter configured with a set of gains to pass the bank-to-turn signal if the lateral force command meets the lateral force threshold. The lateral force threshold activates the BTT segment. For low lateral force commands that the STT alone can handle, there is no need to engage the BTT by changing the commanded roll angle. If the commanded lateral force is below the lateral force threshold, the bank-to-turn signal remains constant. This is the threshold that activates the BTT segment. For low lateral force commands that the STT alone can handle, there may be no need to engage the BTT by changing the commanded roll angle. In one embodiment, the lateral force threshold may be determined through optimization.

[0024]

[0046] In some embodiments, a low pass filter may be used to optimize results. For optimal results, it is very important to decouple the BTT and STT signals with a low pass filter. In some embodiments, the disclosed guidance algorithm may function without a filter.

[0025]

[0047] The gains may include tau_phi_roll_bias, phi_stt_int, phi_lim_roll_bias, and phi_cmd_rate_limit. tau_phi_roll_bias is the time constant of the low pass filter. tau_phi_roll_bias may be the only gain of the low pass filter. phi_stt_int is the gain multiplied with the rudder integrator to add additional roll bias. phi_lim_roll_bias is the maximum roll angle that can be commanded from the BTT. phi_cmd_rate_limit is the slew rate limit of the roll angle commanded from the BTT.

[0026]

[0048] The side force threshold on the aircraft's fuselage that meets the side force threshold may be fyp_shreshold_for_roll_bias, where fyp_shreshold_for_roll_bias is the side force command threshold above which BTT is added if (abs(sideforce command)>fyb_threshold_roll_bias).

[0027]

[0049] In one embodiment, skid-to-turn aircraft guidance control includes a control system that implements a method for manipulating aircraft control surfaces such that the aircraft executes a skid turn, thereby rotating the aircraft about its yaw axis. During a skid turn, the centripetal force experienced by the aircraft is controlled to correspond to a horizontal lift force. This may be accomplished by adjusting the aircraft rudder to rotate the aircraft to a desired yaw angle. In one example, skid-to-turn guidance is suitable for turns that require fast and accurate yaw corrections and only small roll corrections.

[0028]

[0050] One type of aircraft configuration has large horizontal wings mounted near the aircraft's center of gravity and steering to guide the vehicle to its intended target. In this configuration, a large normal force counteracts the vehicle's total gravity force as it rolls to generate a lateral horizontal acceleration toward the target, while a rudder on the vertical stabilizer employs a yaw damper to minimize yaw rate and help coordinate turns. This configuration is suitable for long-range cruise missions and has the added benefit of air-breathing combustion engines, as bank-to-turn steering minimizes sideslip that can cause engine misfires.

[0029]

[0051] Engaging a steep terminal target requires minimal normal force to counteract gravity. To generate side force using bank-to-turn in this condition, the system first requires that a pitch normal force be generated. This may initially disrupt the intended vertical track, but when rolled properly, may eventually provide the desired side force. If the currently available normal force is also small, a small side force adjustment may require a large roll angle deviation. This condition is exacerbated in the presence of target tracking noise and may cause a singularity in the roll angle command.

[0030]

[0052] With sufficient lateral authority, employing skid-to-turn lateral control decouples pitch and yaw motion, improving speed of response and reducing lateral miss distances. Adding vertical wings to create a cruciform configuration provides the necessary lateral authority, but the resulting drag contribution significantly reduces long-range performance.

[0031]

[0053] In one embodiment disclosed herein, the aircraft autopilot guidance control includes skid-to-turn guidance and bank-to-turn guidance, where the skid-to-turn guidance is augmented with the bank-to-turn guidance to provide lateral acceleration control. In a preferred embodiment, the system uses only STT. In some embodiments, when large yaw corrections, e.g., and therefore large lateral forces, are required, STT is insufficient. Since the advantage of BTT is large lateral force capability, when STT is augmented with BTT, this gap is filled.

[0032]

[0054] An embodiment of the guidance method disclosed herein includes calculating a line-of-sight angle and line-of-sight velocity from the aircraft fuselage to the target. The target line-of-sight angle and line-of-sight velocity are used to determine whether the aircraft's yaw angle difference and pitch angle difference meet corresponding selected angle thresholds. If the selected angle thresholds are met, then a skid-to-turn signal is generated, and a bank-to-turn signal having a lower bandwidth than the skid-to-turn signal is generated. After both the bank-to-turn signal and the skid-to-turn signal are generated, a rudder integrator feedback signal is added to the bank-to-turn signal and the skid-to-turn signal, where the rudder integrator feedback signal is proportional to the rudder integrator. In one embodiment, the bank-to-turn signal is filtered using a low-pass filter configured with a set of gains to pass the bank-to-turn signal if a lateral force acting on the aircraft fuselage meets a lateral force threshold.

[0033]

[0055] An embodiment of the system and method disclosed herein provides roll-biased skid-to-turn guidance with rudder integrator feedback. One example of a control system and method includes a skid-to-turn three-loop lateral acceleration control autopilot augmented with bank-to-turn steering proportional to the skid-to-turn three-loop integrator. This blended autopilot gradually offloads large persistent lateral force commands to the bank-to-turn control loop while maintaining high skid-to-turn bandwidth. Optimization of associated gains is employed to provide the desired response and reduce miss distances.

[0034]

[0056] Exemplary embodiments of the disclosed methods and systems are further described herein with reference to the drawings.

[0035]

[0057] 1 shows a diagram 10 of normal forces in the pitch plane acting on an aircraft having control surfaces, such as a missile 30. In this case, the missile 30 is flying at an angle of attack α equal to the pitch angle θ, a bank angle Φ, and a zero sideslip angle. The normal forces in the pitch plane are rotated by controlling the bank angle Φ to guide the missile 30 towards a target.

[0036]

[0058] 2A shows an exemplary missile 40 executing a skid turn 41 in the yaw plane. The missile 40 completes the skid turn by rotating the roll axis of the missile 40 approximately 90 degrees from its original orientation.

[0037]

[0059] 2B shows an exemplary missile 50 executing a bank turn 51 in the roll plane. The missile 50 completes the bank turn by rotating the yaw and pitch axes of the missile 50 approximately 30 degrees from their original orientation.

[0038]

[0060] FIG. 3 illustrates a high-level block diagram of an embodiment of an aircraft autopilot guidance and control system 100. The aircraft autopilot guidance and control system 100 may include a processor 101 having an addressable memory 106. The processor 101 may be configured to calculate a line of sight from the aircraft to a target from one or more optical sensors 107 providing one or more optical sensor measurements. The processor 101 may also be configured to calculate a line of sight velocity from one or more differentiators 108. The one or more differentiators 108 may provide a derivative of the line of sight vector expressed in an inertial frame. One or more angle threshold optimizers 109 may provide one or more angle thresholds to the processor 101. The angle thresholds may be selected through optimization and may be set pre-flight. One or more side force optimizers 111 may provide one or more side force thresholds to the processor 101. The side force thresholds may be selected through optimization and may be set pre-flight. The processor 101 may be further configured to determine whether the yaw angle difference and the pitch angle difference satisfy corresponding angle thresholds provided by one or more angle threshold optimizers 109. In some embodiments, the one or more angle threshold optimizers 109 may determine the angle thresholds through offline optimization to find parameters that give the best accuracy results. In some embodiments, once the angle thresholds are determined, the angle thresholds may be set and may not change during flight. The processor 101 may be further configured to generate a skid-to-turn signal via the skid-to-turn module 105 if the corresponding angle thresholds from the one or more optimizers 109 are satisfied. The processor 101 may be further configured to generate a bank-to-turn signal via the bank-to-turn module 102 having a lower bandwidth than the skid-to-turn signal from the skid-to-turn module 105 if the corresponding thresholds from the one or more optimizers 109 are satisfied. The processor 101 may further be configured to add ladder integrator feedback to the bank-to-turn module 102 via a ladder integrator module 104 that is proportional to the ladder integrator used in the skid-to-turn signal from the skid-to-turn module 105.The processor 101 may be further configured to filter the bank-to-turn signal from the bank-to-turn module 102 using a low pass filter 103 configured with a set of gains to pass the bank-to-turn signal from the bank-to-turn module 102 if the side force of the airframe meets a side force threshold from the one or more side force optimizers 111. In some embodiments, the one or more angle side force optimizers 111 may determine the side force threshold through offline optimization to find the parameters that give the best accuracy results. In some embodiments, once the side force threshold is determined, the side force threshold may be set and may not change during flight. The processor 101 may be further configured to send actuator commands to the vehicle plant dynamics module 112. The actuator commands and vehicle plant dynamics 112 module may control actuators, ailerons, elevators, rudders, etc. to control the aircraft and / or missile in BTT and / or STT maneuvers.

[0039]

[0061] 4A illustrates a bank-to-turn and skid-to-turn fusion guidance system 60 using linear plant dynamics. The system 60 may include a loop 62 that performs bank-to-turn guidance and a loop 61 that performs skid-to-turn guidance. In some embodiments, both loops 61, 62 may run simultaneously. The vehicle lateral ratio force command module 320 is configured to generate a skid-to-turn signal. The roll angle command module 350 may be configured to be set to a non-zero value to generate a bank-to-turn signal having a lower bandwidth than the skid-to-turn signal generated by the vehicle lateral ratio force command module 320.

[0040]

[0062] Loop 62 is configured to implement the bank-to-turn internal control guidance processing, and in one embodiment, loop 62 includes processor modules 341, 342, 343, 344, 345, 346, and 347. These include a roll angle error sum junction 341, a roll angle error proportional gain 342, a roll rate command proportional integral sum junction 343, a roll angle error integral gain 344, a roll angle error integrator 345, a roll rate error sum junction 346, and a roll rate feedback gain 347.

[0041]

[0063] Loop 61 is configured to perform skid-to-turn guidance processing, and in one embodiment, loop 61 includes processor modules 311, 312, 313, 314, 315, 330, 316, and 317. These include skid-to-turn steady-state gain 311, skid-to-turn acceleration error summation junction 312, skid-to-turn acceleration error gain 313, skid-to-turn speed error command summation junction 314, skid-to-turn speed error integrator gain 315, rudder integrator module 330, skid-to-turn speed error summation block 316, and skid-to-turn rudder command control gain 317.

[0042]

[0064] 4B illustrates a block diagram of one embodiment of the guidance and control method and system 300 disclosed herein. System 300 includes a loop 310 for performing skid-to-turn (STT) guidance and a loop 340 for performing bank-to-turn (BTT) guidance coupled to STT loop 310 by linear plant dynamics and rudder integrator feedback.

[0043]

[0065] In one embodiment, the STT loop 310 includes an aircraft lateral ratio force command module 320 for generating a skid-to-turn signal, and a rudder integrator module 330. In one embodiment, the BTT loop 340 may include a roll angle command module 350 set to a non-zero value to generate a bank-to-turn signal having a lower bandwidth than the skid-to-turn signal generated by the aircraft lateral ratio force command module 320.

[0044]

[0066] The bank-to-turn signal from the roll angle command module 350 is extended in the command junction module by including, e.g., adding, a ladder integrator feedback gain 335 from the ladder integrator module 330. A ladder integrator signal 351 is a ladder integrator feedback signal to the ladder integrator 330. The ladder integrator 330 multiplies the ladder integrator feedback gain 335 to generate the ladder integrator signal 351. The extended bank-to-turn signal 352 may be input to a main filter module 360. The main filter 360 may decouple the outer loop 340 and the inner loop 310.

[0045]

[0067] The "Ladder Integrator Feedback" portion includes ladder integrator 330, ladder integrator feedback gain 335, and bank-to-turn component due to ladder integrator feedback 351. A low pass filter in main filter module 360 ​​ensures that the bank-to-turn signal has a lower bandwidth than the skid-to-turn controller. In one embodiment, the bank-to-turn inner control loop includes processor modules 341, 342, 343, 344, 345, 346, and 347. These include roll angle error sum junction 341, roll angle error proportional gain 342, roll velocity command proportional integral sum junction 343, roll angle error integral gain 344, roll angle error integrator 345, roll velocity error sum junction 346, and roll velocity feedback gain 347.

[0046]

[0068] Shown in Figure 4B is a proportional-integral-derivative (PID) feedback control loop. In some embodiments, this "inner control loop" may use other architectures while maintaining roll bias skid-to-turn as in the disclosed systems and methods. In one embodiment, the skid-to-turn inner loop controller comprises processor modules 311, 312, 313, 314, 315, 330, 316, and 317. These include skid-to-turn steady-state gain 311, skid-to-turn acceleration error summation junction 312, skid-to-turn acceleration error gain 313, skid-to-turn speed error command summation junction 314, skid-to-turn speed error integrator gain 315, rudder integrator module 330, skid-to-turn speed error summation block 316, and skid-to-turn rudder command control gain 317.

[0047]

[0069] FIG. 4B illustrates a three-loop inner loop control architecture. In some embodiments, different inner loop control architectures may be substituted while maintaining the disclosed roll biased skid-to-turn algorithm. FIG. 4B also illustrates roll aileron command dynamic pressure scaling gain 348, roll aileron actuator transfer function model 349, roll signal scope 381, skid-to-turn rudder command dynamic pressure scaling gain 318, skid-to-turn rudder actuator transfer function model 319, vehicle lateral dynamics state space model 380, and skid-to-turn signal scope 382. The scopes 381, 382 may be used to display the time history of the signals. The scopes 381, 382 may be used for visualization and / or analysis in the simulation. The scopes 381, 382 may not be part of the algorithm and / or may run on the processor (101, FIG. 3). One or more optical sensors 390 provide line of sight from the vehicle to the target. One or more differentiators 392 provide line of sight velocity.

[0048]

[0070] FIG. 4C illustrates a block diagram of an embodiment of a guidance and control method and system 301 according to an embodiment of the present disclosure. FIG. 4C is an example of FIG. 3. Elements of FIG. 3 are mapped to elements of the embodiment of FIG. 4C. Referring to FIG. 3 and FIG. 4C, the processor 101 includes elements: a loop for performing skid-to-turn (STT) guidance 310, a skid-to-turn steady-state gain 311, a skid-to-turn acceleration error summation junction 312, a skid-to-turn acceleration error gain 313, a skid-to-turn speed error command summation junction 314, a skid-to-turn speed error integrator gain 315, a skid-to-turn speed error summation block 316, a skid-to-turn rudder command control gain 317, a skid-to-turn rudder command dynamic pressure scaling gain 318, a vehicle lateral ratio force command module 32, and a skid-to-turn acceleration error summation junction 330. 0, rudder integrator feedback gain 335, loop for performing bank-to-turn (BTT) guidance 340, roll angle error summation junction 341, roll angle error proportional gain 342, roll rate command proportional integral summation junction 343, roll angle error integral gain 344, roll angle error integrator 345, roll rate error summation junction 346, roll rate feedback gain 347, roll aileron command dynamic pressure scaling gain 348, roll angle command module 350, rudder integrator signal 351, extended bank-to-turn signal 352, and main filter module 360. The bank-to-turn module 102 may include: a loop for performing bank-to-turn (BTT) guidance 340, a roll angle error summation junction 341, a roll angle error proportional gain 342, a roll rate command proportional gain 342, a roll rate command proportional integral summation junction 343, a roll angle error integral gain 344, a roll angle error integrator 345, a roll rate error summation junction 346, a roll rate feedback gain 347, a roll aileron command dynamic pressure scaling gain 348, a roll angle command module 350, a rudder integrator signal 351, an extended bank-to-turn signal 352, and a main filter module 360. The low pass filter 103 may include the following elements: a roll angle command module 350.The rudder integrator module 104 may include an element: rudder integrator feedback gain 335. The skid-to-turn module 105 may include elements: loop for performing skid-to-turn (STT) guidance 310, skid-to-turn steady-state gain 311, skid-to-turn acceleration error summation junction 312, skid-to-turn acceleration error gain 313, skid-to-turn speed error command summation junction 314, skid-to-turn speed error integrator gain 315, skid-to-turn speed error summation block 316, skid-to-turn rudder command control gain 317, skid-to-turn rudder command dynamic pressure scaling gain 318, and vehicle lateral ratio force command module 320. The optical sensor 107 may include an element: optical sensor 390. The differentiator 108 may include an element: differentiator 392. Vehicle plant dynamics 112 may include the elements: skid-to-turn rudder actuator transfer function model 319 , roll aileron actuator transfer function model 349 , and lateral body dynamics state space model 380 .

[0049]

[0071] The optical sensor 390 may provide a line of sight from the vehicle to the target to a differentiator 392, the vehicle lateral force command module 320, and the roll angle command module 350. The differentiator 392 may receive a line of sight from the vehicle to the target from the optical sensor 390. The differentiator 392 may provide a line of sight velocity to the vehicle lateral force command module 320 and the roll angle command module 350.

[0050]

[0072] Vehicle lateral ratio force command module 320 may receive the line of sight from the vehicle to the target from optical sensor 390 and the line of sight velocity from differentiator 392. Vehicle lateral ratio force command module 320 may output a signal to skid-to-turn steady-state gain 311 based on the received line of sight from the vehicle to the target and the line of sight velocity.

[0051]

[0073] Skid-to-turn steady-state gain 311 may receive a signal from vehicle lateral ratio force command module 320. Skid-to-turn steady-state gain 311 may output a signal to skid-to-turn acceleration error summation junction 312. Skid-to-turn acceleration error summation junction 312 may output a signal to skid-to-turn acceleration error gain 313. Skid-to-turn acceleration error gain 313 may output a signal to skid-to-turn speed error command summation junction 314. Skid-to-turn speed error command summation junction 314 may output a signal to skid-to-turn speed error integrator gain 315. Skid-to-turn speed error integrator gain 315 may output a signal to rudder integrator module 330. Rudder integrator module 330 may output a signal to skid-to-turn speed error summation block 316 and rudder integrator feedback gain 335. Rudder integrator 330 is multiplied by rudder integrator feedback gain 335 to generate rudder integrator signal 351. Skid-to-turn speed error summation block 316 may output a signal to skid-to-turn rudder command control gain 317. Skid-to-turn rudder command control gain 317 may output a signal to skid-to-turn rudder command dynamic pressure scaling gain 318.

[0052]

[0074] The roll angle command module 350 may receive the line of sight from the vehicle to the target from the optical sensor 390 and the line of sight velocity from the differentiator 392. The roll angle command module 350 may output a signal based on the received line of sight from the vehicle to the target and the line of sight velocity summed with the generated rudder integrator signal 351 to output an extended bank-to-turn signal 352.

[0053]

[0075] The extended bank-to-turn signal 352 may be input to a main filter module 360. The main filter module 360 ​​may decouple the outer loop 340 from the inner loop 310. The main filter module 360 ​​may output a signal to a roll angle error summing junction 341. The roll angle error summing junction 341 may output a signal to a roll angle error proportional gain 342 and a roll angle error integral gain 344. The roll angle error integral gain 344 may output a signal to a roll angle error integrator 345. The roll angle error integrator 345 may output a signal to a roll rate command proportional integral summing junction 343. The roll angle error proportional gain 342 may output a signal to a roll rate command proportional integral summing junction 343. The roll rate command proportional integral summing junction 343 may sum the signals from the roll angle error integrator 345 and the roll angle error proportional gain 342. The roll rate command proportional integral summation junction 343 may output a signal to a roll rate error summation junction 346. The roll rate error summation junction 346 may receive signals from the roll rate command proportional integral summation junction 343 and a roll rate feedback gain 347. The roll rate error summation junction 346 may output a signal to a roll aileron command dynamic pressure scaling gain 348.

[0054]

[0076] Skid-to-turn rudder actuator transfer function model 319 may receive a signal from skid-to-turn rudder command dynamic pressure scaling gain 318. Skid-to-turn rudder actuator transfer function model 319 may output a signal to vehicle lateral dynamics state space model 380. Roll aileron actuator transfer function model 349 may receive a signal from roll aileron command dynamic pressure scaling gain 348. Roll aileron actuator transfer function model 349 may output a signal to vehicle lateral dynamics state space model 380.

[0055]

[0077] FIG. 4D illustrates a block diagram of an embodiment of a guidance control method and system 302 according to an embodiment of the present disclosure. FIG. 4D is an example of FIG. 3. The processor 101 with the addressable memory 106 may communicate with one or more modules. The one or more modules may be embodied as logic and / or analog circuits in communication with the processor 101. The logic and / or analog circuits include a loop 310 for performing skid-to-turn (STT) guidance, a skid-to-turn steady-state gain 311, a skid-to-turn acceleration error summation junction 312, a skid-to-turn acceleration error gain 313, a skid-to-turn speed error command summation junction 314, a skid-to-turn speed error integrator gain 315, a skid-to-turn speed error summation block 316, a skid-to-turn rudder command control gain 317, a skid-to-turn rudder command dynamic pressure scaling gain 318, a vehicle lateral ratio force command module 320, a rudder integrator feedback gain 335, a loop 34 for performing bank-to-turn (BTT) guidance, and a rudder integrator feedback gain 336. 0, roll angle error summation junction 341, roll angle error proportional gain 342, roll rate command proportional integral summation junction 343, roll angle error integral gain 344, roll angle error integrator 345, roll rate error summation junction 346, roll rate feedback gain 347, roll aileron command dynamic pressure scaling gain 348, roll angle command module 350, rudder integrator signal 351, extended bank-to-turn signal 352, main filter module 360, skid-to-turn rudder actuator transfer function model 319, roll aileron actuator transfer function model 349, vehicle lateral dynamics state space model 380, optical sensors 390 and / or differentiators 392.

[0056]

[0078] FIG. 5 illustrates a block diagram of one implementation of the main filter module 360 ​​according to one embodiment. In one embodiment, the threshold check for modifying the bank to turn signal includes processor modules 370, 361, 350a, 350b, and 362. In one embodiment, the bank to turn filter includes processor modules 363, 364, and 365 that ensure that the bank to turn signal has a lower bandwidth than the skid to turn signal. The main filter module 360 ​​receives as data inputs a current roll angle command input 350a and a previous roll angle command input 350b from the roll angle command module 350 and generates a roll angle command filter output 350c. The switch 362, saturation limit 361, low pass filter 364, and slew rate limit 365 are steps in generating the bank to turn signal 350c. In one embodiment, the roll angle command module 350 implements the skid to turn method and process. The main filter module 360 ​​utilizes an absolute value module 361 to determine the absolute value of the vehicle lateral specific force input 370 from the vehicle lateral specific force command module 320 as a control input.

[0057]

[0079] In one embodiment, the main filter module 360 ​​includes a switch module 362 for switching between the signal from the current roll angle command module 350a and the signal from the previous roll angle command module 350b. In one example, the switch module 362 performs the switching by determining whether the absolute value of the vehicle lateral force input 370 meets a lateral force threshold. If the lateral force threshold is met, the switch module 362 outputs the signal from the current roll angle command module 350a. If the lateral force threshold is not met, the switch module 362 may output the signal from the previous roll angle command module 350b. The output of the switch module 362 is then filtered through a saturation limit module 363, a first order low pass filter module 364, and a velocity limit module 365 before being output as the roll angle command output signal 350c.

[0058]

[0080] 6 shows the overall configuration of a main filter module 400 according to one embodiment of the present invention. The main filter module 400 may be configured by adjusting a set of gains 410 to adjust 411 the bank-to-turn dynamics. In one embodiment, all of these gains may be adjusted to achieve a desired response.

[0059]

[0081] 7 illustrates the contributions 700 from skid-to-turn and bank-to-turn guidance that change over time when a lateral force threshold is met, according to one embodiment of the present disclosure. As time passes and the aircraft approaches the target, the contributions 700 shift from a skid-to-turn (STT) signal to a bank-to-turn (BTT) signal. Fyb_cmd is the lateral force command. Fyb_cmd by STT is the lateral force command due to skid-to-turn. Fyb_cmd by BTT is the lateral force command due to bank-to-turn.

[0060]

[0082] FIG. 8 illustrates an exemplary aircraft model 800 for simulation and testing according to one embodiment of the present disclosure. The aircraft used for the results of FIG. 8 is a scaled Citation II Model 550 aircraft. The mass may be 33.105 lbs. The reference area is 701.6623 in. 2 The reference chord may be 10.1250 inches. The reference wingspan may be 69.3000 inches. The reference center of gravity may be -32.8500 inches from the nose. Other airframes and airframe parameters are possible and considered.

[0061]

[0083] FIG. 9A shows a step response 900 in response to a step input in Fyb_cmd (lateral force command) from a typical skid-to-turn guidance system.

[0062]

[0084] FIG. 9B illustrates a step response 902 from bank-to-turn guidance augmented with guidance-based rudder integrator feedback according to one embodiment of the present disclosure.

[0063]

[0085] 10A shows a table 1000 containing time domain response data. For a basic skid-to-turn, the rise time may be about 2.137 seconds and the settling time may be about 3.030 seconds. For a roll biased skid-to-turn with ladder integrator feedback, the rise time may be about 1.170 seconds and the settling time may be about 2.159 seconds. The rise and settling times of the roll biased skid-to-turn with ladder integrator feedback control architecture are less than the rise and settling times of the basic skid-to-turn control architecture.

[0064]

[0086] FIG. 10B shows a table 1002 including mean error radius results, according to an embodiment of the present disclosure. Mean error radius (CEP) is defined as the radius of a circle centered on the aim point where the probability of hitting is 50%. P90 means that 90% of the estimates are above the P90 estimate. The bank-to-turn control architecture may have a CEP of about 0.188 and a P90 of about 0.681 for stationary targets, and a CEP of about 0.272 and a P90 of about 1.065 for moving targets. The skid-to-turn control architecture may have a CEP of about 0.159 and a P90 of about 0.711 for stationary targets, and a CEP of about 0.259 and a P90 of about 1.271 for moving targets. A roll biased skid-to-turn with rudder integral feedback control architecture may have a CEP of about 0.115 and a P90 of about 0.315 for stationary targets, and a CEP of about 0.236 and a P90 of about 0.656 for moving targets.

[0065]

[0087] FIG. 11A illustrates terminal guidance miss distance for a stationary target based on BTT 1100, STT 1102, and roll biased skid-to-turn guidance 1104 with rudder integrator feedback according to one embodiment disclosed herein.

[0066]

[0088] Figure 11B illustrates the terminal guidance miss distance of a moving target based on BTT 1106, STT 1108, and roll biased skid-to-turn guidance with rudder integrator feedback 1110 according to one embodiment disclosed herein. Figures 11A and 11B therefore illustrate the improvement shown when using the systems and methods disclosed herein for roll biased skid-to-turn guidance with rudder integrator feedback over STT guidance alone and BTT guidance alone.

[0067]

[0089] 12 is a graphical illustration 1200 of a moving target, according to one embodiment of the present disclosure. The moving target is moving, for example, at approximately 18 miles per hour. The systems and methods disclosed herein for roll biased skid-to-turn guidance using rudder integrator feedback may be used to more accurately strike this target as compared to STT guidance alone and BTT guidance alone.

[0068]

[0090] FIG. 13 illustrates a flow chart of a guidance method embodiment 1300 according to an embodiment of the present disclosure. The method 1300 may begin by calculating a line-of-sight angle and line-of-sight velocity from the vehicle to the target (step 1302). After the target line-of-sight angle and line-of-sight velocity are calculated, the method 1300 may then include determining whether the yaw angle difference and the pitch angle difference meet corresponding angle thresholds (step 1304). If the angle thresholds are met, the method 1300 may then generate a skid-to-turn signal (step 1306) and generate a bank-to-turn signal having a lower bandwidth than the skid-to-turn signal (step 1308). After both the bank-to-turn signal and the skid-to-turn signal are generated, a rudder integrator feedback signal is added to the bank-to-turn signal, where the rudder integrator feedback signal is proportional to the rudder integrator (step 1310). In one implementation, after both the bank-to-turn signal and the skid-to-turn signal are generated, the method may then add a rudder integrator feedback signal to the skid-to-turn signal and the bank-to-turn signal. Method 1300 may then filter the bank-to-turn signal using a low pass filter configured with a set of gains to pass the bank-to-turn signal if the vehicle's lateral force meets a lateral force threshold (step 1312).

[0069]

[0091] 14 is a high-level block diagram 1400 illustrating a computing system that includes a computer system useful for implementing an embodiment of the systems and processes disclosed herein. The system embodiments may be implemented in different computing environments. The computer system includes one or more processors 1402, and further includes an electronic display device 1404 (e.g., for displaying graphics, text, and other data), a main memory 1406 (e.g., random access memory (RAM)), a storage device 1408, a removable storage device 1410 (e.g., a removable storage drive, a removable memory module, a magnetic tape drive, an optical disk drive, a computer-readable medium on which computer software and / or data is stored), a user interface device 1411 (e.g., a keyboard, a touch screen, a keypad, a pointing device), and a communication interface 1412 (e.g., a modem, a network interface (e.g., an Ethernet card), a communication port or a PCMCIA slot and card). The communication interface 1412 allows software and data to be transferred between the computer system and external devices. The system further includes a communications infrastructure 1414 (eg, a communications bus, crossover bar, or network) to which the aforementioned devices / modules are connected as shown.

[0070]

[0092] Information transferred via communications interface 1414 may be in the form of signals, such as electronic, electromagnetic, optical or other signals receivable by communications interface 1414 via communications link 1416 carrying the signals, and may be implemented using wire or cable, optical fiber, telephone line, cellular / mobile phone link, radio frequency (RF) link and / or other communications channels. Computer program instructions, represented in the block diagrams and / or flowcharts herein, may be loaded into a computer, programmable data processing device or processor and executed thereon to generate a computer-implemented process by a sequence of operations.

[0071]

[0093] The embodiments have been described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to the embodiments. Each block of such diagrams / schematics, or combinations thereof, may be implemented by computer program instructions. The computer program instructions, when provided to a processor, generate a machine such that the instructions executed by the processor create means for implementing the functions / operations identified in the flowcharts and / or block diagrams. Each block of the flowcharts / block diagrams may represent a module or logic of hardware and / or software for implementing the embodiments. In alternative implementations, the functions illustrated in the blocks may occur out of the order shown in the figures, simultaneously, etc.

[0072]

[0094] Computer programs (i.e., computer control logic) are stored in the main memory and / or secondary memory. Computer programs may be received via communications interface 1412. Such computer programs, when executed, enable the computer system to perform features of the embodiments described herein. In particular, the computer programs, when executed, enable the processor and / or multi-core processor to perform the functions of the computer system. Such computer programs represent the controller of the computer system.

[0073]

[0095] FIG. 15 illustrates a block diagram of an exemplary system 1500 in which an embodiment may be implemented. The system 1500 includes one or more client devices 1501, such as consumer electronics devices, connected to one or more server computing systems 1530. The server 1530 includes a bus 1502 or other communication mechanism for communicating information and a processor (CPU) 1504 coupled to the bus 1502 for processing information. The server 1530 also includes a main memory 1506, such as a random access memory (RAM) or other dynamic storage device, coupled to the bus 1502 for storing information and instructions to be executed by the processor 1504. The main memory 1506 may also be used to store temporary variables or other intermediate information or instructions to be executed by the processor 1504 during execution. The server computing system 1530 further includes a read only memory (ROM) 1508 or other static storage device coupled to the bus 1502 for storing static information and instructions for the processor 1504. A storage device 1510, such as a magnetic disk or optical disk, is provided and coupled to bus 1502 for storing information and instructions. Bus 1502 may include, for example, 32 address lines for addressing a video memory or main memory 1506. Bus 1502 may include, for example, a 32-bit data bus for transferring data between components such as CPU 1504, main memory 1506, video memory and storage 1510. Alternatively, multiple data / address lines may be used in place of separate data and address lines.

[0074]

[0096] The server 1530 may be coupled via the bus 1502 to a display 1512 for displaying information to a computer user. An input device 1514, including alphanumeric and other keys, is coupled to the bus 1502 for communicating information and command selections to the processor 1504. Another type or user input device includes a cursor control 1516, such as a mouse, trackball, or cursor direction keys, for communicating directional information and command selections to the processor 1504 and for controlling cursor movement on the display 1512.

[0075]

[0097] According to one embodiment, the functions are performed by the processor 1504 executing one or more sequences of one or more instructions contained in the main memory 1506. Such instructions may be read into the main memory 1506 from another computer-readable medium, such as the storage device 1510. Execution of the sequences of instructions contained in the main memory 1506 causes the processor 1504 to perform the process steps described herein. One or more processors in a multi-processing arrangement may be employed to execute the sequences of instructions contained in the main memory 1506. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the embodiments. Thus, the embodiments are not limited to any specific combination of hardware circuitry and software.

[0076]

[0098] The terms "computer program medium", "computer usable medium", "computer readable medium" and "computer program product" are generally used to refer to media and signals such as main memory, secondary memory, removable storage drive, hard disk attached to hard disk drive, etc. These computer program products are means for providing software to a computer system. The computer readable medium enables the computer system to read data, instructions, messages or message packets and other computer readable information from the computer readable medium. The computer readable medium may include non-volatile memory such as, for example, floppy disks, ROMs, flash memory, disk drive memory, CD-ROMs and other permanent storage devices. They are useful for transferring information such as, for example, data and computer instructions between computer systems. Furthermore, the computer readable medium may include computer readable information in a temporary state medium such as a network link and / or a network interface, including a wired or wireless network, that enables a computer to read such computer readable information. The computer program (also referred to as computer control logic) is stored in the main memory and / or secondary memory. The computer program may be received via a communication interface. Such computer programs, when executed, enable the computer system to perform the functions of the embodiments described herein. In particular, computer programs, when executed, enable the multi-core processor to perform the functions of the computer system and thus represent the controller of the computer system.

[0077]

[0099] In general, the term "computer-readable medium" as used herein refers to any medium that participates in providing instructions to the processor 1504 for execution. Such media may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as storage device 1510. Volatile media include dynamic memory, such as main memory 1506. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise bus 1502. Transmission media can take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications.

[0078]

[0100] Common types of computer readable media include, for example, a floppy disk, a flexible disk, a hard disk, a magnetic tape or any other magnetic medium, a CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with a pattern of holes, RAM, PROM, EPROM, FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described below, or any other medium from which a computer can read.

[0079]

[0101] Various types of computer readable media may be involved in carrying one or more sequences of one or more instructions to the processor 1504 for execution. For example, the instructions may initially be stored on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to the server 1530 can receive the data on the telephone line and use an infrared transmitter to convert the data to an infrared signal. An infrared detector coupled to the bus 1502 can receive the data carried in the infrared signal and place the data on the bus 1502. The bus 1502 carries the data to main memory 1506, from which the processor 1504 retrieves and executes the instructions. The instructions received from main memory 1506 may optionally be stored on storage device 1510 either before or after execution by the processor 1504.

[0080]

[0102] The server 1530 also includes a communication interface 1518 coupled to the bus 1502. The communication interface 1518 provides a two-way data communication coupling to a network link 1520 that is connected to the worldwide packet data communication network now commonly referred to as the Internet 1528. The Internet 1528 uses electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on the network link 1520 and through the communication interface 1518, which carry the digital data to and from the server 1530, are exemplary forms or carrier waves transporting the information.

[0081]

[0103] In another embodiment of the server 1530, the interface 1518 is connected to the network 1522 via a communications link 1520. For example, the communications interface 1518 may be an Integrated Services Digital Network (ISDN) card or a modem providing a data communications connection to a corresponding type of telephone line, which may form part of the network link 1520. As another example, the communications interface 1518 may be a Local Area Network (LAN) card to provide a data communications connection to a compatible LAN. A wireless link may also be implemented. In any such implementation, the communications interface 1518 sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

[0082]

[0104] Network link 1520 typically provides data communication through one or more networks to other data devices. For example, network link 1520 may provide a connection through local network 1522 to a host computer 1524 or to data equipment operated by an Internet Service Provider (ISP). The ISP, in turn, provides data communication services through the Internet 1528. Local network 1522 and Internet 1528 both use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and through network link 1520 and communication interface 1518, which carry the digital data to and from the server 1530, are exemplary forms or carrier waves transporting the information.

[0083]

[0105] Server 1530 can send and receive messages and data, including e-mail, program code, through the network, network link 1520 and communication interface 1518. Further, communication interface 1518 can comprise a USB / tuner, and network link 1520 can be an antenna or cable for connecting server 1530 to a cable provider, satellite provider or other terrestrial transmission system for receiving messages, data and program code from another source.

[0084]

[0106] Exemplary versions of the embodiments described herein may be implemented as logical operations in a distributed processing system, such as system 1500, including server 1530. The logical operations of the embodiments may be implemented as a series of steps executed on server 1530 and as interconnected machine modules within system 1500. The implementation is a matter of choice and may depend on the capabilities of system 1500 implementing the embodiment. Thus, the logical operations making up the exemplary versions of the embodiments may be referred to as, for example, operations, steps or modules.

[0085]

[0107] Similar to the server 1530 described above, the client device 1501 may include a processor, memory, storage, a display, an input device, and a communication interface (e.g., an email interface) to connect the client device to the Internet 1528, an ISP or a LAN 1522 for communication with the server 1530.

[0086]

[0108] The system 1500 may further include a computer (e.g., a personal computer, a computing node) 1505 that operates similarly to the client device 1501, and a user may utilize one or more computers 1505 to manage data on the server 1530.

[0087]

[0109] Referring now to FIG. 16, an exemplary cloud computing environment 50 is shown. As shown, the cloud computing environment 50 comprises one or more cloud computing nodes 1610, by which local computing devices used by cloud consumers, such as personal digital assistants (PDAs), smartphones, smart watches, set-top boxes, video game systems, tablets, mobile computing devices or mobile phones 54A, desktop computers 54B, laptop computers 54C, and / or automobile computer systems 54N, may communicate with each other. The nodes 1610 may be physically or virtually grouped (not shown) in one or more networks, such as the aforementioned private, community, public, or hybrid clouds, or combinations thereof. The cloud computing environment 1650 thereby enables cloud consumers to provide infrastructure, platforms, and / or software as a service without having to maintain resources on local computing devices. It will be understood that the types of computing devices 54A-N shown in FIG. 16 are for illustrative purposes only, and that the computing node 1610 and cloud computing environment 1650 can communicate with any type of computerized device via any type of network and / or network-addressable connection (e.g., using a web browser).

[0088]

[0110] It is contemplated that various combinations and / or subcombinations of the specific features and aspects of the above-described embodiments may be made and are within the scope of the present invention. Accordingly, it is to be understood that various features and aspects of the disclosed embodiments may be combined with or substituted for one another in order to form varying modes of the disclosed invention. Furthermore, it is intended that the scope of the invention(s) disclosed herein by way of example should not be limited by the specific disclosed embodiments described above.

Claims

1. An aircraft automatic pilot guidance control system for guiding an aircraft having an airframe, the system comprising: a processor configured to determine whether a yaw angle difference and a pitch angle difference satisfy corresponding angle thresholds; a skid-to-turn module configured to generate a skid-to-turn signal when the corresponding angle threshold is satisfied; a bank-to-turn module configured to generate a bank-to-turn signal having a bandwidth lower than that of the generated skid-to-turn signal; a ladder integrator module configured to add a ladder integrator feedback signal to the bank-to-turn signal, the ladder integrator feedback signal being proportional to a ladder integrator; a filter module configured to filter the generated bank-to-turn signal, the filter module comprising a low-pass filter configured by a set of gains for passing the bank-to-turn signal when a lateral force acting on the airframe satisfies a lateral force threshold, an aircraft automatic pilot guidance control system for guiding an aircraft having an airframe.

2. The system according to claim 1, wherein the processor is further configured to receive a line-of-sight signal from the airframe to the target, receive a line-of-sight velocity signal, and determine the yaw angle difference and the pitch angle difference based on the line-of-sight signal from the airframe to the target and the line-of-sight velocity signal.

3. The skid-to-turn module further comprises a loop for implementing the skid-to-turn signal, the ladder integrator module further comprises a ladder integrator feedback gain configured to receive an output from the loop for implementing the skid-to-turn signal, the bank-to-turn module further comprises a loop for implementing the bank-to-turn signal configured to receive an output from the ladder integrator feedback gain, the system according to claim 2.

4. The loop for implementing the skid-to-turn signal comprises an airframe lateral specific force command module; a skid-to-turn steady gain configured to receive a signal from the airframe lateral specific force command module; A skid-to-turn acceleration error summation junction configured to receive a signal from the skid-to-turn steady-state gain; A skid-to-turn acceleration error gain configured to receive a signal from the skid-to-turn acceleration error summation junction; A skid-to-turn velocity error command summation junction configured to receive a signal from the skid-to-turn acceleration error gain; A skid-to-turn velocity error integrator gain configured to receive a signal from the skid-to-turn velocity error command summation junction; A ladder integrator module configured to receive a signal from the skid-to-turn velocity error integrator gain; A skid-to-turn velocity error summation block configured to receive a signal from the ladder integrator module; A skid-to-turn ladder command control gain configured to receive a signal from the skid-to-turn velocity error summation block; A skid-to-turn ladder command dynamic pressure scaling gain configured to receive a signal from the skid-to-turn ladder command control gain, the system according to claim 3.

5. The ladder integrator feedback gain is configured to receive the signal from the ladder integrator module, and the ladder integrator feedback gain is configured to generate a ladder integrator signal, the system according to claim 4.

6. The loop for implementing the bank-to-turn signal is A roll angle command module; An extended bank-to-turn signal generated based on a signal from the roll angle command module and the generated ladder integrator signal; A main filter module configured to receive the extended bank-to-turn signal; A roll angle error summation junction configured to receive a signal from the main filter module; A roll angle error proportional gain configured to receive a signal from the roll angle error summation junction; A roll velocity command proportional integral summation junction configured to receive a signal from the roll angle error proportional gain; A roll angle error integral gain configured to receive a signal from the roll angle error summation junction; A roll angle error integrator configured to receive a signal from the roll angle error integral gain; A roll rate error summing junction configured to receive a signal from the roll angle error integrator, a signal from the roll rate command proportional integral summing junction, and a signal from the roll rate feedback gain; The system according to claim 5, further comprising a roll auxiliary wing command dynamic pressure scaling gain configured to receive a signal from the roll rate error summing junction. **Claim 7** The system according to claim 6, wherein the roll angle command module further comprises the low-pass filter. **Claim 8** The system according to claim 6, wherein the roll angle command module is configured to be set to a non-zero value to generate the bank-to-turn signal with a bandwidth lower than the skid-to-turn signal generated by the body side force command module. **Claim 9** The system according to claim 6, wherein the main filter module is configured to disconnect a loop for implementing the bank-to-turn signal and a loop for implementing the skid-to-turn signal. **Claim 10** The system according to claim 6, wherein the low-pass filter of the main filter module is configured to ensure that the bank-to-turn signal has a bandwidth lower than the skid-to-turn signal. **Claim 11** The processor is configured to generate one or more actuator commands, The system according to claim 6, further configured to output the one or more actuator commands to vehicle plant dynamics. **Claim 12** The vehicle plant dynamics is a skid-to-turn ladder actuator transfer function model configured to receive a signal from the skid-to-turn ladder command dynamic pressure scaling gain, a roll auxiliary wing actuator transfer function model configured to receive a signal from the roll auxiliary wing command dynamic pressure scaling gain, The system according to claim 11, comprising a vehicle lateral dynamics state space model configured to receive a signal from the skid-to-turn ladder actuator transfer function model and a signal from the roll auxiliary wing actuator transfer function model. **Claim 13** The system is The system according to claim 12, further comprising one or more optical sensors configured to generate a line of sight from the aircraft to the target.

14. The system The system according to claim 13, further comprising one or more differentiators configured to generate the line of sight rate.

15. The system according to claim 14, wherein the generated line of sight rate includes the derivative of the line of sight vector represented in the inertial system.

16. The system The system according to claim 15, further comprising one or more lateral force optimizers configured to provide the lateral force threshold to the processor.

17. The system according to claim 16, wherein the lateral force threshold is selected through optimization and set prior to flight.

18. The system The system according to claim 17, further comprising one or more angle threshold optimizers configured to provide the angle threshold to the processor.

19. The system according to claim 17, wherein the angle threshold is selected through optimization and set prior to flight.

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