Tilt rotorcraft transition state tandem chain control distribution method based on incidence angle dynamics

Abstract

The invention discloses a tilt rotorcraft transition state tandem chain control distribution method based on incidence angle dynamics, and the method comprises the steps: constructing a tilt rotorcraft transition state model, and obtaining the real-time incidence angle of a tilt rotorcraft; and comparing the real-time attack angle and the stall attack angle of the tilt rotorcraft, dynamically distributing control authority between the fixed wing pneumatic control surface system and the rotor propulsion system according to the comparison result, and obtaining the optimal distribution parameter of the tilt rotorcraft according to the distribution result of the control authority. Wherein the optimal distribution parameters at least comprise aileron deflection, rudder deflection, elevator deflection, a rotor wing tilting angle and a rotor speed; and inputting the optimal distribution parameters into the tilt rotorcraft transition state model so as to adjust the tilt rotorcraft. By comparing the real-time attack angle with the stall attack angle, the control distribution problem of the tilt rotorcraft in a transition state in a high-attack-angle and low-dynamic-pressure flight environment can be solved, so that the cruising speed and the control efficiency of the tilt rotorcraft can be improved.

Description

Technical Field

[0001] The present application relates to the field of tiltrotor flight dynamics and control technology, and in particular to a tiltrotor transition state cascade chain control allocation method based on angle of attack dynamics. Background Art

[0002] A tilt-rotor aircraft is a multi-purpose, highly flexible aircraft that combines the high speed and long range of a fixed-wing aircraft with the vertical take-off and landing and fixed-point hovering of a helicopter. More importantly, a tilt-rotor aircraft is one of the important ways to develop high-speed helicopters.

[0003] In the prior art, the process of converting a tiltrotor aircraft from helicopter mode to fixed-wing mode involves transitional flight dynamics modeling and control system design. Most of the current modeling and control only cover linear models under small-angle aerodynamic disturbances, and do not deeply explore the impact of large angle of attack and low dynamic pressure flight conditions on aerodynamic coefficients and control system design. Summary of the invention

[0004] The purpose of this application is to provide a tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics, so as to solve the technical problem that the tiltrotor aircraft transition state control authority allocation is improper and it is difficult to achieve the expected flight performance in the prior art. The many technical effects that can be produced by the preferred technical solution among the many technical solutions provided in this application are described in detail below.

[0005] To achieve the above objectives, this application provides the following technical solutions: In the first aspect, the present application provides a method for allocating control of a tiltrotor transition state cascade chain based on angle of attack dynamics, comprising: constructing a tiltrotor transition state model to obtain the real-time angle of attack of the tiltrotor; comparing the real-time angle of attack of the tiltrotor with the stall angle of attack, and dynamically allocating control authority between the fixed-wing aerodynamic control surface system and the rotor propulsion system according to the comparison result, and obtaining the optimal allocation parameters of the tiltrotor according to the allocation result of the control authority, wherein the optimal allocation parameters include at least aileron deflection, rudder deflection, elevator deflection, rotor tilt angle and rotor speed; and inputting the optimal allocation parameters into the tiltrotor transition state model to adjust the tiltrotor.

[0006] In some embodiments, the real-time angle of attack of the tiltrotor aircraft is compared with the stall angle of attack, and control authority is dynamically allocated between the fixed-wing aerodynamic control surface system and the rotor propulsion system based on the comparison result, including: if the real-time angle of attack is greater than the stall angle of attack, the control authority is allocated to the rotor propulsion system; if the rotor propulsion system can provide the force or torque required for the transition state, the control allocation task is terminated; if the rotor propulsion system reaches a position saturation or a rate saturation state, but still fails to meet the force or torque required for the transition state, the remaining force or torque required for the transition state is allocated to the fixed-wing aerodynamic control surface system.

[0007] In some embodiments, the real-time angle of attack of the tiltrotor aircraft is compared with the stall angle of attack, and control authority is dynamically allocated between the fixed-wing aerodynamic control surface system and the rotor propulsion system according to the comparison result, including: if the real-time angle of attack is less than the stall angle of attack, the control authority is allocated to the fixed-wing aerodynamic control surface system; if the fixed-wing aerodynamic control surface system can provide the force or torque required for the transition state, the control allocation task is terminated; if the fixed-wing aerodynamic control surface system reaches a position saturation or a rate saturation state, but still fails to meet the force or torque required for the transition state, the remaining force or torque required for the transition state is allocated to the rotor propulsion system.

[0008] In some embodiments, the method further comprises: designing a nonlinear wash-out function for the wind tunnel data of the helicopter mode, designing a nonlinear wash-in function for the wind tunnel data of the fixed-wing mode, and obtaining aerodynamic coefficients of the forces and moments required for the transition state.

[0009] In some embodiments, the method further includes: designing a transitional flight control law for the tiltrotor aircraft, adopting a multi-loop control structure, and establishing a controller based on nonlinear dynamic inversion.

[0010] In some embodiments, constructing a transition state model of the tiltrotor aircraft may include: defining a body coordinate system and an airflow coordinate system; expressing the aerodynamic force generated by each component of the tiltrotor aircraft in the airflow coordinate system, expressing the aerodynamic torque in the body coordinate system, and constructing a transformation matrix from the airflow coordinate system to the body coordinate system; and obtaining the resultant force and resultant torque of the tiltrotor aircraft in the transition state in the body coordinate system based on the resultant force and resultant torque acting at the center of gravity of the tiltrotor aircraft.

[0011] In some embodiments, in the nonlinear wash-out function, the weight of the wind tunnel data of the helicopter mode is positively correlated with the degree of the tilt angle; in the nonlinear wash-in function, the weight of the wind tunnel data of the fixed-wing mode is negatively correlated with the degree of the tilt angle.

[0012] In some embodiments, the control authority is allocated to the rotor propulsion system. If the rotor propulsion system can provide the force or torque required for the transition state, the control allocation task is terminated, which is expressed by the following formula: , in, is the system function of the rotor propulsion system, is the force or torque required for the transition state, is a saturation function, is the actual input control variable of the rotor propulsion system.

[0013] In some embodiments, if the rotor propulsion system reaches a position saturation or a rate saturation state, but still fails to meet the transition state required force or torque, the remaining transition state required force or torque is allocated to the fixed-wing aerodynamic control surface system, which is expressed by the following formula: , in, is the system function of the fixed-wing aerodynamic control surface system, is the actual input control quantity of the fixed-wing pneumatic control surface system, is the actual control input of the tiltrotor aircraft.

[0014] In a second aspect, the present application provides a computer program product, which includes a computer-readable storage medium storing a computer program, and the computer program is operable to enable a computer to execute the tilt-rotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics as described above.

[0015] Implementing one of the above technical solutions of the present application has the following advantages or beneficial effects: In the present application, on the basis of constructing a nonlinear system model of the transition state of the tilt-rotor aircraft, according to the comparison of the real-time angle of attack and the stall angle of attack, the control priority is dynamically allocated between the fixed-wing aerodynamic control surface system and the rotor propulsion system based on the principle of optimal control efficiency, and the tilt-rotor aircraft is adjusted after obtaining the optimal allocation parameters. In this case, by comparing the real-time angle of attack and the stall angle of attack, the control allocation problem in the high angle of attack and low dynamic pressure flight environment in the transition state of the tilt-rotor aircraft can be effectively solved, thereby improving the cruising speed and control efficiency of the tilt-rotor aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. It is obvious that the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings: Figure 1 It is a flow chart of a tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to an embodiment of the present application; Figure 2 It is a flowchart of the control authority allocation in an embodiment of the present application; Figure 3 is a schematic diagram of a nonlinear wash-out function of an embodiment of the present application; Figure 4 is a schematic diagram of a nonlinear wash-in function according to an embodiment of the present application; Figure 5 It is a structural block diagram of the processing device of an embodiment of the present application.

[0017] In the figure: 1. processing device; 10. memory; 11. processor. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present application clearer, the various exemplary embodiments to be described below will refer to the corresponding drawings, which constitute a part of the exemplary embodiments, wherein various exemplary embodiments that may be used to implement the present application are described. Unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present disclosure. It should be understood that they are only examples of processes, methods, and devices that are consistent with some aspects disclosed in the present application as detailed in the attached claims, and other embodiments may also be used, or the embodiments listed herein may be modified in structure and function without departing from the scope and essence of the present application.

[0019] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", etc. indicate the orientation or positional relationship based on the drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the elements referred to must have a specific orientation, be constructed and operated in a specific orientation. The terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. The term "multiple" means two or more. The terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, a communication connection, a direct connection, an indirect connection through an intermediate medium, and can be the internal connection of two elements or the interaction relationship between two elements. The term "and / or" includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0020] In order to illustrate the technical solution described in the present application, a specific embodiment is provided below, and only the parts related to the embodiment of the present application are shown.

[0021] like Figure 1 As shown, the present application provides a method for allocating control of a tiltrotor aircraft transitional state cascade chain in a dynamic angle of attack, including (steps S1 to S3): S1. Construct a transition state model of a tiltrotor aircraft to obtain the real-time angle of attack of the tiltrotor aircraft. Specifically, the aerodynamic characteristics of the fixed-wing aerodynamic control surface system and the rotor propulsion system of the tiltrotor aircraft can be analyzed to construct the transition state model of the tiltrotor aircraft.

[0022] In some embodiments, a tiltrotor aircraft may include wings, a fuselage, a tail, and a rotor system. The fixed-wing pneumatic control surface system of a tiltrotor aircraft may refer to a movable component for controlling the flight direction and attitude. Specifically, the fixed-wing pneumatic control surface system may change the angle of the control surface to adjust the aerodynamic characteristics, thereby achieving pitch, roll, and yaw control. The fixed-wing pneumatic control surface system may include elevators, ailerons, and rudders. The rotor propulsion system of a tiltrotor aircraft may refer to a device for generating lift and thrust, which controls the flight trajectory and attitude by changing the tilt angle of the rotor-nacelle system and the rotor speed.

[0023] In some embodiments, the aileron may be a pair of movable wing surfaces mounted on the trailing edge of the wing, and used to control the rolling motion of the tiltrotor. Specifically, the aileron may be used to change the angle of attack of the wing, thereby controlling the left and right rolling of the fuselage during horizontal flight. The elevator may be located on the horizontal tail at the tail of the tiltrotor, and used to control the pitching motion of the tiltrotor. Specifically, the elevator may be used to change the angle of attack of the tail to control the tiltrotor to raise or lower its head. The rudder may be located on the vertical tail at the tail of the tiltrotor, and used to control the yaw motion of the tiltrotor, i.e., the left and right turning of the nose of the tiltrotor. Specifically, the rudder may be used to control the yaw of the tiltrotor, so that the tiltrotor turns left or right.

[0024] In some embodiments, constructing a tiltrotor aircraft transition state model may include: defining an inertial coordinate system , body coordinate system , Stable coordinate system and airflow coordinate system ; Express the aerodynamic forces generated by the various components of the tiltrotor in the airflow coordinate system , the aerodynamic moment is expressed in the body coordinate system , construct the airflow coordinate system Convert to body coordinate system According to the resultant force and moment acting on the center of gravity of the tilt-rotor aircraft, the transition state of the tilt-rotor aircraft in the body coordinate system is obtained. The resultant force and moment under .

[0025] In some embodiments, the inertial coordinate system It can refer to a reference coordinate system fixed on the earth; body coordinate system It can refer to a coordinate system fixed to the tilt-rotor aircraft, which can correspond to the pitch, roll and yaw motion of the tilt-rotor aircraft; the airflow coordinate system ( ) can define the angle of attack and sideslip angle of the tiltrotor.

[0026] In some embodiments, from the airflow coordinate system ( ) to the body coordinate system ( ) The orthogonal rotation matrix of the transformation can be expressed by the following formula: .

[0027] In some embodiments, the tiltrotor aircraft transition state model may satisfy the following equation: Among them, the subscript Expressed in the airflow coordinate system ( )Down, In the inertial coordinate system ( ), is the flight speed of the tiltrotor aircraft, is the angle of attack, is the sideslip angle, is the roll angle in the airflow coordinate system, is the track angle, is the heading of the flight path, is the displacement in the inertial coordinate system, is the angular velocity in the body coordinate system, is the angular velocity in the airflow coordinate system, are the roll angle, pitch angle and yaw angle in the body coordinate system, is the mass of the tiltrotor, It is the thrust generated by the rotor propulsion system In the air flow coordinate system The component in the axial direction, is the wing and fuselage in the body coordinate system The aerodynamic drag generated in the axial direction, is the moment of inertia of the tiltrotor, is the product of inertia of the tiltrotor aircraft, The wing, fuselage and rotor propulsion system are in the body coordinate system. , and The resultant moment in the axial direction.

[0028] In some embodiments, the angular velocity in the airflow coordinate system It can be expressed by the following formula: in, and The thrust generated by the rotor propulsion system is In the air flow coordinate system and The component in the axial direction, is the coordinate system of the wing, fuselage and horizontal tail The aerodynamic force generated in the axial direction, is the fuselage in the body coordinate system The aerodynamic sideslip force generated in the axial direction.

[0029] In some embodiments, in the body coordinate system, the resultant force acting at the center of gravity of the tilt-rotor aircraft may include the aerodynamic force generated by the wings, fuselage, horizontal tail and rotor propulsion system, and the resultant moment acting at the center of gravity of the tilt-rotor aircraft may include the aerodynamic moment generated by the wings, fuselage and rotor propulsion system.

[0030] In some embodiments, the resultant force of the tiltrotor aircraft in the transition state in the body coordinate system is The expression can satisfy the following formula: , in, , , and deflections of the rotor tilt angle, aileron, elevator and rudder, respectively. is the dynamic pressure, is the reference area of ​​the wing, is the wingspan, is the aerodynamic chord length of the wing, is the body coordinate system The aerodynamic coefficient of the axial component affects the elevator The derivative of the deflection, is the body coordinate system The aerodynamic coefficient of the axial component affects the aileron The derivative of the deflection, is the body coordinate system The aerodynamic coefficient of the axial component affects the rudder The derivative of the deflection, In the body coordinate system The aerodynamic coefficient of the axial component affects the elevator The derivative of the deflection, is the coordinate system of the wing, fuselage and horizontal tail The aerodynamic force coefficient in the axial direction, In the body coordinate system Aerodynamic force coefficient generated in the axial direction vs. angular velocity The derivative of In the body coordinate system The aerodynamic coefficient generated in the axial direction is related to the sideslip angle The derivative of In the body coordinate system Aerodynamic force coefficient generated in the axial direction vs. angular velocity The derivative of In the body coordinate system Aerodynamic force coefficient generated in the axial direction vs. angular velocity The derivative of is the fuselage in the body coordinate system The aerodynamic force coefficient generated in the axial direction is is the coordinate system of the wing, fuselage and horizontal tail The aerodynamic force coefficient in the axial direction, In the body coordinate system Aerodynamic force coefficient generated in the axial direction vs. angular velocity The rotor tilt angle can be the angle of the rotor system relative to the wing or fuselage. In a tiltrotor aircraft, the rotor can rotate (tilt) about an axis, thereby changing the direction of thrust.

[0031] In some embodiments, the wings, fuselage, and horizontal tail are in the body coordinate system. Aerodynamic force coefficient in the axial direction The following formula can be satisfied: , in, is the wing and fuselage in the body coordinate system The aerodynamic drag coefficient generated in the axial direction is is the coordinate system of the wing, fuselage and horizontal tail The aerodynamic pull coefficient generated in the axial direction.

[0032] In some embodiments, in the body coordinate system Aerodynamic force coefficient generated in the axial direction vs. angular velocity The derivative of The following formula can be satisfied: , in, In the body coordinate system Aerodynamic drag coefficient in the axial direction vs. angular velocity The derivative of In the body coordinate system Aerodynamic force coefficient in the axial direction versus angular velocity The derivative of .

[0033] In some embodiments, the body coordinate system The aerodynamic coefficient of the axial component affects the elevator Derivative of deflection The following formula can be satisfied: , in, In the body coordinate system The aerodynamic drag coefficient generated in the axial direction affects the elevator The derivative of the deflection, In the body coordinate system The aerodynamic force coefficient generated in the axial direction affects the elevator The derivative of the deflection.

[0034] In some embodiments, the wings, fuselage, and horizontal tail are in the body coordinate system. Aerodynamic force coefficient in the axial direction The following formula can be satisfied: , in, is the wing and fuselage in the body coordinate system The aerodynamic drag coefficient generated in the axial direction is is the coordinate system of the wing, fuselage and horizontal tail The aerodynamic pull coefficient generated in the axial direction.

[0035] In some embodiments, in the body coordinate system Aerodynamic force coefficient generated in the axial direction vs. angular velocity The derivative of The following formula can be satisfied: , in, In the body coordinate system Aerodynamic drag coefficient in the axial direction vs. angular velocity The derivative of In the body coordinate system Aerodynamic force coefficient in the axial direction versus angular velocity The derivative of .

[0036] In some embodiments, in the body coordinate system The aerodynamic coefficient of the axial component affects the elevator Derivative of deflection The following formula can be satisfied: , in, In the body coordinate system The aerodynamic drag coefficient generated in the axial direction affects the elevator The derivative of the deflection, In the body coordinate system The aerodynamic force coefficient generated in the axial direction affects the elevator The derivative of the deflection.

[0037] In some embodiments, the wings, fuselage, and horizontal tail are in the body coordinate system. Aerodynamic pull coefficient in the axial direction , and the wing and fuselage in the body coordinate system Aerodynamic drag coefficient in the axial direction The following formula can be satisfied: , Among them, the subscript , and Represent the wing, fuselage and horizontal tail respectively. is the aerodynamic pull coefficient generated by the wing, is the aerodynamic pull coefficient generated by the horizontal tail, is the aerodynamic pull coefficient generated by the fuselage, is the aerodynamic drag coefficient generated by the wing, is the aerodynamic drag coefficient created by the fuselage.

[0038] In some embodiments, the aerodynamic pull coefficient generated by the horizontal tail is The following formula can be satisfied: , in, is the reference area of ​​the horizontal tail, is the effective angle of attack of the horizontal tail.

[0039] In some embodiments, the effective angle of attack of the horizontal tail is The following formula can be satisfied: , in, is the downwash angle of the horizontal tail, It is the longitudinal distance between the aerodynamic center of the horizontal tail and the aerodynamic center of the wing and fuselage.

[0040] In some embodiments, the aerodynamic pull generated by the fuselage And the drag coefficient The following formula can be satisfied: , in, is the sideslip angle of the fuselage, is the derivative of the aerodynamic pull coefficient generated by the fuselage with respect to the angle of attack, is the derivative of the aerodynamic pull coefficient generated by the fuselage with respect to the sideslip angle, It is the aerodynamic pull coefficient generated by the fuselage when the angle of attack and the sideslip angle are both zero. is the additional tension coefficient of the fuselage, is the derivative of the aerodynamic drag coefficient generated by the fuselage with respect to the angle of attack, is the derivative of the aerodynamic drag coefficient generated by the fuselage with respect to the sideslip angle, It is the aerodynamic drag coefficient generated by the fuselage when the angle of attack and the sideslip angle are both zero. is the added drag coefficient of the fuselage.

[0041] In some embodiments, the resultant moment of the tiltrotor aircraft in the transition state in the body coordinate system is The following formula can be satisfied: ,in, is the distance between the two tilt rotors and the center of gravity of the tilt rotor aircraft. is the derivative of the rolling moment coefficient generated by the wing with respect to the sideslip angle, is the rolling moment coefficient with respect to angular velocity The derivative of is the rolling moment coefficient with respect to angular velocity The derivative of is the pitching moment coefficient produced by the wing, is the pitch moment coefficient with respect to angular velocity The derivative of is the derivative of the yaw moment coefficient with respect to the sideslip angle, is the yaw moment coefficient with respect to angular velocity The derivative of is the yaw moment coefficient with respect to angular velocity The derivative of is the rolling moment coefficient produced by the wing on the aileron The derivative of the deflection, is the rolling moment coefficient on the rudder The derivative of the deflection, is the pitch moment coefficient on the elevator The derivative of the deflection, is the yaw moment coefficient produced by the wing on the aileron The derivative of the deflection, is the yaw moment coefficient on the rudder The derivative of the deflection, is the rolling moment coefficient generated by the fuselage, is the pitch moment coefficient produced by the fuselage, is the yaw moment coefficient produced by the fuselage.

[0042] In some embodiments, the pitch moment coefficient generated by the fuselage is The following formula can be satisfied: , in, is the derivative of the pitch moment coefficient produced by the fuselage with respect to the angle of attack, is the derivative of the pitching moment coefficient generated by the fuselage with respect to the sideslip angle, It is the pitch moment coefficient generated by the fuselage when the angle of attack and the angle of sideslip are both zero.

[0043] S2. Compare the real-time angle of attack of the tiltrotor aircraft with the stall angle of attack, dynamically allocate control authority between the fixed-wing aerodynamic control surface system and the rotor propulsion system according to the comparison result, and obtain the optimal allocation parameters of the tiltrotor aircraft according to the allocation result of the control authority, wherein the optimal allocation parameters at least include aileron deflection, rudder deflection, elevator deflection, rotor tilt angle and rotor speed.

[0044] In some embodiments, Figure 2 As shown, the real-time angle of attack of the tilt-rotor aircraft is compared with the stall angle of attack, and the control priority is dynamically allocated between the fixed-wing aerodynamic control surface system and the rotor propulsion system according to the comparison result, which can include: if the real-time angle of attack is greater than the stall angle of attack, the control authority is allocated to the rotor propulsion system, and if the rotor propulsion system meets the force or torque required for the transition state, the control allocation task is terminated; if the rotor propulsion system reaches a position saturation or speed saturation state, it still does not meet the force or torque required for the transition state, and then the remaining force or torque required for the transition state is allocated to the fixed-wing aerodynamic control surface system.

[0045] In some embodiments, the forces and moments required for the transition state may include lift, thrust, pitch force and pitch moment, roll moment, yaw moment, and rotor tilt moment. Allocating control authority to the rotor propulsion system may refer to allocating control instructions generated by the flight control system, such as pitch, roll, yaw, lift, etc., to each rotor of the rotor propulsion system. When the rotor propulsion system reaches a position saturation state, it means that its angle or position has reached a limit, such as pitch angle saturation, roll angle saturation, yaw angle saturation, maximum speed saturation, etc.

[0046] In some embodiments, the control authority is allocated to the rotor propulsion system. If the rotor propulsion system can provide the force or torque required for the transition state, the control allocation task is terminated, which can be expressed by the following formula: , in, is the system function of the rotor propulsion system, is the force or torque required for the transition state of the tiltrotor aircraft, is a saturation function, is the actual input control variable of the rotor propulsion system.

[0047] In some embodiments, if the rotor propulsion system reaches the position saturation or speed saturation state, but still fails to meet the transition state required force or torque, the remaining transition state required force or torque is allocated to the fixed-wing aerodynamic control surface system, which can be expressed by the following formula: , in, is the system function of the fixed-wing aerodynamic control surface system, is the actual input control quantity of the fixed-wing aerodynamic control surface system, is the actual control input of the tiltrotor aircraft in this case.

[0048] In some embodiments, the real-time angle of attack of the tiltrotor aircraft is compared with the stall angle of attack, and the control priority is dynamically allocated between the fixed-wing aerodynamic control surface system and the rotor propulsion system based on the comparison result, including: if the real-time angle of attack is less than the stall angle of attack, the control authority is allocated to the fixed-wing aerodynamic control surface system; if the fixed-wing aerodynamic control surface system can provide the force or torque required for the transition state, the control allocation task is terminated; if the fixed-wing aerodynamic control surface system reaches a position saturation or a rate saturation state, and still does not meet the force or torque required for the transition state, the remaining force or torque required for the transition state is allocated to the rotor propulsion system.

[0049] Specifically, allocating control authority to the fixed-wing pneumatic control surface system may refer to allocating control instructions generated by the flight control system to the ailerons, elevators and rudders of the fixed-wing pneumatic control surface system. When the fixed-wing pneumatic control surface system reaches position saturation or rate saturation, it means that the deflection angle and deflection rate of the control surface have reached saturation.

[0050] In some embodiments, the control authority is allocated to the fixed-wing pneumatic control surface system. If the fixed-wing pneumatic control surface system can provide the force or torque required for the transition state, the control allocation task is terminated, which can be expressed by the following formula: , in, is the actual input control quantity of the fixed-wing aerodynamic control surface system, It is the system function of the fixed-wing aerodynamic control surface system.

[0051] In some embodiments, if the fixed-wing aerodynamic control surface system reaches the position saturation or speed saturation state, but still fails to meet the transition state required force or torque, the remaining transition state required force or torque is allocated to the rotor propulsion system, which can be expressed by the following formula: , in, is the actual input control quantity of the rotor propulsion system, is the actual control input of the tiltrotor aircraft in this case.

[0052] In some embodiments, Figure 3 and Figure 4 As shown, the tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics can also include: designing a nonlinear wash-out function for the wind tunnel data of the helicopter mode, designing a nonlinear wash-in function for the wind tunnel data of the fixed-wing mode, and obtaining the aerodynamic coefficients of the force and torque required for the transition state.

[0053] Specifically, when the tiltrotor is in a transition state, the tiltrotor will switch from helicopter mode to fixed-wing mode, or from fixed-wing mode to helicopter mode. In the transition state, the weight of the wind tunnel data of the helicopter mode can be gradually reduced by using a nonlinear washout function, so that these data can be applied to the construction process of the relevant aerodynamic coefficients and aerodynamic torque coefficients in the above-mentioned tiltrotor transition state model. In the transition state, the weight of the wind tunnel data of the fixed-wing mode can be gradually increased by using a nonlinear washout function, so that these data can be applied to the construction process of the relevant aerodynamic coefficients and aerodynamic torque coefficients in the above-mentioned tiltrotor transition state model, such as the lift curve slope, drag coefficient, torque coefficient, etc.

[0054] In some embodiments, in the nonlinear washout function, the weight of the wind tunnel data of the helicopter mode may be positively correlated with the degree of the tilt angle. Specifically, when the tilt angle is 0 to 30 degrees, the weight of the wind tunnel data of the helicopter mode may increase linearly from 0 to 0.3; when the tilt angle is 30 to 60 degrees, the weight of the wind tunnel data of the helicopter mode may increase linearly from 0.35 to 0.65; when the tilt angle is 60 to 90 degrees, the weight of the wind tunnel data of the helicopter mode may increase linearly from 0.7 to 1.

[0055] In some embodiments, in the nonlinear wash-in function, the weight of the wind tunnel data of the fixed-wing mode may be negatively correlated with the degree of the tilt angle. Specifically, when the tilt angle is 0 to 30 degrees, the weight of the wind tunnel data of the fixed-wing mode may be linearly reduced from 1 to 0.7; when the tilt angle is 30 to 60 degrees, the weight of the wind tunnel data of the fixed-wing mode may be linearly reduced from 0.65 to 0.35; when the tilt angle is 60 to 90 degrees, the weight of the wind tunnel data of the fixed-wing mode may be linearly reduced from 0.3 to 0.

[0056] In summary, by designing nonlinear wash-out functions and nonlinear wash-in functions, the aerodynamic coefficients of the force and torque required for the transition state of the tiltrotor aircraft can be obtained, which can facilitate the subsequent allocation of control authority priorities according to the required force or torque of the tiltrotor aircraft, making the subsequent allocation process more accurate.

[0057] S3. Inputting the optimal allocation parameters into the tiltrotor aircraft transition state model to adjust the tiltrotor aircraft.

[0058] In some embodiments, the optimal allocation parameters can be used to adjust the attitude, heading, altitude and speed of the tiltrotor. Specifically, aileron deflection can be used to control the roll motion of the tiltrotor, rudder deflection can be used to control the yaw motion of the tiltrotor, elevator deflection can be used to control the pitch motion of the tiltrotor, rotor tilt angle can be used to control the transition of the tiltrotor from helicopter mode to fixed-wing mode, and rotor speed can be used to control the lift, thrust and power of the tiltrotor.

[0059] In some embodiments, the tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics may also include: designing a tiltrotor aircraft transition state flight control law, using a multi-loop control structure, and establishing a controller based on nonlinear dynamic inversion. Specifically, nonlinear dynamic inversion may refer to obtaining an input of the control law according to a desired flight state, wherein the desired flight state may be related to an optimal allocation parameter, and then obtaining an output of the control law, that is, directly acting on the controller after obtaining the control input to manipulate the tiltrotor aircraft to achieve the desired flight state.

[0060] In some embodiments, the transition state dynamic equation of the tiltrotor aircraft is formulated as follows: in, It is a slow loop state. It is the fast loop state. is the virtual control input.

[0061] In some embodiments, the tracking error dynamic equation is formulated as: in, and are the tracking errors of the slow loop and the fast loop, respectively, is the slow loop reference signal.

[0062] In some embodiments, the control law of the slow loop may satisfy the following formula: Among them, the control law The following formula can be satisfied: , in, is the error between the current state and the reference signal, , and is the controller gain.

[0063] In some embodiments, the control law of the fast loop may satisfy the following formula: Among them, the control law The following formula can be satisfied: , in, is the error between the current state and the reference signal, , and is the controller gain.

[0064] In this application, on the basis of constructing a nonlinear system model of the transition state of a tiltrotor, according to the comparison of the real-time angle of attack and the stall angle of attack, the control priority is dynamically allocated between the fixed-wing aerodynamic control surface system and the rotor propulsion system based on the principle of optimal control efficiency, and the tiltrotor is adjusted after obtaining the optimal allocation parameters. In this case, by comparing the real-time angle of attack and the stall angle of attack, the control allocation problem in the high angle of attack and low dynamic pressure flight environment in the transition state of the tiltrotor can be effectively solved, thereby improving the cruising speed and control efficiency of the tiltrotor.

[0065] The present application also provides a computer program product, which is stored on a data carrier and is designed to execute the tiltrotor aircraft transition state cascade chain control allocation method based on the angle of attack dynamics as described above. Therefore, the computer program product according to the present application produces the same advantages as those described in detail with reference to the device according to the present application. The computer program product can be executed as a computer-readable instruction code in any appropriate programming language such as JAVA, C++, etc. In addition, the computer program product can be provided on a network, such as the Internet, or a network, such as an Internet user, can download the computer program product from the network, such as the Internet when needed. The computer program product can be implemented by means of a computer program, i.e., software, or by means of one or more dedicated electronic circuits, i.e., hardware, or in any mixed form, i.e., by means of software components and hardware components, or in a mixed form of software, hardware, or software and hardware.

[0066] Those skilled in the art can understand that all or part of the features / steps of the above-mentioned method embodiments can be implemented by methods, data processing systems or computer programs, and these features can be implemented without hardware, entirely by software, or by a combination of hardware and software. The aforementioned computer program can be stored in one or more computer-readable storage media, and the storage medium stores the computer program. When the computer program is executed (such as by a processor), the steps of the above-mentioned tiltrotor aircraft transition state cascade chain control allocation method embodiment based on angle of attack dynamics are executed.

[0067] The aforementioned storage media that can store program codes include: static hard disks, solid-state hard disks, random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), optical storage devices, magnetic storage devices, flash memory, magnetic disks or optical disks and / or combinations of the above devices, that is, they can be implemented by any type of volatile or non-volatile storage device or a combination thereof.

[0068] like Figure 5 As shown, the present application also provides an embodiment of a processing device 1, comprising one or more processors 11 and a memory 10; wherein the memory 10 is used to store one or more computer programs, and the one or more processors 11 are used to execute one or more computer programs stored in the memory 10, so that the processor 11 executes the features / steps of the above-mentioned tiltrotor aircraft transition state cascade chain control allocation method embodiment based on angle of attack dynamics.

[0069] The above is only the preferred embodiment of the present application. Those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present application. In addition, under the guidance of the present application, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present application belong to the protection scope of the present application.

Claims

1. A tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics, characterized in that: include: Construct a transition state model of the tiltrotor aircraft to obtain the real-time angle of attack of the tiltrotor aircraft; Comparing the real-time angle of attack of the tiltrotor with the stall angle of attack, dynamically allocating control authority between the fixed-wing aerodynamic control surface system and the rotor propulsion system according to the comparison result, and obtaining optimal allocation parameters of the tiltrotor according to the allocation result of the control authority, wherein the optimal allocation parameters at least include aileron deflection, rudder deflection, elevator deflection, rotor tilt angle, and rotor speed; The optimal allocation parameters are input into the tiltrotor aircraft transition state model to adjust the tiltrotor aircraft.

2. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 1, characterized in that: The method of comparing the real-time angle of attack of the tiltrotor aircraft with the stall angle of attack and dynamically allocating control authority between the fixed-wing aerodynamic control surface system and the rotor propulsion system according to the comparison result includes: if the real-time angle of attack is greater than the stall angle of attack, allocating the control authority to the rotor propulsion system; if the rotor propulsion system can provide the force or torque required for the transition state, terminating the control allocation task; if the rotor propulsion system reaches a position saturation or a speed saturation state and still fails to meet the force or torque required for the transition state, allocating the remaining force or torque required for the transition state to the fixed-wing aerodynamic control surface system.

3. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 2, characterized in that: The method of comparing the real-time angle of attack of the tiltrotor aircraft with the stall angle of attack and dynamically allocating control authority between the fixed-wing aerodynamic control surface system and the rotor propulsion system according to the comparison result includes: if the real-time angle of attack is less than the stall angle of attack, allocating the control authority to the fixed-wing aerodynamic control surface system; if the fixed-wing aerodynamic control surface system can provide the force or torque required for the transition state, then terminating the control allocation task; if the fixed-wing aerodynamic control surface system reaches a position saturation or a speed saturation state and still fails to meet the force or torque required for the transition state, then allocating the remaining force or torque required for the transition state to the rotor propulsion system.

4. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 1, characterized in that: The method also includes: designing a nonlinear wash-out function for the wind tunnel data of the helicopter mode, designing a nonlinear wash-in function for the wind tunnel data of the fixed-wing mode, and obtaining aerodynamic coefficients of the force and moment required for the transition state.

5. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 1, characterized in that: The method also includes: designing a transitional flight control law for the tiltrotor aircraft, adopting a multi-loop control structure, and establishing a controller based on nonlinear dynamic inversion.

6. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 1, characterized in that: The construction of the tiltrotor aircraft transition state model includes: defining a body coordinate system and an airflow coordinate system; expressing the aerodynamic force generated by each component of the tiltrotor aircraft in the airflow coordinate system, expressing the aerodynamic torque in the body coordinate system, and constructing a conversion matrix from the airflow coordinate system to the body coordinate system; and obtaining the resultant force and resultant torque of the tiltrotor aircraft transition state in the body coordinate system based on the resultant force and resultant torque acting at the center of gravity of the tiltrotor aircraft.

7. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 4, characterized in that: In the nonlinear wash-out function, the weight of the wind tunnel data of the helicopter mode is positively correlated with the degree of the tilt angle; in the nonlinear wash-in function, the weight of the wind tunnel data of the fixed-wing mode is negatively correlated with the degree of the tilt angle.

8. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 2, characterized in that: include: The control authority is allocated to the rotor propulsion system. If the rotor propulsion system can provide the force or torque required for the transition state, the control allocation task is terminated, which is expressed by the following formula: ， in, is the system function of the rotor propulsion system, is the force or torque required for the transition state, is a saturation function, is the actual input control variable of the rotor propulsion system.

9. The tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics according to claim 2, characterized in that: If the rotor propulsion system reaches the position saturation or speed saturation state, but still fails to meet the transition state required force or torque, the remaining transition state required force or torque is allocated to the fixed-wing aerodynamic control surface system, which is expressed by the following formula: ， in, is the system function of the fixed-wing aerodynamic control surface system, is the actual input control quantity of the fixed-wing pneumatic control surface system, is the actual control input of the tiltrotor aircraft.

10. A computer program product, characterized in that The computer program product includes a computer-readable storage medium storing a computer program, and the computer program is operable to cause a computer to execute the tiltrotor aircraft transition state cascade chain control allocation method based on angle of attack dynamics as described in any one of claims 1 to 9.

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