Adaptive anti-disturbance attitude control method for variable-configuration UAV under multi-source interference

Abstract

The present invention proposes an adaptive anti-disturbance attitude control method for a transformable UAV under multi-source interference, which belongs to the field of UAV control, including: considering the influence of environmental wind disturbance, fuselage center of mass offset, rudder deflection execution error, and aerodynamic parameter uncertainty, establishing a transformable UAV attitude dynamics model under multi-source interference in a strict feedback form; taking aerodynamic torque as a virtual control variable, designing an adaptive backstepping attitude controller; taking wingspan, sweep angle, and rudder deflection as heterogeneous execution control variables, designing a closed-loop control distributor of virtual control variables; combining the adaptive backstepping attitude controller and the closed-loop control distributor to complete the design of the adaptive anti-disturbance attitude control method for a transformable UAV under multi-source interference. The present invention can realize high-precision attitude control of a transformable UAV under environmental wind disturbance, fuselage center of mass offset, rudder deflection execution error, and aerodynamic parameter uncertainty.

Description

Technical Field

[0001] The present invention belongs to the field of UAV control, and specifically relates to an adaptive anti-interference attitude control method for a transformable UAV under multi-source interference. Aiming at the multi-source interference suffered by the transformable UAV during its flight process, an adaptive backstepping attitude controller and a closed-loop control distributor are combined to realize the anti-interference attitude control of the transformable UAV under multi-source interference. Background Art

[0002] A transformable UAV is a type of unmanned aerial vehicle that can actively adjust its own configuration. During flight, a transformable UAV can adjust its configuration according to changes in the external environment and the requirements of real-time tasks to improve its aerodynamic performance and complete flight missions more efficiently. However, on the one hand, the dynamic configuration changes of the transformable UAV introduce complex nonlinear dynamic characteristics of the system, making the attitude control of the transformable UAV challenging; on the other hand, in a complex flight mission environment, the transformable UAV is affected by multiple interference factors such as environmental wind disturbance, fuselage center of mass offset, rudder deviation execution error, and aerodynamic parameter uncertainty, which further aggravates the difficulty of stable flight.

[0003] Many methods have been studied for the attitude control problem of UAVs at home and abroad, but the existing methods have rarely studied the attitude control problem of variable-configuration UAVs, especially the analysis of the impact of multi-source interference on variable-configuration UAVs is still insufficient in terms of precision; at the same time, the existing methods mostly use rudder deviation as the control variable, and the configuration parameters are involved in the control allocation as control variables, and are mostly from the optimization perspective. The robustness allocation under the influence of aerodynamic parameter uncertainty, rudder deviation error, etc. is not fully considered, and the actual torque is difficult to accurately track the output of the attitude controller, which in turn affects the UAV mission execution and even causes instability and crash.

[0004] In summary, the existing methods for the attitude control problem of transformable UAVs are still lacking in the robust design of multi-source interference analysis and control allocation links. In order to further improve the attitude control accuracy of transformable UAVs in complex environments, it is urgent to propose an adaptive anti-disturbance attitude control method for transformable UAVs under multi-source interference. Summary of the invention

[0005] Aiming at the attitude control problem of transformable UAV in complex environment, the present invention overcomes the limitations of the existing methods of insufficient anti-interference ability and low robustness of control allocation. This invention proposes an adaptive anti-interference attitude control method for transformable UAV under multi-source interference. From the perspective of flight safety and control robustness, this invention combines an adaptive backstepping attitude controller and a closed-loop control distributor to achieve high-precision attitude control of transformable UAV under multi-source interference. Through adaptive suppression of interference and robust control allocation, this invention can achieve high-precision attitude control of transformable UAV under multi-source interference such as environmental wind disturbance and fuselage center of mass offset, rudder deflection execution error, and aerodynamic parameter uncertainty.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] The adaptive anti-disturbance attitude control method of a variable-configuration UAV under multi-source interference includes the following steps:

[0008] The first step is to establish a posture dynamics model of a transformable UAV under multi-source interference in a strict feedback form; the transformable UAV is a winged UAV with variable wingspan and sweep angle; the multi-source interference includes environmental wind disturbance and the body center of mass offset, rudder deflection execution error, and aerodynamic parameter uncertainty of the transformable UAV;

[0009] The second step is to design an adaptive backstepping attitude controller using aerodynamic torque as a virtual control variable.

[0010] The third step is to design a closed-loop control distributor of virtual control variables using wingspan, sweep angle and rudder deflection as augmented heterogeneous execution variables;

[0011] The fourth step is to combine the adaptive backstepping attitude controller and the closed-loop control distributor to complete the design of the adaptive anti-disturbance attitude control method for the transformable UAV under multi-source interference.

[0012] The beneficial effects of the present invention compared with the prior art are:

[0013] Aiming at the problem of anti-interference attitude control of transformable UAV under multi-source interference, the existing methods have the limitations of insufficient analysis of multi-source interference and low robustness of control allocation methods. The adaptive anti-interference attitude control method of transformable UAV under multi-source interference proposed in the present invention combines the fine analysis of multi-source interference, the design of adaptive backstepping attitude controller and closed-loop control distributor, which can realize adaptive suppression of multi-source interference including environmental wind disturbance and fuselage center of mass offset, rudder deflection execution error, aerodynamic parameter uncertainty of transformable UAV, and realize high-precision attitude control of transformable UAV under multi-source interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention is a flow chart of the adaptive anti-interference attitude control method of a transformable UAV under multi-source interference.

[0015] Figure 2 A diagram of the open-loop control allocation angle of attack tracking results of the adaptive attitude control method for a transformable UAV based on open-loop control allocation under multi-source interference provided in an embodiment of the present invention.

[0016] Figure 3 A diagram of the closed-loop control distribution angle of attack tracking results of the adaptive anti-disturbance attitude control method for a transformable UAV under multi-source interference provided in an embodiment of the present invention.

[0017] Figure 4An open-loop control allocation angle of attack tracking steady-state error diagram of the adaptive attitude control method of a transformable UAV based on open-loop control allocation under multi-source interference provided by an embodiment of the present invention.

[0018] Figure 5 A closed-loop control distribution angle of attack tracking steady-state error diagram of the adaptive anti-disturbance attitude control method for a transformable UAV under multi-source interference provided by an embodiment of the present invention.

[0019] Figure 6 A diagram of the change in sweep angle of a transformable UAV in the method for adaptive anti-disturbance attitude control of a transformable UAV under multi-source interference provided in an embodiment of the present invention.

[0020] Figure 7 A diagram of the wingspan change of a transformable UAV according to the method for adaptive anti-disturbance attitude control of a transformable UAV under multi-source interference provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figure 1 As shown, the present invention proposes a method for adaptive anti-interference attitude control of a transformable UAV under multi-source interference, comprising the following steps:

[0023] The first step is to establish a posture dynamics model of a transformable UAV under multi-source interference in a strict feedback form; the transformable UAV is a winged UAV with variable wingspan and sweep angle; the multi-source interference includes environmental wind disturbance and the body center of mass offset, rudder deflection execution error, and aerodynamic parameter uncertainty of the transformable UAV;

[0024] The second step is to design an adaptive backstepping attitude controller using aerodynamic torque as a virtual control variable.

[0025] The third step is to design a closed-loop control distributor of virtual control variables using wingspan, sweep angle and rudder deflection as augmented heterogeneous execution variables;

[0026] The fourth step is to combine the adaptive backstepping attitude controller and the closed-loop control distributor to complete the design of the adaptive anti-disturbance attitude control method for the transformable UAV under multi-source interference.

[0027] Specifically, a certain type of variable-configuration UAV with variable wingspan and sweep angle is used as the application object, with a maximum wingspan of 2.8 meters (m), a minimum wingspan of 1 meter (m), and a maximum sweep angle of 60 degrees ( )、Minimum sweep angle 0 degrees( ), explain the specific steps of the present invention:

[0028] Specifically, the first step includes:

[0029] Based on the multi-rigid body modeling method, the fuselage of the transformable UAV is regarded as the main rigid body, and the center of mass of the fuselage is taken as the nominal center of mass. The attitude dynamics model of the transformable UAV under multi-source interference in the form of strict feedback is established as follows:

[0030] ;

[0031] in, represents the attitude angle vector, represents the attitude angular velocity vector, , , They represent the angle of attack, sideslip angle, and speed roll angle, respectively. , , Denote the roll angular velocity, yaw angular velocity, and pitch angular velocity, respectively. represents transpose; , Respectively , The derivative of represents the disturbance vector in the attitude angle channel, , , They are Components on the three axes of the track coordinate system; represents the disturbance vector in the attitude angular velocity channel, , , They are Components on the three axes of the body coordinate system; represents the aerodynamic torque, , , express Components on the three axes of the body coordinate system; represents the moment action matrix, , , represents the moment of inertia of the transformable UAV around the three axes of the body coordinate system, with the superscript Represents the inverse operator, Indicates is a diagonal matrix with diagonal elements; , Respectively represent , The related system nominal matrix is ​​expressed as:

[0032] , .

[0033] The multi-source interference includes environmental wind disturbance, the center of mass offset of the fuselage of the transformable UAV, the rudder deviation execution error, and the uncertainty of aerodynamic parameters:

[0034] The ambient wind disturbance is expressed in the ground coordinate system as , is the wind disturbance speed, is the wind acceleration, , , are the components of wind disturbance acceleration on the three axes of the ground coordinate system;

[0035] The expression of fuselage center of mass offset is: ,in , , They are The components on the three axes of the body coordinate system, , are the mass center offset velocity and mass center offset acceleration respectively;

[0036] The rudder deviation execution error includes the execution error of roll rudder deviation, yaw rudder deviation and pitch rudder deviation, which are respectively expressed as error coefficients between 0 and 1. , and It means that the expressions of actual roll rudder deviation, actual yaw rudder deviation and actual pitch rudder deviation under execution error are as follows: , and ,in , and are the desired rudder deflections for roll, yaw and pitch channels respectively;

[0037] Aerodynamic parameter uncertainty includes drag coefficient uncertainty , lift coefficient uncertainty , uncertainty of lateral force coefficient , Rolling moment coefficient uncertainty , Yaw moment coefficient uncertainty , Pitch moment coefficient uncertainty For ease of description, the aerodynamic parameters in the present invention include drag coefficient, lift coefficient, side force coefficient, rolling moment coefficient, yaw moment coefficient, and pitch moment parameters, wherein the drag coefficient, lift coefficient, and side force coefficient are collectively referred to as aerodynamic parameters, and the rolling moment coefficient, yaw moment coefficient, and pitch moment parameters are collectively referred to as aerodynamic moment parameters.

[0038] The influence of multi-source interference on the attitude system of the variable-configuration UAV is reflected in the above attitude dynamics model. , and middle. , and The specific expressions of each component in are:

[0039] ;

[0040] in, represents the mass of the allosteric drone, represents the track inclination of the transformable UAV, is the acceleration due to gravity; represents the speed of the transformable UAV in the speed coordinate system; , , It represents the components of the additional wind force caused by the environmental wind disturbance on the three axes of the track coordinate system, and the expression is: , It is the coordinate transformation matrix from the ground coordinate system to the track coordinate system; , , It represents the three-axis components of the center of mass offset additional force in the track coordinate system, and the expression is , It represents the rotational angular velocity of the body coordinate system relative to the track coordinate system. It represents the rotational angular velocity of the body coordinate system relative to the ground coordinate system. It represents the rotational angular acceleration of the body coordinate system relative to the ground coordinate system. is the mass of wing i, represents the vector cross product operator; , , It represents the component of the additional moment of mass center offset on the three axes of the body coordinate system, and its expression is: ,in is the coordinate of the fuselage velocity in the track coordinate system, is the coordinate of the gravity acting on the fuselage in the ground coordinate system, is the body mass, , They represent the coordinate conversion matrix from the track coordinate system to the fuselage coordinate system and the coordinate conversion matrix from the ground coordinate system to the fuselage coordinate system respectively; , , It represents the nominal aerodynamic drag, nominal aerodynamic lift, and nominal aerodynamic lateral force of the transformable UAV without interference. , , It represents the three-axis components of the nominal aerodynamic moment of the transformable UAV in the body coordinate system without interference; , , , , , They represent the uncertainty of drag, lift, lateral force, rolling moment, yaw moment and pitch moment caused by rudder deviation and aerodynamic parameter uncertainty, respectively. Their expressions are , , , , , ,in, is the atmospheric density, is the aerodynamic reference area, is the average aerodynamic chord length, , , , , , It represents the deviation between the actual aerodynamic parameters and the nominal aerodynamic parameters, and the expressions are , , , , , ; , , , , , are the nominal aerodynamic parameters and aerodynamic torque parameters of the transformable UAV without interference, , , , , , are the actual aerodynamic parameters and aerodynamic torque parameters affected by the rudder deviation execution error and the aerodynamic parameter uncertainty, respectively, and the expressions are:

[0041] ;

[0042] in, , , , , , is a function related to deformation, flight state, and rudder deviation, is the sweep angle of the transformable UAV, The wingspan of the variable-speed UAV.

[0043] The dynamic characteristics of the transformable UAV due to the configuration change are also reflected in , and middle. , , They represent the three-axis components of the additional force introduced by the wing deformation in the track coordinate system, and the expression is , To represent the wing The additional force of deformation on the fuselage, i=1,2; , represents the wing mass, Indicates the wing The position vector of the center of mass relative to the center of mass of the fuselage, , Respectively The first and second derivatives of Respectively represent wings The angular velocity of rotation relative to the fuselage coordinate system, Represents the coordinate transformation matrix from the track coordinate system to the velocity coordinate system, Represents the coordinate transformation matrix from the velocity coordinate system to the body coordinate system; , , They represent the three-axis components of the additional moment introduced by the wing deformation in the body coordinate system, and their expressions are: , Indicates the wing The additional moment of deformation on the fuselage is expressed as , Represents the coordinate transformation matrix from the ground coordinate system to the body coordinate system, represents the heading angle of the allostatic UAV, represents the angular velocity of the UAV, represents the angular velocity of the track of the variable-configuration UAV, Represents the acceleration of the transformable UAV in the velocity coordinate system.

[0044] The mass of the transformable drone in the embodiment of the present invention is kg, the reference area is m 2 The average aerodynamic chord length is m, and the moments of inertia of the three axes are kg·m 2 , kg·m 2 , kg·m 2 . Initial speed of the allostatic drone m / s, initial height m, initial track inclination ° , the initial attitude angle vector and the initial angular velocity vector are both zero vectors. In terms of multi-source interference settings, is the simulation time in seconds (s). , and The wind disturbance acceleration is , , , the rest of the simulation time is taken as 0; the fuselage mass center offset related variables are taken as , ; The correlation coefficients of the rudder deflection execution error are , , , the uncertainty of aerodynamic parameters is , , , , , .

[0045] Specifically, the second step includes:

[0046] The aerodynamic torque is used as the virtual control variable to design an adaptive backstepping attitude controller. for:

[0047] ;

[0048] in, , , are the controller parameters to be designed; is a 3D unit matrix; , , , is an intermediate variable, and the expression is , , , , represents the partial derivative operator, sech represents the hyperbolic secant function; Represents the attitude angle error variable, and the expression is , represents the desired attitude angle, represents the desired attitude angular velocity, represents the desired attitude angular acceleration; represents the intermediate error variable, and the expression is ; , They represent the system interference vectors , Adaptive estimate of the numerical upper bound, , They are , The derivative of , the interference adaptive estimation law is designed as , , tanh represents the hyperbolic tangent function, is an intermediate variable, and the expression is , is the virtual control quantity, and its expression is , , are the estimated parameters to be designed; , They represent the posture dynamics model respectively. Elements of the first and second rows of a column vector.

[0049] The relevant parameter values ​​of the adaptive backstepping attitude controller for the transformable UAV are: , , , , .

[0050] Specifically, the third step includes:

[0051] The wingspan, sweep angle and rudder deflection are used as augmented heterogeneous execution variables, denoted as , the expression is ; The closed-loop control distributor of the designed virtual control variable is characterized as the following optimization problem:

[0052] ;

[0053] in, Indicates the current sampling step of the system. represents the last sampling step of the system, is the augmented heterogeneous execution variable of the current sampling step k, is the heterogeneous execution control variable of the previous sampling step; the symbol find represents the optimization variable of the optimization problem, and the symbol It means finding the minimum value of a function, and the symbol subject to represents the constraints of the optimization problem; represents the performance function of the optimization problem, represents the weight matrix, symbol Represents the square of the vector's two-norm, symbol / indicates vector ratio; and They are The minimum and maximum execution capabilities of , , , They are The physical constraints of the upper and lower bounds are symbolized as It means to find the maximum value of the function. for The maximum rate of change, is the system sampling step; is the torque to be distributed in the current sampling step, which is obtained by compensation under the closed-loop structure, and its expression is , is the torque to be distributed in the previous sampling step, is the control torque given by the current sampling step controller, is the aerodynamic torque of the modified UAV in the previous sampling step, Represents the control effectiveness matrix of the current sampling step k, expressed as The augmented heterogeneous execution variables of the current sampling step can be solved based on the quadratic programming method , realizing the dynamic allocation mapping of attitude control torque to be allocated to heterogeneous actuators.

[0054] For this allostatic drone, the weight matrix is , heterogeneous execution control variables The physical constraints are bounded by , , heterogeneous execution control variables Maximum rate of change ,symbol represents infinity, that is, there is no constraint on the deflection rate of the three-axis rudder of the transformable UAV, and the system sampling step length .

[0055] Specifically, the fourth step includes: combining the adaptive backstepping attitude controller and the closed-loop control distributor to complete the design of the adaptive anti-disturbance attitude control method of the transformable UAV under multi-source interference. Numerical simulation is carried out based on the parameter values ​​of the above steps. The simulation results are as follows: Figure 2-Figure 7 As shown in the figure, according to the open-loop control distribution angle of attack tracking results, closed-loop control distribution angle of attack tracking results, open-loop control distribution angle of attack tracking steady-state error, closed-loop control distribution angle of attack tracking steady-state error, variable UAV sweep angle change, variable UAV wingspan change, the analysis shows that the variable UAV can change its own deformation in real time to assist the rudder deflection, and jointly form an adaptive aerodynamic torque to participate in attitude control, and realize high-precision attitude tracking under multi-source interference. Compared with the open-loop control distributor (the distribution constraint is , the other is the same as the closed-loop control distributor) of the adaptive attitude control method. The present invention can reduce the attack angle tracking error of the variable-configuration UAV by one order of magnitude, effectively improving the accuracy of the attitude control of the variable-configuration UAV.

[0056] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. It is easy for the technical personnel in the field to understand that the above description is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The adaptive anti-disturbance attitude control method of a transformable UAV under multi-source interference is characterized by: The steps include: The first step is to establish a posture dynamics model of a transformable UAV under multi-source interference in a strict feedback form; the transformable UAV is a winged UAV with variable wingspan and sweep angle; the multi-source interference includes environmental wind disturbance and the body center of mass offset, rudder deflection execution error, and aerodynamic parameter uncertainty of the transformable UAV; Step 2: Design an adaptive backstepping attitude controller using aerodynamic torque as a virtual control variable for; ； in, represents the attitude angle vector, represents the attitude angular velocity vector, , , They represent the angle of attack, sideslip angle, and speed roll angle, respectively. , , Denote the roll angular velocity, yaw angular velocity, and pitch angular velocity, respectively. represents the transpose operator; , Respectively represent , The associated system nominal matrix; represents the aerodynamic moment action matrix, , , Indicates the moment of inertia of the fuselage around the three axes of the fuselage coordinate system. Represents the inverse operator, Indicates is a diagonal matrix with diagonal elements; , , are the controller parameters to be designed; is a 3D unit matrix; , , , is an intermediate variable, and the expression is , , , , represents the partial derivative operator, sech represents the hyperbolic secant function; Represents the attitude angle error variable, and the expression is , represents the desired attitude angle, represents the desired attitude angular velocity, represents the desired attitude angular acceleration; represents the intermediate error variable, and the expression is ; , They represent the system interference vectors , system interference vector Adaptive estimate of the numerical upper bound, , They are The derivative adaptive law of The derivative adaptive law of , , tanh represents the hyperbolic tangent function, is an intermediate variable, and the expression is , is the virtual control quantity, and its expression is , , are the estimated parameters to be designed; , They represent the posture dynamics model respectively. The first and second row elements of the column vector; The third step is to design a closed-loop control distributor of virtual control variables using wingspan, sweep angle and rudder deflection as augmented heterogeneous execution variables, including: The wingspan, sweep angle and rudder deviation are used as augmented heterogeneous execution variables, denoted as , the expression is , is the sweep angle of the transformable UAV, The wingspan of the variable-speed UAV is , and are the expected rudder deflection of the roll channel, the expected rudder deflection of the yaw channel and the expected rudder deflection of the pitch channel respectively; the closed-loop control distributor is , expressed as the solution of the following optimization problem: ； in, Indicates the current sampling step of the system. represents the last sampling step of the system, is the augmented heterogeneous execution variable of the current sampling step k, is the heterogeneous execution control variable of the previous sampling step; the symbol find represents the optimization variable of the optimization problem, and the symbol It means finding the minimum value of a function, and the symbol subject to represents the constraints of the optimization problem; represents the performance function of the optimization problem, represents the weight matrix, symbol Represents the square of the vector's two-norm, symbol / indicates vector ratio; and They are The minimum and maximum execution capabilities of , , , They are The physical constraints of the upper and lower bounds are symbolized as It means to find the maximum value of the function. for The maximum rate of change, is the system sampling step; is the torque to be distributed in the current sampling step, which is obtained by compensation under the closed-loop structure, and its expression is , is the torque to be distributed in the previous sampling step, is the control torque given by the current sampling step controller, is the aerodynamic torque of the modified UAV in the previous sampling step, Represents the control effectiveness matrix of the current sampling step k, expressed as ; Solve the augmented heterogeneous execution variables of the current sampling step k based on the quadratic programming method , realize the dynamic allocation mapping of attitude control torque to be allocated to heterogeneous actuators; The fourth step is to combine the adaptive backstepping attitude controller and the closed-loop control distributor to complete the design of the adaptive anti-disturbance attitude control method for the transformable UAV under multi-source interference.

2. The adaptive anti-disturbance attitude control method for a transformable UAV under multi-source interference according to claim 1 is characterized in that: In the first step, the attitude dynamics model of the allostatic UAV under multi-source interference in the strict feedback form is: ； in, represents the attitude angle vector, represents the attitude angular velocity vector, , , They represent the angle of attack, sideslip angle, and speed roll angle respectively. , , Denote the roll angular velocity, yaw angular velocity, and pitch angular velocity, respectively. represents the transpose operator; , Respectively The derivative of The derivative of , Respectively represent , The associated system nominal matrix; represents the aerodynamic moment action matrix, , , Indicates the moment of inertia of the fuselage around the three axes of the fuselage coordinate system. Represents the inverse operator, represents a diagonal matrix with * as diagonal elements; the dynamic characteristics introduced by configuration changes and the influence of multi-source interference on the attitude system of the variable-configuration UAV are reflected in , and middle, represents the disturbance vector in the attitude angle channel, , , are the interference vectors of the attitude angle channel Components on the three axes of the track coordinate system; represents the disturbance vector in the attitude angular velocity channel, , , are the interference vectors of the attitude angular velocity channel respectively Components on the three axes of the body coordinate system; represents the aerodynamic torque, , , express The components on the three axes of the body coordinate system.

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