Robust fault-tolerant attitude control method and system for non-overshoot preset performance aircraft

Abstract

The invention discloses a robust fault-tolerant attitude control method and system for a non-overshoot preset performance aircraft, and belongs to the technical field of rigid aircraft control. According to the method, the boundary of attitude tracking errors is limited by establishing an aircraft attitude tracking error motion model considering input saturation and faults; acquiring a non-overshoot preset performance attitude error behavior boundary; based on the aircraft attitude tracking error motion model and the non-overshoot preset performance attitude error behavior boundary, determining an unconstrained conversion error dynamic equation; based on an aircraft attitude tracking error motion model and a dynamic equation, an unconstrained attitude tracking motion model is established, a virtual control instruction is designed, an anti-saturation auxiliary system is introduced, and a dynamic equation of an attitude conversion error and a corrected angular velocity tracking error is determined; a disturbance estimator is designed based on an immersion and invariant theory, a complete form of a controller is determined, tracking control is performed on the attitude of the aircraft, and the method can realize non-overshoot constraint so as to reduce the collision risk.

Description

Technical Field

[0001] The present invention relates to the technical field of rigid body aircraft control, and more specifically to a robust fault-tolerant attitude control method and system for an aircraft with preset performance without overshoot. Background Art

[0002] With the continuous expansion of aircraft application fields, the increasingly complex and diverse aerospace missions have put forward more precise and strict requirements on the transient steady-state performance of the aircraft attitude tracking process, such as convergence speed, overshoot, and steady-state accuracy. Although traditional control methods can change parameters to adjust the transient steady-state performance of the system, they cannot provide theoretical constraints and guarantees for the transient steady-state performance of the closed-loop system from the controller design level.

[0003] In view of the contradiction between current task requirements and the performance of traditional controllers, preset performance control is an effective solution. It can pre-set the transient steady-state performance of the system during the controller design process and provide strict theoretical guarantees.

[0004] Traditional preset performance control technology can impose constraints on the transient and steady-state performance of the system to a certain extent, but this method will produce a large overshoot during the convergence of the attitude tracking error. Since the behavior boundary set by the commonly used preset performance function is not compact enough, the overshoot cannot be effectively limited. A large overshoot will not only reduce the efficiency of the aircraft in performing its mission, but may also prevent it from quickly reaching its intended target. Therefore, when designing a controller, it is necessary to consider how to effectively reduce the overshoot while achieving rapid convergence of the attitude tracking error. Various internal and external disturbances are prevalent in attitude tracking control. Due to complex and changeable environmental conditions, such as wind speed, temperature, humidity, wear and aging of the equipment itself, etc., the attitude tracking performance will be greatly affected. Therefore, in the controller design process, system disturbance is also one of the issues that must be considered.

[0005] Ideally, the control instructions given by the attitude control algorithm can be accurately executed. However, in actual operation, the control instructions need to be implemented by the actuator. Due to physical limitations, the actuator may experience output saturation, partial failure, bias drift and other fault phenomena, which will lead to the deterioration of the aircraft's attitude control performance, causing drastic fluctuations in flight attitude, and seriously threatening flight safety. Summary of the invention

[0006] In response to the problems existing in the above-mentioned fields, the present invention proposes a method and system for robust fault-tolerant attitude control of a preset performance aircraft, which can solve the technical problems in the prior art that due to physical limitations, the actuators may experience output saturation, partial failure, bias drift and other fault phenomena, which will lead to the deterioration of the aircraft attitude control performance, cause drastic fluctuations in flight attitude, and seriously threaten flight safety.

[0007] In order to solve the above technical problems, the present invention discloses a method for robust fault-tolerant attitude control of a preset performance aircraft, comprising the following steps:

[0008] Establish a vehicle attitude tracking error motion model considering input saturation and failure;

[0009] According to the aircraft attitude tracking error motion model, by constructing a boundary function of the non-overshoot preset performance behavior, the boundary of the attitude error behavior without overshoot preset performance is determined;

[0010] Based on the aircraft attitude tracking error motion model and the attitude error behavior boundary of the preset performance without overshoot, an error conversion function is constructed to determine the unconstrained conversion error dynamic equation; the aircraft attitude tracking error motion model is substituted into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model;

[0011] According to the unconstrained attitude tracking motion model, the virtual control instructions are designed, the attitude tracking loop error variables are defined, and the dynamic equation of the attitude conversion error is solved; the angular velocity tracking error is defined and the anti-saturation auxiliary system is introduced to solve the dynamic equation of the corrected angular velocity tracking error;

[0012] A disturbance estimator is designed based on the immersion and invariance theory, and substituted into the dynamic equations of attitude conversion error and corrected angular velocity tracking error to obtain a robust fault-tolerant attitude control law for an aircraft with preset performance without overshoot, and the attitude of the aircraft is tracked and controlled.

[0013] Preferably, the establishment of the aircraft attitude tracking error motion model taking into account input saturation and failure comprises the following steps:

[0014] The dynamic and kinematic models of the aircraft attitude tracking error are established as follows:

[0015]

[0016] Among them, q e =[q e0 ,q e1 ,q e2 ,q e3 ] T is the attitude tracking error quaternion, is the error angular velocity, J B is the vehicle's moment of inertia, is the angular velocity of the aircraft, is the desired angular velocity, is the desired angular acceleration, C e is the rotation matrix, τ is the actual control torque, and d(t) is the internal and external disturbance torque of the system;

[0017] Considering the failure and saturation of the actuator, the actual control torque τ is rewritten into the following mathematical form:

[0018]

[0019] Among them, Γ is the efficiency loss function, τ S is the control torque after saturation limiting, b represents the additive fault of the actuator, sat(·) is the saturation function, τ B The control torque to be designed is: and τ B They are the upper and lower limits of the output torque of the actuator respectively;

[0020] The actual control torque τ is further rewritten as:

[0021]

[0022] Among them, Θ is the impact caused by actuator failure and additive fault;

[0023] The actual control torque τ containing Θ is substituted into the dynamic and kinematic models of the aircraft attitude tracking error, and the aircraft attitude tracking error motion model considering input saturation and failure is obtained.

[0024] Preferably, the determining of the preset performance attitude error behavior boundary without overshoot comprises the following steps:

[0025] Define the nonlinear function l i (t) is:

[0026] l i (t) = csch(l i t+h i,0 )+h i,∞ i=1,2,3

[0027] Where csch(·) is the hyperbolic cosecant function; l i is a positive constant;

[0028] According to the characteristics of the hyperbolic cosecant function, when l is selected i When the hyperbolic cosecant function is large enough, it will converge to zero quickly, that is, the parameter l is set i The larger it is, the faster the convergence speed;

[0029] Based on the nonlinear function, the behavior boundary function of the preset performance without overshoot is designed as:

[0030]

[0031] Among them, λ i , hi,0 and h i,∞ are all positive numbers, sign(·) is the sign function, q ei (0) is the initial value of trajectory tracking error;

[0032] Based on the designed behavior boundary function of the preset performance without overshoot, the behavior boundary of the attitude error without overshoot preset performance is designed as:

[0033]

[0034] Among them, q ei (t) is the trajectory tracking error at time t, H i (t) is the lower boundary of the behavior boundary function of the preset performance without overshoot at time t, The upper boundary of the behavior boundary function for the preset performance without overshoot at time t.

[0035] Preferably, the establishing of the unconstrained posture tracking motion model specifically comprises the following steps:

[0036] Based on the designed behavior boundary function with no overshoot preset performance, the error conversion function z i (t) Designed to:

[0037]

[0038] By taking the derivative of the error transfer function, the unconstrained transfer error dynamic equation is obtained:

[0039]

[0040] In which, define ξ i (t) and H i (t) are:

[0041]

[0042] Substitute the aircraft attitude tracking error motion model into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model:

[0043]

[0044] in, H=[H1(t),H2(t),H3(t)] T , and are the derivatives of the attitude tracking error vector.

[0045] Preferably, the dynamic equation for solving the posture conversion error specifically includes:

[0046] Design virtual control instructions for kinematic loops based on unconstrained conversion error dynamic equations for:

[0047]

[0048] Among them, k1>0 is a positive constant;

[0049] Based on the backstepping method, the error variable of the attitude tracking loop is defined as:

[0050]

[0051] According to the error variable of the attitude tracking loop, the dynamic equation of the attitude conversion error η1 is constructed as follows:

[0052]

[0053] Define the angular velocity tracking error α ω for:

[0054]

[0055] By taking the derivative of the angular velocity tracking error, we get the dynamic equation of the angular velocity tracking error:

[0056]

[0057] in, is the derivative of the virtual instruction, represents various nonlinear terms of the system, and D=d(t)+Θ is the lumped disturbance term of the system.

[0058] Preferably, solving the dynamic equation of the corrected angular velocity tracking error comprises the following steps:

[0059] According to the dynamics and kinematics model of the aircraft attitude tracking error, its dynamics model is simplified:

[0060]

[0061] The anti-saturation auxiliary system is defined as:

[0062]

[0063] Wherein, μ is a positive constant, χ is the state of the anti-saturation auxiliary system;

[0064] Based on the backstepping method, the corrected angular velocity tracking error variable η2 is defined as:

[0065]

[0066] According to the corrected angular velocity tracking error variable, the dynamic equation of the corrected angular velocity tracking error η2 is constructed as follows:

[0067]

[0068] Preferably, obtaining a robust fault-tolerant attitude control law for an aircraft with preset performance without overshoot specifically comprises the following steps:

[0069] The estimated value of D designed based on the immersion and invariance principle is:

[0070]

[0071] Among them, γ is the dynamic part of the estimate, is the angular velocity Related vector functions;

[0072] The estimated error of interference is defined as:

[0073]

[0074] By taking the derivative of the estimated error of the interference, the dynamic equation of the estimated error of the interference is obtained as follows:

[0075]

[0076] definition for:

[0077]

[0078] According to the definition The dynamic equation of the estimated error of the updated interference is obtained as:

[0079]

[0080] Define β as The dynamic equation of the estimated error of the updated disturbance is simplified:

[0081]

[0082] Among them, λ>0 is a dynamically adjusted parameter;

[0083] According to the immersion and invariance principle, the estimation of D is designed, and the robust fault-tolerant control law for attitude tracking with preset performance without overshoot is obtained:

[0084]

[0085] Among them, k2>0 is a positive constant;

[0086] According to the attitude tracking robust fault-tolerant control law with no overshoot preset performance, the complete form of the robust fault-tolerant attitude controller of the aircraft with no overshoot preset performance is determined as:

[0087]

[0088] According to the complete form of the robust fault-tolerant attitude controller of the aircraft with preset performance without overshoot, the attitude of the aircraft is tracked and controlled.

[0089] Preferably, it also includes a robust fault-tolerant attitude control system for an aircraft with preset performance without overshoot, comprising:

[0090] Aircraft attitude tracking error motion model building module, used to build an aircraft attitude tracking error motion model taking into account input saturation and failure;

[0091] An attitude error boundary acquisition module is used to determine the attitude error behavior boundary of the preset performance without overshoot by constructing a boundary function of the preset performance behavior without overshoot according to the aircraft attitude tracking error motion model;

[0092] The unconstrained attitude tracking motion model building module is used to construct an error conversion function and determine the unconstrained conversion error dynamic equation based on the aircraft attitude tracking error motion model and the no-overshoot preset performance attitude error behavior boundary; substitute the aircraft attitude tracking error motion model into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model;

[0093] The aircraft attitude control module is used to design virtual control instructions based on the unconstrained attitude tracking motion model, define the attitude tracking loop error variables, and solve the dynamic equation of the attitude conversion error; define the angular velocity tracking error and introduce the anti-saturation auxiliary system to solve the dynamic equation of the corrected angular velocity tracking error; design the disturbance estimator based on the immersion and invariance theory, and substitute it into the dynamic equations of the attitude conversion error and the corrected angular velocity tracking error to obtain the robust fault-tolerant attitude control law of the aircraft with preset performance without overshoot, and track the attitude of the aircraft.

[0094] Compared with the prior art, the present invention has the following beneficial effects:

[0095] The robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot proposed by the present invention restricts the boundary of the attitude error behavior without overshoot preset performance by constructing the boundary function of the behavior of preset performance without overshoot and the nonlinear trajectory constraint function containing the hyperbolic cosecant function. This smooth and stable boundary function can effectively constrain the overshoot, realize the constraint without overshoot and thus reduce the risk of collision. Based on the aircraft attitude tracking error motion model and the boundary of the attitude error behavior without overshoot preset performance, an error conversion function is constructed to obtain an unconstrained attitude tracking motion model. By designing virtual control instructions and introducing an anti-saturation auxiliary system, when the actuator input is saturated, the auxiliary system will generate a new output, which will be used to generate a new reference instruction, and further change the output of the robust fault-tolerant control law to maintain the stability of the closed-loop system; a disturbance estimator designed based on the immersion and invariance theory is adopted, which can quickly and accurately estimate the lumped disturbance including internal and external disturbances and actuator failures, and by performing disturbance compensation in the controller, the tracking error of the closed-loop system is reduced, thereby ensuring the robustness of the attitude tracking control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figure 1 It is a flow chart of a robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot provided by an embodiment of the present invention;

[0097] Figure 2 Schematic diagram of three coordinate systems used when performing posture tracking motion modeling in an embodiment of the present invention;

[0098] Figure 3 It is a closed-loop structure diagram of a robust fault-tolerant attitude control system for an aircraft with preset performance without overshoot provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0099] The following will be combined with the attached embodiment of the present invention Figure 1-Figure 3 , the technical solutions in the embodiments of the present invention are clearly and completely described. It should be understood that the terms described in the present invention are only used to describe specific implementation methods and are not used to limit the present invention.

[0100] Example

[0101] like Figure 1 As shown, a robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot proposed by the present invention comprises the following steps:

[0102] Step 1: Based on the actual actuator mathematical model and quaternion description method, a vehicle attitude tracking error motion model considering input saturation and failure is established.

[0103] Step 2: According to the aircraft attitude tracking error motion model, based on nonlinear functions, by designing the boundary function of the preset performance behavior without overshoot, the attitude tracking error boundary is restricted to determine the attitude error behavior boundary without overshoot preset performance.

[0104] Step 3: Based on the aircraft attitude tracking error motion model and the attitude error behavior boundary of the preset performance without overshoot, construct the error transfer function and determine the unconstrained transfer error dynamic equation; based on the aircraft attitude tracking error motion model and the unconstrained transfer error dynamic equation, substitute the aircraft attitude tracking error motion model into the unconstrained transfer error dynamic equation to establish the unconstrained attitude tracking motion model.

[0105] Step 4: Based on the unconstrained attitude tracking motion model, design virtual control instructions, define the attitude tracking loop error variables, and solve the dynamic equation of the attitude conversion error; define the angular velocity tracking error and introduce an anti-saturation auxiliary system to solve the dynamic equation of the corrected angular velocity tracking error.

[0106] Step 5: Design a disturbance estimator based on the immersion and invariance theory, and substitute it into the dynamic equation based on the attitude conversion error and the corrected angular velocity tracking error to obtain the robust fault-tolerant attitude control law for the aircraft with preset performance without overshoot, so as to determine the complete form of the robust fault-tolerant attitude controller for the aircraft with preset performance without overshoot, and track the attitude of the aircraft.

[0107] The specific implementation process of each step in the above technical solution of the present invention is as follows:

[0108] The specific implementation process of the first step includes:

[0109] In order to establish the aircraft attitude tracking error motion model, we define Figure 2 The three coordinate systems shown in the figure, among which the Earth's inertial system is denoted by F I , the aircraft system is denoted as F B , the expected motion system is denoted by F D .

[0110] The motion of the aircraft is represented by F B Relative to F I The single body posture motion model based on quaternion description is:

[0111]

[0112] Among them, q e =[q e0 ,q e1 ,q e2 ,q e3 ] T is the attitude tracking error quaternion, is the error angular velocity, JB is the vehicle's moment of inertia, is the angular velocity of the aircraft, is the desired angular velocity, is the desired angular acceleration, C e is the rotation matrix, τ is the actual control torque, and d(t) is the internal and external disturbance torque of the system.

[0113] The expected motion is described as F D Relative to F I Sports that meet:

[0114]

[0115] Among them, q D and They are the expected attitude and expected angular velocity, which are set according to the task requirements.

[0116] The tracking motion of the aircraft is described as F B Relative to F D Based on the above formula, the dynamic and kinematic models of the aircraft attitude tracking error are established as follows:

[0117]

[0118] Among them, q e =q D q B is the error quaternion, is the error angular velocity, C e By F D to F B The rotation matrix of is the desired angular acceleration, J B is the moment of inertia of the aircraft, τ is the actual control torque, and d(t) is the internal and external disturbance torque acting on the system.

[0119] Considering the saturation and failure of the actuator, the actual control torque τ is rewritten into the following mathematical form:

[0120]

[0121] Among them, Γ is the efficiency loss function, sat(·) is the saturation function, τ B The control torque to be designed is: τ B are the upper and lower limits of the output torque of the actuator mechanism, τ s is the control torque after saturation limiting, b represents the additive fault of the actuator, including offset and drift, ω i is the drift coefficient.

[0122] Further rewrite formula (6) as:

[0123]

[0124] Among them, Θ is the impact of actuator failure and additive fault.

[0125] The specific implementation process of the second step includes:

[0126] Construct the boundary function of the preset performance behavior without overshoot based on nonlinear functions and its attitude error boundary.

[0127] Define the nonlinear function l i (t) is:

[0128] l i (t) = csch(l i t+h i,0 )+h i,∞ i=1,2,3 (9)

[0129] Among them, l i is a positive constant, which determines the convergence speed of the function, and csch(·) is the hyperbolic cosecant function.

[0130] Based on the nonlinear function, the boundary function of the behavior of designing the preset performance without overshoot is:

[0131]

[0132] in λ i , h i,0 and h i,∞ are all positive numbers, sign(·) is the sign function, q ei (0) is the initial value of the trajectory tracking error.

[0133] Due to the characteristics of the hyperbolic cosecant function, when l i When the parameter is chosen to be large enough, the hyperbolic cosecant function will converge to zero quickly, that is, the larger the parameter is set, the faster the convergence speed.

[0134] At the same time, the application of the sign function makes the upper and lower bounds more compact to limit the trajectory tracking error. Therefore, this asymmetric behavior boundary function can ensure fast convergence and effectively limit the overshoot to make it sufficiently small or even zero.

[0135] Based on the designed behavior boundary function of the preset performance without overshoot, the behavior boundary of the attitude error without overshoot preset performance is designed as:

[0136]

[0137] Among them, q ei(t) is the trajectory tracking error at time t, H i (t) is the lower boundary of the behavior boundary function of the preset performance without overshoot at time t, The upper boundary of the behavior boundary function for the preset performance without overshoot at time t.

[0138] The specific implementation process of the third step includes:

[0139] Based on the boundary function of the preset performance behavior without overshoot, the error conversion function of the preset performance behavior without overshoot is constructed and the unconstrained attitude error equation is obtained.

[0140] Construct a conversion function to convert the constrained posture tracking error into an unconstrained posture tracking error. Based on the boundary function of the no-overshoot preset performance behavior in the second step, the error conversion function z i (t) Designed to:

[0141]

[0142] By differentiating the error transfer function, the unconstrained transfer error dynamic equation can be obtained as:

[0143]

[0144] In which, define ξ i (t),H i (t) is:

[0145]

[0146] Substitute the aircraft attitude tracking error motion model into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model:

[0147]

[0148] in, H=[H1(t),H2(t),H3(t)] T , q e =[q e1 ,q e2 ,q e3 ] T , for q e The corresponding cross product matrix.

[0149] The specific implementation process of the fourth step includes:

[0150] Virtual instructions are solved based on the unconstrained posture tracking motion model, and an anti-saturation auxiliary system is introduced.

[0151] Design virtual control instructions for kinematic loops for:

[0152]

[0153] Among them, k1>0 is a normal number.

[0154] Based on the backstepping method, the error variable of the attitude tracking loop is defined as:

[0155]

[0156] According to formula (17), the dynamic equation of the constructed posture transformation error η1 can be obtained as:

[0157]

[0158] Select the candidate Lyapunov function and derive it to obtain:

[0159]

[0160] Among them, V1 and Correspondingly, denoted the candidate Lyapunov function and the derivative of the candidate Lyapunov function.

[0161] Define the angular velocity tracking error α ω for:

[0162]

[0163] Based on the aircraft attitude tracking error motion model in the first step, the dynamic model is simplified as:

[0164]

[0165] in, are various nonlinear terms of the system, D = d(t) + Θ is the lumped disturbance term of the system, and the external disturbance torque and fault term are lumped and estimated through immersion and invariant disturbance estimator, which simplifies the design process.

[0166] By taking the derivative of the angular velocity tracking error, the dynamic equation of the angular velocity tracking error is obtained as follows:

[0167]

[0168] in, is the derivative of the error angular velocity, is the derivative of the virtual instruction.

[0169] The anti-saturation auxiliary system is defined as:

[0170]

[0171] Where μ is a positive constant and χ is the state of the anti-saturation auxiliary system.

[0172] The main function of this auxiliary system is to S ≠τ B , the auxiliary system will generate output χ for generating new reference instructions Further change the output of the robust control law to maintain the stability of the closed-loop system.

[0173] Based on the backstepping method, the corrected angular velocity tracking error variable is defined as:

[0174]

[0175] According to formula (25), the dynamic equation of the corrected angular velocity tracking error η2 can be obtained as:

[0176]

[0177] Select the candidate Lyapunov function and derive it to obtain:

[0178]

[0179] Where V2 represents the candidate Lyapunov function, represents the derivative of the candidate Lyapunov function.

[0180] The overall closed-loop system is verified by the Lyapunov stability principle:

[0181]

[0182] Among them, k2>0 is a normal number.

[0183] According to the basic principle of performance control without overshoot and the Lyapunov stability principle, the aircraft attitude tracking error converges without overshoot and meets the requirements of the performance constraint function.

[0184] The specific implementation process of the fifth step includes:

[0185] A disturbance estimator is designed based on the immersion and invariance theory, and substituted into the dynamic equations of attitude conversion error and corrected angular velocity tracking error to obtain the robust fault-tolerant attitude control law for the aircraft with preset performance without overshoot. The complete form of the robust fault-tolerant attitude controller for the aircraft with preset performance without overshoot is determined to track the attitude of the aircraft.

[0186] Based on the immersion and invariance principle, the estimator of the disturbance estimator D is designed as:

[0187]

[0188] Among them, γ is the dynamic part of the estimate, is the angular velocity Vector functions related to this.

[0189] The estimated error of interference is defined as:

[0190]

[0191] By differentiating the estimated error of the interference, we can obtain:

[0192]

[0193] Observe formula (32), Designed for:

[0194]

[0195] According to formula (33), formula (32) is rewritten to obtain the dynamic equation of the updated interference estimation error:

[0196]

[0197] Define β as By simplifying the dynamic equation of the estimated error of the updated interference, we can get the following equation:

[0198]

[0199] Among them, λ>0 is a dynamically adjusted parameter.

[0200] It can be seen from formula (35) that when λ is selected to be sufficiently large, the interference error Finally, arbitrarily small, so that The system is stable.

[0201] According to the above derivation, the robust fault-tolerant control law of attitude tracking with preset performance without overshoot is given as:

[0202]

[0203] Among them, k2>0 is a normal number.

[0204] The complete form of the robust fault-tolerant attitude controller for the aircraft with preset performance without overshoot is obtained as:

[0205]

[0206] According to the complete form of the robust fault-tolerant attitude controller of the aircraft with preset performance without overshoot, the attitude of the aircraft is tracked and controlled.

[0207] The present invention also proposes a robust fault-tolerant attitude control system for a preset performance aircraft, comprising:

[0208] Aircraft attitude tracking error motion model building module, used to build an aircraft attitude tracking error motion model taking into account input saturation and failure;

[0209] An attitude error boundary acquisition module is used to determine the attitude error behavior boundary of the preset performance without overshoot by constructing a boundary function of the preset performance behavior without overshoot according to the aircraft attitude tracking error motion model;

[0210] The unconstrained attitude tracking motion model building module is used to construct an error conversion function and determine the unconstrained conversion error dynamic equation based on the aircraft attitude tracking error motion model and the no-overshoot preset performance attitude error behavior boundary; substitute the aircraft attitude tracking error motion model into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model;

[0211] The aircraft attitude control module is used to design virtual control instructions according to the unconstrained attitude tracking motion model, define the attitude tracking loop error variable, and solve the dynamic equation of the attitude conversion error; define the angular velocity tracking error and introduce the anti-saturation auxiliary system to solve the dynamic equation of the corrected angular velocity tracking error; design the disturbance estimator based on the immersion and invariance theory, and substitute it into the dynamic equations of the attitude conversion error and the corrected angular velocity tracking error to obtain the robust fault-tolerant attitude control law of the aircraft with preset performance without overshoot, so as to determine the complete form of the robust fault-tolerant attitude controller of the aircraft with preset performance without overshoot, and track the attitude of the aircraft.

[0212] like Figure 3 As shown, the present invention provides a robust fault-tolerant attitude control system for an aircraft with preset performance without overshoot. The present invention constructs an aircraft attitude tracking error motion model that takes into account input actuator saturation and actuator failure, wherein a no-overshoot performance constraint function is designed based on the quaternion motion equation to limit the behavior boundary of the aircraft's preset performance attitude error without overshoot to within the range defined by the constraint function, and an error conversion function is designed based on the no-overshoot performance constraint function. The error conversion function is derived to obtain an unconstrained posture tracking error conversion function, and then an auxiliary system is introduced to design a control torque to solve the actuator saturation problem. According to the designed control torque, an immersion and invariant disturbance estimator is constructed in consideration of actuator failures and internal and external interferences to obtain the actual control torque and feed it back to the aircraft, thereby realizing a no-overshoot preset performance robust fault-tolerant attitude controller composed of an anti-saturation auxiliary system, an immersion and invariant disturbance estimator, and a no-overshoot preset performance robust fault-tolerant attitude control law to perform attitude tracking control on the aircraft.

[0213] The robust fault-tolerant attitude control method for an aircraft without excessive preset performance proposed in the present invention is designed based on a preset performance method, and performance constraints are pre-imposed during the controller design process, thereby theoretically ensuring the constrainability and controllability of the transient and steady-state performance of the closed-loop system.

[0214] The constructed boundary function of the preset performance behavior without overshoot contains a nonlinear trajectory constraint function of the hyperbolic cosecant function. This smooth and stable boundary function can effectively constrain the overshoot, achieve no overshoot constraint and thus reduce the collision risk.

[0215] The anti-saturation auxiliary system introduced will generate a new output when the input of the actuator is saturated. The output will be used to generate a new reference instruction and further change the output of the robust fault-tolerant control law to maintain the stability of the closed-loop system.

[0216] A disturbance estimator based on immersion and invariance theory is adopted, which can quickly and accurately estimate the lumped disturbance including internal and external disturbances and actuator faults, and make the tracking error of the closed-loop system arbitrarily small by performing disturbance compensation in the controller, thereby ensuring the robustness of the attitude tracking control system.

[0217] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0218] In addition, unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods related to the documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail.

Claims

1. A robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot, characterized in that: The following steps are involved: Establish a vehicle attitude tracking error motion model considering input saturation and failure; According to the aircraft attitude tracking error motion model, by constructing a boundary function of the non-overshoot preset performance behavior, the boundary of the attitude error behavior without overshoot preset performance is determined; Based on the aircraft attitude tracking error motion model and the attitude error behavior boundary of the preset performance without overshoot, the error transfer function is constructed and the unconstrained transfer error dynamic equation is determined; Substitute the aircraft attitude tracking error motion model into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model; According to the unconstrained attitude tracking motion model, the virtual control instructions are designed, the attitude tracking loop error variables are defined, and the dynamic equation of the attitude conversion error is solved; the angular velocity tracking error is defined and the anti-saturation auxiliary system is introduced to solve the dynamic equation of the corrected angular velocity tracking error; A disturbance estimator is designed based on the immersion and invariance theory, and substituted into the dynamic equations of attitude conversion error and corrected angular velocity tracking error to obtain a robust fault-tolerant attitude control law for an aircraft with preset performance without overshoot, and the attitude of the aircraft is tracked and controlled.

2. The robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot according to claim 1, characterized in that: The method of establishing an aircraft attitude tracking error motion model taking into account input saturation and failure comprises the following steps: The dynamic and kinematic models of the aircraft attitude tracking error are established as follows: Among them, q e =[q e0 ,q e1 ,q e2 ,q e3 ] T is the attitude tracking error quaternion, is the error angular velocity, J B is the vehicle's moment of inertia, is the angular velocity of the aircraft, is the desired angular velocity, is the desired angular acceleration, C e is the rotation matrix, τ is the actual control torque, and d(t) is the internal and external disturbance torque of the system; Considering the failure and saturation of the actuator, the actual control torque τ is rewritten into the following mathematical form: Among them, Γ is the efficiency loss function, τ S is the control torque after saturation limiting, b represents the additive fault of the actuator, sat(·) is the saturation function, τ B The control torque to be designed is: and τ B They are the upper and lower limits of the output torque of the actuator respectively; The actual control torque τ is further rewritten as: Among them, Θ is the impact caused by actuator failure and additive fault; The actual control torque τ containing Θ is substituted into the dynamic and kinematic models of the vehicle attitude tracking error, and the vehicle attitude tracking error motion model considering input saturation and failure is obtained.

3. The robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot according to claim 2, characterized in that: Determining the preset performance attitude error behavior boundary without overshoot comprises the following steps: Define the nonlinear function l i (t) is: l i (t)=csch(l i t+h i,0 )+h i,∞ i=1,2,3 Where csch(·) is the hyperbolic cosecant function; l i is a positive constant; According to the characteristics of the hyperbolic cosecant function, when l is selected i When the hyperbolic cosecant function is large enough, it will converge to zero quickly, that is, the parameter l is set i The larger it is, the faster the convergence speed; Based on the nonlinear function, the behavior boundary function of the preset performance without overshoot is designed as: in, λ i , h i,0 and h i,∞ are all positive numbers, sign(·) is the sign function, q ei (0) is the initial value of trajectory tracking error; Based on the designed behavior boundary function of the preset performance without overshoot, the behavior boundary of the attitude error without overshoot preset performance is designed as: Among them, q ei (t) is the trajectory tracking error at time t, H i (t) is the lower boundary of the behavior boundary function of the preset performance without overshoot at time t, The upper boundary of the behavior boundary function for the preset performance without overshoot at time t.

4. The robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot according to claim 3, characterized in that: The establishment of the unconstrained posture tracking motion model specifically includes the following steps: Based on the designed behavior boundary function with no overshoot preset performance, the error conversion function z i (t) Designed to: By taking the derivative of the error transfer function, the unconstrained transfer error dynamic equation is obtained: In which, define ξ i (t) and H i (t) are: Substitute the aircraft attitude tracking error motion model into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model: in, H=[H1(t),H2(t),H3(t)] T , and are the derivatives of the attitude tracking error vector.

5. The robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot according to claim 4, characterized in that: The dynamic equation for solving the attitude conversion error specifically includes: Design virtual control instructions for kinematic loops based on unconstrained conversion error dynamic equations for: Among them, k1>0 is a positive constant; Based on the backstepping method, the error variable of the attitude tracking loop is defined as: According to the error variable of the attitude tracking loop, the dynamic equation of the attitude conversion error η1 is constructed as follows: Define the angular velocity tracking error α ω for: By taking the derivative of the angular velocity tracking error, we get the dynamic equation of the angular velocity tracking error: in, is the derivative of the virtual instruction, represents various nonlinear terms of the system, and D=d(t)+Θ is the lumped disturbance term of the system.

6. The robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot according to claim 5, characterized in that: The method for solving the dynamic equation of the corrected angular velocity tracking error comprises the following steps: According to the dynamics and kinematics model of the aircraft attitude tracking error, its dynamics model is simplified: The anti-saturation auxiliary system is defined as: Wherein, μ is a positive constant, χ is the state of the anti-saturation auxiliary system; Based on the backstepping method, the corrected angular velocity tracking error variable η2 is defined as: According to the corrected angular velocity tracking error variable, the dynamic equation of the corrected angular velocity tracking error η2 is constructed as follows:

7. The robust fault-tolerant attitude control method for an aircraft with preset performance without overshoot according to claim 6, characterized in that: The method of obtaining a robust fault-tolerant attitude control law for an aircraft with preset performance without overshoot specifically comprises the following steps: The estimated value of D designed based on the immersion and invariance principle is: Among them, γ is the dynamic part of the estimate, is the angular velocity Related vector functions; The estimated error of interference is defined as: By taking the derivative of the estimated error of the interference, the dynamic equation of the estimated error of the interference is obtained as follows: definition for: According to the definition The dynamic equation of the estimated error of the updated interference is obtained as: Define β as The dynamic equation of the estimated error of the updated disturbance is simplified: Among them, λ>0 is a dynamically adjusted parameter; According to the immersion and invariance principle, the estimation of D is designed, and the robust fault-tolerant control law for attitude tracking with preset performance without overshoot is obtained: Among them, k2>0 is a positive constant; According to the attitude tracking robust fault-tolerant control law with no overshoot preset performance, the complete form of the robust fault-tolerant attitude controller of the aircraft with no overshoot preset performance is determined as: According to the complete form of the robust fault-tolerant attitude controller of the aircraft with preset performance without overshoot, the attitude of the aircraft is tracked and controlled.

8. A robust fault-tolerant attitude control system for an aircraft with preset performance without overshoot, characterized in that: include: Aircraft attitude tracking error motion model building module, used to build an aircraft attitude tracking error motion model taking into account input saturation and failure; An attitude error boundary acquisition module is used to determine the attitude error behavior boundary of the preset performance without overshoot by constructing a boundary function of the preset performance behavior without overshoot according to the aircraft attitude tracking error motion model; An unconstrained attitude tracking motion model building module is used to construct an error transfer function and determine an unconstrained transfer error dynamic equation based on the aircraft attitude tracking error motion model and the attitude error behavior boundary without overshoot preset performance; Substitute the aircraft attitude tracking error motion model into the unconstrained conversion error dynamic equation to establish the unconstrained attitude tracking motion model; The aircraft attitude control module is used to design virtual control instructions based on the unconstrained attitude tracking motion model, define the attitude tracking loop error variables, and solve the dynamic equation of the attitude conversion error; define the angular velocity tracking error and introduce the anti-saturation auxiliary system to solve the dynamic equation of the corrected angular velocity tracking error; design the disturbance estimator based on the immersion and invariance theory, and substitute it into the dynamic equations of the attitude conversion error and the corrected angular velocity tracking error to obtain the robust fault-tolerant attitude control law of the aircraft with preset performance without overshoot, and track the attitude of the aircraft.

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