A robust fault-tolerant attitude control method and system for a non-overshoot pre-set performance aircraft

Abstract

The application discloses a kind of overshoot-free preset performance aircraft robust fault-tolerant attitude control method and system, belong to rigid body aircraft control technical field, this method is by establishing considering input saturation and fault aircraft attitude tracking error motion model, the boundary of attitude tracking error is limited, and overshoot-free preset performance attitude error behavior boundary is obtained;Based on aircraft attitude tracking error motion model and overshoot-free preset performance attitude error behavior boundary, determine unconstrained conversion error dynamic equation;Based on aircraft attitude tracking error motion model and dynamic equation, establish unconstrained attitude tracking motion model, design virtual control instruction, and introduce anti-saturation auxiliary system, determine the dynamic equation of attitude conversion error and modified angular velocity tracking error;Based on immersion and invariant theory design disturbance estimator, determine the complete form of controller, track control to the attitude of aircraft, this method can realize no overshoot constraint and then reduce collision risk.

Description

Technical Field

[0001] This invention relates to the field of rigid body aircraft control technology, and more specifically to a robust fault-tolerant attitude control method and system for a pre-set performance aircraft without overshoot. Background Technology

[0002] As the application fields of aircraft continue to expand, the increasingly complex and diverse aerospace missions are placing more refined and stringent demands on the transient steady-state performance of aircraft attitude tracking processes, such as convergence speed, overshoot, and steady-state accuracy. While traditional control methods can adjust the transient steady-state performance of a system by changing parameters, they cannot provide theoretical constraints and guarantees on the transient steady-state performance of the closed-loop system from the controller design level.

[0003] To address the conflict 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 a theoretically rigorous guarantee.

[0004] Traditional preset performance control techniques can constrain the transient and steady-state performance of a system to a certain extent. However, this method generates significant overshoot during the convergence of attitude tracking errors. Because the behavioral boundaries set by commonly used preset performance functions are not tight enough, they cannot effectively limit overshoot. Large overshoot not only reduces the efficiency of the aircraft in performing its mission but may also prevent it from quickly reaching the predetermined goal. Therefore, when designing a controller, it is necessary to consider how to effectively reduce overshoot while achieving rapid convergence of attitude tracking errors. Various internal and external disturbances are prevalent in attitude tracking control. Due to complex and variable environmental conditions, such as wind speed, temperature, humidity, and wear and aging of the equipment itself, attitude tracking performance can be greatly affected. Therefore, system disturbance considerations are also a crucial factor to consider during controller design.

[0005] Ideally, the control commands given by the attitude control algorithm can be executed precisely. However, in actual operation, the control commands need to be implemented by the actuators. Due to physical limitations, the actuators may experience output saturation, partial failure, bias drift, and other malfunctions, which can lead to a deterioration in the aircraft's attitude control performance, causing severe fluctuations in flight attitude and seriously threatening flight safety. Summary of the Invention

[0006] To address the problems existing in the aforementioned fields, this invention proposes a robust fault-tolerant attitude control method and system for pre-set performance aircraft. This method can solve the technical problem that existing technologies, due to physical limitations, can cause output saturation, partial failure, bias drift, and other fault phenomena in the actuators, leading to deterioration of the aircraft's attitude control performance, causing severe fluctuations in flight attitude, and seriously threatening flight safety.

[0007] To address the aforementioned technical problems, this invention discloses a robust fault-tolerant attitude control method for a pre-defined performance aircraft, comprising the following steps:

[0008] Establish a motion model for aircraft attitude tracking error that considers input saturation and faults;

[0009] Based on the motion model of the aircraft attitude tracking error, the boundary of the attitude error behavior without overshoot is determined by constructing the boundary function of the preset performance behavior without overshoot.

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

[0011] Based on the unconstrained attitude tracking motion model, virtual control commands are designed, attitude tracking loop error variables are defined, and the dynamic equation of attitude transition error is solved; the angular velocity tracking error is defined and an anti-saturation auxiliary system is introduced, and the dynamic equation of the corrected angular velocity tracking error is solved.

[0012] Based on the immersion and invariance theory, a disturbance estimator is designed and substituted into the dynamic equations of attitude transition error and corrected angular velocity tracking error to obtain a robust fault-tolerant attitude control law for a pre-set performance aircraft without overshoot, which is then used to track and control the aircraft's attitude.

[0013] Preferably, the step of establishing a motion model for aircraft attitude tracking error that considers input saturation and faults includes the following steps:

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

[0015]

[0016] Where, q e =[q e0 ,q e1 ,q e2 ,q e3 ] T The attitude tracking error quaternion, J is the error angular velocity. B For the moment of inertia of the aircraft, For the angular velocity of the aircraft, For the desired angular velocity, For the desired angular acceleration, C e Let τ be the rotation matrix, τ be the actual control torque, and d(t) be the internal and external disturbance torques experienced by the system.

[0017] Taking into account actuator failures and saturation, the actual control torque τ can be rewritten in the following mathematical form:

[0018]

[0019] Where Γ is the efficiency loss function, τ S Let τ be the control torque after saturation limiting, b represent the additive fault of the actuator, sat(·) be the saturation function, and τ be the control torque after saturation limiting. B For the control torque that needs to be designed, and τ B These are the upper and lower limits of the output torque of the actuator, respectively;

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

[0021]

[0022] Wherein, Θ represents the impact of actuator failure and additive faults;

[0023] Substituting the actual control torque τ containing Θ into the dynamics and kinematics model of the aircraft attitude tracking error, we obtain the motion model of the aircraft attitude tracking error considering input saturation and faults.

[0024] Preferably, determining the boundary of the pre-set performance attitude error behavior without overshoot includes the following steps:

[0025] Define a 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 It is a positive number;

[0028] Based on the properties of the hyperbolic cosecant function, when the selected l i When the value is sufficiently large, the hyperbolic cosecant function will converge rapidly to zero, i.e., the set parameter l... i The larger the value, the faster the convergence speed;

[0029] Based on nonlinear functions, the behavior boundary function with no overshoot and preset performance is designed as follows:

[0030]

[0031] Where, λ i , hi,0 and h i,∞ All are positive integers, sign(·) is the sign function, and q ei (0) represents the initial value of the trajectory tracking error;

[0032] Based on the designed behavior boundary function with no overshoot preset performance, the attitude error behavior boundary with no overshoot preset performance is designed as follows:

[0033]

[0034] Where, q ei (t) represents the trajectory tracking error at time t, H i (t) represents the lower boundary of the behavior boundary function with no overshoot preset performance at time t. Let t be the upper boundary of the behavior boundary function with no overshoot preset performance at time t.

[0035] Preferably, the establishment of the unconstrained attitude tracking motion model specifically includes the following steps:

[0036] Based on the designed behavior boundary function with no overshoot preset performance, the error transformation function z i (t) is designed as follows:

[0037]

[0038] Taking the derivative of the error transformation function, we obtain the unconstrained transformation error dynamic equation as follows:

[0039]

[0040] Where, ξ is defined i (t) and H i (t) are respectively:

[0041]

[0042] Substituting the motion model of the aircraft attitude tracking error into the dynamic equation of the unconstrained transformation error, the unconstrained attitude tracking motion model is established as follows:

[0043]

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

[0045] Preferably, solving the dynamic equation for the attitude transition error specifically includes:

[0046] Based on the unconstrained transformation error dynamic equation, a virtual control command for the kinematic loop is designed. for:

[0047]

[0048] Where k1 > 0 are positive constants;

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

[0050]

[0051] Based on the error variables of the attitude tracking loop, the dynamic equation for the attitude transition error η1 is constructed as follows:

[0052]

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

[0054]

[0055] Differentiating the angular velocity tracking error, we obtain the dynamic equation for the angular velocity tracking error:

[0056]

[0057] in, The derivative of the virtual instruction. The terms represent 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 for the corrected angular velocity tracking error includes the following steps:

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

[0060]

[0061] Define the anti-saturation auxiliary system as:

[0062]

[0063] Where μ is a positive constant and 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] Based on the corrected angular velocity tracking error variable, the dynamic equation for the corrected angular velocity tracking error η2 is constructed as follows:

[0067]

[0068] Preferably, obtaining the robust fault-tolerant attitude control law for a pre-set performance aircraft without overshoot specifically includes the following steps:

[0069] The estimator of D based on the principles of immersion and invariance is:

[0070]

[0071] Where γ is the estimated dynamic part, For angular velocity Relevant vector functions;

[0072] The estimation error of the disturbance is defined as:

[0073]

[0074] Differentiating the estimation error of the disturbance, we obtain the dynamic equation for the estimation error of the disturbance as follows:

[0075]

[0076] definition for:

[0077]

[0078] According to the definition The dynamic equation for the updated estimation error of the disturbance is as follows:

[0079]

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

[0081]

[0082] Where λ > 0 is a dynamically adjusted parameter;

[0083] Based on the immersion and invariance principle, an estimate of D is designed, and the overshoot-free preset performance attitude tracking robust fault-tolerant control law is obtained as follows:

[0084]

[0085] Where k2 > 0 are positive constants;

[0086] Based on the robust fault-tolerant control law for attitude tracking without overshoot preset performance, the complete form of the robust fault-tolerant attitude controller for aircraft without overshoot preset performance is determined as follows:

[0087]

[0088] Based on the complete form of a robust fault-tolerant attitude controller for aircraft with no overshoot preset performance, the attitude of the aircraft is tracked and controlled.

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

[0090] The aircraft attitude tracking error motion model construction module is used to build an aircraft attitude tracking error motion model that takes into account input saturation and faults.

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

[0092] The module for constructing an unconstrained attitude tracking motion model is used to construct an error transformation function and determine the unconstrained transformation error dynamic equation based on the aircraft attitude tracking error motion model and the pre-defined performance attitude error behavior boundary without overshoot; and to establish an unconstrained attitude tracking motion model by substituting the aircraft attitude tracking error motion model into the unconstrained transformation error dynamic equation.

[0093] The aircraft attitude control module is used to design virtual control commands based on the unconstrained attitude tracking motion model, define attitude tracking loop error variables, and solve the dynamic equation of attitude transition error; define angular velocity tracking error and introduce an anti-saturation auxiliary system to solve the dynamic equation of the corrected angular velocity tracking error; design a disturbance estimator based on immersion and invariance theory, and substitute it into the dynamic equation of attitude transition error and corrected angular velocity tracking error to obtain a robust fault-tolerant attitude control law for aircraft with no overshoot preset performance, and perform attitude tracking control of the aircraft.

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

[0095] The proposed robust fault-tolerant attitude control method for overshoot-free pre-defined performance aircraft in this invention restricts the boundary of the attitude error behavior without overshoot by constructing a boundary function for the behavior without overshoot and a nonlinear trajectory constraint function containing a hyperbolic cosecant function. This smooth and stable boundary function effectively constrains overshoot, achieving overshoot-free constraint and thus reducing collision risk. Based on the aircraft attitude tracking error motion model and the boundary of the attitude error behavior without overshoot, an error transformation function is constructed to obtain an unconstrained attitude tracking motion model. By designing virtual control commands and introducing an anti-saturation auxiliary system, when the actuator experiences input saturation, the auxiliary system generates a new output, which is used to generate a new reference command and further change the output of the robust fault-tolerant control law to maintain the stability of the closed-loop system. A disturbance estimator based on immersion and invariance theory is used. This estimator can quickly and accurately estimate the lumped disturbance including internal and external disturbances and actuator faults. 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. Attached Figure Description

[0096] Figure 1 This is a flowchart of the robust fault-tolerant attitude control method for a pre-set performance aircraft without overshoot provided in this embodiment of the invention;

[0097] Figure 2 This is a schematic diagram of the three coordinate systems used in the attitude tracking motion modeling of this invention embodiment;

[0098] Figure 3 This is a closed-loop structure diagram of the robust fault-tolerant attitude control system for a non-overshoot preset performance aircraft provided in an embodiment of the present invention. Detailed Implementation

[0099] The following will refer to the appendices in the embodiments of the present invention. Figures 1-3 The technical solutions in the embodiments of the present invention will be clearly and completely described. It should be understood that the terminology used in the present invention is only for describing particular implementation methods and is not intended to limit the present invention.

[0100] Example

[0101] like Figure 1 As shown, this invention proposes a robust fault-tolerant attitude control method for a pre-set performance aircraft without overshoot, comprising the following steps:

[0102] Step 1: Based on the mathematical model of the actual actuator and the quaternion description method, establish a motion model of aircraft attitude tracking error that considers input saturation and faults.

[0103] Step 2: Based on the motion model of the aircraft attitude tracking error, and based on nonlinear functions, the boundary of the attitude tracking error is restricted by designing a boundary function with preset performance behavior without overshoot, thereby determining the boundary of attitude error behavior without overshoot preset performance.

[0104] Step 3: Based on the aircraft attitude tracking error motion model and the overshoot-free preset performance attitude error behavior boundary, construct the error transformation function and determine the unconstrained transformation error dynamic equation; based on the aircraft attitude tracking error motion model and the unconstrained transformation error dynamic equation, substitute the aircraft attitude tracking error motion model into the unconstrained transformation 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 commands, define attitude tracking loop error variables, and solve the dynamic equation of attitude conversion error; define angular velocity tracking error and introduce an anti-saturation auxiliary system, and solve the dynamic equation of the corrected angular velocity tracking error.

[0106] Step 5: Design a disturbance estimator based on immersion and invariance theory, and substitute it into the dynamic equation based on attitude transition error and corrected angular velocity tracking error to obtain the robust fault-tolerant attitude control law for the aircraft with no overshoot preset performance. This will determine the complete form of the robust fault-tolerant attitude controller for the aircraft with no overshoot preset performance and enable the aircraft's attitude tracking control.

[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] To establish a motion model for aircraft attitude tracking error, the following definition is made: Figure 2 The three coordinate systems shown are, among which the Earth's inertial frame is denoted as F. I The aircraft system is denoted as F. B The expected motion system is denoted as F. D .

[0110] The motion of a single aircraft is represented by F. B Relative to F I The motion of the individual, based on the quaternion-described single-unit attitude motion model, is as follows:

[0111]

[0112] Where, q e =[q e0 ,q e1 ,q e2 ,q e3 ] T The attitude tracking error quaternion, J is the error angular velocity.B It is the moment of inertia of the aircraft. For the angular velocity of the aircraft, For the desired angular velocity, For the desired angular acceleration, C e Let be the rotation matrix, τ be the actual control torque, and d(t) be the internal and external disturbance torques experienced by the system.

[0113] The desired motion is described as F D Relative to F I The movement satisfies:

[0114]

[0115] Where, q D and These are the desired attitude and the desired angular velocity, which are set according to the mission requirements.

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

[0117]

[0118] Where, q e =q D q B It is an error quaternion. It is the error angular velocity, C e by F D To F B The rotation matrix, It is the desired angular acceleration, J B τ is the moment of inertia of the aircraft, τ is the actual control torque, and d(t) is the internal and external disturbance torques experienced by the system.

[0119] Taking into account actuator saturation and failure, the actual control torque τ can be rewritten in the following mathematical form:

[0120]

[0121] Where Γ is the efficiency loss function, sat(·) is the saturation function, and τ B For the control torque that needs to be designed, τ B τ represents the upper and lower limits of the output torque of the actuator mechanism, respectively. s The control torque after saturation limiting is ω, where b represents the additive fault of the actuator, including bias and drift, and ω represents the control torque after saturation limiting. i This is the drift coefficient.

[0122] Further rewriting equation (6) as:

[0123]

[0124] Here, Θ represents the impact of actuator failure and additive faults.

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

[0126] Construct boundary functions and attitude error boundaries for overshoot-free preset performance behavior based on nonlinear functions.

[0127] Define a 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 The constant is a positive constant, which determines the convergence rate of the function. csch(·) is the hyperbolic cosecant function.

[0130] Based on nonlinear functions, the boundary function for designing the behavior with no overshoot preset performance is as follows:

[0131]

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

[0133] Due to the properties of the hyperbolic cosecant function, when l i When the value is sufficiently large, the hyperbolic cosecant function will converge to zero quickly; that is, the larger the parameter is set, the faster the convergence speed.

[0134] Meanwhile, the application of a sign function allows for a more compact constraint on trajectory tracking errors at the upper and lower boundaries. Therefore, this asymmetric boundary function ensures fast convergence and effectively limits overshoot to a sufficiently small or even zero level.

[0135] Based on the designed behavior boundary function with no overshoot preset performance, the attitude error behavior boundary with no overshoot preset performance is designed as follows:

[0136]

[0137] Where, q ei(t) represents the trajectory tracking error at time t, H i (t) represents the lower boundary of the behavior boundary function with no overshoot preset performance at time t. Let t be the upper boundary of the behavior boundary function with no overshoot preset performance at time t.

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

[0139] Based on the boundary function with no overshoot preset performance behavior, an error transformation function with no overshoot preset performance behavior is constructed and an unconstrained attitude error equation is obtained.

[0140] Construct a transformation function to convert constrained attitude tracking error into unconstrained attitude tracking error. Based on the boundary function of the pre-defined performance behavior without overshoot from the second step, the error transformation function z... i (t) is designed as follows:

[0141]

[0142] Taking the derivative of the error transformation function, we can obtain the unconstrained transformation error dynamic equation as follows:

[0143]

[0144] Where, ξ is defined i (t),H i (t) is:

[0145]

[0146] Substituting the motion model of the aircraft attitude tracking error into the dynamic equation of the unconstrained transformation error, the unconstrained attitude tracking motion model is established as follows:

[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 commands are solved based on an unconstrained attitude tracking motion model, and an anti-saturation auxiliary system is introduced.

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

[0152]

[0153] Where k1 > 0 are positive constants.

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

[0155]

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

[0157]

[0158] By selecting candidate Lyapunov functions and taking their derivatives, we can obtain:

[0159]

[0160] Among them, V1 and The corresponding terms represent the derivatives of the candidate Lyapunov function and the candidate Lyapunov function.

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

[0162]

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

[0164]

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

[0166] Differentiating the angular velocity tracking error, we obtain the dynamic equation for the angular velocity tracking error as follows:

[0167]

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

[0169] Define the anti-saturation auxiliary system 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 respond to saturation of the actuator, i.e., τ S ≠τ B The auxiliary system will generate output χ to generate new reference instructions. Further modify 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 equation (25), the dynamic equation of the corrected angular velocity tracking error η2 can be obtained as follows:

[0176]

[0177] By selecting candidate Lyapunov functions and taking their derivatives, we can obtain:

[0178]

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

[0180] Verification of the overall closed-loop system using Lyapunov stability principles:

[0181]

[0182] Where k2 > 0 are positive constants.

[0183] Based on the fundamental principle of overshoot-free preset performance control and the Lyapunov stability principle, it can be known that the aircraft attitude tracking error is overshoot-free and converges, and satisfies the performance constraint function requirements.

[0184] The specific implementation process of step five includes:

[0185] Based on the immersion and invariance theory, a disturbance estimator is designed and substituted into the dynamic equations of attitude transition error and corrected angular velocity tracking error to obtain a robust fault-tolerant attitude control law for an aircraft with no overshoot preset performance. This allows for the determination of the complete form of a robust fault-tolerant attitude controller for an aircraft with no overshoot preset performance, enabling the tracking control of the aircraft's attitude.

[0186] Based on the principles of immersion and invariance, the estimator of the perturbation estimator D is designed as follows:

[0187]

[0188] Where γ is the estimated dynamic part, For angular velocity Related vector functions.

[0189] The estimation error of the disturbance is defined as:

[0190]

[0191] Taking the derivative of the estimation error of the disturbance, we get:

[0192]

[0193] Observation (32), Designed as follows:

[0194]

[0195] Based on equation (33), equation (32) is rewritten to obtain the dynamic equation for the updated estimation error of the disturbance:

[0196]

[0197] Define β as Simplifying the dynamic equation for the estimated error of the updated disturbance, we obtain the following equation:

[0198]

[0199] Where λ>0 is a dynamically adjusted parameter.

[0200] As can be seen from equation (35), when λ is chosen to be sufficiently large, the interference error... Ultimately arbitrarily small, thus making The system is stable.

[0201] Based on the above derivation, the robust fault-tolerant control law for attitude tracking with no overshoot preset performance is given as follows:

[0202]

[0203] Where k2 > 0 are positive constants.

[0204] The complete form of the robust fault-tolerant attitude controller for the aircraft with no overshoot preset performance is as follows:

[0205]

[0206] Based on the complete form of a robust fault-tolerant attitude controller for aircraft with no overshoot preset performance, the attitude of the aircraft is tracked and controlled.

[0207] This invention also proposes a robust fault-tolerant attitude control system for a pre-defined performance aircraft, comprising:

[0208] The aircraft attitude tracking error motion model construction module is used to build an aircraft attitude tracking error motion model that takes into account input saturation and faults.

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

[0210] The module for constructing an unconstrained attitude tracking motion model is used to construct an error transformation function and determine the unconstrained transformation error dynamic equation based on the aircraft attitude tracking error motion model and the pre-defined performance attitude error behavior boundary without overshoot; and to establish an unconstrained attitude tracking motion model by substituting the aircraft attitude tracking error motion model into the unconstrained transformation error dynamic equation.

[0211] The aircraft attitude control module is used to design virtual control commands based on the unconstrained attitude tracking motion model, define attitude tracking loop error variables, and solve the dynamic equation of attitude transition error; define angular velocity tracking error and introduce an anti-saturation auxiliary system to solve the dynamic equation of the corrected angular velocity tracking error; design a disturbance estimator based on immersion and invariance theory, and substitute it into the dynamic equations of attitude transition error and corrected angular velocity tracking error to obtain a robust fault-tolerant attitude control law for aircraft with no overshoot preset performance, thereby determining the complete form of a robust fault-tolerant attitude controller for aircraft with no overshoot preset performance, and performing attitude tracking control of the aircraft.

[0212] like Figure 3 As shown, this invention provides a robust fault-tolerant attitude control system for aircraft without overshoot preset performance. The invention constructs a motion model for aircraft attitude tracking error that considers actuator saturation and actuator failure. Specifically, a no-overshoot performance constraint function is designed based on quaternion motion equations to limit the no-overshoot preset performance attitude error behavior boundary of the aircraft within the range defined by the constraint function. An error transformation function is then designed based on the no-overshoot performance constraint function, and the derivative of the error transformation function yields an unconstrained pose tracking error transformation function. An auxiliary system is then introduced to design control torque to address actuator saturation. Based on the designed control torque, considering actuator failure and internal / external disturbances, an immersion and invariant disturbance estimator is constructed to obtain the actual control torque, which is then fed back to the aircraft. This results in 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, enabling attitude tracking control of the aircraft.

[0213] The robust fault-tolerant attitude control method for aircraft without excess preset performance proposed in this invention is designed based on the preset performance method. In the process of controller design, performance constraints are applied in advance to theoretically ensure the constrainability and controllability of the transient and steady-state performance of the closed-loop system.

[0214] The constructed boundary function with no overshoot and pre-defined performance behavior contains a nonlinear trajectory constraint function with a hyperbolic cosecant function. This smooth and stable boundary function can effectively constrain overshoot, achieve no overshoot constraint, and thus reduce collision risk.

[0215] The introduced anti-saturation auxiliary system generates a new output when the actuator experiences input saturation. This output is used to generate a new reference command and further modify 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. This estimator can quickly and accurately estimate the lumped disturbance including internal and external disturbances as well as actuator faults. By performing disturbance compensation in the controller, the tracking error of the closed-loop system is made arbitrarily small, thereby ensuring the robustness of the attitude tracking control system.

[0217] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0218] Furthermore, unless otherwise stated, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All references to this specification are incorporated by way of citation to disclose and describe methods relating to those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

Claims

1. A robust fault-tolerant attitude control method for a pre-set performance aircraft without overshoot, characterized in that, Includes the following steps: Establish a motion model for aircraft attitude tracking error that considers input saturation and faults; Based on the motion model of the aircraft attitude tracking error, the boundary of the attitude error behavior without overshoot is determined by constructing the boundary function of the preset performance behavior without overshoot. Based on the motion model of aircraft attitude tracking error and the behavior boundary of attitude error without overshoot preset performance, an error transformation function is constructed and the dynamic equation of unconstrained transformation error is determined. By substituting the motion model of the aircraft attitude tracking error into the dynamic equation of the unconstrained transformation error, an unconstrained attitude tracking motion model is established. Based on the unconstrained attitude tracking motion model, virtual control commands are designed, attitude tracking loop error variables are defined, and the dynamic equation of attitude transition error is solved; the angular velocity tracking error is defined and an anti-saturation auxiliary system is introduced, and the dynamic equation of the corrected angular velocity tracking error is solved. Based on the immersion and invariance theory, a disturbance estimator is designed 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 a pre-set performance aircraft without overshoot, and the attitude of the aircraft is tracked and controlled. Determining the boundary of the pre-set performance attitude error behavior without overshoot includes the following steps: Define nonlinear functions for: in, It is a hyperbolic cosecant function; It is a positive number; Based on the properties of the hyperbolic cosecant function, when the selected When the value is sufficiently large, the hyperbolic cosecant function will converge rapidly to zero, i.e., the set parameter... The larger the value, the faster the convergence speed; Based on nonlinear functions, the behavior boundary function with no overshoot and preset performance is designed as follows: in, , , and All are positive numbers. For symbolic functions, This is the initial value for trajectory tracking error; Based on the designed behavior boundary function with no overshoot preset performance, the attitude error behavior boundary with no overshoot preset performance is designed as follows: in, for The trajectory tracking error at any given moment, for The lower bound of the behavior boundary function for time-invariant performance without overshoot. for The upper bound of the behavior boundary function with no overshoot preset performance at any given time.

2. The robust fault-tolerant attitude control method for a non-overshoot preset performance aircraft according to claim 1, characterized in that, The establishment of a motion model for aircraft attitude tracking error that considers input saturation and faults includes the following steps: The dynamic and kinematic model of the aircraft attitude tracking error is established as follows: in, The attitude tracking error quaternion, For the error angular velocity, For the moment of inertia of the aircraft, For the angular velocity of the aircraft, For the desired angular velocity, For the desired angular acceleration, Let be a rotation matrix. For actual control torque, The internal and external disturbance torques experienced by the system; Taking into account actuator failure and saturation, the actual control torque will be... Rewritten in the following mathematical form: in, For the efficiency loss function, This is the control torque after saturation limiting. This indicates an additive fault in the actuator. It is a saturation function. For the control torque that needs to be designed, and These are the upper and lower limits of the output torque of the actuator, respectively; For actual control torque Further rewriting: in, The impact of actuator failure and additive faults; Will contain Actual control torque Substituting the dynamics and kinematics model of the aircraft attitude tracking error, we obtain the motion model of the aircraft attitude tracking error considering input saturation and faults.

3. The robust fault-tolerant attitude control method for a pre-set performance aircraft without overshoot as described in claim 1, characterized in that, The establishment of the unconstrained attitude tracking motion model specifically includes the following steps: Based on the designed behavior boundary function with no overshoot preset performance, the error transformation function is... Designed as follows: Taking the derivative of the error transformation function, we obtain the unconstrained transformation error dynamic equation as follows: Among them, the definition and They are respectively: Substituting the motion model of the aircraft attitude tracking error into the dynamic equation of the unconstrained transformation error, the unconstrained attitude tracking motion model is established as follows: in, , , , , and All of these are derivatives of the attitude tracking error vector.

4. The robust fault-tolerant attitude control method for a pre-set performance aircraft without overshoot as described in claim 3, characterized in that, The dynamic equation for solving the attitude transition error specifically includes: Based on the unconstrained transformation error dynamic equation, a virtual control command for the kinematic loop is designed. for: in, It is a positive number; Based on the backstepping method, the error variable of the attitude tracking loop is defined as: The attitude transition error is constructed based on the error variables of the attitude tracking loop. The dynamic equation is: Define angular velocity tracking error for: Differentiating the angular velocity tracking error, we obtain the dynamic equation for the angular velocity tracking error: in, The derivative of the virtual instruction. Representing various nonlinear terms of the system, It is the lumped disturbance term of the system.

5. The robust fault-tolerant attitude control method for a pre-set performance aircraft without overshoot as described in claim 4, characterized in that, Solving the dynamic equation for the corrected angular velocity tracking error includes the following steps: Based on the dynamics and kinematics model of the aircraft attitude tracking error, its dynamics model is simplified: Define the anti-saturation auxiliary system as: in, For positive integers, This refers to the state of the anti-saturation auxiliary system; Based on the backstepping method, the corrected angular velocity tracking error variable is defined. for: Based on the corrected angular velocity tracking error variable, the corrected angular velocity tracking error is constructed. The dynamic equation is: 。 6. The robust fault-tolerant attitude control method for a pre-set performance aircraft without overshoot as described in claim 5, characterized in that, The method for obtaining the robust fault-tolerant attitude control law for a pre-defined performance aircraft without overshoot specifically includes the following steps: Design based on the principles of immersion and invariance The estimator is: in, For the estimated dynamic part, For angular velocity Relevant vector functions; The estimation error of the disturbance is defined as: Differentiating the estimation error of the disturbance, we obtain the dynamic equation for the estimation error of the disturbance as follows: definition for: According to the definition The dynamic equation for the updated estimation error of the disturbance is: definition for The dynamic equation for the estimation error of the updated disturbance is simplified as follows: in, These are parameters that are dynamically adjusted. Designed based on the principles of immersion and invariance The estimated quantity yields the following robust fault-tolerant control law for attitude tracking with no overshoot preset performance: in, It is a positive number; Based on the robust fault-tolerant control law for attitude tracking without overshoot preset performance, the complete form of the robust fault-tolerant attitude controller for aircraft without overshoot preset performance is determined as follows: Based on the complete form of a robust fault-tolerant attitude controller for aircraft with no overshoot preset performance, the attitude of the aircraft is tracked and controlled.

7. A robust fault-tolerant attitude control system for a non-overshoot preset performance aircraft, characterized in that, include: The aircraft attitude tracking error motion model construction module is used to build an aircraft attitude tracking error motion model that takes into account input saturation and faults. The attitude error boundary acquisition module is used to determine the attitude error behavior boundary without overshoot preset performance by constructing a boundary function of the attitude tracking error motion model of the aircraft. The module for constructing an unconstrained attitude tracking motion model is used to construct an error transformation function and determine the unconstrained transformation error dynamic equation based on the aircraft attitude tracking error motion model and the overshoot-free preset performance attitude error behavior boundary. By substituting the motion model of the aircraft attitude tracking error into the dynamic equation of the unconstrained transformation error, an unconstrained attitude tracking motion model is established. The aircraft attitude control module is used to design virtual control commands based on the unconstrained attitude tracking motion model, define attitude tracking loop error variables, and solve the dynamic equation of attitude transition error; define angular velocity tracking error and introduce an anti-saturation auxiliary system to solve the dynamic equation of the corrected angular velocity tracking error; design a disturbance estimator based on immersion and invariance theory, and substitute it into the dynamic equation of attitude transition error and corrected angular velocity tracking error to obtain a robust fault-tolerant attitude control law for aircraft with no overshoot preset performance, and perform attitude tracking control of the aircraft; Determining the boundary of the pre-set performance attitude error behavior without overshoot includes the following steps: Define nonlinear functions for: in, It is a hyperbolic cosecant function; It is a positive number; Based on the properties of the hyperbolic cosecant function, when the selected When the value is sufficiently large, the hyperbolic cosecant function will converge rapidly to zero, i.e., the set parameter... The larger the value, the faster the convergence speed; Based on nonlinear functions, the behavior boundary function with no overshoot and preset performance is designed as follows: in, , , and All are positive numbers. For symbolic functions, This is the initial value for trajectory tracking error; Based on the designed behavior boundary function with no overshoot preset performance, the attitude error behavior boundary with no overshoot preset performance is designed as follows: in, for The trajectory tracking error at any given moment, for The lower bound of the behavior boundary function for time-invariant performance without overshoot. for The upper bound of the behavior boundary function with no overshoot preset performance at any given time.

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