CN110851944A - A fault-tolerant control method for automotive active suspension system based on adaptive fusion design - Google Patents

Abstract

The invention discloses a fault-tolerant control method for an automobile active suspension system based on an adaptive fusion design. The method includes the following steps: Step 1: establishing a mathematical model of the automobile active suspension system under the condition of uncertain actuator failure, and using the mathematical model The method expresses the uncertain influence of the actuator fault uncertainty on the system control input; in step 2, the fault-tolerant controller is designed based on the mathematical model of the active suspension under fault, and the basic feedback controller is designed in combination with the inversion control to ensure the closed-loop system problem. A fault compensation controller is designed for each failure mode, and a comprehensive controller that can solve all failure modes is designed based on the fusion algorithm. In step three, the Lyapunov function method is used to test the performance of the fault-tolerant controller. The invention mainly solves the two key uncertain factors of actuator failure mode and failure type, so as to ensure that the automobile active suspension system realizes the desired control target and obtains ideal performance under the condition of uncertain actuator failure.

Description

A fault-tolerant control of automotive active suspension system based on adaptive fusion design method

technical field

The invention relates to the technical field of automobile suspension control, in particular to a fault-tolerant control method of an automobile active suspension system based on adaptive fusion design.

Background technique

Vehicle suspension system is the basis for significantly improving passenger comfort and handling characteristics. Roughly speaking, vehicle suspension can be divided into three types: passive suspension, semi-active suspension and active suspension, and passive suspension system and semi-active suspension system. Compared with the active suspension system, the active suspension system has the best performance potential under different driving conditions, therefore, the control problems of this system have received extensive attention, such as optimal control, predictive control, robust control, fuzzy control, Adaptive control, etc. Among them, the adaptive control method has a strong ability to deal with the uncertainty of the system, and ensures that the system has better transient performance and steady-state performance under uncertainty. In practical applications, the active suspension system actuator Failures are more likely than failures of other components, and these failures can lead to instability or even catastrophic failure of the control gear. Studies have shown that traditional feedback control methods cannot guarantee the desired performance of the system in the event of component failures, and severe actuator failures will lead to system instability. Therefore, new control methods need to be proposed to overcome uncertain failures. The impact of performance, so that the system still has ideal stability and expected performance under normal or fault conditions.

A series of effective methods have been proposed by experts and scholars at home and abroad, such as sliding mode control, reconfiguration control, H∞ control and inversion control, etc. It is an actuator fault of the type of stuck and gain failure in the active suspension system of the automobile, which ensures the stability of the closed-loop system. The Chinese patent document CN201611256758.7 provides "a passive fault-tolerant control method for the active suspension of the automobile" for the active suspension system. In this paper, a passive fault-tolerant control method is proposed. However, in practice, the automotive active suspension system may suffer from time-varying faults, and stability and tracking are the two major factors of the suspension system. The key performance is that for the automotive active suspension system, the tracking control under fault conditions is more complicated than the stability control problem. In actual operation, the actuator fault has inherent uncertainties, that is, the time of failure, the type of failure, the mode of failure and the execution of the failure. The number of controllers is unknown, and the fault-tolerant control method designed to determine the fault type and fault mode cannot be used to solve the uncertain fault situation, which leads to the limitation of the application.

Among the multiple uncertainties of actuator failure, the failure mode uncertainty is the most critical. To eliminate the influence of the failure under multiple uncertain failure modes on the system performance, it is necessary to fundamentally estimate the failure value under each failure mode effectively. Designing a comprehensive control method can effectively solve the fault problem under each fault condition, essentially simultaneously solving the uncertainty of the fault mode and the fault parameters.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a fault-tolerant control method for an automobile active suspension system based on adaptive fusion design. The mathematical model of the fault-tolerant controller is designed based on the mathematical model of the actuator fault uncertainty on the control input of the system; the fault-tolerant controller is designed based on the mathematical model of the active suspension under fault, and the basic feedback controller is designed in combination with the inversion control to ensure For closed-loop system problems, fault compensation controllers are designed for each failure mode, and a comprehensive controller that can solve all failure modes is designed based on fusion algorithm; Lyapunov function method is used to test the performance of fault-tolerant controller. This fault-tolerant control method It mainly solves the two key uncertain factors of actuator failure mode and failure type, and ensures that the automotive active suspension system can achieve the desired control objectives and obtain ideal performance in the case of uncertain actuator failures.

In order to achieve the above-mentioned goals, the present invention provides the following specific technical solutions: a fault-tolerant control method for an automobile active suspension system based on an adaptive fusion design, the fault-tolerant control method comprises the following steps:

The first step is to establish a mathematical model of the vehicle active suspension system under uncertain fault conditions;

The semi-vehicle active suspension system is adopted, and its system dynamics equation is:

In the above formula (1), M and I are the mass and moment of inertia of the car body, respectively, m _f and m _r are the front and rear unsprung masses, respectively, and F _df , F _dr , F _sf and F _sr are generated by the spring damper, respectively. force, F _tf , F _bf , F _tr and F _br are the elastic force and resistance generated by the tire, respectively, z _c is the vertical displacement of the suspension, φ is the pitch angle, z ₁ and z ₂ are the unsprung displacements, z ₀₁ and z ₀₂ is the road excitation, a and b are the distances from the suspension to the center of gravity of the vehicle, u ₁ and u ₂ are the control inputs of the active suspension system, Ψ ₁ (t)=-F _df - F _dr -F _sf -F _sr , Ψ ₂ (t)=-a(F _df +F _sf )+b(F _dr +F _sr ), F _sf =k _f1 Δy _f , F _sr =k _r1 Δy _r , F _tf =k _f2 (z ₁ -z ₀₁ ), F _tr =k _r2 (z ₂ -z ₀₂ ), where k _f1 and k _f2 represent the front and rear spring coefficients, b _f1 and b _r1 are the front and rear damping coefficients, respectively, k _f2 and k _r2 are the elastic coefficients of the front and rear tires, respectively, b _f2 and b _r2 are the damping coefficients of the front and rear tires, respectively, Δy _f =z _c +a sinφ-z ₁ and Δy _r = _ac +b sinφ-z ₂ are the front and rear tires, respectively Suspension space, establish the relationship between uncertain actuator failure and active suspension, and express the influence of the uncertainty of actuator failure on the active suspension system in the form of a mathematical model;

The parameterized actuator failure mathematical model is as follows:

分别 为未知故障参数向量和已知基函数，构成故障向量

定义指示哪一个作动器故障(即故障发生位置)的故障模式集为 σ(t)＝diag{σ₁，σ₂}，当作动器

则σ_j(t)＝1，否则σ_j(t)＝0；In the above formula (2)

are the unknown fault parameter vector and the known basis function respectively, which constitute the fault vector

The set of failure modes that define which actuator fails (ie, where the failure occurs) is defined as σ(t)=diag{σ ₁ ,σ ₂ }, when the actuator

Then σ _j (t)=1, otherwise σ _j (t)=0;

The mathematical model of the control input of the system under the condition of uncertain actuator failure is as follows:

x₃＝φ，

x₅＝z₁，

x₇＝z₂，

x₁₃＝[x₁，x₃]^T，x₂₄＝[x₂，x₄]^T和控制输出y＝[x₁，x₃]^T， 设置期望的控制目标为y_m＝[r_z，r_φ]^T；The selected state vector x ₁ =z _c ,

x ₃ = φ,

x ₅ =z ₁ ,

x ₇ =z ₂ ,

x ₁₃ =[x ₁ , x ₃ ] ^T , x ₂₄ =[x ₂ , x ₄ ] ^T and control output y=[x ₁ , x ₃ ] ^T , set the desired control target as y _m =[r _z , r _φ ] ^T ;

Combining Equation (1) and Equation (3), the mathematical model of the vehicle active suspension system under uncertain fault conditions can be obtained as:

Step 2: Design an adaptive fault-tolerant controller based on the nonlinear model of the semi-vehicle active suspension system under uncertain actuator faults;

In the third step, the Lyapunov function method is used to test the performance of the adaptive fault-tolerant controller.

Further, in the second step, the specific process of designing the adaptive fault-tolerant controller is as follows: According to the error value between the controlled output of the active suspension system and the given command, the closed-loop feedback control law is designed based on the Backs tepping control algorithm to ensure that The stability of the active suspension system and the output y asymptotically track the desired command y _m ,

Perform the following coordinate transformations:

z ₁₃ =x ₁₃ -y _m (5)

z ₂₄ =x ₂₄ -α ₁ (6)

In formula (6), α ₁ is a virtual control variable, and (5) is combined with (4) to obtain the expression:

In formula (7), z ₁₃ represents the tracking error, and the virtual control amount α ₁ is set as follows:

α ₁ =-c ₁ z ₁₃ +[γ _z &,γ _m &] ^T (8)

c ₁ in formula (8) is a design parameter,

Formula (6) is combined with formula (7) and formula (8), and based on the dynamic characteristics of the suspension system, it is obtained:

The feedback control law is set as follows:

u_d为理想的反馈控制律， In the above formula (11)

_ud is the ideal feedback control law,

The control goal implemented by the present invention is to maintain the closed-loop system stability and asymptotic output tracking under the condition of uncertain actuator failures in the vehicle active suspension system, that is, the equation

和

分别如下：It is still true in the case of uncertain actuator faults. Assuming that the fault parameters are known, σ=σ ₁ ={0,0}, σ=σ ₂ ={1,0} can be obtained by combining equations (11) and (12). and σ = σ ₃ = {0, 1} the ideal fault-compensated controller under three fault conditions

and

They are as follows:

in

The fault indication function is introduced as follows:

Combining equations (13)-(16), we obtain a comprehensive controller structure capable of simultaneously solving three fault conditions as follows:

Combining the problem solved by the present invention and equation (17), the failure parameter and fault indication parameters are unknown, that is, v ^* (t) is unknown, and the structure of the adaptive controller v(t) is obtained by parameterizing equation (17) as follows:

和

的估计值； θ_1χ＝χ₂θ₁，θ_2χ＝χ₃θ₂，θ₁和θ₂分别为

和的估计值，参数更新律进 行如下的设定：In equation (18), χ ₁₁ =χ ₁ , χ ₁ , χ ₂ and χ ₃ are respectively

and

The estimated value of θ _1χ =χ ₂ θ ₁ , θ _2χ =χ ₃ θ ₂ , θ ₁ and θ ₂ are respectively

and The estimated value of , the parameter update law is set as follows:

和

为标准的参数投影函 数。In equation (19), f _χ11 , f _χ12 , f _χ2 , f _χ3 ,

and

is a standard parametric projection function.

Further, in the described step 3, adopting the Lyapunov function method to check the fault-tolerant controller is specifically:

Test of fault-tolerant controller design method using Lyapunov function: First, the Lyapunov function equations of the semi-vehicle active suspension system under three failure modes are listed. When σ=σ ₍₁₎ =diag{0,0},

Taking the derivation of the Lyapunov function and combining equation (19), we get:

Among them, c ₁ and c ₂ are two positive design parameters, and the stability analysis under the other two faults is the same as the stability analysis of σ=σ ₍₁₎ =diag{0,0};

The last four equations in equation (4) are the zero dynamic part of the active suspension system of the car, let z ₁₃ =z ₂₄ =0, the input is obtained as follows:

Let u ₁ and u ₂ replace and The zero dynamic characteristics are obtained as follows:

in,

List the Lyapunov function V=x ^T Px, where P is a positive definite matrix, and derive the Lyapunov function to get:

结合不等式

和

得到In equation (24), P and Q are the selected matrices, respectively, η ₁ and η ₂ are design parameters, choose

associative inequality

and

get

Equations (21) and (25) demonstrate that a fault-tolerant controller is used for system stability and asymptotic tracking in automotive active suspension systems.

Compared with the prior art, the beneficial effects of the present invention are as follows:

1. The present invention introduces a parameterized actuator fault model and a fault mode model, which can not only represent typical stuck and gain failure faults, but also other types of time-varying faults, so that the present invention can solve the problem of multi-type actuators. fault, compared with other fault-tolerant control methods of automotive active suspension systems, the fault-tolerant control method proposed by the present invention has stronger applicability;

2. The present invention establishes the relationship between the actuator fault uncertainty and the system control input, and directly adjusts the parameters of the controller by updating the fault parameters online. Compared with other fault-tolerant control methods, the control algorithm proposed by the present invention There is no need to set up a fault diagnosis unit, the controller structure is simpler, and the parameter adjustment is more direct;

3. The present invention effectively compensates for the actuator faults in each fault mode, and designs a comprehensive controller that can solve all fault conditions through the fusion algorithm design, so as to achieve the control objectives of stability and asymptotic tracking. The performance is satisfactory.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and together with the specific embodiments of the present invention, are used to explain the present invention, and do not constitute a limitation to the present invention.

1 is a schematic diagram of an automotive active suspension system of the present invention;

Fig. 2 is the response diagram of the expected command zero of the vertical displacement tracking of the active suspension of the automobile under the condition of the actuator failure;

Fig. 3 is the response diagram of the expected command zero of the vertical displacement tracking of the active suspension of the automobile under the actuator failure condition 2;

Fig. 4 is the response diagram of the pitch angle tracking expected command zero of the active suspension of the automobile under the condition of the actuator failure;

Fig. 5 is a response diagram of the pitch angle tracking expected command zero of the active suspension of the automobile under the second actuator failure condition.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

Example:

As shown in Figure 1, an embodiment of the present invention provides a fault-tolerant control method for an automotive active suspension system based on an adaptive fusion design, and the fault-tolerant control method includes the following steps:

The first step is to establish a mathematical model of the vehicle active suspension system under uncertain fault conditions;

The semi-vehicle active suspension system is adopted, and its system dynamics equation is:

F_tf＝k_f2(z₁-z₀₁)， F_tr＝k_r2(z₂-z₀₂)，其中k_f1和k_f2表示前后弹簧系数，b_f1和b_r1分别为前 后阻尼系数，k_f2和k_r2分别为前后轮胎的弹性系数，b_f2和b_r2分别为前 后轮胎的阻尼系数，Δy_f＝z_c+a sinφ-z₁和Δy_r＝z_c+b sinφ-z₂分别为 前后悬架空间，建立不确定执行器故障与主动悬架的关系，以数学模 型的方式表示作动器故障的不确定性对汽车主动悬架系统的影响；In the above formula (1), M and I are the mass and moment of inertia of the car body, respectively, m _f and m _r are the front and rear unsprung masses, respectively, and F _df , F _dr , F _sf and F _sr are generated by the spring damper, respectively. force, F _tf , F _bf , F _tr and F _br are the elastic force and resistance generated by the tire, respectively, z _c is the vertical displacement of the suspension, φ is the pitch angle, z ₁ and z ₂ are the unsprung displacements, z ₀₁ and z ₀₂ is the road excitation, a and b are the distances from the suspension to the center of gravity of the vehicle, u ₁ and u ₂ are the control inputs of the active suspension system, Ψ ₁ (t)=-F _df - F _dr -F _sf -F _sr , Ψ ₂ (t)=-a(F _df +F _sf )+b(F _dr +F _sr ), F _sf =k _f1 Δy _f , F _sr =k _r1 Δy _r ,

F _tf =k _f2 (z ₁ -z ₀₁ ), F _tr =k _r2 (z ₂ -z ₀₂ ), where k _f1 and k _f2 represent the front and rear spring coefficients, b _f1 and b _r1 are the front and rear damping coefficients, respectively, k _f2 and k _r2 are the elastic coefficients of the front and rear tires respectively, b _f2 and b _r2 are the damping coefficients of the front and rear tires, respectively, Δy _f =z _c +a sinφ-z ₁ and Δy _r =z _c +b sinφ-z ₂ are the front and rear tires, respectively Suspension space, establish the relationship between uncertain actuator failure and active suspension, and express the influence of the uncertainty of actuator failure on the active suspension system in the form of a mathematical model;

The parameterized actuator failure mathematical model is as follows:

分别 为未知故障参数向量和已知基函数，构成故障向量

定义指示哪一个作动器故障(即故障发生位置)的故障模式集为 σ(t)＝diag{σ₁，σ₂}，当作动器

则σ_j(t)＝1，否则σ_j(t)＝0；In the above formula (2)

are the unknown fault parameter vector and the known basis function respectively, which constitute the fault vector

The set of failure modes that define which actuator fails (ie, where the failure occurs) is defined as σ(t)=diag{σ ₁ ,σ ₂ }, when the actuator

Then σ _j (t)=1, otherwise σ _j (t)=0;

The mathematical model of the control input of the system under the condition of uncertain actuator failure is as follows:

x₃＝φ，

x₅＝z₁， x₇＝z₂，

x₁₃＝[x₁，x₃]^T，x₂₄＝[x₂，x₄]^T和控制输出y＝[x₁，x₃]^T， 设置期望的控制目标为y_m＝[r_z，r_φ]^T；The selected state vector x ₁ =z _c ,

x ₃ = φ,

x ₅ =z ₁ , x ₇ =z ₂ ,

x ₁₃ =[x ₁ , x ₃ ] ^T , x ₂₄ =[x ₂ , x ₄ ] ^T and control output y=[x ₁ , x ₃ ] ^T , set the desired control target as y _m =[r _z , r _φ ] ^T ;

Combining Equation (1) and Equation (3), the mathematical model of the vehicle active suspension system under uncertain fault conditions can be obtained as:

Step 2: Design an adaptive fault-tolerant controller based on the nonlinear model of the semi-vehicle active suspension system under uncertain actuator faults;

In the third step, the Lyapunov function method is used to test the performance of the adaptive fault-tolerant controller.

Further, in this embodiment, in the second step, the specific process of designing the adaptive fault-tolerant controller is as follows: in FIG. 1, according to the error value between the controlled output of the active suspension system and the given command, based on Backstepping The control algorithm is designed with a closed-loop feedback control law to ensure the stability of the active suspension system and the output y asymptotically track the desired command y _m ,

Perform the following coordinate transformations:

z ₁₃ =x ₁₃ -y _m (5)

z ₂₄ =x ₂₄ -α ₁ (6)

In formula (6), α ₁ is a virtual control variable, and (5) is combined with (4) to obtain the expression:

In formula (7), z ₁₃ represents the tracking error, and the virtual control amount α ₁ is set as follows:

α ₁ =-c ₁ z ₁₃ +[γ _z &,γ _m &] ^T (8)

c ₁ in formula (8) is a design parameter,

Formula (6) is combined with formula (7) and formula (8), and based on the dynamic characteristics of the suspension system, it is obtained:

The feedback control law is set as follows:

u_d为理想的反馈控制律，

In the above formula (11)

_ud is the ideal feedback control law,

The control goal implemented by the present invention is to maintain the closed-loop system stability and asymptotic output tracking under the condition of uncertain actuator failures in the vehicle active suspension system, that is, the equation

和分别如下：It is still true in the case of uncertain actuator faults. Assuming that the fault parameters are known, σ=σ ₁ ={0,0}, σ=σ ₂ ={1,0} can be obtained by combining equations (11) and (12). and σ = σ ₃ = {0, 1} the ideal fault-compensated controller under three fault conditions

and They are as follows:

in

The fault indication function is introduced as follows:

Combining equations (13)-(16), we obtain a comprehensive controller structure capable of simultaneously solving three fault conditions as follows:

和故障指 示参数

均未知，即v^*(t)未知，对等式(17)进行参数化得 到自适应控制器v(t)的结构如下：Combining the problem solved by the present invention and equation (17), the failure parameter

and fault indication parameters

are unknown, that is, v ^* (t) is unknown, and the structure of the adaptive controller v(t) is obtained by parameterizing equation (17) as follows:

的估计值； θ_1χ＝χ₂θ₁，θ_2χ＝χ₃θ₂，θ₁和θ₂分别为

和

的估计值，参数更新律进 行如下的设定：In equation (18), χ ₁₁ =χ ₁ , χ ₁ , χ ₂ and χ ₃ are respectively and

The estimated value of θ _1χ =χ ₂ θ ₁ , θ _2χ =χ ₃ θ ₂ , θ ₁ and θ ₂ are respectively

and

The estimated value of , the parameter update law is set as follows:

和

为标准的参数投影函 数。In equation (19), f _χ11 , f _χ12 , f _χ2 , f _χ3 ,

and

is the standard parametric projection function.

Further, in the present embodiment, in the step 3, adopting the Lyapunov function method to check the fault-tolerant controller is specifically:

Test of fault-tolerant controller design method using Lyapunov function: First, the Lyapunov function equations of the semi-vehicle active suspension system under three failure modes are listed. When σ=σ ₍₁₎ =diag{0,0},

Taking the derivation of the Lyapunov function and combining equation (19), we get:

Among them, c ₁ and c ₂ are two positive design parameters, and the stability analysis under the other two faults is the same as the stability analysis of σ=σ ₍₁₎ =diag{0,0};

The last four equations in equation (4) are the zero dynamic part of the active suspension system of the car, let z ₁₃ =z ₂₄ =0, the input is obtained as follows:

和

得到零动态特性如下：Let u ₁ and u ₂ replace

and

The zero dynamic characteristics are obtained as follows:

in,

List the Lyapunov function V=x ^T Px, where P is a positive definite matrix, and derive the Lyapunov function to get:

结合不等式

和

得到In equation (24), P and Q are the selected matrices, respectively, η ₁ and η ₂ are design parameters, choose

associative inequality

and

get

Equations (21) and (25) demonstrate that a fault-tolerant controller is used for system stability and asymptotic tracking in automotive active suspension systems.

Further, in this embodiment, in order to illustrate that the fault-tolerant control method of the automotive active suspension system based on the adaptive fusion design can effectively solve the uncertain multi-type and multi-mode actuator faults, and can achieve asymptotic output tracking, give under the following simulation conditions:

否则z_o1＝0，其中 路边输入的坡度高h_b＝2cm；Semi-car active suspension system, M=1200kg, mf=mr=100kg, I= ^600kgm2 , _kf1 = _kf2 = _15000N /m, _br1 = _br2 = _2500Ns /m; _kf2 = _kr2 = 200000N/m, b _f2 =b _r2 =1000Ns/m, a=1.2m, b=1.5m, the vehicle's forward speed V=20m/s, when 1s≤t≤1.25s, the road input signal is

Otherwise, z _o1 = 0, where the roadside input slope height h _b = 2cm;

Actuator failure situation 1: when 0s≤t＜3s, no actuator failure occurs; when t≥3s, the first actuator fails u ₁ (t)=10N; when 3s≤t＜7s, the first actuator fails. One actuator returns to normal, no fault; when 7s≤t<9s, the second actuator fails u ₁ (t)=-10N; when t≥9s, the second actuator returns to normal, the system No faults.

Actuator failure case 2: when 0s≤t＜3s, no actuator failure occurs; when t≥3s, the first actuator fails u ₁ (t)=7.5sin(5t)N; when 3s≤3s, the first actuator fails t<7s, the first actuator returns to normal, no fault; when 7s≤t<9s, the second actuator fails u ₁ (t)=5sin(10t)N; when t≥9s, the second actuator fails The actuators returned to normal, and the system was fault-free.

Simulation parameters: x ₁ (0)=1cm, x ₃ (0)=0.01rad, the initial values of other states are 0, c ₁ =12, c ₂ =10, γ _1i =100, γ ₂ =100, Γ _1χ = 100I _2×2 , Γ _2χ =100I _2×2 , fault basis function

Further, in this embodiment, as shown in Fig. 2 to Fig. 5, Fig. 2 and Fig. 3 are respectively the vertical displacement tracking expectation of the active suspension of the automobile in the case of actuator failure and the case of actuator failure. The response diagram of the command zero; Figure 4 and Figure 5 are the response diagrams of the expected command zero of the pitch angle tracking of the active suspension of the automobile under the actuator fault condition 1 and the actuator fault condition 2 respectively; The effectiveness of the proposed fault-tolerant control method is shown in Figures 2 to 5, respectively, and the output response diagrams of the active suspension system without fault-tolerance are given. The fault-tolerant control method proposed in this embodiment can ensure the stability of the closed-loop system and asymptotic output tracking, compared with the control output response of the vehicle active suspension system without fault-tolerant control under the uncertain alternate fault mode.

To sum up, in this embodiment, according to the fault-tolerant control method of the vehicle active suspension system based on the adaptive fusion design of this embodiment, a mathematical model of the semi-vehicle active suspension system under the condition of uncertain actuator failure is established , design a fault compensation controller for each fault mode, design a comprehensive controller that can handle all fault conditions based on fusion algorithm, analyze the performance of the controller based on Lyapunov function, this design designs an effective controller for each fault mode, which greatly improves fault tolerance control effect.

The above descriptions are only preferred examples of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still understand any of the foregoing embodiments. The recorded technical solutions are modified, or some technical features thereof are equivalently replaced. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. a fault-tolerant control method based on the automotive active suspension system of adaptive fusion design, is characterized in that, this fault-tolerant control method comprises the following steps: The first step is to establish a mathematical model of the vehicle active suspension system under uncertain fault conditions; The semi-vehicle active suspension system is adopted, and its system dynamics equation is:

In the above formula (1), M and I are the mass and moment of inertia of the car body, respectively, m _f and m _r are the front and rear unsprung masses, respectively, and F _df , F _dr , F _sf and F _sr are generated by the spring damper, respectively. force, F _tf , F _bf , F _tr and F _br are the elastic force and resistance generated by the tire, respectively, z _c is the vertical displacement of the suspension, φ is the pitch angle, z ₁ and z ₂ are the unsprung displacements, z ₀₁ and z ₀₂ is the road excitation, a and b are the distances from the suspension to the center of gravity of the vehicle, u ₁ and u ₂ are the control inputs of the active suspension system, Ψ ₁ (t)=-F _df -F _dr -F _sf -F _sf , Ψ ₂ (t)=-a(F _df +F _sf )+b(F _dr +F _sr ), F _sf =k _f1 Δy _f , F _sr =k _r1 Δy _r ,

F _tf =k _f2 (z ₁ -z ₀₁ ), F _tr =k _r2 (z ₂ -z ₀₂ ), where k _f1 and k _f2 represent the front and rear spring coefficients, b _f1 and b _r1 are the front and rear damping coefficients, respectively, k _f2 and k _r2 are the elastic coefficients of the front and rear tires, respectively, b _f2 and b _r2 are the damping coefficients of the front and rear tires, respectively, Δy _f =z _c +asinφ-z ₁ and Δy _r =z _c +b sinφ-z ₂ are the front and rear suspensions, respectively. The frame space is established, the relationship between the uncertain actuator fault and the active suspension is established, and the influence of the uncertainty of the actuator fault on the vehicle active suspension system is represented by a mathematical model; The parameterized actuator failure mathematical model is as follows:

In the above formula (2) are the unknown fault parameter vector and the known basis function respectively, which constitute the fault vector

The set of failure modes that define which actuator fails (ie, where the failure occurs) is defined as σ(t)=diag{σ ₁ ,σ ₂ }, when the actuator

Then σ _j (t)=1, otherwise σ _j (t)=0; The mathematical model of the control input of the system under the condition of uncertain actuator failure is as follows: The selected state vector x ₁ =z _c ,

x ₃ = φ,

x ₅ =z ₁ ,

x ₇ =z ₂ ,

x ₁₃ =[x ₁ , x ₃ ] ^T , x ₂₄ =[x ₂ , x ₄ ] ^T and control output y=[x ₁ , x ₃ ] ^T , set the desired control target as y _m =[r _z , r _φ ] ^T ; Combining Equation (1) and Equation (3), the mathematical model of the vehicle active suspension system under uncertain fault conditions can be obtained as:

Step 2: Design an adaptive fault-tolerant controller based on the nonlinear model of the semi-vehicle active suspension system under uncertain actuator faults; The third step is to use the Lyapunov function method to test the performance of the adaptive fault-tolerant controller. 2. the fault-tolerant control method of a kind of auto active suspension system based on self-adaptive fusion design according to claim 1, is characterized in that, in described step 2, the specific process of designing self-adaptive fault-tolerant controller is: according to active suspension The error value between the controlled output of the suspension system and the given command, the closed-loop feedback control law is designed based on the Backstepping control algorithm to ensure the stability of the active suspension system and the output y asymptotically track the desired command y _m , Perform the following coordinate transformations: z ₁₃ =x ₁₃ -y _m (5) z ₂₄ =x ₂₄ -α ₁ (6) In formula (6), α ₁ is a virtual control variable, and (5) is combined with (4) to obtain the expression:

In formula (7), z ₁₃ represents the tracking error, and the virtual control amount α ₁ is set as follows: α ₁ = -c ₁ z ₁₃ + [γ _z &, γ _m &] ^T (8) c ₁ in formula (8) is a design parameter, Formula (6) combines formula (7) and formula (8), and at the same time based on the dynamic characteristics of the suspension system, it is obtained:

The feedback control law is set as follows:

In the above formula (11)

_ud is the ideal feedback control law,

In the case of uncertain actuator fault, it still holds true. Assuming that the fault parameters are known, σ=σ ₁ ={0,0}, σ=σ ₂ ={1,0} can be obtained by combining equations (11) and (12). and σ = σ ₃ = {0, 1} the ideal fault-compensated controller under three fault conditions and

They are as follows:

in

The fault indication function is introduced as follows:

Combining equations (13)-(16), a comprehensive controller structure that can simultaneously solve the three fault conditions is obtained as follows: Combining the problem solved by the present invention and equation (17), the failure parameter

and fault indication parameters

are unknown, that is, v ^* (t) is unknown, and the structure of the adaptive controller v(t) is obtained by parameterizing equation (17) as follows:

In equation (18), χ ₁₁ =χ ₁ , χ ₁ , χ ₂ and χ ₃ are respectively

and

The estimated value of θ _1χ =χ ₂ θ ₁ , θ _2χ =χ ₃ θ ₂ , θ ₁ and θ ₂ are respectively and

The estimated value of , the parameter update law is set as follows:

In equation (19)

and

is the standard parametric projection function. 3. the fault-tolerant control method of a kind of automobile active suspension system based on self-adaptive fusion design according to claim 2, is characterized in that, in described step 3, adopts Lyapu nov function method to check fault-tolerant controller specifically as: : Test of fault-tolerant controller design method using Lyapunov function: First, the Lyapunov function equations of the semi-vehicle active suspension system under three failure modes are listed. When σ=σ ₍₁₎ =diag{0,0},

Taking the derivation of the Lyapunov function and combining equation (19), we get:

Among them, c ₁ and c ₂ are two positive design parameters, and the stability analysis under the other two faults is the same as the stability analysis of σ=σ ₍₁₎ =diag{0,0}; The last four equations in equation (4) are the zero dynamic part of the active suspension system of the car, let z ₁₃ =z ₂₄ =0, the input is obtained as follows:

Let u ₁ and u ₂ replace

and

The zero dynamic characteristics are obtained as follows: in,

List the Lyapunov function V=x ^T Px, where P is a positive definite matrix, and derive the Lyapunov function to get:

In equation (24), P and Q are the selected matrices, respectively, η ₁ and η ₂ are design parameters, choose

associative inequality

and

get

Equations (21) and (25) demonstrate that a fault-tolerant controller is used for system stabilization and asymptotic tracking in an automotive active suspension system.

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