Active suspension control method and system based on structural constraint and bionic reference model

Abstract

The invention provides an active suspension control method and system based on structural constraints and a bionic reference model, and relates to the technical field of active suspension control, and the method comprises the steps: S1, building a two-degree-of-freedom active suspension system model, and designing a disturbance observer to determine disturbance influence parameters; s2, establishing a bionic reference model to provide a reference tracking trajectory for motion control in the two-degree-of-freedom active suspension system; s3, setting a suspension mechanical structure hard constraint condition, and designing a nonlinear coordination function to balance the smoothness of the vehicle and the suspension deflection; s4, designing a preset performance controller according to the sprung mass vertical displacement tracking error; and S5, outputting the final active control force of the controller to realize two-degree-of-freedom active suspension system control. The sprung quality tracking trajectory error is controlled through the preset performance controller; and through a nonlinear coordination function, an active suspension control target is adjusted, and the suspension stroke is prevented from exceeding the structural limitation.

Description

Technical Field

[0001] The present invention relates to the technical field of active suspension control, and in particular to an active suspension control method and system based on structural constraints and a bionic reference model. Background Art

[0002] As a crucial component of the vehicle chassis, the vehicle suspension system plays a crucial role in bearing the vehicle's mass and attenuating vibrations transmitted from the road surface to the vehicle through the wheels. Its performance directly determines the vehicle's ride smoothness and handling stability. Once the stiffness and damping of a passive suspension are determined, they cannot be adjusted, thus preventing the suspension from actively adjusting performance based on road conditions. Semi-active suspensions can only achieve multi-level stiffness and damping adjustments, not continuous stiffness and damping adjustments. Unlike passive and semi-active suspensions, active suspensions output active force through actuators, enabling continuous adjustment of suspension stiffness and damping based on varying road conditions. This improves ride comfort and handling stability, and has garnered widespread attention from scholars both domestically and internationally in recent years.

[0003] In existing active suspension research, researchers have proposed various advanced control algorithms to improve the suspension's vibration damping performance and enhance vehicle ride comfort. However, current research typically sets the desired control target for the active suspension to zero. This results in the suspension deflection not automatically returning to zero within a limited time when the vehicle is traveling on steps or slopes. Excessive suspension travel not only increases the likelihood of the suspension striking the vehicle body's stoppers but also increases unnecessary control energy consumption. Furthermore, there is a contradiction between suspension vibration damping performance and suspension deflection. Generally speaking, improving suspension ride smoothness increases suspension deflection, while excessive suspension deflection can cause the suspension to strike the vehicle body, seriously affecting ride comfort and even endangering the safety of the vehicle and passengers. Existing research has overlooked this important practical issue.

[0004] CN108995495A discloses an anti-saturation adaptive control method for a nonlinear active suspension. This control method effectively addresses the impact of parameter uncertainty on the suspension system, improving driving smoothness, ride comfort, and operational safety. However, this method sets the expected motion trajectory of the sprung mass to zero, resulting in the suspension deflection not being able to return to zero within a finite time. Furthermore, it fails to address the conflicting issues of suspension damping performance and suspension deflection. CN107791773A discloses a vibration control method for a vehicle active suspension system based on a prescribed performance function. This control method ensures the transient and steady-state performance of the suspension system and improves system robustness. However, this method also sets the expected motion trajectory of the sprung mass to zero, resulting in the suspension deflection not being able to return to zero within a finite time. Furthermore, it fails to address the conflicting issues of suspension damping performance and suspension deflection, and it also ignores the energy consumption of active suspension control.

[0005] Based on the above problems, the present invention proposes an active suspension control method and system based on structural constraints and bionic reference models, which solves the defect of most existing control methods that the suspension stroke cannot be restored to the initial position within a limited time. It can also automatically adjust the control target according to the change of suspension deflection, balance the contradiction between vibration reduction performance and suspension stroke limitation, improve the road adaptability of the suspension, and reduce the control force and energy consumption requirements. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention aims to provide an active suspension control method and system based on structural constraints and a bionic reference model. By using a nonlinear coordination function designed with the suspension travel as the independent variable, the control target of the active suspension is automatically adjusted to prevent the suspension travel from exceeding structural constraints, thereby ensuring vehicle safety. Furthermore, a preset performance controller based on the bionic reference model and a disturbance observer ensures that the steady-state and transient errors of the sprung mass tracking the desired trajectory are within preset ranges, thereby ensuring the tracking accuracy of the active suspension control.

[0007] Specifically, the present invention provides an active suspension control method based on structural constraints and a bionic reference model, which includes the following steps: S1: Establish a two-degree-of-freedom active suspension system model with uncertain dynamics and design a disturbance observer to determine the disturbance impact parameters; S2: Establish a bionic reference model with quasi-zero stiffness characteristics based on the bionic structure, which is the body sprung mass in the two-degree-of-freedom active suspension system in step S1. Motion control provides reference tracking trajectory ; S3: Set the hard constraints of the suspension mechanical structure in the control objective of the two-degree-of-freedom active suspension system to is the independent variable, is the displacement of the sprung mass of the vehicle body With tire displacement difference ; Design nonlinear coordination function for: ; ; in, is a nonlinear coordination function; is the nonlinear coordination parameter; is the vertical displacement tracking error of the sprung mass; is the time parameter; is the first positive coordination parameter; is the sprung mass displacement of the vehicle body; is the tire displacement; The maximum suspension deflection constrained by the active suspension structure; is the second positive coordination parameter; is the relative suspension travel; S4: Determine the sprung mass vertical displacement tracking error , design a preset performance controller to control the steady-state and transient errors of the sprung mass displacement tracking of the active suspension system, and obtain the active control force of the controller in the steady state ; S5: Output the active control force of the final controller , to realize the two-degree-of-freedom active suspension system control, specifically: ; in, is the active control force of the controller; is the nominal value of sprung mass; is the observed value of the lumped disturbance of the active suspension system; is the first conversion error; is the conversion error auxiliary function; is the second conversion error; is the second positive control parameter; is the third positive control parameter; is a dummy control variable; is the hyperbolic tangent function.

[0008] Preferably, the bionic reference model in step S2 includes the vibration absorbing mass and ceiling damping force , specifically: ; in, is the entity mass of the bionic reference model; is the vibration absorbing mass; is the length of the fourth connecting rod; is the length of the third link; is the vertical displacement of the bionic structure, is the vertical velocity, is the vertical acceleration; is the first auxiliary equation; is the vertical stiffness coefficient; The entity mass of the bionic reference model Relative motion displacement with the base; The entity mass of the bionic reference model Relative speed with the base; is the joint friction factor; is the number of joints; is the second auxiliary equation; is the ceiling damping force; The entity mass of the bionic reference model Damping coefficient between the base and the bearing; is the tire moving speed.

[0009] Preferably, step S4 is specifically: S41: Setting the tracking error equation for a two-degree-of-freedom active suspension system , we get the positive decreasing function of error , construct the preset boundary of the active suspension system to constrain the tracking error and obtain the error constraint condition; S42: Convert the error constraint condition in step S41 into an unconstrained condition and set the normalized error to , determine the smooth monotonically increasing function Satisfying the constraints, we get The inverse function is the first conversion error ; S43: Set the second state variable of the error system The second conversion error is ; Select dummy control variables , determine the active control force of the controller , we get the Lyapunov function , to judge the stability of the active suspension control system.

[0010] Preferably, the error positive value decreasing function in step S41 The constraints are satisfied: ; ; in, for The error of time is a decreasing function of positive value; is the initial value of the error system; is the steady-state value of the error system; is the error system convergence speed parameter.

[0011] Preferably, in step S41, a preset boundary of the active suspension system is constructed to constrain the tracking error, and the error constraint condition is obtained as follows: ; in, is the first positive parameter; is the second positive parameter; for The first state variable of the time error system; is any time parameter.

[0012] Preferably, in step S42, a smooth monotonically increasing function is determined The constraints that are satisfied are: ; ; in, is a smooth monotonically increasing function, whose inverse function is the first conversion error ; The space of all bounded sequences; is the normalized error.

[0013] Preferably, the virtual control variable in step S43 The method to obtain is: ; in, is a dummy control variable; is the first positive control parameter; is the conversion error auxiliary function; is the conversion error.

[0014] Preferably, the active control force of the controller in step S43 for: ; in, is a symbolic function.

[0015] A second aspect of the present invention provides an active suspension control system based on structural constraints and a bionic reference model, comprising: an active suspension system module, a bionic reference model module, a tracking error module, a nonlinear coordination function module, a disturbance observer module, and a preset performance controller module; The active suspension system module provides a two-degree-of-freedom active suspension system model to simulate the control process of the active suspension control system; The bionic reference model module establishes a bionic reference model with quasi-zero stiffness characteristics based on the bionic damping structure and tail balancing effect of the bionic case, providing a reference tracking trajectory for the motion control of the sprung mass of the vehicle body in the two-degree-of-freedom active suspension system. The tracking error module provides the control error between the actual motion of the vehicle body and the bionic reference model; The nonlinear coordination function module provides coordination rules for coordinated control and sets hard constraints on the suspension mechanical structure in the control objectives of the two-degree-of-freedom active suspension system to balance vehicle ride comfort and suspension deflection. The disturbance observer module is used to determine the lumped disturbance of the two-degree-of-freedom active suspension system and improve the control accuracy; The preset performance controller module controls the steady-state and transient errors of the sprung mass displacement tracking of the active suspension system according to the sprung mass vertical displacement tracking error, thereby realizing the two-degree-of-freedom active suspension system control.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The diamond structure with quasi-zero stiffness characteristics designed based on the bionic principle provides a desired motion trajectory for the motion control of the active suspension sprung mass, solves the defect of the existing control method that the suspension stroke cannot be restored to the initial position within a limited time, and improves the road adaptability of the suspension.

[0017] (2) The present invention uses the nonlinear coordination function designed with the relative suspension travel as the independent variable to automatically adjust the control target of the active suspension. When the suspension travel is small, the primary control target is to improve the vehicle's ride smoothness. When the suspension travel increases, the primary control target is automatically converted to preventing the suspension travel from exceeding the structural limit, thereby ensuring vehicle safety.

[0018] (3) The preset performance controller based on the bionic reference model and disturbance observer of the present invention ensures that the steady-state and transient errors of the sprung mass tracking the desired trajectory are within a preset range, thereby ensuring the tracking accuracy of the active suspension control.

[0019] (4) The control scheme proposed in the present invention adopts a new expected motion trajectory instead of the zero expected motion trajectory, which avoids excessive control of the active suspension and reduces the control force and control energy requirements of the actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the control block diagram of the active suspension control method based on structural constraints and bionic reference model; Figure 2 Schematic diagram of the active control process of the present invention; Figure 3 It is a static schematic diagram of the bionic structure of the present invention; Figure 4 This is a schematic diagram of the motion of the bionic structure of the present invention; Figure 5 Schematic diagram of the nonlinear coordination function curve of the present invention; Figure 6 Schematic diagram of a convex road surface in an embodiment of the present invention; Figure 7 Schematic diagram of the sprung mass acceleration change curve under the excitation of a small convex road surface according to the present invention; Figure 8 Schematic diagram of the control force variation curve under the excitation of a small convex road surface of the present invention; Figure 9 Schematic diagram of the suspension deflection change curve under the excitation of a small convex road surface of the present invention; Figure 10 Schematic diagram of the suspension deflection change curve under the excitation of a large convex road surface in the present invention. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0022] The embodiment of the present invention proposes an active suspension control method based on structural constraints and bionic reference model, such as Figure 1 As shown in the figure, a two-degree-of-freedom active suspension system model is established, and a disturbance observer is designed to determine the disturbance influencing parameters; a bionic reference model is established to provide a reference tracking trajectory for motion control in the two-degree-of-freedom active suspension system; hard constraints on the suspension mechanical structure are set, and a nonlinear coordination function is designed to balance the vehicle's ride comfort and suspension deflection; a preset performance controller is designed based on the sprung mass vertical displacement tracking error; and the active control force of the final controller is output to realize the control of the two-degree-of-freedom active suspension system. Specifically, the following steps are involved: Step S1: Establish a two-degree-of-freedom active suspension system model with uncertain dynamics and design a disturbance observer to determine the disturbance impact parameters. Figure 2 The figure shows the active control process of the present invention. The uneven road stimulates the road through the tire. Sprung mass transferred to the vehicle body, tire displacement As the input of the bionic reference model, the suspension displacement As the input of the nonlinear coordination function, the output of the bionic reference model , body displacement and the output of the non-information coordination function Construct system tracking error ; Based on system tracking error A disturbance observer and preset performance controller are designed to realize active suspension control.

[0023] Step S11: The two-degree-of-freedom active suspension system model is: ; in, is the sprung mass of the vehicle body; is the unsprung mass; is the sprung mass displacement of the vehicle body, is the sprung mass velocity of the vehicle body, is the sprung mass acceleration of the vehicle body; is the tire displacement, is the tire moving speed, is the tire moving acceleration; To provide incentive for road elevation; is the road elevation excitation derivative; is the nonlinear spring force; is the nonlinear damping force; is the tire elastic force; is the tire damping force; is an unknown disturbance; is the active control force of the controller; is the time parameter.

[0024] Nonlinear spring force and nonlinear damping force The calculation method is: ; in, is the linear elastic coefficient of the suspension; is the nonlinear elastic coefficient of the suspension; is the linear damping coefficient of the suspension; is the nonlinear damping coefficient of the suspension.

[0025] Tire elastic force and tire damping force The calculation method is: ; in, is the stiffness coefficient of the tire; is the damping coefficient of the tire.

[0026] Step S12: Design a disturbance observer to determine the internal disturbance influencing parameters of the two-degree-of-freedom active suspension system in step S11 and offset or weaken the influence of the disturbance in feedback control; the expression of the disturbance observer is: ; in, is the perturbation measurement matrix, ; is the perturbation observation vector, ; is the nominal value of sprung mass; is a unit vector, ; The sprung mass motion state The determined value of ; is the sprung mass observation vector, , is its first-order derivative; is the sprung mass displacement Observed values ​​of is the sprung mass velocity Observed values ​​of is the observed value of the lumped disturbance of the active suspension system; is the observer gain vector, In the embodiment ; is the observer bandwidth; is the first coefficient of the observer gain; is the second coefficient of the observer gain; is the third coefficient of the observer gain.

[0027] Step S2: A bionic reference model with quasi-zero stiffness characteristics is established based on the bionic damping structure of the cheetah's legs and the balancing effect of its tail, which is the body sprung mass in the two-degree-of-freedom active suspension system in step S1. Motion control provides reference tracking trajectory , is the vertical displacement of the bionic structure, such as Figure 3 Shown is a static schematic diagram of the bionic structure of the present invention, which is composed of a bionic model mass , vibration absorption quality , ceiling damping , stiffness, damping and connecting rods.

[0028] The bionic reference model of the embodiment of the present invention refers to the X structure of the cheetah's legs, and its leg muscle structure is equivalent to the horizontal stiffness coefficient and vertical stiffness coefficient , its tail function is equivalent to the vibration absorbing mass and ceiling damping force , is the ceiling damping coefficient, such as Figure 4 The figure shows the motion diagram of the bionic structure of the present invention. Vertical movement Provides the desired tracking trajectory for vehicle body motion; the bionic reference model is specifically: ; in, is the physical mass of the bionic reference model, which is the body of a cheetah in the embodiment; is the vibration absorbing mass; is the vertical displacement of the bionic structure, is the vertical velocity, is the vertical acceleration; The entity mass of the bionic reference model The relative motion displacement between the base and the ; The entity mass of the bionic reference model Relative speed with the base; is the length of the first connecting rod; is the length of the second connecting rod; is the length of the third link; is the length of the fourth connecting rod; is the joint friction factor; The entity mass of the bionic reference model Damping coefficient between the base and the bearing; is the ceiling damping coefficient; is the number of joints; is the first auxiliary equation; is the second auxiliary equation; is a virtual function; is the ceiling damping force, ; is the vertical stiffness coefficient.

[0029] First auxiliary equation for: ; in, is the horizontal stiffness coefficient; is a virtual function; is the vertical displacement derivative of the bionic structure; For the first connecting rod Initial angle with the horizontal; is the cosine function; For the second connecting rod The initial angle from the horizontal.

[0030] The second auxiliary equation for: ; Virtual Functions The expression is: ; in, is a sine function.

[0031] Step S3: Set the suspension mechanical structure hard constraint conditions in the control target of the two-degree-of-freedom active suspension system to The sprung mass displacement of the vehicle body With tire displacement The difference is the independent variable, , design nonlinear coordination function Used to balance the contradiction between vehicle smoothness and suspension deflection limit; nonlinear coordination function The expression is: ; ; in, It is a nonlinear coordination function with an adjustment range of [0,1]. The value gradually increases with the increase of the suspension to coordinate the contradiction between smoothness and suspension deflection; is the nonlinear coordination parameter; The maximum suspension deflection constrained by the active suspension structure; is the relative suspension travel; is the first positive coordination parameter, in the embodiment ; is the second positive coordination parameter, in the embodiment .

[0032] like Figure 5 The figure shows a schematic diagram of the nonlinear coordination function curve of the present invention. According to the relative suspension displacement The control target of the active suspension is automatically adjusted according to the changes in the control target to balance the contradiction between vibration reduction performance and suspension deflection.

[0033] Step S4: Tracking error based on vertical displacement of sprung mass Design a pre-set performance controller to control steady-state and transient errors in sprung mass displacement tracking for an active suspension system.

[0034] Step S41: Based on the vehicle body sprung mass displacement in step S1 and tire displacement , the vehicle body sprung mass in step S2 Motion control provides reference tracking trajectory , the nonlinear coordination function in step S3 , the tracking error equation of the two-degree-of-freedom active suspension system is set as: ; in, is the vertical displacement tracking error of the sprung mass.

[0035] When the relative travel of the suspension When it is small, the nonlinear coordination function output Infinitely close to 0, the vertical displacement tracking error of the sprung mass , the primary control goal of the active suspension is to ensure smoothness; when the suspension relative dynamic travel When it is large, the nonlinear coordination function output Infinitely close to 1, the vertical displacement tracking error of the sprung mass At this time, the control target of the active suspension is mainly to ensure that the suspension deflection is within the structural constraint range.

[0036] Assume the first state variable of the error system is , the second state variable of the error system ; Set the positive value decreasing function of the error to: ; in, for The error of time is a decreasing function of positive value; is the initial value of the error system; is the steady-state value of the error system, ; is the error system convergence speed parameter, .

[0037] Positive decreasing error function Satisfy the constraints: ; ; Use the positive decreasing error function The active suspension system preset boundary is constructed to constrain the tracking error, and the error constraint condition is obtained as follows: ; in, is the first positive parameter; is the second positive parameter; for The first state variable of the time error system; is any time parameter.

[0038] Step S42: Convert the error constraint condition in step S41 into an unconstrained condition and set the normalized error to , set a smooth monotonically increasing function : The constraints are satisfied: ; ; in, is a smooth monotonically increasing function, whose inverse function is the first conversion error , the first conversion error The stability is sufficient to ensure the error range of sprung mass displacement tracking; The space of all bounded sequences; is the normalized error.

[0039] Conversion error The derivative of is: ; in, is the conversion error auxiliary function, ; for The second state variable of the time error system; for The error in time is a decreasing function.

[0040] Step S43: Set the second state variable of the error system The second conversion error is ; Select the dummy control variable as: ,in, is the first positive control parameter; the active control force of the controller is designed as: ; in, is the nominal value of sprung mass; is the second positive control parameter; is the third positive control parameter; is a symbolic function; is a dummy control variable.

[0041] Get the Lyapunov function for: ; in, is the Lyapunov function; is the second conversion error.

[0042] For Lyapunov function The derivative is: ; in, is the derivative of the dummy control variable.

[0043] The active control force of the controller Substituting into the above formula we get: ; in, is the derivative of the Lyapunov function.

[0044] The above steps prove that the vertical motion of the active suspension control system is asymptotically stable. The first conversion error and the second conversion error Is bounded, thus ensuring the first state variable of the vertical motion tracking error The preset conditions are always met.

[0045] Step S5: To reduce the vibration of the active suspension control system, the active control force of the controller is The symbolic function in Replaced by hyperbolic tangent function , output the final active control force of the controller for: ; in, is the hyperbolic tangent function.

[0046] like Figure 6 The figure shows a schematic diagram of a convex road surface in an embodiment of the present invention. When performing simulation under convex road excitation, the maximum travel allowed by the suspension structure is set to , under the small convex hull excitation, the convex hull height is 0.05m, the suspension deflection is small, and the nonlinear coordination function approaches 0, at which point the motion of the sprung mass tracks the motion trajectory of the bionic reference model.

[0047] like Figure 7 As shown, the main goal of the active suspension controller is to ensure ride smoothness. The vertical acceleration of the controller proposed in the present invention is significantly smaller than that of the passive suspension and the tracking controller based on the extended state observer. In addition, the control force requirement of the proposed controller is significantly smaller than that of the tracking controller. At this time, the suspension deflections of the three suspensions are relatively small.

[0048] like Figure 8 The figure shows a schematic diagram of the control force variation curve under the excitation of a small convex road surface of the present invention. It can be seen that the active control force required by the method of the present invention is significantly smaller than that of the comparative method, so it can reduce the performance requirements of the active suspension actuator and the control energy consumption.

[0049] like Figure 9 The figure shows a schematic diagram of the suspension deflection change curve under the excitation of a small convex road surface of the present invention. It can be seen that under the excitation of the small convex road, the suspension displacements of the three suspensions do not exceed the suspension limit. The suspension displacements of the method of the present invention and the comparative method are both greater than that of the passive suspension, but the suspension displacement of the method of the present invention is smaller than that of the comparative method.

[0050] When the convex hull height increases by 0.15m, as Figure 10The figure shows a schematic diagram of the suspension deflection change curve under the excitation of a large convex road surface. The suspension deflection of the ESOT controller has exceeded the maximum range allowed by the suspension mechanical structure. The suspension deflection of the controller proposed in the present invention is always kept within the structural constraint range, avoiding the possibility of the suspension hitting the vehicle body due to excessive suspension travel, thereby ensuring vehicle safety.

[0051] The second aspect of the present invention proposes an active suspension control system based on structural constraints and a bionic reference model, which includes: an active suspension system module, a bionic reference model module, a tracking error module, a nonlinear coordination function module, a disturbance observer module and a preset performance controller module.

[0052] The active suspension system module provides a two-degree-of-freedom active suspension system model for simulating the control process of the active suspension control system.

[0053] The bionic reference model module establishes a bionic reference model with quasi-zero stiffness characteristics based on the bionic vibration reduction structure and the balancing effect of the tail of the bionic case, providing a reference tracking trajectory for the motion control of the sprung mass of the vehicle body in the two-degree-of-freedom active suspension system.

[0054] The tracking error module provides the control error between the actual motion of the vehicle body and the bionic reference model.

[0055] The nonlinear coordination function module provides coordination rules for coordinated control and sets hard constraints on the suspension mechanical structure in the control objectives of the two-degree-of-freedom active suspension system to balance the contradiction between vehicle smoothness and suspension deflection limit.

[0056] The Disturbance Observer module is used to determine the lumped disturbance of a two-degree-of-freedom active suspension system and improve control accuracy.

[0057] The preset performance controller module controls the steady-state and transient errors of the sprung mass displacement tracking of the active suspension system according to the sprung mass vertical displacement tracking error, thereby realizing the two-degree-of-freedom active suspension system control.

[0058] The beneficial effects of the present invention are as follows: Based on the bionic principle, the present invention designs a diamond structure with quasi-zero stiffness characteristics, which is composed of components such as vibration-absorbing mass, skyhook damping and quasi-zero stiffness, has better vibration reduction performance, provides a desired motion trajectory for the motion control of the active suspension sprung mass, solves the defect that the suspension stroke cannot be restored to the initial position within a limited time in the existing control method, and improves the road adaptability of the suspension; the present invention designs a nonlinear coordination function with the relative suspension dynamic stroke as the independent variable, divides the suspension displacement change process into a safe area and a dangerous area, and the safe area is based on improving the ride comfort. The control objective is to avoid suspension travel exceeding the limit in the danger zone. This allows for automatic adjustment of the active suspension control objective, adaptive suspension travel, improved ride smoothness, and prevent suspension travel exceeding structural limits, ensuring vehicle safety. Under small convex road excitation, the suspension displacement of the present invention is greater than that of the passive suspension, but less than that of the comparative method, reducing the possibility of suspension travel exceeding the limit. Under large convex road excitation, the suspension displacement of the comparative method exceeds the limits of the suspension mechanical structure, while the suspension displacement of the present invention remains within the suspension limits, preventing the suspension from striking the vehicle body limiter. A preset performance controller based on a bionic reference model and disturbance observer ensures that the steady-state and transient errors of the sprung mass tracking the desired trajectory are within preset ranges, ensuring the tracking accuracy of the active suspension control.

[0059] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. An active suspension control method based on structural constraints and a bionic reference model, characterized by: It includes: S1: Establish a two-degree-of-freedom active suspension system model with uncertain dynamics and design a disturbance observer to determine the disturbance impact parameters; S2: Establish a bionic reference model with quasi-zero stiffness characteristics based on the bionic structure, which is the body sprung mass in the two-degree-of-freedom active suspension system in step S1. Motion control provides reference tracking trajectory ; S3: Set the hard constraints of the suspension mechanical structure in the control objective of the two-degree-of-freedom active suspension system to is the independent variable, is the displacement of the sprung mass of the vehicle body With tire displacement difference ; Design nonlinear coordination function for: ； ； in, is a nonlinear coordination function; is the nonlinear coordination parameter; is the vertical displacement tracking error of the sprung mass; is the time parameter; is the first positive coordination parameter; is the sprung mass displacement of the vehicle body; is the tire displacement; The maximum suspension deflection constrained by the active suspension structure; is the second positive coordination parameter; is the relative suspension travel; S4: Determine the sprung mass vertical displacement tracking error , design a preset performance controller to control the steady-state and transient errors of the sprung mass displacement tracking of the active suspension system, and obtain the active control force of the controller in the steady state ; S5: Output the active control force of the final controller , to realize the two-degree-of-freedom active suspension system control, specifically: ； in, is the active control force of the controller; is the nominal value of sprung mass; is the observed value of the lumped disturbance of the active suspension system; is the first conversion error; is the conversion error auxiliary function; is the second conversion error; is the second positive control parameter; is the third positive control parameter; is a dummy control variable; is the hyperbolic tangent function.

2. The active suspension control method based on structural constraints and bionic reference models according to claim 1, characterized in that: The bionic reference model in step S2 includes the vibration absorbing mass and ceiling damping force , specifically: ； in, is the entity mass of the bionic reference model; is the vibration absorbing mass; is the length of the fourth connecting rod; is the length of the third link; is the vertical displacement of the bionic structure, is the vertical velocity, is the vertical acceleration; is the first auxiliary equation; is the vertical stiffness coefficient; The entity mass of the bionic reference model Relative motion displacement with the base; The entity mass of the bionic reference model Relative speed with the base; is the joint friction factor; is the number of joints; is the second auxiliary equation; is the ceiling damping force; The entity mass of the bionic reference model Damping coefficient between the base and the bearing; is the tire moving speed.

3. The active suspension control method based on structural constraints and bionic reference models according to claim 1, characterized in that: Step S4 is specifically as follows: S41: Setting the tracking error equation for a two-degree-of-freedom active suspension system , we get the positive decreasing function of error , construct the preset boundary of the active suspension system to constrain the tracking error and obtain the error constraint condition; S42: Convert the error constraint condition in step S41 into an unconstrained condition and set the normalized error to , determine the smooth monotonically increasing function Satisfying the constraints, we get The inverse function is the first conversion error ; S43: Set the second state variable of the error system The second conversion error is ; Select dummy control variables , determine the active control force of the controller , we get the Lyapunov function , to judge the stability of the active suspension control system.

4. The active suspension control method based on structural constraints and bionic reference models according to claim 3, characterized in that: The error positive value decreasing function of step S41 The constraints are satisfied: ； ； in, for The error of time is a decreasing function of positive value; is the initial value of the error system; is the steady-state value of the error system; is the error system convergence speed parameter.

5. The active suspension control method based on structural constraints and bionic reference model according to claim 3, characterized in that: In step S41, a preset boundary of the active suspension system is constructed to constrain the tracking error, and the error constraint condition is obtained as follows: ； in, is the first positive parameter; is the second positive parameter; for The first state variable of the time error system; is any time parameter.

6. The active suspension control method based on structural constraints and bionic reference model according to claim 3, characterized in that: In step S42, a smooth monotonically increasing function is determined The constraints that are satisfied are: ； ； in, is a smooth monotonically increasing function, whose inverse function is the first conversion error ; The space of all bounded sequences; is the normalized error.

7. The active suspension control method based on structural constraints and bionic reference models according to claim 3, characterized in that: In step S43, the virtual control variable The method to obtain is: ； in, is a dummy control variable; is the first positive control parameter; is the conversion error auxiliary function; is the conversion error.

8. The active suspension control method based on structural constraints and bionic reference model according to claim 3, characterized in that: The active control force of the controller in step S43 for: ； in, is a symbolic function.

9. An active suspension control system according to any one of claims 1 to 8, characterized in that: It includes: Active suspension system module, bionic reference model module, tracking error module, nonlinear coordination function module, disturbance observer module and preset performance controller module; The active suspension system module provides a two-degree-of-freedom active suspension system model to simulate the control process of the active suspension control system; The bionic reference model module establishes a bionic reference model with quasi-zero stiffness characteristics based on the bionic damping structure and tail balancing effect of the bionic case, providing a reference tracking trajectory for the motion control of the sprung mass of the vehicle body in the two-degree-of-freedom active suspension system. The tracking error module provides the control error between the actual motion of the vehicle body and the bionic reference model; The nonlinear coordination function module provides coordination rules for coordinated control and sets hard constraints on the suspension mechanical structure in the control objectives of the two-degree-of-freedom active suspension system to balance vehicle ride comfort and suspension deflection. The disturbance observer module is used to determine the lumped disturbance of the two-degree-of-freedom active suspension system and improve the control accuracy; The preset performance controller module controls the steady-state and transient errors of the sprung mass displacement tracking of the active suspension system according to the sprung mass vertical displacement tracking error, thereby realizing the two-degree-of-freedom active suspension system control.

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