Control method and system of active suspension system based on all-wheel-drive system

Abstract

The invention provides a control method and system of an active suspension system based on an all-wheel-drive system, and relates to the technical field of active suspension systems.The control method comprises the steps that a kinetic equation of a quarter active suspension system is built; according to the kinetic equation, the active suspension system is converted into an all-wheel-drive system; determining uncertain factors and boundaries of the all-drive system, and constructing a state model of the all-drive system; a controller is designed according to the state model of the all-wheel-drive system, a closed-loop system is formed, and the controller needs to ensure that a system state vector is finally converged to any small area; constructing a Lyapunov candidate function, and proving the stability of the closed-loop system according to the Lyapunov stability theory; the robust control method designed by the invention can ensure that the system state converges to any small area.

Description

Technical Field

[0001] The present disclosure relates to the technical field of active suspension systems, and in particular to a control method and system for an active suspension system of an all-wheel drive system. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] Due to the inevitable uncertainty factors in practical applications, it is very difficult to establish an accurate active suspension system model. In order to solve the problem of uncertainty factors, researchers have designed many robust control methods for active suspension systems, including adaptive control, H∞ control, sliding mode control, output feedback control, and observer-based control. The disadvantage is that these control methods require a full understanding of the upper and lower bounds of uncertainty factors. In the case of unknown uncertainty information, researchers have proposed many intelligent control methods, such as fuzzy logic systems and neural networks.

[0004] Although the control methods of the above active suspension systems are all very meaningful, some methods still require special forms or conditions and there is no general theoretical method. It is well known that in most cases, it is extremely difficult to construct a suitable Lyapunov candidate function, which makes most control methods unusable in practice and lacks theoretical guarantees. In order to solve this problem, all-wheel drive system methods have been proposed. These methods can transform the original nonlinear model into an equivalent all-wheel drive system model, promote the construction of the required closed-loop dynamics model, and deal with unknown system parameters, external interference and other problems.

[0005] However, the existing methods still have some problems as follows:

[0006] 1) For active suspension systems with system uncertainty factors, it is urgent to theoretically ensure that the system state converges to an arbitrarily small area, can adapt to various needs, and simplify the derivation as much as possible.

[0007] 2) Most of the existing active suspension system control methods rely on accurate model parameters. However, for most cases, system parameters, such as sprung mass, may vary greatly in different control tasks and are difficult to measure accurately. Therefore, the control performance of these control methods may be degraded to a great extent. Summary of the invention

[0008] In order to solve the above problems, the present disclosure proposes a control method and system for an active suspension system based on an all-wheel drive system, and designs a robust control method based on the all-wheel drive system method, which does not require precise system parameters and ensures that the system state converges to an arbitrarily small area.

[0009] According to some embodiments, the present disclosure adopts the following technical solutions:

[0010] A control method for an active suspension system based on an all-wheel drive system includes:

[0011] Construct the dynamic equations of a quarter active suspension system;

[0012] According to the dynamic equation, the active suspension system is converted into an all-wheel drive system;

[0013] Determine the uncertainties and boundaries of the all-wheel drive system and build a state model of the all-wheel drive system;

[0014] A controller is designed according to the state model of the all-wheel drive system to form a closed-loop system, wherein the controller needs to ensure that the system state vector eventually converges to an arbitrarily small area;

[0015] Construct Lyapunov candidate functions and prove the stability of the closed-loop system based on Lyapunov stability theory.

[0016] According to some embodiments, the present disclosure adopts the following technical solutions:

[0017] The control system of the active suspension system based on the all-wheel drive system includes:

[0018] A model building module is used to build a dynamic equation of a quarter active suspension system; according to the dynamic equation, the active suspension system is converted into an all-wheel drive system; the uncertain factors and boundaries of the all-wheel drive system are determined, and a state model of the all-wheel drive system is built;

[0019] The control module is used to design a controller according to the state model of the all-wheel drive system and form a closed-loop system. The controller must ensure that the system state vector eventually converges to an arbitrarily small area; construct a Lyapunov candidate function and prove the stability of the closed-loop system according to the Lyapunov stability theory.

[0020] According to some embodiments, the present disclosure adopts the following technical solutions:

[0021] A non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the control method of the active suspension system based on the all-wheel drive system is implemented.

[0022] According to some embodiments, the present disclosure adopts the following technical solutions:

[0023] An electronic device comprises: a processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes the control method of the active suspension system based on the all-wheel drive system.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention discloses a control method for an active suspension system based on an all-wheel drive system. A new robust control method is designed for a quarter vehicle active suspension system using an all-wheel drive system method, and an uncertain active suspension system model is given, in which the system uncertainty only needs to satisfy the bounded assumption. A robust stabilization control method is constructed to ensure that the state eventually converges globally to an arbitrarily small area. According to the Lyapunov stability theory, the stability of the closed-loop system is strictly proved. Based on the all-wheel drive system method, the designed robust control method can ensure that the system state converges to an arbitrarily small area. The proposed control method does not require precise system parameters, has a wide range of applications, and has great practical value.

[0026] The present invention discloses a control method for an active suspension system based on an all-wheel drive system, which fully utilizes the inherent characteristics and advantages of the all-wheel drive system and designs the first robust control method based on an all-wheel drive system for the active suspension system. The all-wheel drive characteristics enable the present invention to completely eliminate any known nonlinear dynamics and realize the required linear closed-loop system. A significant advantage of this method is that it can easily design a controller for a deterministic all-wheel drive system, which can realize any assignable characteristic structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0028] Figure 1 A schematic diagram of a quarter active suspension system according to an embodiment of the present disclosure;

[0029] Figure 2 The present invention is a flowchart of an active suspension system control method based on an all-wheel drive system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] Example 1

[0034] In one embodiment of the present disclosure, a control method for an active suspension system based on an all-wheel drive system is provided, and an uncertain active suspension system model is given, wherein the system uncertainty only needs to satisfy the bounded assumption. A robust stabilization control method is constructed to ensure that the state eventually converges globally to an arbitrarily small region, including:

[0035] Step 1: Construct the dynamic equation of the quarter active suspension system;

[0036] Step 2: Convert the active suspension system into an all-wheel drive system according to the dynamic equation;

[0037] Step 3: Determine the uncertainties and boundaries of the all-wheel drive system and build a state model of the all-wheel drive system;

[0038] Step 4: Design a controller based on the state model of the all-wheel drive system and form a closed-loop system. The controller must ensure that the system state vector eventually converges to an arbitrarily small area.

[0039] Step 5: Construct the Lyapunov candidate function and prove the stability of the closed-loop system based on the Lyapunov stability theory.

[0040] As an embodiment, the specific implementation process of the control method of the active suspension system based on the all-wheel drive system disclosed in the present invention is as follows:

[0041] like Figure 1 As shown, the dynamic equation of the quarter active suspension system can be described as:

[0042]

[0043] Among them, m s ,m u are the sprung mass and the unsprung mass, F s (z s ,zu ) is the suspension spring stiffness, is the suspension damping, z s is the sprung mass displacement, z u is the unsprung mass displacement, z r is the road excitation, F t (z u ,z r ) is the tire spring stiffness, is the tire damping, u(t) is the control input, f 1 is the uncertainty factor of the system.

[0044] The active suspension system includes suspension springs, dampers and tires. The dynamic model of the suspension springs, dampers and tires can be described as:

[0045]

[0046] Among them, k s and k sn represents the suspension spring stiffness coefficient, b s represents the suspension damping coefficient, k t and k b Represent the tire stiffness coefficient and damping coefficient respectively.

[0047] Furthermore, according to the dynamic equation, the active suspension system is converted into an all-wheel drive system as follows:

[0048]

[0049] or

[0050] Assumption 1. System uncertainty factors is bounded, and its mathematical description is:

[0051]

[0052] in, Represents a known constant.

[0053] Due to system uncertainty It consists of internal disturbances and external disturbances of the system. Therefore, the system parameters involved in system (4) are all their nominal values.

[0054] The design of the robust control method based on the all-wheel drive system approach introduces the following three lemmas.

[0055] Lemma 1. Consider the following uncertain all-wheel drive system:

[0056] x (n) =f(x (0～n-1))+Δf(x (0～n-1) )+B(x (0～n-1) ) r (6)

[0057] Among them, x,f(x (0～n-1) ), Respectively represent the state vector, the known continuous function related to the state, and the control input vector, represents the system uncertainty vector, satisfying ||Δf(x (0～n-1) )||≤σ(x (0～n-1) ),σ(x (0～n-1) )≥0 indicates a known continuous function, B(x (0～n-1) ) represents the continuous control direction matrix, det(B(x (0～n-1) ))≠0, or ∞, It can be described as:

[0058]

[0059] make

[0060] (1) are two positive constants;

[0061] (2) Matrix satisfy:

[0062]

[0063] Among them, λ max (·) represents the largest characteristic root, A 0～n-1 ,Ω(A 0～n-1 ) is:

[0064]

[0065] in, is the matrix to be adjusted,

[0066] (3) Positive definite symmetric matrix satisfy:

[0067] Ω T (A 0～n-1 )P+PΩ(A 0～n-1 )≤-μP (8)

[0068] Then, the controller can be designed as:

[0069]

[0070] Then the system state vector x can be guaranteed (0～n-1) Finally it converges to the following range:

[0071]

[0072] Substituting formula (9) into formula (6), we can get:

[0073]

[0074] Then, choose the following Lyapunov candidate function:

[0075]

[0076] By taking the derivative of equation (12) with respect to time, we can obtain:

[0077]

[0078] Lemma 2. Define a and b as two real numbers, and b>0, then:

[0079]

[0080] Lemma 3: Definition is a positive symmetric matrix, then for any Both have:

[0081] λ min (Q)y T y≤y T Qy≤λ max (Q)y T y (15)

[0082] Among them, λ min (·) is the minimum characteristic root.

[0083] Furthermore, the controller is designed and its stability analysis is performed.

[0084] The following robust control method is designed for the quarter active suspension system (4):

[0085]

[0086] in, represents the state vector, a 0 and a 1 is the gain to be adjusted, the positive definite symmetric matrix P 1 The following conditions must be met:

[0087]

[0088] in, Represents a positive number, Ω(A 0～1 ) is:

[0089]

[0090] And the following holds:

[0091] Ω T (A 0～1 ) 1 +P 1 Ω(A 0～1 )≤-μ 1 P 1 (19)

[0092] Among them, K 1 The characteristic structure used to adjust the linear part determines the control performance of the system, K 2 To deal with the uncertainty factor f 1 impact.

[0093] Theorem 1. For the active suspension system (4), design the controller (16). If conditions (17) and (19) are satisfied, the sprung displacement can be guaranteed to converge asymptotically to the following arbitrarily small region:

[0094]

[0095] in, is a positive constant.

[0096] Proof: Substituting formula (16) into formula (4), we can obtain:

[0097]

[0098] According to the structure of formula (21), the closed-loop system can be written as the following state space description:

[0099]

[0100] Among them, Ω(A 0～1 ) is shown in formula (18).

[0101] Then, the Lyapunov candidate function is constructed as follows:

[0102]

[0103] Taking the derivative of both ends of equation (23) with respect to time, we can obtain:

[0104]

[0105] From equations (19) and (23), we can directly obtain equation (25):

[0106]

[0107] According to formula (5) and Lemma 2, the last term of formula (25) can be calculated as:

[0108]

[0109] Substituting formula (26) into formula (25), we can obtain:

[0110]

[0111] Formula (27) can be further calculated as:

[0112]

[0113] This shows that:

[0114]

[0115] From equations (23) and (29), we can know that the system state X Converges to the following region:

[0116]

[0117] Based on Lemma 3, it is easy to obtain:

[0118]

[0119] Therefore, the closed-loop system is stable and the system state vector converges uniformly to an arbitrarily small region.

[0120] By reducing ε 1 or increase μ 1 The value of can be arbitrarily small, so X (0～1) Can be infinitely close to the origin.

[0121] Example 2

[0122] In one embodiment of the present disclosure, a control system of an active suspension system based on an all-wheel drive system is provided, comprising:

[0123] A model building module is used to build a dynamic equation of a quarter active suspension system; according to the dynamic equation, the active suspension system is converted into an all-wheel drive system; the uncertain factors and boundaries of the all-wheel drive system are determined, and a state model of the all-wheel drive system is built;

[0124] The control module is used to design a controller according to the state model of the all-wheel drive system and form a closed-loop system. The controller must ensure that the system state vector eventually converges to an arbitrarily small area; construct a Lyapunov candidate function and prove the stability of the closed-loop system according to the Lyapunov stability theory.

[0125] Example 3

[0126] In one embodiment of the present disclosure, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the control method of the active suspension system based on the all-wheel drive system is implemented.

[0127] Example 4

[0128] In one embodiment of the present disclosure, an electronic device is provided, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes the control method of the active suspension system based on the all-wheel drive system.

[0129] The present disclosure is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present disclosure. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0130] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0131] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A control method for an active suspension system based on an all-wheel drive system, characterized in that: include: Construct the dynamic equations of a quarter active suspension system; According to the dynamic equation, the active suspension system is converted into an all-wheel drive system; Determine the uncertainties and boundaries of the all-wheel drive system and build a state model of the all-wheel drive system; A controller is designed according to the state model of the all-wheel drive system to form a closed-loop system, wherein the controller needs to ensure that the system state vector eventually converges to an arbitrarily small area; Construct Lyapunov candidate functions and prove the stability of the closed-loop system based on Lyapunov stability theory.

2. The control method of the active suspension system based on the all-wheel drive system according to claim 1, characterized in that: The active suspension system includes suspension springs, dampers and tires. The dynamic equation of a quarter active suspension system is: Among them, m s ,m u are the sprung mass and the unsprung mass, F s (z s ,z u ) is the suspension spring stiffness, is the suspension damping, z s is the sprung mass displacement, z u is the unsprung mass displacement, z r is the road excitation, F t (z u ,z r ) is the tire spring stiffness, is the tire damping, u(t) is the control input, and f1 is the system uncertainty factor.

3. The control method of the active suspension system based on the all-wheel drive system according to claim 2, characterized in that: The dynamic model of the suspension spring, damper, and tire is described as: F s (With s ,With u )=k s (With s -With u )+k sn (With s -With u ) 3 Among them, k s and k sn represents the suspension spring stiffness coefficient, b s represents the suspension damping coefficient, k t and k b Represent the tire stiffness coefficient and damping coefficient respectively.

4. The control method of the active suspension system based on the all-wheel drive system according to claim 1, characterized in that: According to the dynamic equation, the active suspension system is converted into an all-wheel drive system: System uncertainty factors is bounded, and its mathematical description is: in, Represents a known constant.

5. The control method of the active suspension system based on the all-wheel drive system according to claim 4, characterized in that: Unsure of the AWD system: x (n) =f(x (0～n-1) )+Δf(x (0～n-1) )+B(x( 0～n-1) )u r in, Respectively represent the state vector, the known continuous function related to the state, and the control input vector, represents the system uncertainty vector, satisfying ||Δf(x (0～n-1) )||≤σ(x (0～n-1) ),σ(x (0 ～n-1) )≥0 indicates a known continuous function, B(x (0～n-1) ) represents the continuous control direction matrix.

6. The control method of the active suspension system based on the all-wheel drive system according to claim 1, characterized in that: The controller is designed to: in, represents the state vector, a0 and a1 are the gains to be adjusted, and P1 is a positive definite symmetric matrix.

7. The control method of the active suspension system based on the all-wheel drive system according to claim 1, characterized in that: For active suspension systems, the controller design needs to ensure that the sprung displacement converges asymptotically to the following arbitrarily small region: in, is a positive constant.

8. A control system for an active suspension system based on an all-wheel drive system, characterized in that: include: A model building module is used to build a dynamic equation of a quarter active suspension system; according to the dynamic equation, the active suspension system is converted into an all-wheel drive system; Determine the uncertainties and boundaries of the all-wheel drive system and build a state model of the all-wheel drive system; The control module is used to design a controller according to the state model of the all-wheel drive system and form a closed-loop system. The controller needs to ensure that the system state vector eventually converges to an arbitrarily small area; construct a Lyapunov candidate function and prove the stability of the closed-loop system according to the Lyapunov stability theory.

9. A non-transitory computer-readable storage medium, characterized in that: The non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by the processor, the control method of the active suspension system based on the all-wheel drive system as described in any one of claims 1 to 7 is implemented.

10. An electronic device, characterized in that: include: A processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes the control method of the active suspension system based on the all-wheel drive system as described in any one of claims 1 to 7.

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