Method for controlling shimmy of vehicle corner module, method for controlling stability of vehicle, and vehicle

Abstract

This invention relates to a shimmy control method for a vehicle corner module, a vehicle stability control method, and a vehicle in the field of vehicle control technology. The shimmy control method includes: when the vehicle corner module's travel speed... v In v b ≤ v ≤ v u At that time, the actuator outputs a oscillation control force. F c It acts on the vehicle frame to suppress the shimmy of the vehicle corner modules. v b The lower limit of the vehicle speed that triggers the control. v u The upper limit of the vehicle speed for trigger control. This invention, by considering the vehicle corner module dynamics model that incorporates random disturbances from the actuators, quantifies and characterizes the random disturbances experienced during shimmy control, making it more consistent with the actual driving state of the vehicle corner module, thereby effectively improving the suppression of shimmy phenomena in the vehicle corner module.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and in particular to a method for controlling the sway of a vehicle corner module, a method for controlling vehicle stability, and a vehicle. Background Technology

[0002] The vehicle corner module highly integrates chassis actuators such as drive, steering, suspension, and braking, improving its controllable degrees of freedom. However, by eliminating the steering tie rod, the vehicle corner module is highly susceptible to steering shimmy after initial external disturbances during driving, severely impacting vehicle stability and hindering the full realization of its dynamic performance. Therefore, research on shimmy control methods for vehicle corner modules has attracted widespread attention from OEMs and consumers. Existing technologies, such as the Chinese invention patent with patent application number CN202510169986.3, entitled "A Shimmy Suppression Method for a Dual-Winding Steer-by-Wire Kingpin Steering System," disclose the following: establishing a mathematical model of a four-wheel independent steering vehicle and a mathematical model of a dual-winding kingpin steering system. By calculating the current control signals of the two windings separately and applying them to a dual-winding permanent magnet synchronous motor, shimmy suppression control of the dual-winding steer-by-wire kingpin steering system is achieved. Chinese invention patent application number CN202510475133.2, entitled "A Method for Suppressing Wagging in a Four-Wheel Independent Steer-by-Wire System," discloses: establishing a dynamic model of wheel wagging in a four-wheel independent steer-by-wire system, designing a self-tuning strategy and controller for backstepping sliding mode controller parameters based on the wagging frequency, and thus suppressing the wagging phenomenon in the four-wheel independent steer-by-wire system. However, current technical solutions are all based on deterministic theoretical frameworks to establish vehicle wagging dynamic models, without considering the random interference of actuators, and have not yet studied the corresponding vehicle corner module structural dynamic characteristics and their wagging control methods. This cannot accurately reflect the random dynamic characteristics of the vehicle corner modules during actual driving, making it difficult to meet consumers' high-quality demands for vehicle corner module wagging control. Summary of the Invention

[0003] To address the technical problem that existing technologies have poor suppression effects on vehicle corner module swaying, this invention provides a vehicle corner module swaying control method, a vehicle stability control method, and a vehicle.

[0004] This invention is achieved through the following technical solution:

[0005] In a first aspect, the present invention provides a sway control method for a vehicle corner module, wherein when the vehicle corner module travels at a certain speed... v In v b ≤ v ≤ v uAt that time, the actuator outputs a oscillation control force. F c It acts on the vehicle frame to suppress the shimmy of the vehicle corner modules; v b The lower limit of the vehicle speed that triggers the control. v u The maximum speed limit for triggering control. F c satisfy:

[0006] .

[0007] In the formula, p These are the random control parameters of the actuator, which are determined by... v The results are obtained by inputting the vehicle angle module dynamics model that considers random disturbances of the actuators. y It is the lateral displacement of the vehicle's corner module. for t Gaussian white noise at any given time.

[0008] Secondly, the present invention also proposes a vehicle stability control method, which includes:

[0009] Determine the speed of the vehicle's four corner modules v Is it in v b ≤ v ≤ v u ; v b The lower limit of the vehicle speed that triggers control. v u The maximum speed limit for triggering control.

[0010] If one of the vehicle corner modules is a vehicle corner module, then the sway control method of the vehicle corner module in the first aspect is triggered to control the corresponding vehicle corner module.

[0011] If not, return to the judgment step.

[0012] Thirdly, the present invention also proposes a vehicle comprising: a frame, an angle module, a wheel speed sensor, an actuator, and an electronic control unit.

[0013] The corner module is mounted on the chassis. Wheel speed sensors are used to collect the travel speed of the corner module. v The actuator is used to output the oscillation control force. F c This is applied to the chassis to suppress the sway of the corner modules. The electronic control unit employs the vehicle stability control method described in the second aspect, based on the driving speed. v Control actuator output oscillation control force Fc .

[0014] In a fourth aspect, the present application further provides a computer readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the steps of the shimmy control method of the vehicle corner module in the first aspect are implemented.

[0015] The present application has the following beneficial effects:

[0016] 1. The present application quantitatively characterizes the random disturbance in the shimmy control process by considering the vehicle corner module dynamics model with random disturbance of the actuator, which is more consistent with the actual driving state of the vehicle corner module, thereby effectively improving the suppression effect on the shimmy phenomenon of the vehicle corner module.

[0017] 2. The present application first establishes a vehicle corner module dynamics model considering the random disturbance of the actuator, then processes the vehicle corner module dynamics model based on the center flow theorem to obtain a two-dimensional center flow, and obtains the random stability boundary of the vehicle corner module under different vehicle speeds and random control parameters based on the stochastic averaging method, so as to obtain the lateral control force of the vehicle corner module, thereby effectively suppressing the shimmy phenomenon of the vehicle corner module. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0019] Figure 1 is a flowchart of the shimmy control method of the vehicle corner module;

[0020] Figure 2 is a result graph of the simulation test of the shimmy control method of the vehicle corner module;

[0021] Figure 3 is a structural schematic diagram of a four-wheel steering vehicle. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments only constitute some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] It should be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled or connected to the other element or intervening elements can be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0025] The embodiment provides a shimmy control method of a vehicle corner module, which considers random disturbance factors of external actuators. First, the driving speed and dynamic state parameters of the vehicle corner module are collected v , and then the two-dimensional center flow of the vehicle corner module system is solved by using the center flow theorem based on the vehicle corner module dynamics model considering the random disturbance of the actuator, and the random stability boundary of the vehicle corner module under different driving speeds and control parameters is solved based on the stochastic averaging method, so as to obtain the shimmy control force for suppressing the shimmy phenomenon of the vehicle corner module F c , thereby effectively suppressing the shimmy phenomenon of the vehicle corner module and providing technical support for improving the driving stability of the vehicle corner module. Specifically, please refer to Figure 1 The shimmy control method of the vehicle corner module comprises the following steps:

[0026] The driving speed and dynamic state parameters of the vehicle corner module are collected v , and then it is judged whether v v b ≤ v ≤ v u , and v b is the lower limit of the driving speed for triggering control, v u is the upper limit of the driving speed for triggering control. If not, return to the above judgment step to continue monitoring v . If yes, the external actuator outputs the shimmy control force F c acting on the frame of the vehicle to suppress the shimmy of the vehicle corner module. The F c Considering the random disturbance of the actuator, it satisfies: ​

[0027] .

[0028] In the formula, p These are the random control parameters of the actuator, which are determined by... v The results are obtained by inputting the data into the vehicle angular module dynamics model that considers random disturbances of the actuators. y It is the lateral displacement of the vehicle's corner module. for t Gaussian white noise at any given time.

[0029] One of the design focuses of this invention is on random control parameters. p The solution, through a vehicle corner module dynamic model considering random disturbances in the actuators, quantifies and characterizes the random disturbances experienced during shimmy control, thus better reflecting the actual driving state of the vehicle corner module and laying the model foundation for achieving stability control of the vehicle corner module. This vehicle corner module dynamic model is a two-degree-of-freedom dynamic model including the vehicle corner module's rotation angle and lateral displacement.

[0030] .

[0031] .

[0032] .

[0033] In the formula, m It is the quality of the vehicle corner module. m 2 is the frame quality. b For the center of mass of the vehicle corner module O 2 to the center of the main pin axis O A distance of 1. yes y The derivative, yes y The second derivative of . For vehicle corner module turning angle, for The derivative, for The second derivative, c 1 is the lateral damping of the frame. k 1 is the lateral stiffness of the frame. F y The lateral force acting on the vehicle's corner module. J It is the moment of inertia of the vehicle's angular module. c 2 is the frame torsional damping. k 2 is the frame torsional stiffness. M z It is the tire return torque, and M z = Fy t p , t p This indicates the tire's mechanical trail distance. k t1 This is the linear stiffness coefficient of the tire. k t2 This represents the cubic stiffness coefficient of the tire. α This refers to the tire slip angle. σ This refers to the tire slack length.

[0034] After the vehicle corner module dynamics model was constructed, it was processed based on the central flow theorem to obtain a two-dimensional central flow. Then, the stochastic stability boundary of the vehicle corner module under different vehicle speeds and stochastic control parameters was obtained using the stochastic averaging method, thereby obtaining the stochastic control parameters. p Then the oscillation control force is calculated. F c This effectively suppresses the swaying phenomenon of the vehicle's corner modules. (Acquire) p The method and process are as follows:

[0035] First, we introduce state variables. Transform the vehicle corner module dynamics model into state equations:

[0036] .

[0037] In the formula, A The Jacobian matrix of the vehicle angular module dynamics model:

[0038] .

[0039] F The matrix containing nonlinear terms:

[0040] .

[0041] U The coefficient matrix is ​​based on random perturbations:

[0042] .

[0043] intermediate variables m t for: Intermediate variables J t for: . x 1~ x 5 is a state variable. x The components in.

[0044] Next, the Jacobian matrixA The first bifurcation speed is obtained by Hopf bifurcation theory v 1, and let the bifurcation parameter μ be μ = v-v 1, i.e. v = μ + v 1. Then introduce a new state variable Y : Y ∈ R 5 , so that: x = pY , and v = μ + v 1 and x = pY are substituted into to convert the state equation into:

[0045] .

[0046] where p is a transformation matrix, which can be recombined from the real part and the imaginary part of the eigenvectors in the state equation.

[0047] Then set the center manifold function as:

[0048] .

[0049] In the formula, i = 3, 4, 5. That is, Y ( y 1, y 2, y 3, y 4, y 5), y 1 ~ y 5 are the components in the state variable Y . h i (·) represents the center manifold function, is the coefficient of the corresponding matrix element in the center manifold function. The initial condition of this center manifold function is that the values of the center manifold function at the origin are all zero. is a Gaussian white noise. Further, according to the differential theorem, the center manifold function after differentiation can be expressed as:

[0050] .

[0051] Substitute the differentiated center manifold function into the converted state equation to obtain the initial two-dimensional center manifold of the vehicle angle module:

[0052] .

[0053] where, a ij is the coefficient of the corresponding matrix element in the two-dimensional center manifold, i , j are the indices of the matrix elements. Let and substitute into the original two-dimensional center manifold to obtain the two-dimensional center manifold of the vehicle angle module after simplification:

[0054] .

[0055] .

[0056] where, f 11 , f 21 are the intermediate variables, r is the amplitude in the polar coordinate system, θ is the phase angle in the polar coordinate system. g ij is the coefficient of the corresponding matrix element in the average Itô stochastic differential equation, i , j are the indices of the matrix elements.

[0057] Further, to analyze the stochastic stability of the vehicle angle module, the two-dimensional center manifold is converted into an average Itô stochastic differential equation:

[0058] .

[0059] where, m ( r ) represents the drift coefficient, σ ( r ) represents the diffusion coefficient, W ( t ) represents the standard Wiener process.

[0060] The solution formula of the average Itô stochastic differential equation is:

[0061] .

[0062] .

[0063] .

[0064] .

[0065] where, F 1, F 2, F 3 are the intermediate variables, D is the intensity of the Gaussian white noise.

[0066] At the same time, based on the random average method, the random stability condition of the vehicle corner module can be obtained from the average Itô stochastic differential equation solution formula:

[0067] .

[0068] At this point, by collecting the driving speed v The random control parameters p can be calculated F The roll control force F c can be calculated, which is applied to the frame to suppress the occurrence of roll phenomenon and improve the driving stability of the vehicle corner module.

[0069] To verify the effect of the roll control method of the vehicle corner module, a simulation test is carried out. First, set the simulation parameters as follows:

[0070] m =15kg, m 2=4kg, J =0.48kg·m 2 , c 1=220N·s / m, c 2=60 N·s·m / rad, k 1=150000 N / m, k 2=25000 N·m / rad, D =0.15, b =0.2m, v b =45km / h, v u =65km / h.

[0071] According to the above vehicle corner module dynamics model and random stability condition, the stability boundary of the random control parameters v corresponding to different driving speeds p can be obtained, as shown in Figure 2 From Figure 2 it can be seen that, taking v =56.5km / h as an example, the calculated random control parameters p are: p =1848N / m, and the vehicle corner module roll control force F c ， generated thereby can effectively suppress the occurrence of roll phenomenon and improve the driving stability of the vehicle corner module.

[0072] In another embodiment, a stability control method for a four-wheel steering vehicle is also proposed, which comprises the following steps:

[0073] determining the running speed of the four vehicle corner modules of the vehicle v whether it is in v b ≤ v ≤ v u ; v b a lower limit of the vehicle speed for triggering the control, v u an upper limit of the vehicle speed for triggering the control.

[0074] if one of the vehicle corner modules is, the shimmy control method for the vehicle corner module described in the above embodiment is triggered to control the corresponding vehicle corner module.

[0075] otherwise, the determination step is returned to, and the running speed of the vehicle corner module is continuously monitored.

[0076] In another embodiment, as shown in Figure 3 , a four-wheel steering vehicle is also proposed, which comprises four vehicle frames, four corner modules (only one is shown in the figure), a wheel speed sensor, an actuator, and an electronic control unit. The four corner modules are respectively installed on the four vehicle frames as the driving wheels of the vehicle. The vehicle frame is connected to the vehicle body (such as the chassis) through a kingpin. Figure 3 In the figure, O 2 is the center of mass of the vehicle corner module, O 1 is the center of the kingpin. The wheel speed sensor can also be installed on the vehicle frame to collect the running speed of the four corner modules v . The actuator can be installed on the vehicle body to output a shimmy control force F c acting on the vehicle frame. The F c is a lateral control force of the vehicle corner module, which acts on the lateral side of the vehicle corner module to suppress the shimmy of the corner module. The electronic control unit is connected to the wheel speed sensor through a signal input line and connected to the actuator through a signal input line. And the electronic control unit adopts the stability control method of the four-wheel steering vehicle in the above embodiment, and controls the actuator to output the shimmy control force v F c .

[0077] ​In another embodiment, a computer readable storage medium is also provided. The computer readable storage medium stores a computer program. When the computer program is executed by a processor, the steps of the shimmy control method of the vehicle angle module in the above embodiment are implemented. The computer readable storage medium can include, but is not limited to, an electrical connection having one or more conductive wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0078] Any combination of the technical features in the above-described embodiments can be made, and in order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist, it should be considered that they are within the scope of the description.

[0079] The above-described embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent right of the present application. It should be pointed out that, for ordinary skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent right of the present application should be subject to the appended claims.

Claims

1. A method for controlling the swaying of a vehicle corner module, characterized in that, When the vehicle corner module travels at speed v In v b ≤ v ≤ v u At that time, the actuator outputs a oscillation control force. F c It acts on the vehicle frame to suppress the shimmy of the vehicle corner modules; v b The lower limit of the vehicle speed that triggers control. v u The maximum vehicle speed that triggers the control; F c satisfy: ； In the formula, ρ These are the random control parameters of the actuator, which are determined by... v The results are obtained by inputting the vehicle angle module dynamics model that considers random disturbances of the actuators. y It is the lateral displacement of the vehicle corner module, which is t Gaussian white noise at any given time; The vehicle corner module dynamics model is as follows: ； ； ； In the formula, m It is the quality of the vehicle corner module. m 2 is the frame quality. b The distance from the center of mass of the vehicle corner module to the center of the kingpin axis. φ For vehicle corner module turning angle, c 1 is the lateral damping of the frame. k 1 is the lateral stiffness of the frame. F y The lateral force acting on the vehicle's corner module. J It is the moment of inertia of the vehicle's angular module. c 2 is the frame torsional damping. k 2 is the frame torsional stiffness. M z It is the tire return torque. k t1 This is the linear stiffness coefficient of the tire. k t2 This represents the cubic stiffness coefficient of the tire. α This refers to the tire slip angle. σ This refers to the tire slack length. get ρ The methods include: Introducing state variables Transform the vehicle corner module dynamics model into state equations: ； In the formula, A Let be the Jacobian matrix of the vehicle angular module dynamics model. F This is a matrix of nonlinear terms containing nonlinear terms. U The coefficient matrix is ​​based on random perturbation; Solving for the two-dimensional central manifold of the vehicle angle module using state equations: ； In the formula, f 11 , f 21 Both represent intermediate variables. r The magnitude is in polar coordinates. θ The phase angle is in polar coordinates. g ij (·) represents the coefficients of the corresponding matrix elements in the average Iton stochastic differential equation; The two-dimensional central manifold is transformed into an average Itō stochastic differential equation, which is then solved to obtain... ρ .

2. The sway control method for the vehicle corner module according to claim 1, characterized in that, Jacobian matrix A The speed of the first bifurcation is obtained using Hope's bifurcation theory. v 1; Let the bifurcation parameters μ for μ = vv 1. And introduce intermediate transformation variables into the state equation: To transform the state equation into: ； in, p Let be the transformation matrix. Y Represents a new state variable; Let the central manifold function be: ； In the formula, i =3, 4, 5 y 1~ y 5 is a state variable. Y The components in h i (·) represents the central flow function. h i1 ~ h i7 The coefficients of the corresponding matrix elements in the central manifold function are Gaussian white noise; Substituting the differential of the central manifold function into the transformed state equation, and simplifying, we obtain the two-dimensional central manifold of the vehicle angle module.

3. The sway control method for the vehicle corner module according to claim 2, characterized in that, Substituting the differential of the central manifold function into the transformed state equation, the initial two-dimensional central manifold is obtained as follows: ； In the formula, a ij These are the coefficients of the corresponding matrix elements in the two-dimensional central manifold of the vehicle corner module. i , j All are the indexes of the matrix elements; Let , and substitute into the initial two-dimensional central manifold to simplify, and then obtain the two-dimensional central manifold of the vehicle corner module.

4. The sway control method for the vehicle corner module according to claim 1, characterized in that, In the state equation, the Jacobian matrix A for: ； Nonlinear term matrix F for: ； coefficient matrix U for: ； Among them, intermediate variables m t for: Intermediate variables J t for: ; t p Indicates tire mechanical trail; And / or, in the two-dimensional central manifold of the vehicle corner module, f 11 , f 21 The expression is: ； In the formula, a ij These are the coefficients of the corresponding matrix elements in the two-dimensional central manifold of the vehicle corner module. i , j All are the indexes of the matrix elements.

5. The sway control method for the vehicle corner module according to claim 4, characterized in that, The average Itoh stochastic differential equation is: ； The solution formula is: ； ； ； ； In the formula, m ( r ) represents the drift coefficient. σ ( r ) represents the diffusion coefficient. W ( t ) represents the standard Wiener process; F 1. F 2. F 3 is an intermediate variable; D The intensity of Gaussian white noise; By applying the stochastic averaging method to the solution formula of the average Itoh stochastic differential equation, the stochastic stability condition of the angle module is obtained: 。 6. A vehicle stability control method, characterized in that, It includes: Determine the speed of the vehicle's four corner modules v Is it in v b ≤ v ≤ v u ; v b The lower limit of the vehicle speed that triggers control. v u The maximum vehicle speed that triggers the control; If one of the vehicle corner modules is a vehicle corner module, then the sway control method of the vehicle corner module as described in any one of claims 1 to 5 is triggered to control the corresponding vehicle corner module. If not, return to the judgment step.

7. A vehicle, characterized in that, It includes: Frame; Corner modules, which are mounted on the vehicle frame; Wheel speed sensor, used to collect the travel speed of the angle module. v ; Actuator, used to output oscillation control force F c It acts on the frame to suppress the swaying of the corner modules; The electronic control unit employs the vehicle stability control method as described in claim 6, based on the driving speed. v Control actuator output oscillation control force F c .

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the sway control method for the vehicle corner module as described in any one of claims 1 to 5.

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