A method for optimizing design of automobile chassis for steering stability control

Abstract

The present application relates to the technical field of computer-aided design of automobile chassis, and provides an automobile chassis optimization design method for handling stability control. The method comprises the following steps: obtaining automobile chassis design requirements and basic parameters; designing multiple sets of arrangement schemes and building a chassis LPV control system model, calculating eigenvalues of all arrangement schemes under the chassis LPV control system model, according to the first Lyapunov stability principle, screening and removing arrangement schemes with positive eigenvalues of the state matrix under the chassis LPV control system model, retaining arrangement schemes with all negative eigenvalues, and calculating and selecting an arrangement scheme with the smallest upper bound as the target arrangement scheme. The present application avoids the limitations brought by the experience-based arrangement method, selects the scheme with the optimal performance index, and the final scheme obtained has stronger robustness.

Description

Technical Field

[0001] This invention relates to the field of computer-aided design technology for automotive chassis, and in particular to an optimized design method for automotive chassis oriented towards handling stability control. Background Technology

[0002] With the continuous development of autonomous driving technology in closed environments, more and more engineering vehicles are adopting autonomous control methods for operation. Taking airport support vehicle chassis as an example, this chassis needs to carry heavy superstructure equipment such as high-power batteries, working equipment, and range extenders. The total mass of these devices exceeds the chassis mass, resulting in a high center of gravity and placing high demands on the chassis's driving stability. Furthermore, these superstructures are generally large in size, requiring rational arrangement on the chassis to improve driving stability while meeting space constraints. Traditional chassis layout methods generally rely on experience, placing various load devices as close to the chassis's center of symmetry as possible. However, for airport support vehicle chassis, due to the large mass and volume of the superstructure equipment, and the limited and often irregular chassis space, it is difficult to place all equipment at the chassis's center of symmetry. Additionally, airport support vehicle chassis operate autonomously on airport runways, requiring rapid autonomous obstacle avoidance capabilities and quick removal from the site after work to avoid disrupting normal airport operations. Therefore, the chassis operates over a wide speed range, placing high demands on its driving stability. Therefore, it is of great significance to define the layout range of each piece of equipment according to the working requirements and volume constraints, and then determine the appropriate position of each piece of equipment within the layout range based on the stability of the chassis at different speeds. Summary of the Invention

[0003] In view of this, the present invention provides an automotive chassis optimization design method for handling stability control, in order to solve the problem that the existing technology cannot specify the layout range of each device and the chassis driving stability at different speeds according to the working needs and volume constraints of the equipment, and determine the appropriate position of each device in the layout range.

[0004] This invention provides a method for optimizing the design of a car chassis for handling stability control, comprising: S1 obtains the chassis design requirements and basic parameters, and designs multiple layout schemes based on the basic parameters. The layout schemes include the installation positions of each superstructure load on the chassis. Based on chassis design requirements and basic parameters, S2 builds a chassis LPV control system model. S21 simplifies the chassis model into a two-degree-of-freedom vehicle model; S22 uses the sideslip angle and yaw rate of the center of gravity of the two-degree-of-freedom vehicle model as state variables and the front wheel steering angle as control input to obtain a state space model from the state variables and the control input. S23 obtains the chassis LPV control system model based on the state-space model; S3 calculates the eigenvalues ​​of all layout schemes under the LPV control system model based on the chassis LPV control system model. According to the Lyapunov first stability principle, the layout schemes with positive eigenvalues ​​in the state matrix under the chassis LPV control system model are screened and removed, while the layout schemes with negative eigenvalues ​​in the state matrix under the chassis LPV control system model are retained. Based on the chassis LPV control system model, S4 calculates the upper bound of the output change caused by the input in all layout schemes, and selects the layout scheme with the smallest upper bound as the target layout scheme.

[0005] Furthermore, the vehicle chassis design requirements in S1 include the speed range of chassis operation and the dimensional constraints of chassis layout; The basic parameters of the chassis include the mass and dimensions of the chassis, as well as the mass and dimensions of the superstructure load.

[0006] Furthermore, the expression for the state-space model in S22 is as follows: Wherein, the state vector The derivative of the state vector is , y z ( t ) is the output. t For time, input matrix Control matrix Output matrix C z =[0 1]; Among them, curb weight m It is the sum of the chassis mass and the mass of the superstructure load. δ Front wheel angle, β The sideslip angle of the center of mass of the two-degree-of-freedom vehicle model. ω The yaw rate of the two-degree-of-freedom vehicle model. l f and l r These are the distances from the center of mass of the two-degree-of-freedom vehicle model to the front and rear axles, respectively. c f and c r These are the lateral stiffness of the front and rear wheels of the chassis, respectively. v x The longitudinal speed of the chassis. I z This is the total moment of inertia of the chassis.

[0007] Furthermore, obtaining the chassis LPV control system model in S23 includes: a. Simplify each load cell into a cube, and assume that each cube has a different size. Obtain the moment of inertia of each cube about its own geometric center. in, l i The length of the upper load cube. w i The width of the upper load cube. m i For the mass of the upper load cube, I i The moment of inertia of the load cube about its own geometric center. i Number the load cell; According to the parallel axis theorem, calculate the moment of inertia of each load cell to the geometric center of the chassis. in, The moment of inertia of the load mounted on the chassis at its geometric center. L dis The distance between the geometric center of the superstructure load and the geometric center of the chassis; Based on the moment of inertia of each superstructure load to the geometric center of the chassis Thus, the total moment of inertia is obtained; b. The lateral stiffness of the front and rear tires of the chassis is obtained by measuring the distance from the center of mass of the two-degree-of-freedom vehicle model to the front axle and the distance from the center of mass of the two-degree-of-freedom vehicle model to the rear axle. c. Based on the total moment of inertia, the lateral stiffness of the front and rear tires of the chassis, and the preset vehicle speed range, obtain the chassis LPV control system model.

[0008] Furthermore, the superstructure load includes superstructure working equipment, control assembly, range extender, and battery. The formula for calculating the total moment of inertia is as follows: in, I Z This represents the total moment of inertia of the chassis. I chassis It is the moment of inertia of the chassis frame. It is the moment of inertia of the superstructure working equipment to the geometric center of the chassis. It controls the moment of inertia of the control assembly to the geometric center of the chassis. It is the moment of inertia of the range extender to the geometric center of the chassis. It is the moment of inertia of the battery at the geometric center of the chassis. The formula for calculating the lateral stiffness of the front and rear tires of the chassis is as follows: c f = kG 1 c r = kG 2 in, G 1 and G 2 These represent the vertical loads on the front and rear axles, respectively. k It is a proportionality constant; in, L Indicates the chassis wheelbase. The vehicle's operating speed range is: in, v x The longitudinal speed of the chassis. This is the minimum longitudinal speed of the chassis. This is the maximum longitudinal speed of the chassis.

[0009] Furthermore, the expression for the chassis LPV control system model in S23 is as follows: The state vector of the chassis LPV control system model is: The derivative of the state vector of the chassis LPV control system model is , α l These are time-varying parameters obtained based on velocity, matrix pairs ( A l , B l ) represents the vertex of the chassis LPV control system model. l =1, 2, 3; In the state-space model A and B The matrix pairs formed ( A , B Transformed into: .

[0010] Furthermore, S4 specifically includes: Define Hamiltonian matrix H : in, H It is a Hamiltonian matrix. γ This is the upper bound of the output change caused by the input of the chassis LPV control system model. C This is the output matrix of the chassis LPV control system model, located in the upper right corner. T This is the matrix transpose. Solve for the eigenvalues ​​of the Hamiltonian matrix for each layout scheme. λ j ,if λ j Add to the imaginary axis γ Otherwise reduce γ Through iterative calculation, the... γ It converges to a fixed constant. Calculate the fixed constants for all layout schemes, and select the layout scheme with the smallest fixed constants as the target layout scheme.

[0011] Furthermore, the aforementioned γ The expression is as follows: in, G(s) For transfer functions, This is the operator for the infinite norm.

[0012] Furthermore, the transfer function G(s) The calculation formula is as follows: in, Z ( s The yaw rate is the Laplace transform of the output signal of the chassis LPV control system model, that is, the Laplace transform of the difference between the actual chassis yaw rate and the ideal chassis yaw rate. U ( s ) is the Laplace transform of the input signal of the chassis LPV control system model, that is, the Laplace transform of the front wheel steering angle.

[0013] The advantages of this invention compared to the prior art are: 1. The method of the present invention starts from the perspective of chassis handling stability, and arranges the automobile chassis. The optimal arrangement is obtained through theoretical calculation, avoiding the limitations of arrangement methods based on experience.

[0014] 2. The method of the present invention takes into account the stability of the vehicle at different speeds. Based on the speed range of the chassis operation, an LPV control system model is established, and design schemes that do not meet the operating speed range are removed according to the Lyapunov first stability principle.

[0015] 3. The method of this invention utilizes a computing system. Performance metrics: Selecting the solution with the optimal performance metrics results in a final solution with stronger robustness. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of an automotive chassis optimization design method for handling stability control provided by the present invention; Figure 2 This is a two-degree-of-freedom vehicle model diagram provided by the present invention; Figure 3 This is a top view of the automobile chassis layout provided by the present invention; Figure 4 This is a bottom view of the automobile chassis layout provided by the present invention; Among them, 1-range extender, 2-control center, 3-working equipment, 4-battery. Detailed Implementation

[0018] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0019] The present invention will now be described in detail with reference to the accompanying drawings. Figure 1 This invention provides a method for optimizing the design of a car chassis for handling stability control.

[0020] Figure 1 This is a flowchart of an automotive chassis optimization design method for handling stability control provided by the present invention.

[0021] like Figure 1 As shown, the automotive chassis optimization design method includes: S1 obtains the chassis design requirements and basic parameters, and designs multiple layout schemes based on the basic parameters. The layout schemes include the installation positions of each superstructure load on the chassis. The chassis design requirements in S1 include the speed range of chassis operation and the dimensional constraints on chassis layout; the basic chassis parameters include the mass and dimensions of each part of the chassis and the mass and dimensions of the superstructure load.

[0022] Based on chassis design requirements and basic parameters, S2 builds a chassis LPV control system model. Figure 2 This is a two-degree-of-freedom vehicle model diagram provided by the present invention, wherein, v The chassis speed, v x The longitudinal speed of the chassis, v y The lateral speed of the chassis. F yf and F yf These represent the lateral forces of the front and rear tires of the chassis, respectively.

[0023] S21 simplifies the chassis model into a two-degree-of-freedom vehicle model; S22 uses the sideslip angle and yaw rate of the center of gravity of the two-degree-of-freedom vehicle model as state variables and the front wheel steering angle as control input to obtain the state space model from the state variables and control input. The expression for the S22 state-space model is as follows: Wherein, the state vector The derivative of the state vector is , y z ( t ) is the output. t For time, input matrix Control matrix Output matrix C z =[0 1]; Among them, curb weight m It is the sum of the chassis mass and the mass of the superstructure load. δ For the front wheel steering angle, β The sideslip angle of the center of mass of the two-degree-of-freedom vehicle model. ω The yaw rate of the two-degree-of-freedom vehicle model. l f and l r These are the distances from the center of mass of the two-degree-of-freedom vehicle model to the front and rear axles, respectively. c f and cr These are the lateral stiffness of the front and rear wheels of the chassis, respectively. v x The longitudinal speed of the chassis. I z This is the total moment of inertia of the chassis.

[0024] Distance from the center of mass to the front axle of a two-DOF vehicle model l f The calculation formula is as follows: in, m i Indicates the chassis number i The mass of each component l i This represents the distance from the i-th component of the chassis to the front axle of the chassis. n This indicates the total number of chassis components, which include the frame, superstructure, control assembly, range extender, and battery. It also represents the distance from the center of gravity to the rear axle of the two-degree-of-freedom vehicle model. l r =L-l f ,in, L This refers to the chassis wheelbase; Figure 3 and Figure 4 These are, respectively, a top view and a bottom view of the automobile chassis layout provided by this invention.

[0025] S23 obtains the chassis LPV control system model based on the state-space model; The acquisition of the chassis LPV control system model in S23 includes: a. Simplify each load cell into a cube, and assume that each cube has a different size. Obtain the moment of inertia of each cube about its own geometric center. in, l i The length of the upper load cube. w i The width of the upper load cube. m i For the mass of the upper load cube, I i The moment of inertia of the load cube about its own geometric center. i Number the load cell; According to the parallel axis theorem, calculate the moment of inertia of each load cell to the geometric center of the chassis. in, The moment of inertia of the load mounted on the chassis at its geometric center.L dis The distance between the geometric center of the superstructure load and the geometric center of the chassis; Based on the moment of inertia of each superstructure load to the geometric center of the chassis Thus, the total moment of inertia is obtained; b. The lateral stiffness of the front and rear tires of the chassis is obtained by measuring the distance from the center of mass of the two-degree-of-freedom vehicle model to the front axle and the distance from the center of mass of the two-degree-of-freedom vehicle model to the rear axle. c. Based on the total moment of inertia, the lateral stiffness of the front and rear tires of the chassis, and the preset vehicle speed range, obtain the chassis LPV control system model.

[0026] The formula for calculating the total moment of inertia is as follows: in, I Z This represents the total moment of inertia of the chassis. I chassis It is the moment of inertia of the chassis frame. It is the moment of inertia of the superstructure working equipment to the geometric center of the chassis. It controls the moment of inertia of the control assembly to the geometric center of the chassis. It is the moment of inertia of the range extender to the geometric center of the chassis. It is the moment of inertia of the battery at the geometric center of the chassis. The formula for calculating the lateral stiffness of the front and rear tires of the chassis is as follows: c f = kG 1 c r = kG 2 in, G 1 and G 2 These represent the vertical loads on the front and rear axles, respectively. k It is a proportionality constant; in, L Indicates the chassis wheelbase. The vehicle's operating speed range is: in, v x The longitudinal speed of the chassis. This is the minimum longitudinal speed of the chassis. This is the maximum longitudinal speed of the chassis.

[0027] The expression for the chassis LPV control system model in S23 is as follows: The state vector of the chassis LPV control system model is: The derivative of the state vector of the chassis LPV control system model is , α l These are time-varying parameters obtained based on velocity, matrix pairs ( A l , B l ) represents the vertex of the chassis LPV control system model. l =1, 2, 3; In the state-space model A and B The matrix pairs formed ( A , B Transformed into: .

[0028] S3 calculates the eigenvalues ​​of all layout schemes under the LPV control system model based on the chassis LPV control system model. According to Lyapunov's first stability principle, layout schemes with positive eigenvalues ​​in the state matrix under the chassis LPV control system model are selected and removed, while layout schemes with negative eigenvalues ​​in the state matrix under the chassis LPV control system model are retained. S4, based on the chassis LPV control system model, calculates the upper bound of the output change caused by the input in all layout schemes, and selects the layout scheme with the smallest upper bound as the target layout scheme.

[0029] S4 specifically includes: Define Hamiltonian matrix H : in, H It is a Hamiltonian matrix. γ This is the upper bound of the output change caused by the input of the chassis LPV control system model. C This is the output matrix of the chassis LPV control system model, located in the upper right corner. T This is the matrix transpose. Solve for the eigenvalues ​​of the Hamiltonian matrix for each layout scheme. λ j ,if λ j Add to the imaginary axis γ Otherwise reduce γ Through iterative calculation, it becomes possible to achieve the desired result. γ It converges to a fixed constant. Calculate the fixed constants for all layout schemes, and select the layout scheme with the smallest fixed constants as the target layout scheme.

[0030] γ The expression is as follows: in, G(s) For transfer functions, This is the operator for the infinite norm.

[0031] Furthermore, the transfer function G(s) The calculation formula is as follows: in, Z ( s The yaw rate is the Laplace transform of the output signal of the chassis LPV control system model, that is, the Laplace transform of the difference between the actual chassis yaw rate and the ideal chassis yaw rate. U ( s ) is the Laplace transform of the input signal of the chassis LPV control system model, that is, the Laplace transform of the front wheel steering angle.

[0032] All of the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this application, and will not be described in detail here.

[0033] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for optimizing the design of a vehicle chassis for handling stability control, characterized in that, include: S1 obtains the chassis design requirements and basic parameters, and designs multiple layout schemes based on the basic parameters. The layout schemes include the installation positions of each superstructure load on the chassis. Based on chassis design requirements and basic parameters, S2 builds a chassis LPV control system model. S21 simplifies the chassis model into a two-degree-of-freedom vehicle model; S22 uses the sideslip angle and yaw rate of the center of gravity of the two-degree-of-freedom vehicle model as state variables and the front wheel steering angle as control input to obtain a state space model from the state variables and the control input. S23 obtains the chassis LPV control system model based on the state-space model; The expression for the chassis LPV control system model is as follows: The state vector of the chassis LPV control system model is: The derivative of the state vector of the chassis LPV control system model is , α l These are time-varying parameters obtained based on velocity, matrix pairs ( A l , B l ) represents the vertex of the chassis LPV control system model. l =1, 2, 3 β The sideslip angle of the center of mass of the two-degree-of-freedom vehicle model. ω The yaw rate of the two-degree-of-freedom vehicle model. δ The steering angle of the front wheels; S3 calculates the eigenvalues ​​of all layout schemes under the LPV control system model based on the chassis LPV control system model. According to the Lyapunov first stability principle, the layout schemes with positive eigenvalues ​​in the state matrix under the chassis LPV control system model are screened and removed, while the layout schemes with negative eigenvalues ​​in the state matrix under the chassis LPV control system model are retained. Based on the chassis LPV control system model, S4 calculates the upper bound of the output change caused by the input in all layout schemes, and selects the layout scheme with the smallest upper bound as the target layout scheme.

2. The automotive chassis optimization design method according to claim 1, characterized in that, The automotive chassis design requirements in S1 include the speed range of chassis operation and the dimensional constraints of chassis layout. The basic parameters of the chassis include the mass and dimensions of the chassis, as well as the mass and dimensions of the superstructure load.

3. The automotive chassis optimization design method according to claim 1, characterized in that, The expression for the state-space model in S22 is as follows: Wherein, the state vector The derivative of the state vector is , y z ( t ) is the output. t For time, input matrix Control matrix Output matrix C z =[0 1]; Among them, curb weight m It is the sum of the chassis mass and the mass of the superstructure load. l f and l r These are the distances from the center of mass of the two-degree-of-freedom vehicle model to the front and rear axles, respectively. c f and c r These are the lateral stiffness of the front and rear wheels of the chassis, respectively. v x The longitudinal speed of the chassis. I z This is the total moment of inertia of the chassis.

4. The automotive chassis optimization design method according to claim 3, characterized in that, The acquisition of the chassis LPV control system model in S23 includes: a. Simplify each load cell into a cube, and assume that each cube has a different size. Obtain the moment of inertia of each cube about its own geometric center. in, l i The length of the upper load cube. w i The width of the upper load cube. m i For the mass of the upper load cube, I i The moment of inertia of the load cube about its own geometric center. i Number the load cell; According to the parallel axis theorem, calculate the moment of inertia of each load cell to the geometric center of the chassis. in, The moment of inertia of the load mounted on the chassis at its geometric center. L dis The distance between the geometric center of the superstructure load and the geometric center of the chassis; Based on the moment of inertia of each superstructure load to the geometric center of the chassis Thus, the total moment of inertia is obtained; b. The lateral stiffness of the front and rear tires of the chassis is obtained by measuring the distance from the center of mass of the two-degree-of-freedom vehicle model to the front axle and the distance from the center of mass of the two-degree-of-freedom vehicle model to the rear axle. c. Based on the total moment of inertia, the lateral stiffness of the front and rear tires of the chassis, and the preset vehicle speed range, obtain the chassis LPV control system model.

5. The automotive chassis optimization design method according to claim 4, characterized in that, The superstructure load includes superstructure working equipment, control assembly, range extender, and battery. The formula for calculating the total moment of inertia is as follows: in, I Z This represents the total moment of inertia of the chassis. I chassis It is the moment of inertia of the chassis frame. It is the moment of inertia of the superstructure working equipment to the geometric center of the chassis. It controls the moment of inertia of the control assembly to the geometric center of the chassis. It is the moment of inertia of the range extender to the geometric center of the chassis. It is the moment of inertia of the battery at the geometric center of the chassis. The formula for calculating the lateral stiffness of the front and rear tires of the chassis is as follows: c f =kG 1 c r =kG 2 in, G 1 and G 2 represents the vertical loads on the front and rear axles, respectively. k It is a proportionality constant; in, L Indicates the chassis wheelbase. The vehicle's operating speed range is: in, v x The longitudinal speed of the chassis. This is the minimum longitudinal speed of the chassis. This is the maximum longitudinal speed of the chassis.

6. The automotive chassis optimization design method according to claim 5, characterized in that, In the state-space model A and B The matrix pairs formed ( A , B Transformed into: 。 7. The automobile chassis optimization design method according to claim 6, characterized in that, S4 specifically includes: Define Hamiltonian matrix H : in, H It is a Hamiltonian matrix. γ This is the upper bound of the output change caused by the input of the chassis LPV control system model. C This is the output matrix of the chassis LPV control system model, located in the upper right corner. T This is the matrix transpose. Solve for the eigenvalues ​​of the Hamiltonian matrix for each layout scheme. λ j ,if λ j Add to the imaginary axis γ Otherwise reduce γ Through iterative calculation, the... γ It converges to a fixed constant. Calculate the fixed constants for all layout schemes, and select the layout scheme with the smallest fixed constants as the target layout scheme.

8. The automotive chassis optimization design method according to claim 7, characterized in that, The γ The expression is as follows: in, G(s) For transfer functions, This is the operator for the infinite norm.

9. The automobile chassis optimization design method according to claim 8, characterized in that, The transfer function G(s) The calculation formula is as follows: in, Z ( s The yaw rate is the Laplace transform of the output signal of the chassis LPV control system model, that is, the Laplace transform of the difference between the actual chassis yaw rate and the ideal chassis yaw rate. U ( s ) is the Laplace transform of the input signal of the chassis LPV control system model, that is, the Laplace transform of the front wheel steering angle.

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