A method for precise modeling of a vehicle tire and applications thereof

Abstract

The application discloses a kind of vehicle tire accurate modeling method and its application, the steps of this method include: first, the simplified physical model of tire considering tire hysteresis characteristics is established, introduce the spring damping hysteresis system describing the force displacement characteristics of viscoelastic material, second, the composite force deformation relationship characteristic model of spring damping hysteresis system loading and unloading process is established in combination with RC operator, again, the interaction relationship between tire and ground under pure working condition is also divided into loading stage and unloading stage, and the uniform semi-empirical tire model (HysTire) based on hysteresis characteristics under SAE tire coordinate system is established.Longitudinal slip and cornering condition expression unification.The application can reveal the internal relationship of tire force between small slip rate and large slip rate or between small side angle and large side angle, so as to solve the shortcomings of existing tire model, such as complex form, numerous identification parameters and large amount of calculation.

Description

Technical Field

[0001] This invention relates to the field of vehicle dynamics and its control, and more particularly to tire dynamics, specifically a tire force characteristic modeling method based on elastic hysteresis theory and its application. Background Technology

[0002] The most widely used tire model internationally is the Magic Formula (MF). MF is a set of trigonometric function formulas used to fit the six component forces of a tire. The model formula is ingenious and has a good ability to express the tire's mechanical properties under various operating conditions. Although MF has a remarkably ingenious and versatile expressive function, its predictive ability for untested characteristics is poor, and practical results can only be obtained through a large amount of experimental data. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention proposes a precise tire modeling method and its application, aiming to establish the intrinsic relationship between tire forces and small slip ratios or small slip angles and large slip angles, thereby solving the problems of existing tire models being complex in form, having numerous identification parameters, and requiring a large amount of computation.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] The present invention provides a method for accurate modeling of vehicle tires, which includes the following steps:

[0006] Step 1: Establish a simplified physical model of the tire that considers the tire hysteresis characteristics, and introduce the force-displacement characteristics to describe the viscoelastic material, thereby establishing a spring-damped hysteresis system.

[0007] Step 1.1: Consider the tire as being composed of a concave support ring made of viscoelastic material and a flexible high-friction tread ring that ignores elasticity and damping, thereby establishing a simplified physical model of the tire;

[0008] Step 1.2: Under pure longitudinal slip conditions, let the angle of deflection of the tire contact point relative to the wheel hub be the longitudinal deformation generated by the concave support ring; let the combined force of the longitudinal elastic force, damping force and hysteresis force of all concave support rings be the longitudinal force of the tire.

[0009] Under pure lateral slip conditions, the lateral deformation caused by the friction between the tire tread and the ground squeezing the concave support ring is the tire slip angle; the combined force of the lateral elastic force, damping force and hysteresis force of all concave support rings is the tire lateral force; thus establishing a spring-damped hysteresis system.

[0010] Step 2: Using the RC operator, establish a composite force-deformation relationship characteristic model of the loading and unloading process of the spring-damped hysteresis system;

[0011] Step 3: Divide the interaction between the tire and the ground under pure working conditions into loading and unloading stages;

[0012] Step 3.1: Define the angle of tire crown deflection relative to the rim as the tire deformation angle. Based on the composite force deformation relationship characteristic model of the loading and unloading process, the braking process is divided into the first loading stage, the second loading stage, and the unloading stage.

[0013] In the first stage of loading: the tire crown is relatively stationary with respect to the ground, and the static friction between the tire crown and the ground reaches μF. N The longitudinal deformation angle of the tire is Where μ is the road surface friction coefficient, F N This refers to the vertical load on the tire;

[0014] In the second stage of loading: the tire's longitudinal deformation angle reaches its maximum deformation angle. The tires reach maximum static friction with the ground.

[0015] During the unloading phase: friction transitions from static friction to sliding friction, until the tire locks up and friction becomes pure sliding friction, at which point the tire force stabilizes at μF. N The longitudinal deformation angle of the tire starts from the maximum deformation angle. Falling back to

[0016] Step 3.2: The change in slip ratio from 0 to 1 represents the change in tire speed from free rotation to complete lock-up, and corresponds to the longitudinal deformation angle of the simplified physical model of the tire compressing from 0 to... And eventually bounced back The process also divides the tire force-slip ratio relationship curve into the first loading stage, the second loading stage, and the unloading stage.

[0017] During the first stage of loading, there was no significant relative slippage between the tire crown and the ground; the slip ratio increased from 0 to s. b ;

[0018] During the second phase of loading, the slip ratio changes from s b Achieving the optimal slip ratio s m Tire force reaches maximum value There was no obvious relative slippage between the tire crown and the ground;

[0019] During the unloading phase, the slip ratio exceeds s m The tire force begins to decrease until the slip ratio reaches 1, at which point the tire tread completely slides against the ground, and the tire force drops from its maximum value. Gradually falling back to μF N ;

[0020] Step 3.3: Based on the process of the slip angle changing from 0 to 90°, which corresponds to the spring lateral compression and eventual partial rebound in the simplified physical model of the tire, the relationship curve between lateral force and slip angle is still divided into the first loading stage, the second loading stage, and the unloading stage.

[0021] During the first stage of loading, there was no significant relative slippage between the tire crown and the ground; the side slip angle reached α from 0. b ;

[0022] During the second loading phase, the sideslip angle changes from α. b Reaching α m Lateral force reaches adhesion limit There was no significant slippage between the tire crown and the ground;

[0023] During the unloading phase; when the sideslip angle exceeds α m Until the angle reaches 90°, the tire force drops from its maximum value. The sliding friction μF gradually decreases back to the level of complete sideslip. N ;

[0024] Step 4: Using equations (1)-(5), establish a semi-empirical tire model in the SAE tire coordinate system for longitudinal slip and lateral slip conditions based on hysteresis characteristics:

[0025]

[0026] M z =F(α)·d (2)

[0027]

[0028]

[0029]

[0030] In equations (1)-(5), F(x) is the longitudinal or lateral force of the tire in the SAE coordinate system, and the corresponding independent variable x is the slip ratio s or the tire's slip angle α; M Z d represents the tire's self-centering torque; d represents the tire's trail; x represents the tire's freewheeling distance. b x m and x o These represent the slip ratios s corresponding to the loading start point, maximum value point, and unloading end point, respectively. o =1 or sideslip angle α o =90°, where the tire force corresponding to the loading start point and the unloading end point is the same; f is called the scaling factor; p, q, β, and r are the corresponding parameters of the tire force; p d q d β d r d These are the parameters corresponding to tire trail.

[0031] The present invention provides an electronic device, including a memory and a processor, characterized in that the memory is used to store a program supporting the processor in executing the method, and the processor is configured to execute the program stored in the memory.

[0032] The present invention provides a computer-readable storage medium on which a computer program is stored, characterized in that the computer program is executed by a processor to perform the steps of the method.

[0033] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0034] 1. This invention proposes a simplified physical model of a tire that considers tire compression hysteresis. The tire is considered to be composed of a certain number of viscoelastic concave support rings that surround the rim and flexible high-friction tread rings that ignore elasticity and damping. When the tread rings are subjected to ground forces, they compress the concave elastic support rings to generate tire forces. This model emphasizes the important role of tire deformation in the tire force generation process, avoids the complex process of tread-road friction, and simplifies the calculation of tire forces.

[0035] 2. This invention deeply analyzes the mechanical characteristics of the spring-damped hysteresis system and, in conjunction with the RC operator, establishes force-deformation relationship characteristic models for the loading and unloading processes of the spring-damped hysteresis system. It also introduces the RC operator hysteresis model, laying the foundation for subsequent descriptions of tire force-displacement characteristics during tire deformation.

[0036] 3. This invention also divides the interaction between the tire and the ground under pure working conditions into loading and unloading stages, and analyzes the changes in the mechanical properties of the tire during loading and unloading. Through the study of the mechanical properties of the tire under loading and unloading conditions under pure working conditions, the intrinsic relationship between tire force characteristics under small slip ratios or sideslip angles and tire force characteristics under large slip ratios or sideslip angles is revealed. This provides a completely new theoretical explanation for the tire mechanical properties under pure working conditions and establishes a novel tire model, HysTire, resulting in a tire model with advantages such as simple form, few identifications, and low computational cost. Attached Figure Description

[0037] Figure 1a This is a schematic diagram of a concave ring tire model;

[0038] Figure 1b This is a schematic diagram of tire deformation under longitudinal force for a concave ring tire model.

[0039] Figure 1c This is a schematic diagram of tire deformation under lateral force for a concave ring tire model;

[0040] Figure 2 For tire longitudinal slip condition Fx - Relationship curve diagram;

[0041] Figure 3 For tire longitudinal slip condition F x -s relationship curve;

[0042] Figure 4 For tire lateral deviation F y -α relationship curve;

[0043] Figure 5 A flowchart for identifying longitudinal slip characteristics in a HysTire tire model;

[0044] Figure 6 This is a flowchart for identifying the lateral slip characteristics in the HysTire tire model. Detailed Implementation

[0045] In this embodiment, a method for accurate modeling of vehicle tires is a tire force characteristic modeling method that requires less experimental data and has a simpler process. Specifically, it includes the following steps:

[0046] Step 1: Establish a simplified physical model of the tire that considers the tire hysteresis characteristics, and introduce the force-displacement characteristics to describe the viscoelastic material, thereby establishing a spring-damped hysteresis system.

[0047] Step 1.1, see Figure 1a As shown, the tire is considered to be composed of a certain number of concave support rings made of viscoelastic material that surround the rim and flexible high-friction tread rings that ignore elasticity and damping. When the tread rings are subjected to ground forces, they compress the concave support rings to generate tire forces, thus establishing a simplified physical model of the tire.

[0048] Step 1.2 Figure 1b This is a schematic diagram of tire deformation under pure longitudinal slip conditions for the established tire model. Under pure longitudinal slip conditions, the friction between the tire tread and the ground compresses the concave support ring, causing longitudinal deformation. The magnitude of the deformation is the angle of deflection of the tire ground contact point relative to the wheel hub. Let the angle of deflection of the tire ground contact point relative to the wheel hub be the longitudinal deformation generated by the concave support ring. Let the combined force of the longitudinal elastic force, damping force, and hysteresis force of all concave support rings be the longitudinal force of the tire.

[0049] Figure 1c This is a schematic diagram of tire deformation under pure sideslip conditions. Under pure sideslip conditions, the lateral deformation caused by the friction between the tire tread and the ground compressing the concave support ring is the tire sideslip angle; according to Figure 1cWhen the tire is stationary, the amount of deformation is the distance between the center of the tire's contact patch and the wheel plane. When the tire is rolling, the amount of deformation is the size of the angle between the center of the contact patch and the wheel plane, which is also the size of the slip angle. Let the combined force of the lateral elastic force, damping force and hysteresis force of all concave support rings be the tire's lateral force. The concave ring tire model simplifies the tire in all directions into a spring-damped hysteresis system, qualitatively explaining the generation and action mechanism of tire forces and torques.

[0050] Step 2: Combine the RC operator to establish a composite force-deformation relationship characteristic model of the loading and unloading process of the spring-damped hysteresis system;

[0051] Step 3: Divide the interaction between the tire and the ground under pure working conditions into loading and unloading stages;

[0052] Step 3.1: Define the angle of tire crown deflection relative to the rim as the tire deformation angle. Based on the composite force-deformation relationship characteristic model during loading and unloading, see... Figure 2 The figure shows F under the condition of tire longitudinal slip. x - The relationship curve divides the braking process into three stages: the first loading stage, the second loading stage, and the unloading stage.

[0053] In the first stage of loading: as the braking force applied to the tire by the ground increases, the tire deformation angle gradually increases, the tire crown and the ground become relatively stationary, and the static friction force between the tire crown and the ground reaches μF. N The longitudinal deformation angle of the tire is Where μ is the road surface friction coefficient, F N This refers to the vertical load on the tire;

[0054] In the second stage of loading: due to the adhesive contact between the tire crown surface and the road surface, the tire force continues to increase, and the tire deformation angle further increases until the tire longitudinal deformation angle reaches its maximum. The tires reach maximum static friction with the ground.

[0055] During the unloading phase: As the sliding component between the tire crown and the ground increases, friction transitions from static friction to sliding friction. The frictional force provided by the ground is insufficient to maintain tire deformation until the tire locks up, at which point friction transforms into pure sliding friction, and the tire force stabilizes at μF. N The longitudinal deformation angle of the tire starts from the maximum deformation angle. Falling back to The second loading and unloading stages are the loading and unloading curves of the viscoelastic spring-damped hysteresis system under the same deformation range, and the region enclosed by them represents energy loss.

[0056] Step 3.2: In practical tire applications, the deformation angle is difficult to measure, but there is a one-to-one correspondence between the slip ratio, which characterizes the wheel's slip component, and the tire deformation angle. (See also...) Figure 3 The figure shows F under the condition of tire longitudinal slip. x -s relationship curve. The change in slip ratio from 0 to 1 represents the tire's transition from free rotation to complete lock-up, corresponding to the longitudinal deformation angle of the simplified tire physical model from 0 to... And eventually bounced back The process is divided into three stages: the first loading stage, the second loading stage, and the unloading stage. The slip ratio is calculated using the difference between vehicle speed and wheel speed, which is the speed difference between the rim and the tire crown.

[0057] During the first stage of loading, i.e. at a low slip ratio, the speed difference comes from the longitudinal compression of the tire carcass, and there is no significant relative slippage between the tire crown and the ground. The slip ratio increases from 0 to s. b ;

[0058] During the second phase of loading, the slip ratio changes from s b Achieving the optimal slip ratio s m Tire force reaches maximum value There was no obvious relative slippage between the tire crown and the ground;

[0059] During the unloading phase, the slip ratio exceeds the optimal slip ratio s. m As the slip ratio between the tire crown and the ground gradually increases, the tire force begins to decrease until the slip ratio reaches 1, at which point the tire crown completely slips between itself and the ground, and the tire force drops from its maximum value. Gradually falling back to μF N ;correspond Figure 2 China F x - The tire force change process during the unloading phase of the curve. Based on the above analysis, we can conclude... Figure 3 The mn and mo segments are unloading path curves under the same longitudinal deformation angle but different abscissas within the same time period.

[0060] Step 3.3: The lateral force change process also reaches its maximum value at a specific slip angle and then begins to decrease. The same method is used to analyze the tire slip condition. For example... Figure 4 The tire side deviation F shown y -α relationship curve. Based on the process of the slip angle changing from 0 to 90° corresponding to the lateral compression of the spring in the simplified physical model of the tire, and the eventual partial rebound, the relationship curve between lateral force and slip angle is still divided into three processes: the first loading stage, the second loading stage, and the unloading stage.

[0061] During the first stage of loading, there was no significant relative slippage between the tire crown and the ground; the side slip angle reached α from 0.b ;

[0062] During the second loading phase, the sideslip angle changes from α. b Reaching α m Lateral force reaches adhesion limit There was no significant slippage between the tire crown and the ground;

[0063] During the unloading phase; when the sideslip angle exceeds α m Until the angle reaches 90°, the tire force drops from its maximum value. The sliding friction μF gradually decreases back to the level of complete sideslip. N ;

[0064] Step 4: Using equations (1)-(5), establish a semi-empirical tire model in the SAE tire coordinate system that unifies the expression of longitudinal slip and lateral slip conditions based on hysteresis characteristics:

[0065]

[0066] M z =F(α)·d (2)

[0067]

[0068]

[0069]

[0070] In equations (1)-(5), F(x) is the longitudinal or lateral force of the tire in the SAE coordinate system, and the corresponding independent variable x is the slip ratio s or the tire's slip angle α; M Z d represents the tire's self-centering torque; d represents the tire's trail; x represents the tire's freewheeling distance. b x m and x o These represent the slip ratios s corresponding to the loading start point, maximum value point, and unloading end point, respectively. o =1 or sideslip angle α o =90°, where the tire force corresponding to the loading start point and the unloading end point is the same; f is called the scaling factor; p, q, β, and r are the corresponding parameters of the tire force; p d q d β d r d These are the parameters corresponding to tire trail.

[0071] like Figure 5 The diagram shows the identification process of the HysTire tire model under pure longitudinal slip conditions. At that time, the longitudinal force increases with the increase of the slip ratio, until... When the longitudinal force reaches its maximum value, the slip ratio is denoted as s. mThis is called the maximum point. At this point, within 0-s... m In this stage, a genetic algorithm is used to fit and identify the longitudinal slip condition of the HysTire tire model, obtaining the fitting parameters p, q, β, and r, thus yielding the 0-s... m The longitudinal force model of the stage. When When, the range of variable slip rate is from s m To the maximum slip ratio s o =1,s o This is called the unloading endpoint, and the corresponding tire force is... In 0-s m There is a point s in the stage b , making s b As the starting point for loading, s b Point through 0-s m The longitudinal force model of the stage is obtained by inverse solution. The fitted parameters p, q, β, r, and s are then used. b s m s o , μF N Substituting the values ​​into the HysTire tire model, we can obtain s. m -1 stage longitudinal force model, thus obtaining the tire longitudinal force characteristic model.

[0072] Figure 6 The identification process of the HysTire tire model under pure sideslip conditions is given. At that time, the lateral force increases with the increase of the lateral angle, until... When the lateral force reaches its maximum value, the lateral angle is denoted as α. m This is called the maximum point. At this point, 0-α... m In this stage, a genetic algorithm is used to fit and identify the HysTire tire model under the side-slip condition, obtaining the fitting parameters p, q, β, and r, from which 0-α can be obtained. m The phased lateral force model. When At that time, the range of sideslip angle variation is from α m Up to the maximum sideslip angle α tested o =90°, α o This is called the unloading endpoint, and the corresponding lateral force is... In 0-α m There is a point α in the stage. b , making α b As the starting point for loading, α b Through 0-α m The inverse solution of the lateral force model for this stage is obtained. The fitted parameters p, q, β, r, and α are then used. b α m αo , Substituting into the HysTire tire model, we can obtain α. m -α o The lateral force model for the stage. Given the tire lateral force model, the self-aligning torque model can be obtained by identifying the tire trailing distance d. A genetic algorithm is used to calculate the self-aligning torque M of the HysTire tire model. z Perform fitting to obtain the fitting parameters p d q d β d r d This allows us to obtain a model of the tire's lateral slip characteristics.

Claims

1. A method for accurate modeling of vehicle tires, characterized by including: The following steps are required: Step 1: Establish a simplified physical model of the tire that considers the tire hysteresis characteristics, and introduce the force-displacement characteristics to describe the viscoelastic material, thereby establishing a spring-damped hysteresis system. Step 1.1: Consider the tire as being composed of a concave support ring made of viscoelastic material and a flexible high-friction tread ring that ignores elasticity and damping, thereby establishing a simplified physical model of the tire; Step 1.2: Under pure longitudinal slip conditions, let the angle of deflection of the tire contact point relative to the wheel hub be the longitudinal deformation generated by the concave support ring; let the combined force of the longitudinal elastic force, damping force and hysteresis force of all concave support rings be the longitudinal force of the tire. Under pure lateral slip conditions, the lateral deformation caused by the friction between the tire tread and the ground squeezing the concave support ring is the tire slip angle; the combined force of the lateral elastic force, damping force and hysteresis force of all concave support rings is the tire lateral force; thus establishing a spring-damped hysteresis system. Step 2: Using the RC operator, establish a composite force-deformation relationship characteristic model of the loading and unloading process of the spring-damped hysteresis system; Step 3: Divide the interaction between the tire and the ground under pure working conditions into loading and unloading stages; Step 3.1: Define the angle of tire crown deflection relative to the rim as the tire deformation angle. Based on the composite force deformation relationship characteristic model of the loading and unloading process, the braking process is divided into the first loading stage, the second loading stage, and the unloading stage. In the first stage of loading: the tire crown is relatively stationary with respect to the ground, and the static friction between the tire crown and the ground reaches... The longitudinal deformation angle of the tire is ,in, The coefficient of friction of the road surface. This refers to the vertical load on the tire; In the second stage of loading: the tire's longitudinal deformation angle reaches its maximum deformation angle. The tires reach maximum static friction with the ground; During the unloading phase: friction transitions from static friction to sliding friction, until the tire locks up and friction changes to pure sliding friction, at which point the tire force stabilizes. The longitudinal deformation angle of the tire starts from the maximum deformation angle. Falling back to ; Step 3.2: The change in slip ratio from 0 to 1 represents the change in tire speed from free rotation to complete lock-up, and corresponds to the longitudinal deformation angle of the simplified physical model of the tire compressing from 0 to... And eventually bounced back The process also divides the tire force-slip ratio relationship curve into the first loading stage, the second loading stage, and the unloading stage. During the first stage of loading, there was no significant relative slippage between the tire crown and the ground; the slip ratio reached from 0. ; During the second phase of loading, the slip ratio from Achieving optimal slip ratio Tire force reaches maximum value There was no obvious relative slippage between the tire crown and the ground; During the unloading phase, the slip ratio exceeds The tire force begins to decrease until the slip ratio reaches 1, at which point the tire tread completely slides against the ground, and the tire force drops from its maximum value. Gradually falling back to ; Step 3.3: Based on the process of the slip angle changing from 0 to 90°, which corresponds to the spring lateral compression and eventual partial rebound in the simplified physical model of the tire, the relationship curve between lateral force and slip angle is still divided into the first loading stage, the second loading stage, and the unloading stage. During the first stage of loading, there was no significant relative slippage between the tire crown and the ground; the side slip angle reached from 0. ; During the second loading phase, the sideslip angle from... achieve Lateral force reaches adhesion limit The tire crown remained in contact with the ground without significant slippage. During the unloading phase; when the sideslip angle exceeds Until the angle reaches 90°, the tire force drops from its maximum value. The sliding friction gradually decreases to the level of a full sideslip. ; Step 4: Using equations (1)-(5), establish a semi-empirical tire model in the SAE tire coordinate system for longitudinal slip and lateral slip conditions based on hysteresis characteristics: (1) (2) (3) (4) (5) In equations (1)-(5), The longitudinal or lateral force of the tire in the SAE coordinate system, and the corresponding independent variable. The slip ratio s or the tire slip angle ; This indicates the tire's self-aligning torque; Indicates tire trail; and These represent the slip ratios corresponding to the loading start point, maximum value point, and unloading end point, respectively. =1 or side deflection angle The tire forces at the loading start point and the unloading end point are the same. This is called the scaling factor; The parameters corresponding to the tire forces are obtained by fitting and identifying the longitudinal slip condition of the HysTire tire model using a genetic algorithm. The parameters corresponding to the tire trail distance are determined, and a genetic algorithm is used to determine the aligning torque of the HysTire tire model. It is obtained by fitting.

2. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program that supports a processor in executing the method of claim 1, the processor being configured to execute the program stored in the memory.

3. A computer-readable storage medium storing a computer program, characterized in that, The computer program is executed by the processor to perform the steps of the method of claim 1.

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