Vehicle, method and device for acquiring adhesion coefficient of wheels and vehicle

Abstract

The invention relates to a vehicle, a method and a device for acquiring adhesion coefficients of wheels, and the vehicle. The method includes: acquiring fusion speed of a vehicle; based on the motion state parameters of the wheels, the motion state parameters of the vehicle, the geometrical characteristic parameters of the vehicle and the fusion vehicle speed, the slip angle and the tire slip rate of each wheel are obtained; based on the motion state parameters of the wheels, the geometrical characteristic parameters of the vehicle and the motion state parameters of the vehicle, the vehicle speed, the slip angle and the tire slip rate are fused, and the plane component force of the vehicle and the plane component force of each wheel are obtained; based on the plane component force of each wheel, the plane component force of the vehicle, the geometrical characteristic parameters of the vehicle and the motion state parameters of the vehicle, the tire attachment coefficient of each wheel and the attachment coefficient of the vehicle are obtained. According to the method, on-line accurate updating of the attachment coefficients of the vehicle and the four tires can be achieved only through the motion geometrical relationship and the tire dynamics law.

Description

Technical Field

[0001] This invention relates to the field of vehicle dynamics and control technology, specifically to a method, device, and vehicle for obtaining the adhesion coefficient of a vehicle and its wheels. Background Technology

[0002] Vehicles interact with the ground through their tires, and the adhesion between the tires and the ground directly determines whether the vehicle can accelerate, brake, and steer according to the driver's intentions. The coefficient of friction reflects the force on the tire at any given moment, and combined with the position of the coefficient of friction within the friction circle, it indicates the remaining maneuverability of the vehicle. In actual driving, due to wheel steering, vehicle yaw, load transfer, and other factors, the available longitudinal and lateral adhesion of each wheel varies; at certain times, the entire vehicle may maintain a stable motion, but a particular wheel may be in a critical state. Therefore, the overall adhesion of the vehicle cannot fully characterize its motion; it is necessary to observe and update the adhesion of all four wheels.

[0003] In existing technologies, the observation and updating of tire adhesion depends on the analysis of tire stress conditions. The calculation of longitudinal forces and longitudinal adhesion coefficients for each wheel is typically based on longitudinal dynamics, relying on the accurate acquisition of the driving torque and braking torque on the wheel. The longitudinal adhesion force is then solved using the single-wheel rolling dynamics equations to obtain the longitudinal adhesion coefficient. The calculation of lateral forces and lateral adhesion coefficients is usually based on various tire nonlinear models, substituted with the measured or estimated tire slip angle into the known tire model to solve for the lateral forces and lateral adhesion coefficients. However, in traditional longitudinal force calculations, the accurate acquisition of braking torque is difficult. As the performance of the braking system degrades, the accuracy of the braking torque is hard to guarantee, thus affecting the accuracy of the longitudinal force and longitudinal adhesion coefficient calculations. In lateral force calculation, traditional methods typically use wheel speed gauges and acceleration sensors to fuse the vehicle speed, making it difficult to accurately measure the longitudinal and lateral velocities at the wheel center of a four-wheel drive vehicle. Consequently, the accuracy of the tire slip angle is hard to guarantee. At the same time, due to tire wear, there will be a significant deviation between the initial tire model and the actual tire model, further affecting the calculation of lateral force and lateral adhesion coefficient.

[0004] Therefore, traditional methods are difficult to effectively calculate the longitudinal and lateral forces of the four tires, making it difficult to use them for accurate online updates of the vehicle and the coefficient of friction of the four wheels. Summary of the Invention

[0005] In view of the above problems, embodiments of the present invention provide a method, device and vehicle for obtaining the adhesion coefficient of a vehicle and its wheels, which solves the problem that the longitudinal force and lateral force of the wheel calculated by the tire model introduced in the prior art have large deviations and are difficult to use for online accurate updating of the adhesion coefficient and friction circle of four wheels.

[0006] According to one aspect of the present invention, a method for obtaining the adhesion coefficient of a vehicle and its wheels is provided. The method includes: obtaining the vehicle's fused speed; obtaining the sideslip angle and tire slip ratio of each wheel based on the wheel's motion state parameters, the vehicle's motion state parameters, the vehicle's geometric feature parameters, and the fused speed; obtaining the vehicle's planar force component and the planar force component of each wheel based on the wheel's motion state parameters, the vehicle's geometric feature parameters, the vehicle's motion state parameters, the fused speed, the sideslip angle, and the tire slip ratio; and obtaining the tire adhesion coefficient of each wheel and the vehicle's adhesion coefficient based on the planar force component of each wheel, the vehicle's planar force component, the vehicle's geometric feature parameters, and the vehicle's motion state parameters.

[0007] According to another aspect of the present invention, a device for obtaining the coefficient of adhesion of a vehicle and its wheels is provided. The device includes: an acquisition module for acquiring the vehicle's fused speed; a first obtaining module for obtaining the sideslip angle and tire slip ratio of each wheel based on the motion state parameters of the wheels, the motion state parameters of the vehicle, the geometric feature parameters of the vehicle, and the fused speed; a second obtaining module for obtaining the planar force component of the vehicle and the planar force component of each wheel based on the motion state parameters of the wheels, the geometric feature parameters of the vehicle, the motion state parameters of the vehicle, the fused speed, the sideslip angle, and the tire slip ratio; and a third obtaining module for obtaining the tire adhesion coefficient of each wheel and the vehicle's adhesion coefficient based on the planar force component of each wheel, the planar force component of the vehicle, and the geometric feature parameters of the vehicle.

[0008] According to another aspect of the present invention, a computer device is provided, including: a processor, a memory, a communication interface, and a communication bus, wherein the processor, the memory, and the communication interface communicate with each other through the communication bus; The memory is used to store at least one executable instruction that causes the processor to perform the operation of the method for obtaining the adhesion coefficient of the vehicle and wheels in the first aspect.

[0009] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein at least one executable instruction is stored in the storage medium, the executable instruction causing a computer device / apparatus to perform the operation of the method for obtaining the adhesion coefficient of a vehicle and wheels of the first aspect.

[0010] According to another aspect of the present invention, a vehicle is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for obtaining the adhesion coefficient of the vehicle and wheels according to the first aspect. The technical solution provided by the present invention has the following advantages: This invention, through acquiring the vehicle's basic parameters, geometric parameters, vehicle speed information, three-axis attitude angles, inertial motion parameters, planar acceleration, yaw rate, and the wheel speed and steering angle of each wheel, accurately calculates the wheel slip ratio and sideslip angle. Simultaneously, without introducing a tire model, it calculates the planar components of the vehicle and wheels using only kinematic geometry and tire dynamics. Then, based on the planar components of the wheels and the vehicle, it determines the tire adhesion coefficient of each wheel and the vehicle's adhesion coefficient, further obtaining the friction circle radius of the vehicle and the tire friction circle radius of each wheel. This invention avoids the errors caused by calculating the longitudinal forces of the four wheels through driving / braking torque and the lateral forces of the four wheels through a tire model. The entire calculation process does not rely on a tire model; it only utilizes kinematic geometry and tire dynamics to achieve accurate online updates of the vehicle and the adhesion coefficients of the four tires. This solves the problem in related technologies where the longitudinal and lateral forces calculated using a tire model have significant deviations, making it difficult to use for accurate online updates of the vehicle and the four-wheel adhesion coefficients.

[0011] The above description is merely an overview of the technical solutions of the embodiments of the present invention. In order to better understand the technical means of the embodiments of the present invention and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0012] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 The diagram shows a flowchart of a first embodiment of a method for obtaining the adhesion coefficient of a vehicle and its wheels provided by the present invention. Figure 2 A schematic diagram of a second embodiment of the main geometric parameters of a vehicle and the position numbers of the four wheels provided by the present invention is shown. Figure 3 A schematic diagram of the third embodiment of the kinematic geometry relationship between the wheel center velocity and the overall vehicle velocity provided by the present invention is shown; Figure 4 A schematic diagram of the fourth embodiment of the four-wheel adhesion point and tire friction circle provided by the present invention is shown; Figure 5 A schematic diagram of the structure of a vehicle and wheel adhesion coefficient acquisition device provided by the present invention is shown; Figure 6 A schematic diagram of an embodiment of a computer device provided by the present invention is shown. Detailed Implementation

[0013] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0014] Figure 1 This diagram illustrates a first embodiment of a method for obtaining the adhesion coefficient of a vehicle and its wheels according to the present invention. The method is executed by the vehicle. Figure 1 As shown, the method includes the following steps: Step S101: Obtain the vehicle's fused speed.

[0015] Specifically, in this embodiment of the invention, some vehicle-related information and wheel-related information are obtained through GNSS (Global Navigation Satellite System)-INS (Inertial Navigation System). Furthermore, the current vehicle's geometric parameters can be obtained through factory settings, including basic parameters such as vehicle weight. M Gravitational acceleration g Effective radius of tire R i Air density ρ, vehicle drag coefficient C x With C y The vehicle's geometric characteristics also include: vehicle geometric parameters, such as half track width. T i Front axle distance to center of gravity L f Rear axle distance from center of gravity L r Center of mass height H g. Frontal area of ​​the entire vehicle S x and S y The main geometric parameters and the position numbers of the four wheels are as follows: Figure 2 As shown.

[0016] Where i = 1, 2, 3, 4, representing the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. The meaning of i in subsequent embodiments is consistent with the definition here.

[0017] GNSS satellite navigation data, such as vehicle speed information, is obtained by parsing on the bus. V 1 、V 2 、V 3. The vehicle speed is defined in the ENU (Northeast-Sky) or NED (Northeast-Earth) coordinate system; the motion parameters of the wheels, such as wheel speed, are obtained by parsing on the bus. wi (i=1, 2, 3, 4, representing the left front wheel, right front wheel, left rear wheel, and right rear wheel respectively) and the steering angle α of each wheel. i ; The vehicle's motion state parameters provided by the INS are obtained by parsing on the bus, including: the vehicle's three-axis attitude angles (the vehicle coordinate system is defined according to the ISO8855 standard), inertial motion parameters (including the vehicle's acceleration and angular velocity provided by the INS), and the vehicle's planar acceleration (including longitudinal acceleration). a x lateral acceleration a y ), vehicle yaw rate w r .

[0018] When acquiring the vehicle's fused speed, satellite navigation data, such as vehicle speed information, is provided by GNSS. V 1 、 V 2 、V 3， It is converted to the original vehicle speed in the vehicle coordinate system through coordinate rotation transformation. Vgx , Vgy , Vgz Then, a loosely coupled Kalman filter model is constructed, using the original vehicle speed in the vehicle coordinate system as the observation value and the inertial motion parameters as the state prediction basis. The filtering algorithm corrects the low update frequency of GNSS and the accumulated error of INS, and finally outputs a high-precision, high-update-frequency vehicle fusion speed (fusion longitudinal speed). Vx , Integration of lateral speed Vy ).

[0019] Furthermore, the vehicle speed signal provided by GNSS V 1 、V 2 、V 3. Coordinate system transformation is performed using three-axis attitude angles (roll angle, pitch angle, and yaw angle). Coordinate system differences are eliminated using coordinate rotation transformation formulas to obtain the vehicle's longitudinal speed in the vehicle coordinate system. Vgx Lateral speed Vgy Vertical speed Vgz .

[0020] Longitudinal vehicle speed provided by GNSS Vgx Lateral speed Vgy Vertical speed VgzGNSS vehicle speed is typically updated at a frequency of 10Hz. Acceleration and angular velocity data provided by the INS are typically updated at frequencies ranging from 100Hz to 1000Hz. A loosely coupled Kalman filter is used to fuse the GNSS vehicle speed with the acceleration and angular velocity data provided by the INS. For example, the Kalman filter algorithm dynamically corrects the shortcomings of the low update frequency (10Hz) of GNSS and the accumulated error of the INS, outputting a fused longitudinal vehicle speed with an update frequency of 20Hz to 200Hz and an accuracy exceeding 0.1km / h. Vx , Integration of lateral speed Vy This meets the requirement of high-precision, high-frequency vehicle speed data for four-wheel adhesion coefficient calculation. High-precision fused vehicle speed is obtained at an update frequency of 20Hz~200Hz: fused longitudinal vehicle speed. Vx , Integration of lateral speed Vy .

[0021] It should be noted that the core of vehicle dynamics control is longitudinal (acceleration / braking) and lateral (steering) stability control. In actual driving, driver operation and vehicle safety status are mainly determined by planar motion, and vertical vehicle speed has no key role in core decision-making and does not need to be included in the fusion objective.

[0022] Step S102: Based on the motion state parameters of the wheels, the motion state parameters of the vehicle, the geometric feature parameters of the vehicle, and the fused vehicle speed, the sideslip angle and tire slip ratio of each wheel are obtained.

[0023] Based on the obtained wheel motion parameters, such as wheel speed and steering angle, combined with vehicle geometric parameters, such as vehicle geometry parameters and vehicle motion parameters, such as yaw rate and fused vehicle speed provided by INS, the longitudinal velocity at the wheel center of each wheel is calculated through motion geometry relationships. Vx i With lateral velocity Vy i ; Then, according to the side slip angle formula β i =atan( Vy i ÷ Vx i Slip ratio formula l i = ( VW i -Vx i )÷max( VW i , Vx i )( VW i The equivalent wheel speed is determined by the wheel rotation speed and the effective tire radius. R i(Calculated), the slip angle and tire slip ratio of each wheel are obtained respectively.

[0024] The above step S102 includes: Step S1021: Obtain the equivalent wheel speed of each wheel based on the motion state parameters of the wheels.

[0025] Specifically, the motion state parameters of the wheels, such as wheel speed, are obtained by parsing on the bus. w i (i=1, 2, 3, 4, representing the left front wheel, right front wheel, left rear wheel, and right rear wheel respectively), the equivalent wheel speed of each wheel is calculated: VW i = w i × R i (i=1, 2, 3, 4, representing the front left wheel, front right wheel, rear left wheel, and rear right wheel, respectively).

[0026] Step S1022: Based on the motion state parameters of the wheels, the geometric feature parameters of the vehicle, the motion state parameters of the vehicle, and the fused vehicle speed, the speed at the center of each wheel is obtained.

[0027] Specifically, the motion state parameters of the wheels, such as the steering angle of each wheel, are obtained by parsing on the bus. α i And vehicle motion parameters, such as the vehicle yaw rate provided by INS. w r Use the half-track from the vehicle's geometric parameters. T i Front axle distance to center of gravity L f Rear axle distance from center of gravity L r In step S101, the vehicle's fused longitudinal speed is obtained. Vx、 Integrating lateral speed Vy The velocities at the center of each wheel are calculated using kinematic geometry: Vx 1 = ( Vx-T 1× w r )×cos α 1 + ( Vy + L f × w r )×sin α 1 Vy 1 = - ( Vx-T 1× w r )×sinα 1+( Vy + L f × w r )×cos α 1 Vx 2=( Vx + T 2× w r )×cos α 2+( Vy + L f × w r )×sin α 2 Vy 2=-( Vx + T 2× w r )×sin α 2+( Vy + L f × w r )×cos α 2 Vx 3=( Vx-T 3× w r )×cos α 3+( Vy - L r × w r )×sin α 3 Vy 3=-( Vx-T 3× w r )×sin α 3+( Vy - L r × w r )×cos α 3 Vx 4=( Vx + T 4× w r )×cos α 4+( Vy + L r × wr )×sin α 4 Vy 4 = - ( Vx + T 4× w r )×sin α 4+( Vy + L r × w r )×cos α 4 Step S1023: Obtain the slip angle of each wheel based on the speed at the wheel center.

[0028] Specifically, calculate the slip angle of each wheel: β i =atan( Vy i ÷ Vx i ) Taking the left front wheel as an example, the kinematic geometry relationship between the speed at the wheel center and the overall vehicle speed, and the wheel slip angle. β 1. Vehicle turning corner α 1. Figure 3 As shown.

[0029] Step S1024: Based on the speed at the wheel center and the equivalent wheel speed, obtain the tire slip ratio of each wheel.

[0030] Specifically, the speed at the wheel center obtained in step S1022 is used. Vx i Step S1021 yields the equivalent wheel speed. VW i Calculate tire slip ratio: l i = ( VW i -Vx i )÷max( VW i , Vx i ) Step S103: Based on the motion state parameters of the wheels, the geometric characteristic parameters of the vehicle, the vehicle speed, the sideslip angle, and the tire slip ratio, the planar component of the vehicle and the planar component of each wheel are obtained.

[0031] Specifically, first call the vehicle's geometric feature parameters: vehicle basic parameters (vehicle mass) M(air density ρ, etc.), geometric parameters (half wheel track) T i etc); Vehicle motion parameters: whole vehicle planar acceleration (longitudinal acceleration) a x lateral acceleration a y ) and fusion speed ( Vx , Vy The planar force component (longitudinal force) of the entire vehicle is calculated using dynamic formulas. F x With lateral force F y ); and then combine the motion parameters of the wheels: the steering angle of each wheel α i and sideslip angle β i Tire slip ratio l i And the previously calculated vertical force on the wheel Fz i By distributing the planar force components of the entire vehicle through tire dynamics, the planar force component (longitudinal force) of each wheel is obtained. Fx i With lateral force Fy i ).

[0032] The above step S103 includes: Step S1031: Based on the vehicle's geometric feature parameters and motion state parameters, obtain the vertical force of each wheel.

[0033] Specifically, using the vehicle's geometric characteristic parameters: vehicle mass M Gravitational acceleration g Center of mass height H g. Distance between front axle and center of gravity L f Rear axle distance from center of gravity L r Half wheel track T i The vehicle's motion state parameters provided by the INS are parsed in the bus: vehicle longitudinal acceleration. a x lateral acceleration a y The vertical force on the wheel is calculated using the following formula: L = L r + L f Fz 1 = Lr × M ×g÷(2× L )- H g× M × a x ÷(2× L )- L r × M × a y × H g÷( L × T 1) Fz 2= L r × M ×g÷(2× L )- H g× M × a x ÷(2× L )+ L r × M × a y × H g÷( L × T 2) Fz 3= L f × M ×g÷(2× L )+ H g× M × a x ÷(2× L )- L f × M × a y × H g÷( L × T 3) Fz 4= L f × M ×g÷(2× L )+ H g× M × a x ÷(2× L )+ L f × M × ay × H g÷( L × T 4) Step S1032: Based on the vehicle's geometric feature parameters, the vehicle's motion state parameters, and the fused vehicle speed, the planar component force of the vehicle is obtained.

[0034] Using the vehicle's geometric parameters: vehicle mass M gravitational acceleration g, air density ρ, drag coefficient C x With C y The frontal area of ​​the whole vehicle S x and S y The vehicle fusion longitudinal speed obtained in step S101 Vx , Integration of lateral speed Vy The vehicle's motion state parameters, provided by the INS, are obtained from the bus: whole-vehicle planar acceleration (longitudinal acceleration). a x lateral acceleration a y Calculate the planar components of the forces (longitudinal forces) on the entire vehicle. F x With lateral force F y ): F x = M × a x -ρ×C x × S x × Vx 2 F y = M × a y -ρ×C y × S y × Vy 2 Step S1033: Based on the motion state parameters of the wheel, the slip angle, the tire slip ratio, the vertical force of the wheel, and the planar force of the vehicle, the reference planar force is obtained.

[0035] Specifically, the motion state parameters of the wheels are obtained by parsing on the bus: the steering angle of each wheel. α i The wheel slip angles calculated in step S1023 β iThe slip ratios of each tire calculated in step S1024 l i The vertical forces of each wheel calculated in step S1031 Fz i The result calculated in step S1032 F x and F y The reference longitudinal force is calculated using the following equation. Fx 0 and reference lateral force Fy 0:

[0036] Step S1034: Based on the reference plane component force, wheel vertical force, wheel motion state parameters, sideslip angle and tire slip ratio, obtain the plane component force of each wheel.

[0037] Specifically, the planar component of the force (longitudinal force) for each wheel is calculated using the following formula. Fx i With lateral force Fy i ):

[0038] Taking the left rear wheel as an example, the tire force and longitudinal force Fx 3 and lateral force Fy 3 directions such as Figure 3 As shown. Step S104: Based on the planar force component of each wheel, the planar force component of the vehicle, the geometric characteristic parameters of the vehicle, and the motion state parameters of the vehicle, the tire adhesion coefficient of each wheel and the adhesion coefficient of the vehicle are obtained.

[0039] Specifically, the vertical force of each wheel is calculated by combining the vehicle's geometric characteristic parameters and motion state parameters; then, the planar component of each wheel is divided by the corresponding vertical force to obtain the tire adhesion coefficient of each wheel; finally, the vehicle's adhesion coefficient is obtained by dividing the vehicle's planar component by the total vertical force of the entire vehicle.

[0040] The above step S104 includes: Step S1041: Based on the vehicle's geometric feature parameters and motion state parameters, obtain the vertical force of each wheel.

[0041] For details, please refer to step S1031, which will not be repeated here.

[0042] Step S1042: Based on the planar component force and the vertical force of each wheel, obtain the tire adhesion coefficient of each wheel.

[0043] Use the wheel vertical force calculated in step S1031 and the tire longitudinal force calculated in step S1034. Fx i Tire lateral force Fy i Calculate the coefficient of adhesion (longitudinal coefficient of adhesion) of each tire according to the formula. m xi With lateral adhesion coefficient m yi ): m xi = Fx i ÷ Fz i m yi = Fy i ÷ Fz i Step S1043: Based on the basic parameters and the planar force component of the vehicle, the adhesion coefficient of the vehicle is obtained.

[0044] The longitudinal force of the whole vehicle is calculated using step S1032. Fx With lateral force Fy The vehicle mass set in the vehicle's geometric characteristic parameters M Given the acceleration due to gravity g, calculate the vehicle's adhesion coefficient (longitudinal adhesion coefficient) using the formula. m x With lateral adhesion coefficient m y ): m x = Fx ÷( M × g ) m y = Fy ÷( M × g ) At this point, without the need to introduce a tire model, the calculation of the longitudinal and lateral forces of the four tires, as well as the longitudinal and lateral adhesion coefficients, can be completed solely by combining the speed, attitude, and acceleration information provided by GNSS and INS with the steering state of the four wheels.

[0045] As an optional embodiment, the method further includes: step S105, determining the friction circle radius of the vehicle and the tire friction circle radius of each wheel based on the vehicle's adhesion coefficient and the tire adhesion coefficient of each wheel.

[0046] Specifically, the initial value of the current maximum adhesion coefficient of the road surface is obtained on the bus. m max Then calculate. and If there is any m i ≥ m max， ,renew m max The value of makes m max =max( m i ); if all m i < m max , No updates m max The value of is then used to obtain the final maximum adhesion coefficient of the current road surface.

[0047] Then, based on the current maximum adhesion coefficient of the road surface, basic parameters, and wheel vertical force, the friction circle radius of the vehicle and the tire friction circle radius of each wheel are obtained, specifically: The above steps yielded m max Obtained from the geometric feature parameters of the vehicle M , g The vertical forces of each wheel calculated in step S1031 Fz i Calculate the radii of the friction circle of the entire vehicle and the friction circles of the four tires, respectively: 1 / 4 × M ×g× m max , Fz i × m max .

[0048] This invention, through acquiring the vehicle's basic parameters, geometric parameters, vehicle speed information, three-axis attitude angles, inertial motion parameters, planar acceleration, yaw rate, and the wheel speed and steering angle of each wheel, accurately calculates the wheel slip ratio and sideslip angle. Simultaneously, without introducing a tire model, it calculates the planar components of the vehicle and wheels using only kinematic geometry and tire dynamics. Then, based on the planar components of the wheels and the vehicle, it determines the tire adhesion coefficient of each wheel and the vehicle's adhesion coefficient, further obtaining the friction circle radius of the vehicle and the tire friction circle radius of each wheel. This invention avoids the errors caused by calculating the longitudinal forces of the four wheels through driving / braking torque and the lateral forces of the four wheels through a tire model. The entire calculation process does not rely on a tire model; it only utilizes kinematic geometry and tire dynamics to achieve accurate online updates of the vehicle and the adhesion coefficients of the four tires. This solves the problem in related technologies where the longitudinal and lateral forces calculated using a tire model have significant deviations, making it difficult to use for accurate online updates of the vehicle and the four-wheel adhesion coefficients.

[0049] As an optional embodiment, the method further includes: Step a1: Based on the tire adhesion coefficient and wheel vertical force of each wheel, construct the adhesion points within the radius of the tire friction circle of each wheel.

[0050] Step a2: Based on the tire friction circle radius and the attachment points within the tire friction circle radius of each wheel, determine the vehicle's maneuverability and motion trend.

[0051] Optionally, coordinate points ( ) are used in the friction circle formed by the radius of the tire friction circle. Fz i × m xi , Fz i × m yi Draw the adhesion points. Where i = 1, 2, 3, 4. The friction circles and adhesion points of the four wheels are shown below. Figure 4 As shown.

[0052] The radius of the friction circle of the four wheels reflects the difference between the local and the whole. If the friction circle radius of the vehicle is smaller than the friction circle radius of the tire, it is determined that the current wheel's maneuverability is greater than the average maneuverability of the whole vehicle.

[0053] The position of the adhesion point relative to the corresponding tire friction circle reflects the maneuverable space for driving, rotation, and steering, as well as the current motion state. In this embodiment of the invention, the driver can observe the change in the friction circle radius and the position of the four wheel adhesion points within the friction circle to understand the friction adhesion of each tire and the load transfer situation. This allows for precise vehicle control to ensure that all four wheels are in good adhesion condition and that the entire vehicle maintains sufficient maneuverability, thus ensuring driving safety.

[0054] As an optional embodiment, step a2 includes: Step a21: Obtain the coordinates of the attachment point.

[0055] Step a22: Based on the distance between the coordinates and the boundary of the tire friction circle, determine the vehicle's operable space and determine the vehicle's motion trend according to the coordinates, wherein the tire friction circle is obtained based on the radius of the tire friction circle.

[0056] Optionally, The coordinates of the attachment point can reflect the vehicle's maneuverability and movement trend.

[0057] When the point of adhesion is inside the tire friction circle and far from its boundary, there is a large maneuvering space. When the point of adhesion is located at or near the boundary of the tire friction circle, it indicates that the actual force on the wheel is close to or exceeds the theoretical limit, and the remaining force space is insufficient. It is determined that the vehicle's maneuvering space is small, and the braking or drive should be adjusted carefully to avoid loss of wheel control.

[0058] The horizontal axis of the attachment point coordinates corresponds to the contribution value of the wheel's lateral force, and the vertical axis corresponds to the contribution value of the wheel's longitudinal force.

[0059] If the absolute value of the longitudinal coordinate of the attachment point is large, it indicates that the longitudinal force on the vehicle is high, and it can be determined that the vehicle has a clear tendency to accelerate or brake. If the absolute value of the abscissa of the attachment point is large, it indicates that the vehicle is subjected to a high proportion of lateral force, and it can be determined that the vehicle has a tendency to turn or tilt. By combining the distribution differences of the four-wheel attachment point coordinates (such as the horizontal coordinate of the front wheel attachment point being generally larger than that of the rear wheel), the specific motion state of the vehicle can be further refined (such as the front wheel being the main brake, or the single wheel having a tendency to lateral deflection), providing a basis for decision-making for driver operation or vehicle control system.

[0060] like Figure 4 As shown, the four-wheel adhesion point is located on the rear right, and the friction circle radius of the front wheel is greater than 1 / 4 × M × g × m max The radius of the rear wheel friction circle is less than 1 / 4 × M × g × m maxThe driver can then know that the vehicle is in the process of positioning and has a tendency to move to the right. The front wheels have more traction space than the rear wheels. If the braking torque is increased further, the rear wheels will reach the traction limit more quickly.

[0061] Figure 5 This diagram illustrates a structural schematic of an embodiment of a vehicle and wheel adhesion coefficient acquisition device according to the present invention. The device includes: The acquisition module 501 is used to acquire the vehicle's fused speed; The first module 502 is used to obtain the slip angle and tire slip ratio of each wheel based on the motion state parameters of the wheel, the motion state parameters of the vehicle, the geometric feature parameters of the vehicle, and the fused vehicle speed. The second module 503 is used to obtain the planar force component of the vehicle and the planar force component of each wheel based on the motion state parameters of the wheels, the geometric feature parameters of the vehicle, the motion state parameters of the vehicle, the vehicle speed, the sideslip angle, and the tire slip ratio. The third module 504 is used to obtain the tire adhesion coefficient of each wheel and the vehicle adhesion coefficient based on the planar component force of each wheel, the planar component force of the vehicle, and the geometric characteristic parameters of the vehicle.

[0062] This invention, through acquiring the vehicle's basic parameters, geometric parameters, vehicle speed information, three-axis attitude angles, inertial motion parameters, planar acceleration, yaw rate, and the wheel speed and steering angle of each wheel, accurately calculates the wheel slip ratio and sideslip angle. Simultaneously, without introducing a tire model, it calculates the planar components of the vehicle and wheels using only kinematic geometry and tire dynamics. Then, based on the planar components of the wheels and the vehicle, it determines the tire adhesion coefficient of each wheel and the vehicle's adhesion coefficient, further obtaining the friction circle radius of the vehicle and the tire friction circle radius of each wheel. This invention avoids the errors caused by calculating the longitudinal forces of the four wheels through driving / braking torque and the lateral forces of the four wheels through a tire model. The entire calculation process does not rely on a tire model; it only utilizes kinematic geometry and tire dynamics to achieve accurate online updates of the vehicle and the adhesion coefficients of the four tires. This solves the problem in related technologies where the longitudinal and lateral forces calculated using a tire model have significant deviations, making it difficult to use for accurate online updates of the vehicle and the four-wheel adhesion coefficients.

[0063] In one alternative approach, module 501 is used to acquire satellite navigation data; and the fused vehicle speed is obtained based on the satellite navigation data.

[0064] In one alternative approach, the first obtaining module 502 is used to obtain the equivalent wheel speed of each wheel based on the motion state parameters of the wheels; obtain the speed at the wheel center of each wheel based on the motion state parameters of the wheels, the geometric feature parameters of the vehicle, the motion state parameters of the vehicle, and the fused vehicle speed; obtain the slip angle of each wheel based on the speed at the wheel center; and obtain the tire slip ratio of each wheel based on the speed at the wheel center and the equivalent wheel speed.

[0065] In one alternative approach, the second obtaining module 503 is used to obtain the vertical force of each wheel based on the vehicle's geometric feature parameters and motion state parameters; to obtain the planar component force of the vehicle based on the vehicle's geometric feature parameters, motion state parameters, and fused vehicle speed; to obtain the reference planar component force based on the wheel's motion state parameters, sideslip angle, tire slip ratio, wheel vertical force, and vehicle planar component force; and to obtain the planar component force of each wheel based on the reference planar component force, wheel vertical force, wheel motion state parameters, sideslip angle, and tire slip ratio.

[0066] In one alternative approach, the third obtaining module 504 is used to obtain the wheel vertical force of each wheel based on the vehicle's geometric feature parameters and the vehicle's motion state parameters; to obtain the tire adhesion coefficient of each wheel based on the planar component force and wheel vertical force of each wheel; and to obtain the vehicle's adhesion coefficient based on the vehicle's geometric feature parameters and the vehicle's planar component force.

[0067] In one alternative embodiment, the device further includes: The first determining module is used to determine the friction circle radius of the vehicle and the tire friction circle radius of each wheel based on the vehicle's coefficient of adhesion and the tire coefficient of adhesion of each wheel.

[0068] In one alternative approach, a determination module is used to determine the current maximum road surface adhesion coefficient based on the vehicle's adhesion coefficient and the tire adhesion coefficient of each wheel; and to obtain the vehicle's friction circle radius and the tire friction circle radius of each wheel based on the current maximum road surface adhesion coefficient, the vehicle's geometric characteristic parameters, and the wheel vertical force.

[0069] In one alternative embodiment, the device further includes: The module is used to construct the adhesion points within the radius of the tire friction circle of each wheel, based on the tire adhesion coefficient and wheel vertical force of each wheel. The second determining module is used to determine the vehicle's maneuverability and motion trend based on the tire friction circle radius and the attachment points within the tire friction circle radius of each wheel.

[0070] In one alternative approach, the second determining module is used for Obtain the coordinates of the attachment point; determine the vehicle's operable space based on the distance between the coordinates and the boundary of the tire friction circle, and determine the vehicle's motion trend based on the coordinates, where the tire friction circle is obtained based on the radius of the tire friction circle.

[0071] Figure 6 The diagram illustrates a structural schematic of an embodiment of the computer device of the present invention. The specific embodiments of the present invention do not limit the specific implementation of the computer device.

[0072] like Figure 6 As shown, the computer device may include: a processor 602, a communications interface 604, a memory 606, and a communications bus 608.

[0073] The processor 602, communication interface 604, and memory 606 communicate with each other via communication bus 608. Communication interface 604 is used to communicate with other network elements, such as clients or other servers. Processor 602 executes program 610, specifically performing the relevant steps in the above-described embodiment of the method for estimating the driving performance and power generation capacity of the motor.

[0074] Specifically, program 610 may include program code, which includes computer-executable instructions.

[0075] Processor 602 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention. The computer device includes one or more processors, which may be processors of the same type, such as one or more CPUs; or processors of different types, such as one or more CPUs and one or more ASICs.

[0076] Memory 606 is used to store program 610. Memory 606 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0077] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0078] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. Similarly, for the sake of brevity and to aid in understanding one or more aspects of the invention, in the description of exemplary embodiments of the invention above, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0079] Those skilled in the art will understand that the modules in the device of the embodiment can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiment can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components, except that at least some of such features and / or processes or units are mutually exclusive.

[0080] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names. The steps in the above embodiments, unless otherwise specified, should not be construed as limiting the order of execution.

Claims

1. A method of acquiring a coefficient of adhesion of a vehicle and a wheel, characterized by, The method comprises: obtaining a fusion vehicle speed of the vehicle; obtaining a side slip angle and a tire slip ratio of each wheel based on a motion state parameter of the wheel, a motion state parameter of the vehicle, a geometric feature parameter of the vehicle and the fusion vehicle speed; obtaining a planar force of the vehicle and a planar force of each wheel based on the motion state parameter of the wheel, the geometric feature parameter of the vehicle, the motion state parameter of the vehicle, the fusion vehicle speed, the side slip angle and the tire slip ratio; obtaining a tire adhesion coefficient of each wheel and an adhesion coefficient of the vehicle based on the planar force of each wheel, the planar force of the vehicle, the geometric feature parameter of the vehicle and the motion state parameter of the vehicle.

2. The method of claim 1, wherein, The obtaining of the fusion vehicle speed of the vehicle comprises: obtaining satellite navigation data; obtaining the fusion vehicle speed based on the satellite navigation data.

3. The method of claim 1, wherein, The obtaining of the side slip angle and the tire slip ratio of each wheel based on the motion state parameter of the wheel, the motion state parameter of the vehicle, the geometric feature parameter of the vehicle and the fusion vehicle speed comprises: obtaining an equivalent wheel speed of each wheel based on the motion state parameter of the wheel; obtaining a wheel center speed of each wheel based on the motion state parameter of the wheel, the geometric feature parameter of the vehicle, the motion state parameter of the vehicle and the fusion vehicle speed; obtaining the side slip angle of each wheel based on the wheel center speed; obtaining the tire slip ratio of each wheel based on the wheel center speed and the equivalent wheel speed.

4. The method of claim 1, wherein, The obtaining of the planar force of the vehicle and the planar force of each wheel based on the motion state parameter of the wheel, the geometric feature parameter of the vehicle, the motion state parameter of the vehicle, the fusion vehicle speed, the side slip angle and the tire slip ratio comprises: obtaining a wheel vertical force of each wheel based on the geometric feature parameter of the vehicle and the motion state parameter of the vehicle; obtaining the planar force of the vehicle based on the geometric feature parameter of the vehicle, the motion state parameter of the vehicle and the fusion vehicle speed; obtaining a reference planar force based on the motion state parameter of the wheel, the side slip angle, the tire slip ratio, the wheel vertical force and the planar force of the vehicle; obtaining the planar force of each wheel based on the reference planar force, the wheel vertical force, the motion state parameter of the wheel, the side slip angle and the tire slip ratio.

5. The method of claim 1, wherein, The obtaining of the tire adhesion coefficient of each wheel and the adhesion coefficient of the vehicle based on the planar force of each wheel, the planar force of the vehicle, the geometric feature parameter of the vehicle and the motion state parameter of the vehicle comprises: obtaining the wheel vertical force of each wheel based on the geometric feature parameter of the vehicle and the motion state parameter of the vehicle; obtaining the tire adhesion coefficient of each wheel based on the planar force of each wheel and the wheel vertical force; obtaining the adhesion coefficient of the vehicle based on the geometric feature parameter of the vehicle and the planar force of the vehicle.

6. The method of claim 4, wherein, The method further comprises: determining a friction circle radius of the vehicle and a tire friction circle radius of each wheel based on the adhesion coefficient of the vehicle and the tire adhesion coefficient of each wheel.

7. The method of claim 6, wherein, The method further comprises: constructing an attachment point within the tire friction circle radius range of each wheel based on the tire attachment coefficient of each wheel and the wheel vertical force; determining the operable space and motion trend of the vehicle based on the tire friction circle radius and the attachment point within the tire friction circle radius range of each wheel.

8. The method of claim 6, wherein, The method further comprises: constructing an attachment point within the tire friction circle radius range of each wheel based on the tire attachment coefficient of each wheel and the wheel vertical force; determining the operable space and motion trend of the vehicle based on the tire friction circle radius and the attachment point within the tire friction circle radius range of each wheel.

9. The method of claim 8, wherein, The method further comprises: acquiring the coordinates of the attachment point; determining the operable space of the vehicle based on the distance between the coordinates and the boundary of the tire friction circle, and determining the motion trend of the vehicle according to the coordinates, wherein the tire friction circle is obtained based on the tire friction circle radius.

10. A device for acquiring a coefficient of adhesion of a vehicle and a wheel, characterized in that, The device comprises: an acquisition module configured to acquire a fusion vehicle speed of a vehicle; a first obtaining module configured to obtain a side slip angle and a tire slip ratio of each wheel based on a motion state parameter of the wheel, a motion state parameter of the vehicle, a geometric characteristic parameter of the vehicle, and the fusion vehicle speed; a second obtaining module configured to obtain a planar component force of the vehicle and a planar component force of each wheel based on the motion state parameter of the wheel, the geometric characteristic parameter of the vehicle, the motion state parameter of the vehicle, the fusion vehicle speed, the side slip angle, and the tire slip ratio; a third obtaining module configured to obtain a tire attachment coefficient of each wheel and an attachment coefficient of the vehicle based on the planar component force of each wheel, the planar component force of the vehicle, and the geometric characteristic parameter of the vehicle.

11. A vehicle characterized by comprising: The device comprises: an acquisition module configured to acquire a fusion vehicle speed of a vehicle; a first obtaining module configured to obtain a side slip angle and a tire slip ratio of each wheel based on a motion state parameter of the wheel, a motion state parameter of the vehicle, a geometric characteristic parameter of the vehicle, and the fusion vehicle speed; a second obtaining module configured to obtain a planar component force of the vehicle and a planar component force of each wheel based on the motion state parameter of the wheel, the geometric characteristic parameter of the vehicle, the motion state parameter of the vehicle, the fusion vehicle speed, the side slip angle, and the tire slip ratio; a third obtaining module configured to obtain a tire attachment coefficient of each wheel and an attachment coefficient of the vehicle based on the planar component force of each wheel, the planar component force of the vehicle, and the geometric characteristic parameter of the vehicle. The device comprises: an acquisition module configured to acquire a fusion vehicle speed of a vehicle; a first obtaining module configured to obtain a side slip angle and a tire slip ratio of each wheel based on a motion state parameter of the wheel, a motion state parameter of the vehicle, a geometric characteristic parameter of the vehicle, and the fusion vehicle speed; a second obtaining module configured to obtain a planar component force of the vehicle and a planar component force of each wheel based on the motion state parameter of the wheel, the geometric characteristic parameter of the vehicle, the motion state parameter of the vehicle, the fusion vehicle speed, the side slip angle, and the tire slip ratio; a third obtaining module configured to obtain a tire attachment coefficient of each wheel and an attachment coefficient of the vehicle based on the planar component force of each wheel, the planar component force of the vehicle, and the geometric characteristic parameter of the vehicle. Memory, a processor, and a computer program stored on the memory and executable on the processor, the processor executing the program to implement the method of claim 1 9 The vehicle and the method of acquiring the coefficient of adhesion of the wheel according to any one of the preceding claims.

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