Tire mechanical property data determination method, apparatus, controller, and vehicle

Abstract

The application embodiment provides a tire mechanical property data determination method, device, controller and vehicle. Relates to vehicle control technical field, the method comprises: in the process of vehicle driving, according to vehicle dynamic data, tire side slip angle, tire slip rate, tire vertical force, tire longitudinal force and tire lateral force are estimated, and target tire friction coefficient is determined;According to tire vertical force and target tire friction coefficient, the tire mechanical property estimation formula is used to obtain target tire mechanical property data;Wherein, the tire mechanical property estimation formula is constructed according to the test tire mechanical property data corresponding to the nominal wheel load and the regression coefficient of the tire mechanical property data with the change of wheel load, and the test tire mechanical property data and the regression coefficient are determined by bench test under the nominal tire friction coefficient. The method is used to improve the accuracy of tire mechanical property data.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and in particular to a method, apparatus, controller, and vehicle for determining tire mechanical property data. Background Technology

[0002] Tire mechanical properties are the comprehensive characteristics of a tire in vehicle dynamics that describe the forces acting on the tire during its movement. They can be used to analyze the dynamic behavior of the tire when it interacts with the ground.

[0003] In related technologies, a linear tire model is usually used to estimate the coefficient of friction by measuring the longitudinal slip stiffness of the tire in the small slip zone, and then to estimate the tire mechanical property data. However, this method requires the tire to be in the longitudinal small slip zone to maintain accuracy. When the estimation conditions are not met, the estimated value obtained when the estimation conditions are met is used, resulting in inaccurate tire mechanical property data. Summary of the Invention

[0004] This application provides a method, apparatus, controller, and vehicle for determining tire mechanical property data, thereby improving the accuracy of tire mechanical property data.

[0005] In a first aspect, embodiments of this application provide a method for determining tire mechanical property data, including:

[0006] During vehicle operation, tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, and tire lateral force are estimated based on vehicle dynamic data.

[0007] The target tire friction coefficient is determined based on the tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, tire lateral force, and tire vertical force.

[0008] Based on the tire vertical force and the target tire friction coefficient, the tire mechanical property data are obtained using the tire mechanical property estimation formula. The tire mechanical property estimation formula is constructed based on the test tire mechanical property data corresponding to the nominal wheel load and the regression coefficient of the tire mechanical property data as a function of wheel load. The test tire mechanical property data and regression coefficient are determined by bench testing under the nominal tire friction coefficient.

[0009] Secondly, embodiments of this application provide a tire mechanical property data determination device, comprising:

[0010] The estimation module is used to estimate the tire slip angle, tire slip ratio, and tire vertical force based on vehicle dynamic data during vehicle operation.

[0011] The friction coefficient determination module is used to determine the target tire friction coefficient based on the tire slip angle, tire slip ratio, and tire vertical force.

[0012] The tire mechanical property data determination module is used to obtain the target tire mechanical property data based on the tire vertical force and the target tire friction coefficient using the tire mechanical property estimation formula. The tire mechanical property estimation formula is constructed based on the test tire mechanical property data corresponding to the nominal wheel load and the regression coefficient of the tire mechanical property data as a function of wheel load. The test tire mechanical property data and regression coefficient are determined by bench testing under the nominal tire friction coefficient.

[0013] Thirdly, embodiments of this application provide an electronic device, including: a memory and a processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0014] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0015] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0016] The tire mechanical property data determination method, device, controller, and vehicle provided in this application embodiment obtain test tire mechanical property data and regression coefficients in advance based on bench tests under nominal tire friction coefficient. Based on the test tire mechanical property data corresponding to nominal wheel load and the regression coefficients of tire mechanical property data as a function of wheel load, a tire mechanical property estimation formula is constructed. This realizes the mapping relationship between the nominal tire friction coefficient, the test tire mechanical property data under nominal wheel load, and the tire mechanical property data corresponding to the tire friction coefficient and tire vertical force under actual working conditions. Then, during vehicle operation, the tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, and tire lateral force are estimated based on vehicle dynamic data. The actual target tire friction coefficient is determined by considering tire slip ratio, tire vertical force, tire longitudinal force, and tire lateral force. Combining the tire longitudinal force and tire lateral force to determine the target tire friction coefficient improves the accuracy of the target tire friction coefficient compared to estimating the tire friction coefficient using only the tire longitudinal force. Substituting the tire vertical force and target tire friction coefficient into the tire mechanical property estimation formula yields the target tire mechanical property data under actual working conditions, ensuring that the target tire mechanical property data matches the tire vertical force and tire friction coefficient under actual working conditions. Furthermore, this application does not limit the estimation conditions; estimation can be performed regardless of whether the tire is in the linear region, transition region, or extreme region, improving the accuracy of estimating the target tire mechanical property data across the entire tire working range. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figure 1 Flowchart of the method for determining tire mechanical property data provided in this application Figure 1 ;

[0019] Figure 2 Flowchart of the method for determining tire mechanical property data provided in this application Figure 2 ;

[0020] Figure 3 Flowchart of the method for determining tire mechanical property data provided in this application Figure 3 ;

[0021] Figure 4 A schematic diagram of the tire mechanical property data determination device provided in this application;

[0022] Figure 5 A schematic diagram of the structure of the electronic device provided in this application.

[0023] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0024] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0025] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0026] Figure 1 Flowchart of the method for determining tire mechanical property data provided in this application Figure 1 ,like Figure 1 As shown, the methods for determining tire mechanical property data include:

[0027] S101. During vehicle operation, estimate tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, and tire lateral force based on vehicle dynamic data.

[0028] Among them, vehicle dynamic data refers to data related to the vehicle's motion state, including but not limited to: suspension travel, longitudinal vehicle speed, yaw rate, lateral vehicle speed at the center of gravity, wheel angle, tire speed, tire angular acceleration, wheel end torque, and braking torque.

[0029] Tire slip angle is used to characterize the degree of deviation between the actual direction of tire movement and the direction the wheel is pointing; tire slip ratio is used to characterize the relative slip state between tire rolling and vehicle movement.

[0030] Tire vertical force is used to characterize the magnitude of the normal load between the tire and the road surface. Tire vertical force includes: left front tire vertical force, right front tire vertical force, left rear tire vertical force, and right front tire vertical force.

[0031] The longitudinal force of a tire is the force exerted on the tire in the rolling direction, which can characterize the tire's acceleration and braking capabilities. The longitudinal force of a tire includes: the longitudinal force of the left front tire, the longitudinal force of the right front tire, the longitudinal force of the left rear tire, and the longitudinal force of the right rear tire.

[0032] Tire lateral force is the force exerted on the tire in the lateral direction of the vehicle, which can characterize the tire's steering and anti-skid ability; tire lateral force includes: left front tire lateral force, right front tire lateral force, left rear tire lateral force, and right rear tire lateral force.

[0033] In actual implementation, the controller acquires vehicle dynamic data in real time and estimates tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force and tire lateral force in real time based on the vehicle dynamic data.

[0034] Specifically, the tire slip angle includes the front wheel slip angle and the rear wheel slip angle; the front wheel slip angle and the rear wheel slip angle are estimated based on vehicle dynamic data; the tire slip ratio is estimated based on vehicle dynamic data; the tire vertical force is estimated based on vehicle dynamic data; the tire longitudinal force is estimated based on vehicle dynamic data and the tire vertical force; the initial front axle lateral force and the initial rear axle lateral force are determined based on vehicle dynamic data, and the initial front axle lateral force and the initial rear axle lateral force are corrected by the tire vertical force to obtain the tire lateral force, which includes: the left front tire lateral force, the right front tire lateral force, the left rear tire lateral force, and the right rear tire lateral force.

[0035] S102. Determine the target tire friction coefficient based on the tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, tire lateral force, and tire vertical force.

[0036] The target tire friction coefficient includes the target tire lateral friction coefficient and the target tire longitudinal friction coefficient.

[0037] Specifically, the target tire's lateral friction coefficient is determined based on the tire slip angle, tire slip ratio, tire vertical force, and tire lateral force; the target tire's longitudinal friction coefficient is determined based on the tire slip angle, tire slip ratio, tire vertical force, and tire longitudinal force.

[0038] The vertical forces of the tires include: the vertical forces of the left front tire, the right front tire, the left rear tire, and the right rear tire; the lateral forces of the tires include: the lateral forces of the left front tire, the right front tire, the left rear tire, and the right rear tire; the longitudinal forces of the tires include: the longitudinal forces of the left front tire, the right front tire, the left rear tire, and the right rear tire.

[0039] The lateral friction coefficient of the left front tire is obtained based on the tire slip angle, the vertical force of the left front tire, and the lateral force of the left front tire; the lateral friction coefficient of the right front tire is obtained based on the tire slip angle, the vertical force of the right front tire, and the lateral force of the right front tire; the lateral friction coefficient of the left rear tire is obtained based on the tire slip angle, the vertical force of the left rear tire, and the lateral force of the left rear tire; the lateral friction coefficient of the right rear tire is obtained based on the tire slip angle, the vertical force of the right rear tire, and the lateral force of the right rear tire.

[0040] The longitudinal friction coefficient of the left front tire is obtained based on the tire slip ratio, the vertical force of the left front tire, and the longitudinal force of the left front tire; the longitudinal friction coefficient of the right front tire is obtained based on the tire slip ratio, the vertical force of the right front tire, and the longitudinal force of the right front tire; the longitudinal friction coefficient of the left rear tire is obtained based on the tire slip ratio, the vertical force of the left rear tire, and the longitudinal force of the left rear tire; the longitudinal friction coefficient of the right rear tire is obtained based on the tire slip ratio, the vertical force of the right rear tire, and the longitudinal force of the right rear tire.

[0041] S103. Based on the tire vertical force and the target tire friction coefficient, the tire mechanical characteristic estimation formula is used to obtain the target tire mechanical characteristic data. The tire mechanical characteristic estimation formula is constructed based on the test tire mechanical characteristic data corresponding to the nominal wheel load and the regression coefficient of the tire mechanical characteristic data with the wheel load. The test tire mechanical characteristic data and the regression coefficient are determined by bench testing under the nominal tire friction coefficient.

[0042] Among them, the tire mechanical property estimation formula is used to extend the test tire mechanical property data obtained under nominal wheel load and nominal tire friction coefficient to the tire vertical force and target tire friction coefficient to obtain the target tire mechanical property data.

[0043] The test data for tire mechanical properties include: maximum lateral force, lateral stiffness, maximum longitudinal force, and longitudinal slip stiffness.

[0044] The target tire mechanical property data include: target maximum lateral force, target lateral stiffness, target maximum longitudinal force, and target longitudinal slip stiffness.

[0045] It should be noted that the maximum lateral force is the peak value of the lateral force, representing the upper limit of the tire's grip; the lateral stiffness can reflect the tire's steering sensitivity. The greater the lateral stiffness, the greater the lateral force the vehicle can obtain under the same slip angle; the maximum longitudinal force is the peak value of the longitudinal force, representing the tire's acceleration and braking capabilities; the longitudinal slip stiffness can reflect the tire's braking and acceleration sensitivity. The greater the longitudinal slip stiffness, the greater the driving force or braking force that can be output under the same slip ratio.

[0046] Specifically, test tire mechanical characteristic data corresponding to multiple test wheel loads are obtained in advance through bench testing under the nominal tire friction coefficient, and regression coefficients of tire mechanical characteristic data with wheel load variation are obtained by fitting. Based on the test tire mechanical characteristic data corresponding to the nominal wheel load and the regression coefficients, a tire mechanical characteristic estimation formula is constructed and stored in the controller.

[0047] During vehicle driving, the currently determined vertical force of the tire and the target tire friction coefficient are substituted into the tire mechanical property estimation formula to obtain the current target tire mechanical property data.

[0048] The tire mechanical property data determination method provided in this application embodiment obtains test tire mechanical property data and regression coefficients in advance based on bench tests under nominal tire friction coefficient. Based on the test tire mechanical property data corresponding to nominal wheel load and the regression coefficients of tire mechanical property data as a function of wheel load, a tire mechanical property estimation formula is constructed. This realizes the mapping relationship between the nominal tire friction coefficient, the test tire mechanical property data under nominal wheel load, and the tire mechanical property data corresponding to the tire friction coefficient and tire vertical force under actual working conditions. Then, during vehicle operation, the tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, and tire lateral force are estimated based on vehicle dynamic data. Furthermore, based on the tire slip angle and tire slip ratio... This method uses the tire vertical force, tire longitudinal force, and tire lateral force to determine the actual target tire friction coefficient. Combining the tire longitudinal force and tire lateral force improves the accuracy of the target tire friction coefficient compared to estimating it solely using the tire longitudinal force. Substituting the tire vertical force and target tire friction coefficient into the tire mechanical property estimation formula yields the target tire mechanical property data under actual working conditions. This ensures that the target tire mechanical property data matches the actual tire vertical force and tire friction coefficient under actual working conditions. Furthermore, this application does not limit the estimation conditions; estimation can be performed regardless of whether the tire is in the linear, transition, or extreme regions, improving the accuracy of estimating the target tire mechanical property data across the entire tire working range.

[0049] In some embodiments, such as Figure 2 As shown, the process of constructing the tire mechanical property estimation formula includes: S201, obtaining test tire mechanical property data corresponding to multiple test wheel loads under the nominal tire friction coefficient through bench testing; wherein, the multiple test wheel loads include the nominal test wheel load; S202, fitting the test tire mechanical property data corresponding to multiple test wheel loads to obtain the regression coefficient of the tire mechanical property data as a function of wheel load; S203, constructing the tire mechanical property estimation formula based on the test tire mechanical property data corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the regression coefficient.

[0050] Among them, the bench test can be a tire six-component force bench test. The bench test is carried out under constant road surface adhesion conditions, so the friction coefficient is fixed and is called the nominal tire friction coefficient.

[0051] Specifically, the tire six-force bench test includes longitudinal slip test and lateral slip test to test the changes in longitudinal force and lateral force under different wheel loads.

[0052] For example, in the tire six-component bench test, multiple test wheel loads include: 175% wheel load, 137.5% wheel load, 100% wheel load, 62.5% wheel load, and 25% wheel load, to ensure the coverage of tire usage load. Among them, 100% wheel load is the nominal test wheel load. The tire test slip angle range is ±15 degrees, the loading speed of the test slip angle is 0.5 degrees / s, the tire test slip ratio range is ±30%, the loading speed of the test slip ratio is 10% / sec, and the loading method for both the test slip angle and the test slip ratio is a triangular wave signal.

[0053] For each test wheel load, a test sideslip angle is applied under longitudinal slip conditions to obtain the maximum test lateral force and test sideslip stiffness corresponding to that test wheel load; a test slip ratio is applied under sideslip conditions to obtain the maximum test longitudinal force and test longitudinal slip stiffness corresponding to that test wheel load.

[0054] The regression coefficients of the tire mechanical properties data as a function of wheel load are obtained by fitting the test tire mechanical property data corresponding to multiple test wheel loads. Among them, the regression coefficients include: maximum lateral force regression coefficient, lateral stiffness regression coefficient, maximum longitudinal force regression coefficient, and longitudinal slip stiffness regression coefficient.

[0055] Based on the test tire mechanical property data corresponding to 100% wheel load, the nominal tire friction coefficient, and the regression coefficient, a tire mechanical property estimation formula is constructed.

[0056] In the above embodiments, based on the actual test data of the test bench and using the nominal working condition as a unified reference, the load variation law is parameterized and written into the estimation formula, so that the formula remains calculable and consistent under different wheel load conditions.

[0057] In some embodiments, the test tire mechanical property data includes: test longitudinal slip stiffness, test maximum longitudinal force, test lateral stiffness, and test maximum lateral force; fitting the test tire mechanical property data corresponding to multiple test wheel loads to obtain regression coefficients of tire mechanical property data as a function of wheel load includes: determining the longitudinal slip stiffness regression coefficient based on the test longitudinal slip stiffness corresponding to multiple test loads; determining the maximum longitudinal force regression coefficient based on the test maximum longitudinal force corresponding to multiple test loads; determining the lateral stiffness regression coefficient based on the test lateral stiffness corresponding to multiple test loads; and determining the maximum lateral force regression coefficient based on the test maximum lateral force corresponding to multiple test loads.

[0058] Specifically, after obtaining the test longitudinal slip stiffness corresponding to multiple test wheel loads through bench testing, the test wheel load is used as the independent variable and the test longitudinal slip stiffness as the dependent variable. Linear regression fitting is used to establish the mapping relationship between the test wheel load and the test longitudinal slip stiffness, and the regression coefficient of the test longitudinal slip stiffness is obtained. .

[0059] After obtaining the maximum longitudinal force corresponding to multiple test wheel loads through bench testing, the test wheel load was used as the independent variable and the maximum longitudinal force as the dependent variable. Linear regression fitting was used to establish the mapping relationship between the test wheel load and the maximum longitudinal force, and the regression coefficient of the maximum longitudinal force was obtained. .

[0060] After obtaining the test lateral stiffness corresponding to multiple test wheel loads through bench testing, the test wheel load was used as the independent variable and the test lateral stiffness as the dependent variable. Linear regression fitting was then used to establish the mapping relationship between the test wheel load and the test lateral stiffness, and the regression coefficient of the test lateral stiffness was obtained. .

[0061] After obtaining the maximum lateral force corresponding to multiple test wheel loads through bench testing, the test wheel load was used as the independent variable and the maximum lateral force as the dependent variable. Linear regression fitting was used to establish the mapping relationship between the test wheel load and the maximum lateral force, and the regression coefficient of the maximum lateral force was obtained. .

[0062] For example, the test longitudinal slip stiffness, maximum longitudinal force, test lateral stiffness, and maximum lateral force are fitted according to the test values ​​corresponding to 175% wheel load, 137.5% wheel load, 100% wheel load, 62.5% wheel load, and 25% wheel load, respectively, to obtain the regression coefficient of the test longitudinal slip stiffness. Test the regression coefficient of the maximum longitudinal force Test the regression coefficient of lateral stiffness and the regression coefficient of maximum lateral force During the fitting process, and The recommended initial value range is 0.60-0.85. and The recommended initial value range is 0.75-0.95.

[0063] In the above embodiments, the regression coefficient of tire mechanical property data with wheel load variation is determined so that the mechanical property data of tire under different loads can be uniformly represented. This facilitates the estimation of target tire mechanical property data corresponding to real-time tire vertical force during vehicle operation, thereby improving the consistency of the representation of tire force boundary under complex working conditions and enhancing the reliability of the parameters on which braking, steering and stability control are based.

[0064] In some embodiments, the test tire mechanical property data includes: test longitudinal stiffness, test maximum longitudinal force, test lateral stiffness, and test maximum lateral force; the regression coefficients include: longitudinal stiffness regression coefficient, maximum longitudinal force regression coefficient, lateral stiffness regression coefficient, and maximum lateral force regression coefficient; based on the test tire mechanical property data corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the regression coefficients, a tire mechanical property estimation formula is constructed, including: constructing a longitudinal stiffness estimation formula based on the test longitudinal stiffness, nominal tire friction coefficient, and longitudinal stiffness regression coefficient corresponding to the nominal test wheel load; constructing a maximum longitudinal force estimation formula based on the test maximum longitudinal force, nominal tire friction coefficient, and maximum longitudinal force regression coefficient corresponding to the nominal test wheel load; constructing a lateral stiffness estimation formula based on the test lateral stiffness, nominal tire friction coefficient, and lateral stiffness regression coefficient corresponding to the nominal test wheel load; and constructing a maximum lateral force estimation formula based on the test maximum lateral force, nominal tire friction coefficient, and maximum lateral force regression coefficient corresponding to the nominal test wheel load.

[0065] Specifically, under real-world vehicle conditions, wheel load changes in real time, and tire mechanical property data are all related to tire load. Moreover, as wheel load increases, tire mechanical property data also increases, but the rate of increase becomes slower and slower. The tire mechanical property estimation formula can reflect the changes in tire mechanical property data with wheel load.

[0066] For example, an initial estimation formula for tire mechanical property data as a function of wheel load is constructed; formula (1) is the initial estimation formula for longitudinal slip stiffness, formula (2) is the initial estimation formula for maximum longitudinal force, formula (3) is the initial estimation formula for lateral stiffness, and formula (4) is the initial estimation formula for maximum lateral force.

[0067] Formula (1): ;

[0068] Formula (2): ;

[0069] Formula (3): ;

[0070] Formula (4): ;

[0071] in, It is the longitudinal slip stiffness corresponding to the actual vertical force of the tire, which is an unknown quantity; It is the test longitudinal slip stiffness corresponding to the nominal wheel load. It is the actual vertical force of the wheel load. It is the nominal load. It is the regression coefficient for testing longitudinal slip stiffness.

[0072] It is the maximum longitudinal force corresponding to the actual vertical force of the tire, and it is an unknown quantity; It is the maximum longitudinal force corresponding to the nominal wheel load in the test. It is the regression coefficient for testing the maximum longitudinal force.

[0073] It is the lateral stiffness corresponding to the actual vertical force of the tire, which is an unknown quantity; It is the test longitudinal slip stiffness corresponding to the nominal wheel load. It is the regression coefficient for testing lateral stiffness.

[0074] It is the maximum lateral force corresponding to the actual vertical force of the tire, and it is an unknown quantity; It is the maximum lateral force corresponding to the nominal wheel load in the test. It is the regression coefficient for testing the maximum lateral force.

[0075] Since the test tire mechanical property data are obtained under the nominal tire friction coefficient, and considering that the actual vehicle conditions correspond to different tire friction coefficients, the initial estimation formulas for longitudinal slip stiffness, maximum longitudinal force, lateral stiffness, and maximum lateral force are adjusted to obtain the estimation formulas for longitudinal slip stiffness, maximum longitudinal force, lateral stiffness, and maximum lateral force.

[0076] For example, formula (5) is the longitudinal slip stiffness estimation formula, formula (6) is the maximum longitudinal force estimation formula, formula (7) is the lateral slip stiffness estimation formula, and formula (8) is the maximum lateral force estimation formula.

[0077] Formula (5): ;

[0078] Formula (6): ;

[0079] Formula (7): ;

[0080] Formula (8): ;

[0081] in, It is the longitudinal slip stiffness corresponding to the actual vertical force of the tire, which is an unknown quantity; It is the actual tire friction coefficient, determined in actual driving. It is the nominal tire friction coefficient. It is the test longitudinal slip stiffness corresponding to the nominal wheel load. It is the actual vertical force of the wheel load. It is the nominal load. It is the regression coefficient for testing longitudinal slip stiffness.

[0082] It is the maximum longitudinal force corresponding to the actual vertical force of the tire, and it is an unknown quantity; It is the maximum longitudinal force corresponding to the nominal wheel load in the test. It is the regression coefficient for testing the maximum longitudinal force.

[0083] It is the lateral stiffness corresponding to the actual vertical force of the tire, which is an unknown quantity; It is the test longitudinal slip stiffness corresponding to the nominal wheel load. It is the regression coefficient for testing lateral stiffness.

[0084] It is the maximum lateral force corresponding to the actual vertical force of the tire, and it is an unknown quantity; It is the maximum lateral force corresponding to the nominal wheel load in the test. It is the regression coefficient for testing the maximum lateral force.

[0085] In the above embodiments, estimation formulas are constructed for longitudinal slip stiffness, maximum longitudinal force, lateral stiffness, and maximum lateral force, respectively, so that tire mechanical property data can be independently estimated based on tire vertical force and tire friction coefficient, thereby improving the consistency between tire mechanical property data and actual working conditions.

[0086] In some embodiments, the target tire longitudinal friction coefficient is determined based on a friction coefficient estimation formula. The process of constructing the friction coefficient estimation formula includes: determining the friction coefficient estimation formula based on the tire mechanical property estimation formula and the exponential tire saturation model.

[0087] Among them, the exponential tire saturation model includes the exponential tire longitudinal force saturation model, as shown in formula (9), and the exponential tire lateral force saturation model, as shown in formula (10).

[0088] Formula (9): ;

[0089] Formula (10): ;

[0090] in, Indicates the longitudinal force of the tire. Indicates the maximum longitudinal force. It is longitudinal stiffness. It is the tire slip ratio; A is the first preset coefficient, which can be set according to actual needs. For example, A is 200.

[0091] It is the lateral force of the tire. It is the maximum lateral force. It is the sideslip stiffness. It is the tire slip angle, and B is the second preset coefficient. B can be set according to actual needs. For example, B is 2.

[0092] The friction coefficient estimation formula includes the tire longitudinal friction coefficient estimation formula and the tire lateral friction coefficient estimation formula.

[0093] Taking A=200 and B=2 as an example, the exponential tire longitudinal force saturation model and the tire mechanical property estimation formula are combined to derive the tire longitudinal friction coefficient estimation formula, as shown in formula (11); the exponential tire lateral force saturation model and the tire mechanical property estimation formula are combined to derive the tire lateral friction coefficient estimation formula, as shown in formula (12).

[0094] Formula (11): ;

[0095] Formula (12): ;

[0096] in, It is the longitudinal friction coefficient of the tire. It is the longitudinal force of the tire. It is the nominal tire friction coefficient. It is the maximum longitudinal force under nominal wheel load. It is the nominal load. It is the vertical force of the tire. It is the lateral stiffness under nominal wheel load. It is the tire slip ratio. It tests the regression coefficient of longitudinal slip stiffness. It is the regression coefficient for testing the maximum longitudinal force.

[0097] It is the tire's lateral friction coefficient. It is the lateral force of the tire. It is the maximum lateral force under nominal wheel load. It is the longitudinal slip stiffness under nominal wheel load. It is the tire slip angle. It tests the regression coefficient of lateral stiffness. It is the regression coefficient for testing the maximum lateral force.

[0098] It should be noted that the tire mechanical property estimation formula describes the mapping relationship between tire mechanical property data and the proportional change of the tire friction coefficient under actual working conditions, as well as the proportional change of the tire vertical force. Specifically, it only analyzes the proportional change of tire mechanical property data with the tire friction coefficient under actual working conditions. When the tire friction coefficient increases from... Become At that time, the maximum lateral force, maximum longitudinal force, lateral stiffness, and longitudinal slip stiffness are all proportional to the coefficients. / Scaling by year.

[0099] The essence of the exponential tire saturation model is a normalized mapping function that describes the tire's full working range from the linear region to the limit region. The ratio of the actual tire force to the maximum force depends on the normalized slip parameter. For example, referring to formula (9), the ratio of the tire longitudinal force to the maximum longitudinal force in the tire's full working range is... It depends on the normalized slip parameter: .

[0100] By combining the tire mechanical property estimation formula with the exponential tire saturation model, the tire friction coefficient estimation formula is obtained. For example, taking the tire longitudinal characteristics as an example, the longitudinal slip stiffness estimation formula (5) is used to replace the longitudinal slip stiffness in the exponential tire longitudinal force saturation model (9), and the maximum longitudinal force estimation formula (6) is used to replace the maximum longitudinal force in the exponential tire longitudinal force saturation model (9), thus deriving the tire longitudinal friction coefficient estimation formula (10). When the longitudinal slip stiffness estimation formula and the maximum longitudinal force estimation formula are substituted into the exponential tire longitudinal force saturation model, the tire friction coefficient in the normalized slip parameter is canceled out. It can be seen that in the exponential tire saturation model, the ratio of tire force to maximum force is only related to the test tire mechanical property data under the actual slip ratio and nominal tire friction coefficient, and is not related to the actual tire friction coefficient. That is, the ratio of tire force to maximum force is completely decoupled from the tire friction coefficient in the entire working area of ​​the tire.

[0101] Furthermore, as can be seen from the tire longitudinal friction coefficient estimation formula (10), the tire longitudinal friction coefficient estimation formula does not include segmented judgment statements for different tire working areas. That is, the tire longitudinal friction coefficient estimation formula is naturally applicable to the entire tire working area. Therefore, by using the tire longitudinal friction coefficient estimation formula, the actual tire friction coefficient can be obtained. It can be uniquely determined, and the entire process does not require prior judgment of whether the tires are slipping or whether they have entered the limit zone.

[0102] The tire characteristic estimation formula does not include segmented judgment statements for different tire working zones, and is naturally applicable to the entire tire working zone. From the tire characteristic estimation formula, it can be seen that the maximum lateral force, maximum longitudinal force, lateral stiffness, and longitudinal slip stiffness are all calculated using proportional coefficients. / By scaling the values ​​proportionally, the actual tire friction coefficient can be calculated. Subsequently, the target tire mechanical property data can be obtained by scaling using the tire mechanical property estimation formula, without needing to distinguish the tire's working zone.

[0103] In other words, the proportional scaling characteristic provided by the tire mechanical property estimation formula decouples the ratio of tire force to maximum force in the tire saturation model from the tire friction coefficient in the entire working area of ​​the tire. This decoupling ensures that the estimation of the tire friction coefficient and subsequent estimation of tire mechanical property data can be performed uniformly across the entire working area without distinguishing between the tire's working areas.

[0104] It should also be noted that the related technologies, which pre-set slip ratio judgment thresholds for linear, transition, and extreme zones and set different estimation strategies for different working zones, have at least the following drawbacks: For the transition zone, the estimation strategy of the linear zone is usually used, resulting in inaccurate tire force estimation data in the transition zone; In actual driving, the working zone is first determined based on the slip ratio, and then the tire force is estimated using the estimation formula corresponding to the working zone. However, in actual driving, under complex road conditions and dynamic changes in vehicle movement, the slip ratio estimation is prone to inaccurate, leading to incorrect working zone judgment and inaccurate tire force estimation data; In addition, when changes in slip ratio cause switching of working zones, estimation is performed using different estimation methods for different working zones, resulting in jumps in tire force estimation data and poor output continuity.

[0105] In the embodiments of this application, the estimation of tire friction coefficient and tire mechanical property data does not require distinguishing the tire's working area, thus avoiding the problem of inaccurate estimation of tire mechanical property data caused by misjudging the working area based on slip ratio. Furthermore, the estimation is performed uniformly throughout the tire's entire working area, avoiding the problem of using the linear area estimation strategy in the transition area, eliminating the jump caused by working area switching, and improving the accuracy and continuity of tire mechanical property data estimation.

[0106] In the above embodiments, the tire friction coefficient estimation formula is determined by using the tire index type tire longitudinal force saturation model and the tire mechanical property estimation formula, so as to calculate the tire friction coefficient under actual working conditions and improve the accuracy of the tire friction coefficient.

[0107] In some embodiments, determining the target tire friction coefficient based on tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, tire lateral force, and tire vertical force includes: substituting the tire slip ratio, tire vertical force, and tire longitudinal force into a tire longitudinal friction coefficient estimation formula to obtain the target tire longitudinal friction coefficient; wherein the tire longitudinal friction coefficient estimation formula is determined based on a tire mechanical property estimation formula and an exponential tire longitudinal force saturation model; and substituting the tire slip angle, tire vertical force, and tire lateral force into a tire lateral friction coefficient estimation formula to obtain the target tire lateral friction coefficient; wherein the tire lateral friction coefficient estimation formula is determined based on a tire mechanical property estimation formula and an exponential tire lateral force saturation model.

[0108] Specifically, the formula for estimating the longitudinal friction coefficient of a tire is shown in formula (11). In the formula for estimating the longitudinal friction coefficient of a tire, the tire slip ratio and the tire vertical force are determined based on vehicle dynamic data. The tire slip ratio and the tire vertical force are substituted into the formula for estimating the longitudinal friction coefficient of a tire to obtain the target tire longitudinal friction coefficient.

[0109] The vertical force of the tires includes the vertical force of the left front tire, the vertical force of the right front tire, the vertical force of the left rear tire, and the vertical force of the right rear tire. Substituting the tire slip angle and the vertical force of the left front tire into the tire longitudinal friction coefficient estimation formula, the longitudinal friction coefficient of the left front tire is obtained. In the same way, the longitudinal friction coefficients of the right front tire, the left rear tire, and the right rear tire can be determined.

[0110] The formula for estimating the tire lateral friction coefficient is shown in formula (12). Substitute the tire slip angle, tire slip ratio, and tire vertical force into the formula for estimating the tire longitudinal friction coefficient to obtain the target tire longitudinal friction coefficient.

[0111] Similarly, by substituting the vertical forces of the left front tire, right front tire, left rear tire, and right front tire respectively, we can obtain the lateral friction coefficients of the left front tire, right front tire, left rear tire, and right rear tire.

[0112] In the above embodiments, the target tire longitudinal friction coefficient and the target tire lateral friction coefficient are determined based on the tire vertical force under actual working conditions, as well as the current slip and lateral states, respectively. This improves the accuracy of the target tire longitudinal friction coefficient and the target tire lateral friction coefficient, and provides a basis for subsequent tire mechanical property data calculation.

[0113] In some embodiments, the tire mechanical property estimation formula includes: a longitudinal slip stiffness estimation formula, a maximum longitudinal force estimation formula, a lateral stiffness estimation formula, and a maximum lateral force estimation formula; the target tire friction coefficient includes the target tire longitudinal friction coefficient and the target tire lateral friction coefficient; such as Figure 3 As shown, based on the tire vertical force and the target tire friction coefficient, the tire mechanical characteristic estimation formula is used to obtain the target tire mechanical characteristic data, including: S301, substituting the tire vertical force and the target tire longitudinal friction coefficient into the longitudinal skid stiffness estimation formula to obtain the target longitudinal skid stiffness; S302, substituting the tire vertical force and the target tire longitudinal friction coefficient into the maximum longitudinal force estimation formula to obtain the target maximum longitudinal force; S303, substituting the tire vertical force and the target tire lateral friction coefficient into the lateral stiffness estimation formula to obtain the target lateral stiffness; S304, substituting the tire vertical force and the target tire lateral friction coefficient into the maximum lateral force estimation formula to obtain the target maximum lateral force.

[0114] Specifically, the longitudinal skid stiffness estimation formula is shown in formula (5). In the longitudinal skid stiffness estimation formula, the nominal tire friction coefficient, the test longitudinal skid stiffness corresponding to the nominal wheel load, the nominal wheel load, and the regression coefficient of the test longitudinal skid stiffness are obtained from bench tests. Corresponding to the target tire's longitudinal friction coefficient, For the corresponding tire vertical force, substitute the tire vertical force and the target tire longitudinal friction coefficient into the longitudinal skid stiffness estimation formula to obtain the target longitudinal skid stiffness. Since the tire vertical force and the target tire longitudinal friction coefficient both include the vertical force and longitudinal friction coefficient corresponding to the left front tire, right front tire, left rear tire, and right rear tire respectively, substitute the vertical force and longitudinal friction coefficient corresponding to the left front tire, right front tire, left rear tire, and right rear tire respectively into the longitudinal skid stiffness estimation formula to obtain the longitudinal skid stiffness corresponding to the left front tire, right front tire, left rear tire, and right rear tire respectively.

[0115] The formula for estimating the maximum longitudinal force is shown in formula (6). Substituting the tire vertical force and the target tire longitudinal friction coefficient into the formula for estimating the maximum longitudinal force, we obtain the target maximum longitudinal force. Since the tire vertical force and the target tire longitudinal friction coefficient both include the vertical force and longitudinal friction coefficient corresponding to the left front tire, right front tire, left rear tire and right rear tire respectively, substituting the vertical force and longitudinal friction coefficient corresponding to the left front tire, right front tire, left rear tire and right rear tire respectively into the formula for estimating the maximum longitudinal force, we obtain the target maximum longitudinal force corresponding to the left front tire, right front tire, left rear tire and right rear tire respectively.

[0116] Similarly, the formula for estimating the lateral stiffness is shown in formula (7). Substitute the vertical force and longitudinal friction coefficient corresponding to the left front tire, right front tire, left rear tire and right rear tire into the formula for estimating the lateral stiffness to obtain the target lateral stiffness corresponding to the left front tire, right front tire, left rear tire and right rear tire respectively.

[0117] Similarly, the maximum lateral force estimation formula is shown in formula (8). Substitute the vertical force and longitudinal friction coefficient corresponding to the left front tire, right front tire, left rear tire and right rear tire into the maximum lateral force estimation formula to obtain the target maximum lateral force corresponding to the left front tire, right front tire, left rear tire and right rear tire respectively.

[0118] In the above embodiments, the tire vertical force and the target tire friction coefficient under actual working conditions are substituted into the tire mechanical property estimation formula to obtain the target tire mechanical property data. This allows the target tire mechanical property data to accurately reflect the force boundary and response characteristics of the tire under the current working conditions, thereby improving the accuracy of the target tire mechanical property data.

[0119] In some embodiments, the target tire mechanical property data includes: target maximum longitudinal force, target maximum lateral force, target longitudinal slip stiffness, and target lateral stiffness; the method further includes: determining the working area of ​​tire longitudinal slip based on the target maximum longitudinal force and tire longitudinal force; determining the working area of ​​tire lateral slip based on the target maximum lateral force and tire lateral force; performing vehicle feedforward control based on the target longitudinal slip stiffness when the working area of ​​tire longitudinal slip is a linear region; and performing vehicle feedforward control based on the target lateral stiffness when the working area of ​​tire lateral slip is a linear region.

[0120] Specifically, the ratio of the tire longitudinal force to the target maximum longitudinal force is used as the longitudinal force margin. If the longitudinal force margin belongs to the first interval, the working area of ​​tire longitudinal slip is determined to be the linear zone. If the longitudinal force margin belongs to the second interval, the working area of ​​tire longitudinal slip is determined to be the transition zone. If the longitudinal force margin belongs to the third interval, the working area of ​​tire longitudinal slip is determined to be the limit zone.

[0121] Specifically, the ratio of the tire lateral force to the target maximum lateral force is used as the lateral force margin. If the lateral force margin belongs to the first interval, the tire lateral motion state is determined to be in the linear region. If the lateral force margin belongs to the second interval, the tire lateral motion state is determined to be in the transition region. If the lateral force margin belongs to the third interval, the tire lateral motion state is determined to be in the limit region.

[0122] When the working zone of tire longitudinal slip is linear, vehicle feedforward control is performed based on the target longitudinal slip stiffness; when the working zone of tire sideslip is linear, vehicle feedforward control is performed based on the target sideslip stiffness.

[0123] For example, if The working zone for tire longitudinal slippage is determined to be the linear zone; if The working area for tire longitudinal slippage is defined as the transition zone; if Then the working area of ​​tire longitudinal slippage is determined as the limit zone.

[0124] like If so, it is determined that the tire lateral movement is currently in the linear region. Then the working zone for tire longitudinal slippage is determined as the limit zone. If so, the lateral motion state of the tire is determined to be the limit zone.

[0125] In the above embodiments, the longitudinal and lateral motion states of the tire are determined by the tire longitudinal force, the target maximum longitudinal force, the tire lateral force, and the target maximum lateral force. This allows for the determination of whether the tire is approaching its working limit and converts the tire force results into state variables for control decisions, thereby improving the accuracy of tire working zone identification under complex working conditions.

[0126] In some embodiments, estimating the front wheel slip angle and the rear wheel slip angle based on vehicle dynamic data includes: determining the front wheel slip angle based on longitudinal vehicle speed, yaw rate, lateral vehicle speed at the center of gravity, front wheel steering angle, and a first distance between the center of gravity and the front axle; and determining the rear wheel slip angle based on longitudinal vehicle speed, yaw rate, lateral vehicle speed at the center of gravity, rear wheel steering angle, and a second distance between the center of gravity and the rear axle.

[0127] For example, the front wheel slip angle is calculated by formula (13), and the rear wheel slip angle is calculated by formula (14).

[0128] Formula (13): ;

[0129] Formula (14): ;

[0130] in, It is the front wheel slip angle. It's the rear wheel slip angle. For longitudinal vehicle speed, The yaw rate of the entire vehicle. The lateral velocity at the vehicle's center of gravity. It's the front wheel's turning angle. It's the rear wheel's turning angle. It is the first distance between the center of gravity and the front axle. It is the second distance between the center of mass and the rear axle. , The quantity is known.

[0131] In practical applications, the front wheel steering angle and rear wheel turning angle The determination method can be to obtain the steering wheel angle or rack travel signal through the vehicle's CAN signal, and then look up a preset correspondence table between wheel angle and steering wheel angle or rack travel to obtain the front wheel angle. and rear wheel turning angle .

[0132] longitudinal speed and the yaw rate of the whole vehicle It can be obtained through the vehicle's CAN signal, based on the longitudinal vehicle speed. yaw rate of the whole vehicle and lateral acceleration The lateral velocity at the vehicle's center of gravity can be calculated. As shown in formula (15).

[0133] Formula (15): ;

[0134] in, It is the lateral velocity at the vehicle's center of gravity. It is lateral acceleration. It is the longitudinal speed. It is the yaw rate of the entire vehicle; in order to reduce the error accumulation caused by the zero bias of the sensor, the observation formula can be established by combining the two-degree-of-freedom model, and the estimation result can be corrected by Kalman filtering.

[0135] In some embodiments, estimating the tire slip ratio based on vehicle dynamic data includes: determining the tire slip ratio based on longitudinal vehicle speed, tire rolling radius, tire rotation speed, and longitudinal acceleration, as shown in formula (16).

[0136] Formula (16): ;

[0137] in, It is the tire slip ratio. It is the longitudinal speed. It is the tire rolling radius. It's the tire speed. It is longitudinal acceleration; the tire rolling radius is a known quantity, and the tire speed can be obtained through the vehicle's CAN signal.

[0138] In some embodiments, estimating the tire vertical force based on vehicle dynamic data includes: differentiating the suspension travel to obtain the suspension speed; determining the suspension elastic force based on the suspension travel; determining the suspension damping force based on the suspension speed; and determining the tire vertical force based on the suspension elastic force and the suspension damping force.

[0139] Specifically, the suspension travel includes the left front suspension travel, right front suspension travel, left rear suspension travel, and right rear suspension travel. A first-order inertial filter is applied to the left front suspension travel to obtain the filtered left front suspension travel. A first-order inertial filter is applied to the right front suspension travel to obtain the filtered right front suspension travel. A first-order inertial filter is applied to the left rear suspension travel to obtain the filtered left rear suspension travel. A first-order inertial filter is applied to the right rear suspension travel to obtain the filtered right rear suspension travel. .

[0140] For the left front suspension travel Differentiate to obtain the speed of the left front suspension. ; Regarding the travel of the right front suspension Differentiate to obtain the speed of the right front suspension. For the left rear suspension travel Differentiate to obtain the speed of the left rear suspension. ; Regarding the right rear suspension travel Differentiate to obtain the speed of the right rear suspension. .

[0141] Left front suspension travel Substituting the preset suspension travel-front suspension elastic force interpolation function into the interpolation calculation, the left front suspension elastic force is obtained. ; Adjust the speed of the left front suspension Substituting the preset suspension speed-front suspension damping force interpolation function into the interpolation calculation, the damping force of the left front suspension is obtained. ;

[0142] Right front suspension travel Substituting the preset suspension travel-front suspension elastic force interpolation function into the interpolation calculation, the right front suspension elastic force is obtained. ; Adjust the speed of the right front suspension Substituting the preset suspension speed-front suspension damping force interpolation function into the interpolation calculation, the right front suspension damping force is obtained. .

[0143] Among them, the preset suspension travel-front suspension elastic force interpolation function is the correspondence expression between the suspension travel and the elastic force of the front suspension (including the left front suspension and the right front suspension) obtained through calibration; the preset suspension speed-front suspension damping force interpolation function is the correspondence expression between the suspension speed and the damping force of the front suspension (including the left front suspension and the right front suspension) obtained through calibration.

[0144] Left rear suspension travel Substituting the preset suspension travel-rear suspension elastic force interpolation function into the interpolation calculation, the left rear suspension elastic force is obtained. ; Adjust the speed of the left rear suspension Substituting the preset suspension speed-rear suspension damping force interpolation function into the interpolation calculation, the damping force of the left rear suspension is obtained. .

[0145] Right rear suspension travel Substituting the preset suspension travel-rear suspension elastic force interpolation function into the interpolation calculation, the right rear suspension elastic force is obtained. ; Adjust the speed of the right rear suspension Substituting the preset suspension speed-rear suspension damping force interpolation function into the interpolation calculation, the damping force of the right rear suspension is obtained. .

[0146] The preset suspension travel-rear suspension elastic force interpolation function is a calibration-derived expression relating suspension travel to the elastic force of the rear suspension (including the left and right rear suspensions). The preset suspension speed-rear suspension damping force interpolation function is a calibration-derived expression relating suspension speed to the damping force of the rear suspension (including the left and right rear suspensions).

[0147] The vertical force of the left front tire is determined based on the initial vertical force of the front wheel, the elastic force of the left front suspension, the damping force of the left front suspension, the unsprung mass of the front tire, and the unsprung acceleration of the left front tire, as shown in formula (17).

[0148] Formula (17): ;

[0149] in, It is the vertical force of the left front tire. It is the initial vertical force of the front wheel. It is the elastic force of the left front suspension. It is the damping force of the left front suspension. It is the unsprung mass of the front spring. It is the left front unsprung acceleration; the initial vertical force of the front wheel is the vertical force of the front wheel when the travel of the front suspension (including the left front suspension and the right front suspension) is 0; the left front unsprung acceleration can be detected by the left front unsprung acceleration sensor and obtained by first-order inertial filtering.

[0150] The vertical force of the right front tire is determined based on the initial vertical force of the front wheel, the elastic force of the right front suspension, the damping force of the right front suspension, the unsprung mass of the front tire, and the unsprung acceleration of the right front tire, as shown in formula (18).

[0151] Formula (18): ;

[0152] in, It is the vertical force of the right front tire. It is the initial vertical force of the front wheel. It is the elastic force of the right front suspension. It is the damping force of the right front suspension. It is the unsprung mass of the front spring. It is the right front unsprung acceleration; the right front unsprung acceleration can be detected by the right front unsprung acceleration sensor and obtained by first-order inertial filtering.

[0153] The vertical force of the left rear tire is determined based on the initial vertical force of the rear wheel, the elastic force of the left rear suspension, the damping force of the left rear suspension, the unsprung mass of the rear and the unsprung acceleration of the front and rear, as shown in formula (19).

[0154] Formula (19): ;

[0155] in, It is the vertical force of the left rear tire. It is the initial vertical force of the rear wheel. It is the elastic force of the left rear suspension. It is the damping force of the left rear suspension. It is the unsprung mass of the rear spring. It is the left rear unsprung acceleration; the initial vertical force of the rear wheel is the vertical force of the rear wheel when the travel of the rear suspension (including the left and right rear suspensions) is 0; the left rear unsprung acceleration can be detected by the left rear unsprung acceleration sensor and obtained by first-order inertial filtering.

[0156] The vertical force of the right rear tire is determined based on the initial vertical force of the rear wheel, the elastic force of the right rear suspension, the damping force of the right rear suspension, the unsprung mass of the rear tire, and the unsprung acceleration of the front and rear tires, as shown in formula (20).

[0157] Formula (20): ;

[0158] in, It is the vertical force of the right rear tire. It is the initial vertical force of the rear wheel. It is the right rear suspension elastic force. It is the damping force of the right rear suspension. It is the unsprung mass of the rear spring. It is the right rear spring unsprung acceleration; the right rear spring unsprung acceleration can be detected by the left rear spring unsprung acceleration sensor and obtained through first-order inertial filtering.

[0159] In some embodiments, estimating the longitudinal force of the tire based on vehicle dynamic data and the vertical force of the tire includes: determining the rolling resistance of the tire based on the vertical force of the tire and the rolling resistance coefficient of the tire; and determining the longitudinal force of the tire based on the wheel moment of inertia, the tire rolling radius, the tire angular acceleration, the wheel end torque, the braking torque, and the rolling resistance of the tire.

[0160] For example, as shown in formula (21).

[0161] Formula (21): ;

[0162] in, The moment of inertia of the wheel assembly (including brake disc and hub bearing). The tire's rolling radius, Tire angular acceleration can be obtained directly from the vehicle's CAN signal, which is the tire rotation speed. After low-pass filtering, differential acquisition ; The wheel-end torque is generated by the motor torque, which can be obtained from the vehicle's CAN bus and then multiplied by the speed ratio and efficiency to determine the torque. The braking torque can be obtained directly from the vehicle's CAN signal, specifically the wheel cylinder pressure, and calculated using the brake specifications and the friction coefficient of the friction block. The rolling resistance is calculated by multiplying the vertical force of the tire by the rolling resistance coefficient.

[0163] In the case of four tires including left front, right front, left rear and right rear, the vertical force of the tires includes the vertical force of the left front tire, the vertical force of the right front tire, the vertical force of the left rear tire and the vertical force of the right rear tire. Based on the rolling resistance coefficient of the tires and the vertical forces of the left front tire, the right front tire, the left rear tire and the right rear tire, the rolling resistance of the four tires is determined. Substituting the rolling resistance of the four tires into formula (21), the longitudinal forces of the four tires are obtained, including: the longitudinal force of the left front tire, the longitudinal force of the right front tire, the longitudinal force of the left rear tire and the longitudinal force of the right rear tire.

[0164] In some embodiments, determining the initial front axle lateral force and the initial rear axle lateral force based on vehicle dynamic data includes: determining the initial front axle lateral force and the initial rear axle lateral force based on lateral acceleration, vehicle yaw acceleration, a first distance between the center of gravity and the front axle, a second distance between the center of gravity and the rear axle, and the vehicle yaw inertia, as shown in formulas (22) and (23).

[0165] Formula (22): ;

[0166] Formula (23): ;

[0167] in, It is the initial front axle lateral force. This is the initial rear axle lateral force, where m is the total vehicle mass. It is lateral acceleration. It is the first distance between the center of gravity and the front axle. It is the second distance between the center of mass and the rear axle. It is the yaw inertia of the entire vehicle. It is the yaw acceleration of the entire vehicle.

[0168] Because tire lateral force has a load-dependent characteristic, meaning that the lateral forces of the left and right tires on the same axle will differ during cornering, the side with the larger vertical force will be the one with the larger vertical force. Therefore, the estimation of the lateral force of a single tire also needs to take into account the difference in load between the left and right tires. Thus, by correcting the initial front axle lateral force and the initial rear axle lateral force using the tire vertical force, an accurate tire lateral force can be obtained.

[0169] Specifically, the initial front axle lateral force is corrected by the vertical force of the left front tire and the vertical force of the right front tire, and the lateral forces of the left front tire and the right front tire are obtained as shown in formulas (24) and (25).

[0170] Formula (24): ;

[0171] Formula (25): ;

[0172] in, It is the lateral force of the left front tire. It is the lateral force of the right front tire. It is the initial front axle lateral force. It is the regression coefficient for testing sideslip stiffness.

[0173] Specifically, the initial rear axle lateral force is corrected by the vertical force of the left rear tire and the vertical force of the right rear tire, and the lateral forces of the left rear tire and the right rear tire are obtained as shown in formulas (26) and (27).

[0174] Formula (26): ;

[0175] Formula (27): ;

[0176] in, It is the lateral force of the left rear tire. It is the lateral force of the right rear tire. It is the initial rear axle lateral force. It is the regression coefficient for testing sideslip stiffness.

[0177] The tire mechanical property data determination method provided in this application is based on the longitudinal and lateral force characteristics of the tire obtained from bench tests. Combined with the real-time estimated tire-road friction coefficient, it can estimate the lateral and longitudinal force characteristics of the tire in the entire working area under various road conditions in a low-cost and high-precision manner. It uses a combination of longitudinal and lateral forces to estimate the tire friction coefficient, rather than only using longitudinal force, thus improving the accuracy of the target tire friction coefficient. By estimating the longitudinal slip and lateral stiffness characteristics of the tire in real time, it identifies whether the tire is in the linear, transition, or limit zone based on the differences in stiffness characteristics in different working zones of the tire. The estimation method is not limited by the tire's motion state, while traditional methods can only estimate tires in the linear zone. At the same time, this application considers the tire friction circle characteristics, which can achieve accurate real-time estimation throughout the entire process.

[0178] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0179] Figure 4 A schematic diagram of the tire mechanical property data determination device provided in this application is shown below. Figure 4 As shown, the tire mechanical property data determination device 40 provided in this embodiment includes:

[0180] The estimation module 401 is used to estimate the tire slip angle, tire slip ratio and tire vertical force based on vehicle dynamic data during vehicle operation.

[0181] Friction coefficient determination module 402 is used to determine the target tire friction coefficient based on tire slip angle, tire slip ratio and tire vertical force;

[0182] The tire mechanical property data determination module 403 is used to obtain the target tire mechanical property data based on the tire vertical force and the target tire friction coefficient using the tire mechanical property estimation formula. The tire mechanical property estimation formula is constructed based on the test tire mechanical property data corresponding to the nominal wheel load and the regression coefficient of the tire mechanical property data with the wheel load. The test tire mechanical property data and the regression coefficient are determined by bench testing under the nominal tire friction coefficient.

[0183] In some embodiments, the apparatus further includes a testing module, configured to acquire test tire mechanical characteristic data corresponding to multiple test wheel loads under a nominal tire friction coefficient through bench testing; wherein the multiple test wheel loads include a nominal test wheel load; to fit the test tire mechanical characteristic data corresponding to the multiple test wheel loads to obtain regression coefficients of tire mechanical characteristic data as a function of wheel load; and to construct a tire mechanical characteristic estimation formula based on the test tire mechanical characteristic data corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the regression coefficients.

[0184] In some embodiments, the test tire mechanical property data includes: test longitudinal skid stiffness, test maximum longitudinal force, test lateral stiffness, and test maximum lateral force; the test module is used to determine the longitudinal skid stiffness regression coefficient based on the test longitudinal stiffness corresponding to the multiple test loads; determine the maximum longitudinal force regression coefficient based on the test maximum longitudinal force corresponding to the multiple test loads; determine the lateral stiffness regression coefficient based on the test lateral stiffness corresponding to the multiple test loads; and determine the maximum lateral force regression coefficient based on the test maximum lateral force corresponding to the multiple test loads.

[0185] In some embodiments, the test tire mechanical property data includes: test longitudinal stiffness, test maximum longitudinal force, test lateral stiffness, and test maximum lateral force; the regression coefficients include: longitudinal stiffness regression coefficient, maximum longitudinal force regression coefficient, lateral stiffness regression coefficient, and maximum lateral force regression coefficient;

[0186] The testing module is used to construct a longitudinal skid stiffness estimation formula based on the longitudinal skid stiffness, nominal tire friction coefficient, and longitudinal skid stiffness regression coefficient corresponding to the nominal test wheel load; to construct a maximum longitudinal force estimation formula based on the maximum longitudinal force, nominal tire friction coefficient, and maximum longitudinal force regression coefficient corresponding to the nominal test wheel load; to construct a lateral stiffness estimation formula based on the lateral stiffness, nominal tire friction coefficient, and lateral stiffness regression coefficient corresponding to the nominal test wheel load; and to construct a maximum lateral force estimation formula based on the maximum lateral force, nominal tire friction coefficient, and maximum lateral force regression coefficient corresponding to the nominal test wheel load.

[0187] In some embodiments, the tire mechanical property estimation formula includes: a longitudinal skid stiffness estimation formula, a maximum longitudinal force estimation formula, a lateral stiffness estimation formula, and a maximum lateral force estimation formula; the target tire friction coefficient includes the target tire longitudinal friction coefficient and the target tire lateral friction coefficient; the testing module is used to substitute the tire vertical force and the target tire longitudinal friction coefficient into the longitudinal skid stiffness estimation formula to obtain the target longitudinal skid stiffness; substitute the tire vertical force and the target tire longitudinal friction coefficient into the maximum longitudinal force estimation formula to obtain the target maximum longitudinal force; substitute the tire vertical force and the target tire lateral friction coefficient into the lateral stiffness estimation formula to obtain the target lateral stiffness; and substitute the tire vertical force and the target tire lateral friction coefficient into the maximum lateral force estimation formula to obtain the target maximum lateral force.

[0188] In some embodiments, the friction coefficient determination module is used to substitute the tire slip ratio, tire vertical force, and tire longitudinal force into the tire longitudinal friction coefficient estimation formula to obtain the target tire longitudinal friction coefficient; wherein, the tire longitudinal friction coefficient estimation formula is determined based on the tire mechanical property estimation formula and the exponential tire longitudinal force saturation model; and to substitute the tire slip angle, tire vertical force, and tire lateral force into the tire lateral friction coefficient estimation formula to obtain the target tire lateral friction coefficient; wherein, the tire lateral friction coefficient estimation formula is determined based on the tire mechanical property estimation formula and the exponential tire lateral force saturation model.

[0189] In some embodiments, the target tire mechanical property data includes: target maximum longitudinal force, target maximum lateral force, target longitudinal slip stiffness, and target side slip stiffness; the device further includes a control module for determining the working zone of tire longitudinal slip based on the target maximum longitudinal force and tire longitudinal force; the working zone is a linear zone, a transition zone, or a limit zone; determining the working zone of tire side slip based on the target maximum lateral force and tire lateral force; when the working zone of tire longitudinal slip is a linear zone, performing vehicle feedforward control based on the target longitudinal slip stiffness; when the working zone of tire side slip is a linear zone, performing vehicle feedforward control based on the target side slip stiffness.

[0190] The tire mechanical property data determination device provided in this embodiment can execute the tire mechanical property data determination method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0191] Figure 5 This is a schematic diagram of the controller provided in this application. Figure 5 As shown, the controller 50 provided in this embodiment includes at least one processing unit 501 and a storage unit 502. Optionally, the controller further includes a communication component 503. The processing unit 501, the storage unit 502, and the communication component 503 are connected via a bus.

[0192] In a specific implementation, at least one processing unit 501 executes computer execution instructions stored in the storage unit 502, causing at least one processing unit 501 to perform the above-described method.

[0193] The specific implementation process of the processing unit 501 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0194] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0195] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0196] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0197] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0198] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0199] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0200] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0201] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0202] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0203] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0204] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0205] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0206] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for determining tire mechanical property data, characterized in that, include: During vehicle operation, tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, and tire lateral force are estimated based on vehicle dynamic data. The target tire friction coefficient is determined based on the tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, tire lateral force, and tire vertical force. Based on the vertical force of the tire and the friction coefficient of the target tire, the mechanical property data of the target tire are obtained using the tire mechanical property estimation formula. The tire mechanical property estimation formula is constructed based on the mechanical property data of the test tire corresponding to the nominal wheel load and the regression coefficient of the tire mechanical property data as a function of the wheel load. The test tire mechanical property data and the regression coefficient are determined by bench testing under the nominal tire friction coefficient.

2. The method according to claim 1, characterized in that, The process of constructing the tire mechanical property estimation formula includes: Through bench testing, under the nominal tire friction coefficient, mechanical characteristic data of test tires corresponding to multiple test wheel loads are obtained; wherein, the multiple test wheel loads include the nominal test wheel load; The regression coefficients of tire mechanical property data as a function of wheel load are obtained by fitting the mechanical property data of the test tires corresponding to multiple test wheel loads. Based on the test tire mechanical property data corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the regression coefficient, a tire mechanical property estimation formula is constructed.

3. The method according to claim 2, characterized in that, The test tire mechanical property data include: test longitudinal stiffness, test maximum longitudinal force, test lateral stiffness, and test maximum lateral force; The process of fitting the mechanical property data of the test tires corresponding to multiple test wheel loads to obtain the regression coefficients of the tire mechanical property data as a function of wheel load includes: Determine the longitudinal slip stiffness regression coefficient based on the test longitudinal slip stiffness corresponding to multiple test loads; The regression coefficient of the maximum longitudinal force is determined based on the maximum longitudinal force corresponding to multiple test loads. Determine the lateral stiffness regression coefficient based on the test lateral stiffness corresponding to multiple test loads; The regression coefficient of the maximum lateral force is determined based on the maximum lateral force corresponding to multiple test loads.

4. The method according to claim 2, characterized in that, The test tire mechanical property data include: test longitudinal stiffness, test maximum longitudinal force, test lateral stiffness, and test maximum lateral force; the regression coefficients include: longitudinal stiffness regression coefficient, maximum longitudinal force regression coefficient, lateral stiffness regression coefficient, and maximum lateral force regression coefficient; The step of constructing a tire mechanical property estimation formula based on the test tire mechanical property data corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the regression coefficient includes: Based on the test longitudinal slip stiffness corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the longitudinal slip stiffness regression coefficient, a longitudinal slip stiffness estimation formula is constructed. Based on the maximum longitudinal force corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the maximum longitudinal force regression coefficient, a formula for estimating the maximum longitudinal force is constructed. Based on the test lateral stiffness corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the lateral stiffness regression coefficient, a lateral stiffness estimation formula is constructed. A formula for estimating the maximum lateral force is constructed based on the maximum test lateral force corresponding to the nominal test wheel load, the nominal tire friction coefficient, and the maximum lateral force regression coefficient.

5. The method according to any one of claims 1 to 4, characterized in that, The tire mechanical property estimation formulas include: longitudinal slip stiffness estimation formula, maximum longitudinal force estimation formula, lateral stiffness estimation formula, and maximum lateral force estimation formula; the target tire friction coefficient includes the target tire longitudinal friction coefficient and the target tire lateral friction coefficient. The step of obtaining target tire mechanical property data based on the tire vertical force and the target tire friction coefficient using a tire mechanical property estimation formula includes: Substituting the tire vertical force and the target tire longitudinal friction coefficient into the longitudinal skid stiffness estimation formula, the target longitudinal skid stiffness is obtained; Substituting the tire vertical force and the target tire longitudinal friction coefficient into the maximum longitudinal force estimation formula, the target maximum longitudinal force is obtained; Substituting the tire vertical force and the target tire lateral friction coefficient into the lateral stiffness estimation formula, the target lateral stiffness is obtained; Substituting the tire vertical force and the target tire lateral friction coefficient into the maximum lateral force estimation formula, the target maximum lateral force is obtained.

6. The method according to any one of claims 1 to 4, characterized in that, The step of determining the target tire friction coefficient based on the tire slip angle, tire slip ratio, tire vertical force, tire longitudinal force, tire lateral force, and tire vertical force includes: Substituting the tire slip ratio, the tire vertical force, and the tire longitudinal force into the tire longitudinal friction coefficient estimation formula, the target tire longitudinal friction coefficient is obtained; wherein, the tire longitudinal friction coefficient estimation formula is determined based on the tire mechanical property estimation formula and the exponential tire longitudinal force saturation model; Substituting the tire slip angle, the tire vertical force, and the tire lateral force into the tire lateral friction coefficient estimation formula, the target tire lateral friction coefficient is obtained; wherein, the tire lateral friction coefficient estimation formula is determined based on the tire mechanical property estimation formula and the exponential tire lateral force saturation model.

7. The method according to any one of claims 1 to 4, characterized in that, The target tire mechanical property data includes: target maximum longitudinal force, target maximum lateral force, target longitudinal slip stiffness, and target lateral stiffness; the method further includes: The working zone of tire longitudinal slip is determined based on the target maximum longitudinal force and the tire longitudinal force; the working zone is a linear zone, a transition zone, or a limit zone. The working zone for tire lateral deviation is determined based on the target maximum lateral force and the tire lateral force. When the working zone of tire longitudinal slip is linear, vehicle feedforward control is performed based on the target longitudinal slip stiffness. When the working area of ​​tire lateral deviation is in the linear region, vehicle feedforward control is performed based on the target lateral deviation stiffness.

8. A device for determining tire mechanical property data, characterized in that, The device includes: The estimation module is used to estimate the tire slip angle, tire slip ratio, and tire vertical force based on vehicle dynamic data during vehicle operation. The friction coefficient determination module is used to determine the target tire friction coefficient based on the tire slip angle, the tire slip ratio, and the tire vertical force. The tire mechanical property data determination module is used to obtain the target tire mechanical property data based on the tire vertical force and the target tire friction coefficient using a tire mechanical property estimation formula. The tire mechanical property estimation formula is constructed based on the test tire mechanical property data corresponding to the nominal wheel load and the regression coefficient of the tire mechanical property data as a function of wheel load. The test tire mechanical property data and the regression coefficient are determined by bench testing under the nominal tire friction coefficient.

9. A controller, characterized in that, include: A processing unit, and a storage unit communicatively connected to the processing unit; The storage unit stores computer-executed instructions; The processing unit executes the computer execution instructions stored in the storage unit to implement the method as described in any one of claims 1 to 7.

10. A vehicle, characterized in that, It includes the vehicle body and the controller as described in claim 9.

11. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 7.

12. A computer program product, characterized in that, Includes computer execution instructions, which, when executed by a processor, implement the method as described in any one of claims 1 to 7.

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