Vehicle road adhesion coefficient determination method, system, equipment and medium

Abstract

The invention discloses a vehicle road adhesion coefficient determination method, system and device and a medium, and relates to the technical field of vehicle control, and the method comprises the following steps: obtaining tire dynamics response parameters of a vehicle; performing calculation and comparison based on the tire dynamic response parameters to obtain an axial longitudinal adhesion coefficient and an axial transverse adhesion coefficient of the vehicle; performing calculation and comparison on the basis of the axial longitudinal adhesion coefficient and the axial transverse adhesion coefficient to obtain a whole vehicle actual utilization adhesion coefficient of the vehicle; and performing retention attenuation analysis based on the actual utilization adhesion coefficient of the whole vehicle, and determining a target road adhesion coefficient of the vehicle. The problem that in the prior art, the road adhesion coefficient calculation mode is single, influences of external factors on vehicle driving cannot be handled, and consequently the vehicle control performance is limited is solved.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and in particular to a method, system, device and medium for determining the road surface adhesion coefficient of a vehicle. Background Technology

[0002] With the rapid development of automotive electrification and intelligence, active safety control technology has increasingly become a focus of attention. During vehicle operation, the condition of the road surface directly affects driving safety, and the road surface adhesion coefficient (BPCC) characterizes the maximum interaction force that can be generated between the tires and the road surface. It directly affects the vehicle's braking, driving, and steering performance, playing a crucial role in vehicle safety. Therefore, accurately obtaining the BPCC in real time is a prerequisite for achieving vehicle stability control and an important reference for rationally formulating active safety control strategies and coordinating control between various chassis subsystems. Existing methods for determining the BPCC generally involve directly calculating and applying information such as vehicle speed.

[0003] However, when external environmental factors such as road surface conditions affect vehicle operation, the single road adhesion coefficient obtained using existing methods may not be accurate. It may differ significantly from the actual road adhesion coefficient, making it unsuitable for use in vehicle control algorithms and thus limiting vehicle performance improvement. In other words, current technologies rely on a single method for calculating the road adhesion coefficient, which cannot address the impact of external factors on vehicle operation, thereby restricting vehicle control performance. Summary of the Invention

[0004] In order to overcome the problem that the existing technology has a single method for calculating the road surface adhesion coefficient, which cannot cope with the impact of external factors on vehicle driving and thus restricts the vehicle control performance, this application provides a method, system, device and medium for determining the road surface adhesion coefficient of a vehicle.

[0005] Firstly, in order to solve the above-mentioned technical problems, this application provides a method for determining the vehicle road surface adhesion coefficient, including: Obtain the vehicle's tire dynamics response parameters; The longitudinal and lateral adhesion coefficients of the vehicle are obtained by calculating and comparing the tire dynamic response parameters. The actual adhesion coefficient of the vehicle is obtained by calculating and comparing the longitudinal and transverse adhesion coefficients of the shaft. Based on the actual adhesion coefficient of the whole vehicle, the retention attenuation analysis is performed to determine the target road adhesion coefficient of the vehicle.

[0006] Secondly, this application also provides a system for determining the coefficient of friction of a vehicle road surface, comprising: The acquisition module is used to acquire the vehicle's tire dynamics response parameters; The first calculation and comparison module is used to calculate and compare based on tire dynamic response parameters to obtain the vehicle's longitudinal adhesion coefficient and lateral adhesion coefficient. The second calculation and comparison module is used to calculate and compare the longitudinal adhesion coefficient and the transverse adhesion coefficient of the axle to obtain the actual adhesion coefficient of the vehicle. The adhesion coefficient determination module is used to perform retention attenuation analysis based on the actual adhesion coefficient of the whole vehicle to determine the target road surface adhesion coefficient of the vehicle.

[0007] Thirdly, this application also provides a computing device, including a memory, a processor, and a program stored in the memory and running on the processor, wherein the processor executes the program to implement the steps of the method for determining the vehicle road surface adhesion coefficient as described above.

[0008] Fourthly, this application also provides a computer-readable storage medium storing instructions that, when executed on a terminal device, cause the terminal device to perform the steps of a method for determining the coefficient of adhesion of a vehicle road surface.

[0009] The beneficial effects of this application are as follows: First, based on the tire dynamic response parameters of the vehicle, the longitudinal and lateral adhesion coefficients of the axle are calculated and compared to obtain the actual adhesion coefficient of the entire vehicle. Then, based on the longitudinal and lateral adhesion coefficients of the axle, the actual adhesion coefficient of the entire vehicle is calculated and compared to obtain the actual adhesion coefficient of the entire vehicle. In this way, by introducing the tire dynamic response parameters of the vehicle into the determination of the actual adhesion coefficient of the entire vehicle, the actual road surface adhesion coefficient of the entire vehicle is matched with the current driving conditions of the vehicle. Second, based on the actual adhesion coefficient of the entire vehicle, a hold-down analysis is performed to determine the target road surface adhesion coefficient of the vehicle. This allows the target road surface adhesion coefficient to flexibly respond to the influence of various external factors on vehicle driving, thereby improving the performance of vehicle control based on the target road surface adhesion coefficient. Attached Figure Description

[0010] Figure 1 This is a flowchart illustrating a method for determining the road surface adhesion coefficient of a vehicle, as shown in an exemplary embodiment of this application. Figure 2 This is a schematic diagram illustrating the process of determining the actual adhesion coefficient utilized by the vehicle in an exemplary embodiment of this application; Figure 3 This is a schematic diagram illustrating the process of determining the target road surface adhesion coefficient in an exemplary embodiment of this application; Figure 4 This is a schematic diagram illustrating the structure of a vehicle road surface adhesion coefficient determination system, which is an exemplary embodiment of this application. Detailed Implementation

[0011] The following embodiments are further explanations and supplements to this application and do not constitute any limitation on this application.

[0012] The following describes, with reference to the accompanying drawings, a method, system, device, and medium for determining the vehicle road surface adhesion coefficient according to an embodiment of this application.

[0013] The method for determining the vehicle road surface adhesion coefficient provided in this application embodiment can be specifically executed by a server. It should be noted that the server can be an independent server, or it can be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, content delivery networks (CDN), and big data and artificial intelligence platforms. No limitation is imposed here.

[0014] This application provides a method for determining the road surface adhesion coefficient of a vehicle, used to calculate the road surface adhesion coefficient during vehicle operation, applicable to new energy vehicles with four-motor drive. By utilizing parameters collected from commonly used onboard sensors and combining them with vehicle dynamic response information, the road surface adhesion coefficient is estimated, improving the accuracy of the estimation. This allows for better utilization of tire adhesion characteristics, optimization of vehicle slip ratio, and improved stability control, thereby enhancing vehicle performance and driving safety.

[0015] Please see Figure 1 , Figure 1 A method for determining the vehicle road surface adhesion coefficient is shown as an exemplary embodiment of this application, such as... Figure 1 As shown, this application provides a method for determining the vehicle road surface adhesion coefficient, including: S11, obtain the vehicle's tire dynamics response parameters; S12, based on tire dynamic response parameters, calculate and compare to obtain the vehicle's longitudinal and lateral adhesion coefficients. S13, based on the longitudinal and transverse adhesion coefficients of the shaft, the actual adhesion coefficient of the vehicle is obtained by calculation and comparison. S14. Based on the actual adhesion coefficient of the whole vehicle, a retention attenuation analysis is performed to determine the target road adhesion coefficient of the vehicle.

[0016] The vehicle road surface adhesion coefficient determination method provided in this application firstly calculates and compares the longitudinal and lateral adhesion coefficients of the axle based on the vehicle's tire dynamic response parameters, and then calculates and compares the actual vehicle road surface adhesion coefficient based on these coefficients. By incorporating the vehicle's tire dynamic response parameters into the determination of the actual vehicle road surface adhesion coefficient, the method ensures that the actual vehicle road surface adhesion coefficient matches the vehicle's current driving conditions. Secondly, based on the actual vehicle road surface adhesion coefficient, a hold-down analysis is performed to determine the vehicle's target road surface adhesion coefficient. This target coefficient allows for flexible responses to the influence of various external factors on vehicle driving, thereby improving the performance of vehicle control based on the target road surface adhesion coefficient.

[0017] Optionally, obtain the vehicle's tire dynamics response parameters, including: Obtain the vehicle's operating parameters, including longitudinal acceleration and lateral acceleration; Based on the operating parameters, the longitudinal force, lateral force and vertical force of each wheel of the vehicle are calculated. The tire dynamics response parameters of a vehicle are formed based on the longitudinal force, lateral force, and vertical force of the wheel.

[0018] In the embodiment provided in this application, based on the vehicle's operating parameters including longitudinal acceleration and lateral acceleration, the longitudinal force, lateral force, and vertical force of each wheel of the vehicle are calculated to form the vehicle's tire dynamic response parameters. This facilitates the subsequent introduction of the vehicle's tire dynamic response parameters into the determination of the actual road surface adhesion coefficient of the whole vehicle, so that the actual road surface adhesion coefficient of the whole vehicle matches the current driving conditions of the vehicle, thereby improving the accuracy of the determined target road surface adhesion coefficient and thus improving the performance of vehicle control.

[0019] In an exemplary embodiment provided in this application, the calculation of wheel forces such as longitudinal force, lateral force, and vertical force is based on obtaining two operating parameters: lateral acceleration Ay and longitudinal acceleration Ax. The specific steps for calculating the longitudinal force, lateral force, and vertical force of each wheel of the vehicle based on these operating parameters are as follows: (1) Calculate the lateral force of each axle, i.e., the lateral force of the wheel, Fy, based on lateral acceleration. The calculation formula is as follows: in, The unloaded mass allocated to the front or rear axle of the vehicle; This is lateral acceleration.

[0020] (2) Calculate the vertical force of each wheel. Wheel vertical force = |wheel load| + |change in wheel load due to lateral acceleration| - |change in axle load due to longitudinal acceleration|.

[0021] Taking the left front wheel as an example: in, Let m be the vertical force on the left front wheel, m be the unloaded mass of the vehicle, and g be the acceleration due to gravity. For longitudinal acceleration, This is the distance from the rear axle to the center of gravity. Wheelbase This refers to the lateral force on the front axle. For the height of the center of gravity, This refers to the front wheelbase.

[0022] (3) Calculate the longitudinal force of each wheel. Based on physical torque and braking torque, calculate the longitudinal force of each wheel in the wheel coordinate system. : =(Physical torque - Braking torque) / Rolling radius.

[0023] Based on the longitudinal wheel force and the actual acquired lateral acceleration data, the resultant force of the lateral and longitudinal wheel forces in the x-direction is calculated in the vehicle coordinate system. The calculation equation is as follows: in, The slope angle, The resultant force of the lateral and longitudinal wheel forces in the y-direction, for each wheel. The distribution of the lateral force Fy on the corresponding wheel is estimated to follow the load distribution law of Fz.

[0024] In one exemplary embodiment provided in this application, longitudinal acceleration is obtained using information from an acceleration sensor. Calculate the longitudinal force of the whole vehicle using Newton's second law. Its absolute value is calculated using the following formula: Where m is the unloaded mass of the vehicle; The longitudinal acceleration is obtained by summing the values ​​collected by the vehicle's longitudinal acceleration sensor and the acceleration lost to overcome wind resistance; Based on the accelerometer, the actual longitudinal adhesion coefficient is calculated. The calculation formula is as follows: in, For longitudinal acceleration, It is the acceleration due to gravity; Obtain the longitudinal force Fx, lateral force Fy, and vertical force Fz of each wheel, and use the sum of the longitudinal forces acting on each wheel. The sum of the vertical forces of each wheel The sum of the absolute values ​​of the longitudinal forces of each wheel and the absolute value of the sum of the longitudinal forces of each wheel are calculated for use in the subsequent estimation and verification process.

[0025] Optionally, the longitudinal and lateral adhesion coefficients of the vehicle are calculated and compared based on tire dynamic response parameters, including: For each wheel, the wheel longitudinal adhesion coefficient and wheel lateral adhesion coefficient are calculated based on the wheel longitudinal force, wheel lateral force and wheel vertical force. The formula for calculating the longitudinal adhesion coefficient of a wheel is as follows: in, , , These represent the longitudinal adhesion coefficient, longitudinal force, and vertical force of a given wheel; The formula for calculating the lateral adhesion coefficient of a wheel is as follows: in, , , These are the wheel lateral adhesion coefficient, wheel lateral force, and wheel vertical force, respectively, for a given wheel. Based on a comparative analysis of the longitudinal adhesion coefficients of the four wheels and the vertical forces of the four wheels, the axle longitudinal adhesion coefficient of the vehicle is obtained; Based on a comparative analysis of the lateral adhesion coefficients of the four wheels, the lateral adhesion coefficient of the axle is obtained.

[0026] In the embodiment provided in this application, for each wheel, the wheel longitudinal adhesion coefficient and wheel lateral adhesion coefficient are calculated based on the wheel longitudinal force, wheel lateral force, and wheel vertical force. The axle longitudinal adhesion coefficient and axle lateral adhesion coefficient are obtained by comparing and analyzing the four wheel longitudinal adhesion coefficients, four wheel vertical forces, and four wheel lateral adhesion coefficients. This allows the actual road surface adhesion coefficient of the vehicle to be matched one by one in a decomposed form, so that the target road surface adhesion coefficient determined based on the axle longitudinal adhesion coefficient and axle lateral adhesion coefficient can flexibly cope with the influence of various external factors on vehicle driving, thereby improving the performance of vehicle control based on the target road surface adhesion coefficient.

[0027] Optionally, based on a comparative analysis of the longitudinal adhesion coefficients of the four wheels and the vertical forces of the four wheels, the longitudinal adhesion coefficient of the axle is obtained, including: The longitudinal adhesion coefficient of the main shaft is calculated based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the main shaft of the vehicle. The longitudinal adhesion coefficient of the secondary axle is calculated based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the secondary axle of the vehicle. The longitudinal adhesion coefficient of the vehicle shaft is formed based on the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft.

[0028] In the embodiment provided in this application, the longitudinal adhesion coefficient of the main axle is calculated based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the main axle of the vehicle, and the longitudinal adhesion coefficient of the secondary axle is calculated based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the secondary axle of the vehicle, so as to form the longitudinal adhesion coefficient of the vehicle axle. This facilitates the subsequent determination of the target road surface adhesion coefficient based on the longitudinal adhesion coefficient of the axle, thereby improving the performance of vehicle control.

[0029] In an exemplary embodiment provided in this application, the calculation methods for the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft are the same. Taking the calculation of the longitudinal adhesion coefficient of the main shaft as an example, assuming the main shaft is the front shaft, the calculation process of the longitudinal adhesion coefficient of the main shaft is as follows: (a) Calculate the ratio of the larger and smaller vertical forces of the left and right wheels of the front axle at the axle, and obtain a transfer coefficient from a table based on this ratio. ; (b) Based on the transfer coefficient and the longitudinal adhesion coefficients of the left and right wheels, calculate the longitudinal adhesion coefficient of the main shaft at the axle end. The corresponding calculation formula is as follows: +(1- ) in, The longitudinal adhesion coefficient of the main shaft, For the transfer coefficient, The longitudinal adhesion coefficient of the left wheel. The longitudinal adhesion coefficient of the right wheel; The principle of the above calculation method is that the larger the transfer coefficient, the more reliable the larger value calculated for the left and right wheels, and the utilization adhesion coefficient of the shaft is always calculated from the side with greater longitudinal force.

[0030] Optionally, the lateral adhesion coefficient of the axle is obtained by comparing and analyzing the lateral adhesion coefficients of the four wheels, including: The larger value of the lateral adhesion coefficients of the two wheels corresponding to the main axle of the vehicle is determined as the lateral adhesion coefficient of the main axle. The larger of the lateral adhesion coefficients of the two wheels corresponding to the secondary axle of the vehicle is determined as the lateral adhesion coefficient of the secondary axle. The lateral adhesion coefficient of the vehicle shaft is formed based on the lateral adhesion coefficient of the main shaft and the lateral adhesion coefficient of the secondary shaft.

[0031] In the embodiment provided in this application, the larger value of the wheel lateral adhesion coefficients corresponding to the two wheels of the main axle of the vehicle is determined as the main axle lateral adhesion coefficient, and the larger value of the wheel lateral adhesion coefficients corresponding to the two wheels of the secondary axle of the vehicle is determined as the secondary axle lateral adhesion coefficient, so as to form the axle lateral adhesion coefficient of the vehicle. This facilitates the subsequent determination of the target road surface adhesion coefficient based on the axle lateral adhesion coefficient, thereby improving the performance of vehicle control.

[0032] Optionally, the longitudinal adhesion coefficient of the shaft includes the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft, and the transverse adhesion coefficient of the shaft includes the transverse adhesion coefficient of the main shaft and the transverse adhesion coefficient of the secondary shaft. The actual vehicle adhesion coefficient is obtained by calculating and comparing the longitudinal and lateral adhesion coefficients of the axle, including: Based on the longitudinal adhesion coefficient and the lateral adhesion coefficient of the main shaft, the actual utilization adhesion coefficient of the vehicle's main shaft is calculated. Based on the longitudinal and lateral adhesion coefficients of the subshaft, the actual utilization adhesion coefficient of the vehicle's subshaft is calculated. The larger of the actual utilized adhesion coefficient of the main shaft and the actual utilized adhesion coefficient of the secondary shaft is determined as the actual utilized adhesion coefficient of the vehicle as a whole.

[0033] In the embodiment provided in this application, the actual utilized adhesion coefficient of the vehicle's main axle is calculated based on the longitudinal and lateral adhesion coefficients of the main axle. Similarly, the actual utilized adhesion coefficient of the vehicle's secondary axle is calculated based on the longitudinal and lateral adhesion coefficients of the secondary axle. The larger of the two values ​​is then determined as the overall actual utilized adhesion coefficient of the vehicle. By using the larger of the main and secondary axle adhesion coefficients as the overall vehicle adhesion coefficient, the system can maximize the prevention of wheel slippage, thereby improving vehicle control performance while ensuring driving safety.

[0034] In this embodiment, the adhesion coefficients utilized in the longitudinal and transverse directions of the main shaft and the secondary shaft are calculated separately. The calculation method for the actual adhesion coefficient utilized by the secondary shaft is the same as that for the main shaft. Taking the actual adhesion coefficient utilized by the main shaft as an example, its calculation formula is as follows: in, The actual adhesion coefficient utilized by the main shaft The actual longitudinal adhesion coefficient of the spindle used in the spindle longitudinal direction. The actual lateral adhesion coefficient of the spindle is used in the lateral direction.

[0035] In an exemplary embodiment provided in this application, the confidence level effective value is calculated based on the longitudinal force of each wheel. The specific steps are as follows: (a) The consistency of the longitudinal force direction of each wheel is verified by the ratio of the sum of the absolute values ​​of the longitudinal forces of each wheel to the absolute value of the sum of the longitudinal forces of each wheel, and this ratio is used as the detection coefficient 1. (b) The ratio of the absolute value of the sum of the longitudinal forces of each wheel to the absolute value of the longitudinal force of the whole vehicle calculated by the sensor is used to verify the longitudinal acceleration of each wheel and serve as the detection coefficient 2. (c) Calculate the ratio of the absolute value of the longitudinal force of the whole vehicle to the absolute value of the sum of the longitudinal forces of each wheel based on the sensor, and verify the longitudinal acceleration reflected in the longitudinal force of each wheel, as the detection coefficient 3; The smallest value among detection coefficient 1, detection coefficient 2, and detection coefficient 3 is taken as the effective confidence value for detecting the longitudinal force distribution. .

[0036] The limiting weight coefficient for the longitudinal adhesion coefficient is calculated based on longitudinal acceleration. The specific steps are as follows: If the accelerometer reading is abnormally low and does not match the wheel force, calculate the limiting weighting coefficient. Calculation formula: in, This is the sum of the longitudinal forces of each wheel. This is the longitudinal force calculated using an accelerometer.

[0037] Based on the above confidence level valid values and limiting weight coefficients In this embodiment, the estimation and verification are based on longitudinal acceleration. The specific steps are as follows: (a) Calculate the ratio Co1 of the vertical force of a single wheel to the vertical force of the whole vehicle (which can be the sum of the vertical forces of all wheels), and calculate the ratio Co2 of the longitudinal force of a single wheel to the longitudinal force of the whole vehicle. (b) Calculate the final ratio, where the weight between the longitudinal and normal forces depends on the RMS confidence level of the longitudinal force distribution. ; (c) Calculate the ratio of Co1 to Co2 calculated in (a) above. This value represents the contribution of the wheel to the overall vehicle's utilization of the adhesion coefficient. Combining the contribution share of each wheel from step (c) with the average actual vehicle adhesion coefficient utilized by the entire vehicle based on the longitudinal acceleration sensor, the final adhesion coefficient utilized by each wheel is calculated; the weight allocation is adjusted to calculate the adhesion coefficient utilized by the longitudinal wheels, wherein the weight coefficient is limited. The larger the value, the more reliable the calculations based on model forces become.

[0038] Please see Figure 2 , Figure 2This is a schematic diagram illustrating the process of determining the actual adhesion coefficient of the whole vehicle in an exemplary embodiment of this application, as shown below. Figure 2 As shown, the specific process for determining the actual adhesion coefficient of the whole vehicle is as follows: Calculate the verification factor and allocation coefficient for subsequent adhesion coefficient verification and allocation of larger values; The first road surface adhesion coefficient (axial longitudinal adhesion coefficient) is calculated using tire dynamic response information. Calculate the second road surface adhesion coefficient (axial lateral adhesion coefficient) based on the vehicle acceleration information. The actual adhesion coefficient (actual adhesion coefficient of the whole vehicle) is determined based on the aforementioned parameters.

[0039] Optionally, based on the actual utilization coefficient of the vehicle's adhesion, a retention decay analysis is performed to determine the vehicle's target road adhesion coefficient, including: A sudden drop test was conducted on the vehicle, and the test results were obtained. If the detection result is that no sudden drop in the adhesion coefficient is detected, and / or the actual duration of the vehicle's use of the adhesion coefficient does not reach the preset time limit, and / or the vehicle is stationary, then the actual used adhesion coefficient will be determined as the vehicle's target road surface adhesion coefficient. Otherwise, the target road surface adhesion coefficient of the vehicle is obtained by filtering and attenuating based on the actual adhesion coefficient of the whole vehicle.

[0040] In the embodiment provided in this application, since the actual coefficient of adhesion used by the vehicle is generally maintained for a certain period of time, it is necessary to detect in a timely manner whether there is a sudden drop in the actual coefficient of adhesion used by the vehicle in order to avoid overestimation. Therefore, this embodiment performs a sudden drop detection on the vehicle, obtains the detection results, and determines a target road surface adhesion coefficient that matches the current driving state of the vehicle based on the sudden drop detection results, the maintenance duration, and the vehicle's driving state. This allows the target road surface adhesion coefficient to flexibly respond to the influence of various external factors on vehicle driving, thereby improving the performance of vehicle control based on the target road surface adhesion coefficient.

[0041] In an exemplary embodiment provided in this application, the sudden drop detection includes longitudinal actual utilization adhesion coefficient sudden drop detection and lateral actual utilization adhesion coefficient sudden drop detection. The larger value between the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft can be determined as the longitudinal actual utilization adhesion coefficient, and the larger value between the lateral adhesion coefficient of the main shaft and the lateral adhesion coefficient of the secondary shaft can be determined as the lateral actual utilization adhesion coefficient. Therefore, in this embodiment, sudden drop detection of the vehicle is actually a sudden drop detection performed on both the longitudinal and lateral actual utilization adhesion coefficients.

[0042] The specific steps for detecting sudden drops in the adhesion coefficient in the longitudinal direction are as follows: (1) Preprocessing stage (a) Wheel acceleration analysis Since the focus is on the maximum coefficient of adhesion, the most stable wheel on the axle is selected as the analysis object (e.g., the coefficient of adhesion of the wheel on the higher adhesion side in separated road conditions, or the coefficient of adhesion of the outer wheel when turning). However, further differentiation is needed under acceleration conditions: if the other wheel on the same axle is in a braking slip state, the opposing wheel is selected, and the wheel must exhibit the minimum traction slip to enhance robustness. Finally, the acceleration data used for sudden drop detection is the maximum value between the main axle and the secondary axle.

[0043] (b) Actual longitudinal adhesion coefficient (μ_used_veh); (c) Vehicle acceleration Ax (sensor data); (2) Logic for determining sudden drops in adhesion coefficient; The following conditions may indicate that a sudden drop in the adhesion coefficient was detected: (a) The actual coefficient of adhesion of the whole vehicle is significantly reduced (the rate of reduction is greater than the set value in a short period of time), or, an abnormal sudden change occurs just before the reduction. (b) Accompanied by high wheel acceleration; (c) At the same time, the vehicle's acceleration is abnormal; The specific judgment strategy is divided into two cases: (a) When the vehicle is accelerating: If the motor torque is not limited: descent detection is triggered only when "extremely high" wheel acceleration is observed; if the motor torque of any axle is limited: descent detection is triggered using a "lower" wheel acceleration threshold setting; the determination of "extremely high" and "lower" is based on the set threshold.

[0044] (b) When the vehicle is decelerating: A "low" acceleration threshold is consistently used to improve system sensitivity. Furthermore, to determine a sudden drop in the adhesion coefficient, the deviation from the final estimated adhesion coefficient (μEst) must be sufficiently large.

[0045] Finally, under separated road surface conditions, instability caused by wheel instability should not trigger a judgment, and the sudden drop detection function will be turned off at this time.

[0046] The specific steps for detecting sudden drops in adhesion coefficient in lateral applications are as follows: (1) In the preprocessing stage, obtain information on lateral acceleration, yaw rate, target yaw rate and vehicle speed, calculate Ackerman yaw rate and Ackerman lateral acceleration, and detect sudden drops in adhesion coefficient through lateral acceleration. (2) Activation condition for adhesion coefficient drop detection: Detection is triggered only when there is a minimum turning requirement; (a) Condition 1: Adhesion coefficient decreases during turning. Any decrease in lateral acceleration (Ay) caused by non-driver operation is considered a potential sudden drop in the coefficient of adhesion. To enhance robustness, a de-shaking mechanism is employed.

[0047] (b) Condition 2: If a sudden drop in the coefficient of adhesion is not detected in time (e.g., after passing through a region of sudden change in negative coefficient of adhesion and entering a low-adhesion road surface), and the vehicle understeers (the actual turning angle is lower than the theoretical value that the current preset coefficient of adhesion should have), it is determined that the coefficient of adhesion has dropped, and the same anti-shaking mechanism is used.

[0048] (3) Final judgment logic: If any of the above detection conditions are met, the adhesion coefficient sudden drop judgment is triggered, and the judgment state is maintained for at least a preset time threshold.

[0049] The ratio of the vehicle's utilized coefficient of adhesion (μusedveh) to the estimated road surface coefficient of adhesion (μEst) is calculated. If the ratio is less than a threshold, a significant decrease in the coefficient of adhesion is detected.

[0050] In an exemplary embodiment provided in this application, before determining the target road surface adhesion coefficient of the vehicle, the maximum value (μusedveh_max) or local peak value (μusedveh_peak) of the longitudinal actual utilized adhesion coefficient (μusedveh) is maintained for a certain period of time. This maintenance duration is determined based on the following principles: Higher adhesion coefficient μ values ​​and values ​​learned from lateral acceleration sensors (Ay) are generally considered more reliable, hence longer hold times are set. This time can be specifically calibrated for different driving modes (e.g., extended trust duration for adhesion coefficient μ values ​​in track mode).

[0051] Early termination condition: When a sudden drop in adhesion coefficient is detected, the holding phase should be terminated (holding time should be set to zero).

[0052] Furthermore, when the vehicle is stationary, the estimated road adhesion coefficient (μEst) is uncertain. If the adhesion coefficient (μusedveh) used does not significantly decrease to below the maximum value (μusedveh_max) or local peak value (μusedveh_peak), the difference is considered insignificant and the difference is judged to be within a reasonable range.

[0053] In an exemplary embodiment provided in this application, the final calculated target road surface adhesion coefficient is estimated based on a comprehensive judgment of the previously calculated correlation coefficients. This process is divided into a maintenance phase and a decay phase. (1) Maintenance phase The adhesion coefficient peak (μusedveh_peak) is maintained when any of the following conditions are met: a. The actual retention time of the vehicle's adhesion coefficient did not exceed the retention time limit (preset time limit). b. No sudden drop in adhesion coefficient was detected; c. The vehicle is stationary.

[0054] (2) Decay Phase The actual adhesion coefficient of the vehicle is filtered to converge to the maximum value between the currently used adhesion coefficient (actual adhesion coefficient of the whole vehicle, actual longitudinal adhesion coefficient, and actual lateral adhesion coefficient) and another potential peak (the peak value of the aforementioned three types of coefficients over a period of time). If a sudden change in the adhesion coefficient is detected, the filtering constant is accelerated.

[0055] (3) The final output of the road surface adhesion coefficient estimate is the result of the combined effect of the maintenance stage and the decay stage.

[0056] Please see Figure 3 , Figure 3 This is a schematic diagram illustrating the process of determining the target road surface adhesion coefficient in an exemplary embodiment of this application, as shown below. Figure 3 As shown, the specific process for determining the target road surface adhesion coefficient is as follows: The longitudinal adhesion coefficient of the main shaft, the longitudinal adhesion coefficient of the secondary shaft, the lateral adhesion coefficient of the main shaft, and the lateral adhesion coefficient of the secondary shaft are calculated based on the tire dynamic response parameters. The adhesion coefficients used by the vehicle (actual adhesion coefficients of the whole vehicle) are calculated and compared based on the longitudinal adhesion coefficient of the main shaft, the longitudinal adhesion coefficient of the secondary shaft, the lateral adhesion coefficient of the main shaft, and the lateral adhesion coefficient of the secondary shaft. Then, the vehicle is subjected to sudden drop detection: longitudinal adhesion coefficient sudden drop detection and lateral adhesion coefficient sudden drop detection. The detection results are obtained, and the actual duration of adhesion coefficient maintenance of the whole vehicle is determined, as well as whether the vehicle is in a stationary state or a driving state. Based on the test results, the duration of contact, and the vehicle's condition, the target road surface adhesion coefficient for the vehicle is determined.

[0057] The method for determining the vehicle road surface adhesion coefficient in this application is based on the calculation of longitudinal acceleration, longitudinal adhesion coefficient of the main / secondary axle wheels, longitudinal adhesion coefficient of the main / secondary axle, lateral adhesion coefficient of the main / secondary axle, adhesion coefficient of the whole vehicle, detection of sudden drops in longitudinal / lateral adhesion coefficient, adhesion coefficient estimation and maintenance, and road surface adhesion coefficient estimation. The target road surface adhesion coefficient obtained through comprehensive calculation is then applied to vehicle control. This method can accurately estimate the road surface adhesion coefficient when there are separate road surfaces and uneven road surface water films, facilitating better utilization of tire adhesion characteristics to improve vehicle performance and optimize the control of vehicle slip ratio and stability. Therefore, the method of this application can scientifically and accurately estimate the vehicle's road surface adhesion coefficient, with good reliability and robustness. It can accurately estimate the road surface adhesion coefficient under the influence of various external factors, including separate road surfaces and uneven road surface water films, without adding additional force sensors, resulting in lower overall design costs.

[0058] Please see Figure 4 , Figure 4 A vehicle road surface adhesion coefficient determination system is shown as an exemplary embodiment of this application, such as Figure 4 As shown, this application provides a vehicle road surface adhesion coefficient determination system 400, including: The acquisition module 401 is used to acquire the tire dynamics response parameters of the vehicle; The first calculation and comparison module 402 is used to calculate and compare based on tire dynamic response parameters to obtain the vehicle's longitudinal adhesion coefficient and lateral adhesion coefficient. The second calculation and comparison module 403 is used to calculate and compare the longitudinal adhesion coefficient and the transverse adhesion coefficient of the shaft to obtain the actual adhesion coefficient of the vehicle. The adhesion coefficient determination module 404 is used to perform retention attenuation analysis based on the actual adhesion coefficient of the whole vehicle to determine the target road surface adhesion coefficient of the vehicle.

[0059] The vehicle road surface adhesion coefficient determination system 400 of this application firstly calculates and compares the longitudinal and lateral adhesion coefficients of the axle using a first calculation and comparison module 402 based on the tire dynamic response parameters of the vehicle acquired by the acquisition module 401. Then, a second calculation and comparison module 403 calculates and compares the longitudinal and lateral adhesion coefficients of the axle to obtain the actual vehicle adhesion coefficient. By introducing the vehicle's tire dynamic response parameters into the determination of the actual vehicle adhesion coefficient, the actual road surface adhesion coefficient is matched to the vehicle's current driving conditions. Secondly, the adhesion coefficient determination module 404 performs a hold-down analysis based on the actual vehicle adhesion coefficient to determine the target road surface adhesion coefficient. This allows the target road surface adhesion coefficient to flexibly respond to the influence of various external factors on vehicle driving, thereby improving the performance of vehicle control based on the target road surface adhesion coefficient.

[0060] Optionally, module 401 is used specifically for: Obtain the vehicle's operating parameters, including longitudinal acceleration and lateral acceleration; Based on the operating parameters, the longitudinal force, lateral force and vertical force of each wheel of the vehicle are calculated. The tire dynamics response parameters of a vehicle are formed based on the longitudinal force, lateral force, and vertical force of the wheel.

[0061] Optionally, the first calculation and comparison module 402 is specifically used for: For each wheel, the wheel longitudinal adhesion coefficient and wheel lateral adhesion coefficient are calculated based on the wheel longitudinal force, wheel lateral force and wheel vertical force. Based on a comparative analysis of the longitudinal adhesion coefficients of the four wheels and the vertical forces of the four wheels, the axle longitudinal adhesion coefficient of the vehicle is obtained; Based on a comparative analysis of the lateral adhesion coefficients of the four wheels, the lateral adhesion coefficient of the axle is obtained.

[0062] Optionally, the first calculation and comparison module 402 is specifically used for: The longitudinal adhesion coefficient of the main shaft is calculated based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the main shaft of the vehicle. The longitudinal adhesion coefficient of the secondary axle is calculated based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the secondary axle of the vehicle. The longitudinal adhesion coefficient of the vehicle shaft is formed based on the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft.

[0063] Optionally, the first calculation and comparison module 402 is specifically used for: The larger value of the lateral adhesion coefficients of the two wheels corresponding to the main axle of the vehicle is determined as the lateral adhesion coefficient of the main axle. The larger of the lateral adhesion coefficients of the two wheels corresponding to the secondary axle of the vehicle is determined as the lateral adhesion coefficient of the secondary axle. The lateral adhesion coefficient of the vehicle shaft is formed based on the lateral adhesion coefficient of the main shaft and the lateral adhesion coefficient of the secondary shaft.

[0064] Optionally, the longitudinal adhesion coefficient of the shaft includes the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft, and the transverse adhesion coefficient of the shaft includes the transverse adhesion coefficient of the main shaft and the transverse adhesion coefficient of the secondary shaft. The second calculation and comparison module 403 is specifically used for: Based on the longitudinal adhesion coefficient and the lateral adhesion coefficient of the main shaft, the actual utilization adhesion coefficient of the vehicle's main shaft is calculated. Based on the longitudinal and lateral adhesion coefficients of the subshaft, the actual utilization adhesion coefficient of the vehicle's subshaft is calculated. The larger of the actual utilized adhesion coefficient of the main shaft and the actual utilized adhesion coefficient of the secondary shaft is determined as the actual utilized adhesion coefficient of the vehicle as a whole.

[0065] Optionally, the adhesion coefficient determination module 404 is specifically used for: A sudden drop test was conducted on the vehicle, and the test results were obtained. If the detection result is that no sudden drop in the adhesion coefficient is detected, and / or the actual duration of the vehicle's use of the adhesion coefficient does not reach the preset time limit, and / or the vehicle is stationary, then the actual used adhesion coefficient will be determined as the vehicle's target road surface adhesion coefficient. Otherwise, the target road surface adhesion coefficient of the vehicle is obtained by filtering and attenuating based on the actual adhesion coefficient of the whole vehicle.

[0066] It should be noted that the vehicle road surface adhesion coefficient determination system and the vehicle road surface adhesion coefficient determination method provided in the above embodiments belong to the same concept. The specific operation methods of each module and unit have been described in detail in the method embodiments and will not be repeated here. In practical applications, the vehicle road surface adhesion coefficient determination system provided in the above embodiments can be assigned to different functional modules as needed, that is, the internal structure of the system can be divided into different functional modules to complete all or part of the functions described above. This is not a limitation here.

[0067] A computing device according to an embodiment of this application includes a memory, a processor, and a program stored in the memory and running on the processor. When the processor executes the program, it implements some or all of the steps of the above-described method for determining the vehicle road surface adhesion coefficient.

[0068] The computing device can be a computer, and the corresponding program is computer software. The parameters and steps in the computing device described above can be referred to the parameters and steps in the embodiment of the method for determining the vehicle road surface adhesion coefficient mentioned above, and will not be repeated here.

[0069] This application embodiment provides a computer-readable storage medium storing instructions that, when executed, perform the steps of the above-described method for determining the vehicle road surface adhesion coefficient.

[0070] The computer-readable storage medium may be a transient computer-readable storage medium or a non-transitory computer-readable storage medium.

[0071] The technical solutions of this disclosure can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes one or more 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 this disclosure. The aforementioned computer-readable storage medium can be a non-transitory computer-readable storage medium, including: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks, and other media capable of storing program code; it can also be a transient computer-readable storage medium.

[0072] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. Each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0073] Those skilled in the art will recognize that this application can be implemented as a system, method, or computer program product. Therefore, this disclosure can be implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "module" or "system." Furthermore, in some embodiments, this application can also be implemented as a computer program product contained in one or more computer-readable media, which contains computer-readable program code. Computer-readable storage media can be, for example, but not limited to—electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof.

[0074] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0075] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for determining the road surface adhesion coefficient of a vehicle, characterized in that, include: Obtain the vehicle's tire dynamics response parameters; The longitudinal adhesion coefficient and lateral adhesion coefficient of the vehicle are obtained by calculating and comparing the tire dynamic response parameters. The actual utilization adhesion coefficient of the vehicle is obtained by calculating and comparing the longitudinal adhesion coefficient and the transverse adhesion coefficient of the shaft. Based on the actual adhesion coefficient of the vehicle, a retention attenuation analysis is performed to determine the target road adhesion coefficient of the vehicle.

2. The method according to claim 1, characterized in that, The acquisition of the vehicle's tire dynamics response parameters includes: The vehicle's operating parameters are obtained, including longitudinal acceleration and lateral acceleration; Based on the operating parameters, the longitudinal force, lateral force, and vertical force of each wheel of the vehicle are calculated. The tire dynamic response parameters of the vehicle are formed based on the wheel longitudinal force, the wheel lateral force, and the wheel vertical force.

3. The method according to claim 1, characterized in that, The calculation and comparison based on the tire dynamic response parameters to obtain the longitudinal and lateral adhesion coefficients of the vehicle includes: For each wheel, the wheel longitudinal adhesion coefficient and wheel lateral adhesion coefficient are calculated based on the wheel longitudinal force, wheel lateral force and wheel vertical force. Based on a comparative analysis of the longitudinal adhesion coefficients of the four wheels and the vertical forces of the four wheels, the longitudinal adhesion coefficient of the vehicle's axle is obtained. Based on a comparative analysis of the lateral adhesion coefficients of the four wheels, the lateral adhesion coefficient of the axle is obtained.

4. The method according to claim 3, characterized in that, The longitudinal adhesion coefficient of the shaft is obtained by comparing and analyzing the longitudinal adhesion coefficients of the four wheels and the vertical forces of the four wheels, including: Based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the main axle of the vehicle, the longitudinal adhesion coefficient of the main axle is calculated. Based on the longitudinal adhesion coefficient and vertical force of the two wheels corresponding to the secondary axle of the vehicle, the longitudinal adhesion coefficient of the secondary axle is calculated. The longitudinal adhesion coefficient of the vehicle is formed based on the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft.

5. The method according to claim 3, characterized in that, The lateral adhesion coefficient of the axle is obtained by comparing and analyzing the lateral adhesion coefficients of the four wheels, including: The larger value of the lateral adhesion coefficients of the two wheels corresponding to the main axle of the vehicle is determined as the lateral adhesion coefficient of the main axle. The larger of the wheel lateral adhesion coefficients of the two wheels corresponding to the secondary axle of the vehicle is determined as the secondary axle lateral adhesion coefficient. The lateral adhesion coefficient of the vehicle's axle is formed based on the lateral adhesion coefficient of the main shaft and the lateral adhesion coefficient of the secondary shaft.

6. The method according to claim 1, characterized in that, The longitudinal adhesion coefficient of the shaft includes the longitudinal adhesion coefficient of the main shaft and the longitudinal adhesion coefficient of the secondary shaft, and the transverse adhesion coefficient of the shaft includes the transverse adhesion coefficient of the main shaft and the transverse adhesion coefficient of the secondary shaft. The calculation and comparison based on the longitudinal adhesion coefficient and the lateral adhesion coefficient of the axle to obtain the actual adhesion coefficient of the vehicle includes: Based on the longitudinal adhesion coefficient and the lateral adhesion coefficient of the main shaft, the actual utilized adhesion coefficient of the vehicle's main shaft is calculated. Based on the longitudinal adhesion coefficient and the lateral adhesion coefficient of the subshaft, the actual utilization adhesion coefficient of the vehicle's subshaft is calculated. The larger of the actual utilized adhesion coefficient of the main shaft and the actual utilized adhesion coefficient of the secondary shaft is determined as the overall actual utilized adhesion coefficient of the vehicle.

7. The method according to any one of claims 1 to 6, characterized in that, The step of determining the target road surface adhesion coefficient of the vehicle based on the actual adhesion coefficient used by the vehicle through retention attenuation analysis includes: A sudden drop test was performed on the vehicle, and the test results were obtained. If the detection result is that no sudden drop in the adhesion coefficient is detected, and / or the actual retention time of the adhesion coefficient used by the vehicle does not reach the preset time limit, and / or the vehicle is stationary, then the actual adhesion coefficient used is determined as the target road surface adhesion coefficient of the vehicle. Otherwise, the target road surface adhesion coefficient of the vehicle is obtained by filtering and attenuating based on the actual adhesion coefficient of the entire vehicle.

8. A system for determining the coefficient of friction of a vehicle road surface, characterized in that, include: The acquisition module is used to acquire the vehicle's tire dynamics response parameters; The first calculation and comparison module is used to calculate and compare the tire dynamic response parameters to obtain the longitudinal adhesion coefficient and the lateral adhesion coefficient of the vehicle. The second calculation and comparison module is used to calculate and compare the longitudinal adhesion coefficient and the transverse adhesion coefficient of the axle to obtain the actual adhesion coefficient of the vehicle. The adhesion coefficient determination module is used to perform a retention attenuation analysis based on the actual adhesion coefficient used by the vehicle to determine the target road surface adhesion coefficient of the vehicle.

9. A computing device, comprising a memory, a processor, and a program stored in the memory and running on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for determining the vehicle road surface adhesion coefficient as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed on a terminal device, cause the terminal device to perform the steps of a method for determining the vehicle road surface adhesion coefficient as described in any one of claims 1 to 7.

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