Method for detecting peak adhesion coefficient of road surface and related device and vehicle

Abstract

The application provides a detection method for a peak road surface adhesion coefficient, and related devices and a vehicle. The detection method comprises the following steps: acquiring a longitudinal slip rate of a wheel based on a driving state parameter of the vehicle; determining that the wheel is in a first working state based on the longitudinal slip rate of the wheel; acquiring at least one road surface estimated adhesion coefficient when the wheel is in the first working state, and determining a maximum value in the at least one road surface estimated adhesion coefficient as the peak road surface adhesion coefficient. The application can improve the detection accuracy of the peak road surface adhesion coefficient, and can expand the driving working condition range of the vehicle for detecting the peak road surface adhesion coefficient, and has low cost, simple operation and strong applicability.

Description

Technical Field

[0001] This application relates to the field of electronic technology, and in particular to a method and related device and vehicle for detecting the peak adhesion coefficient of road surface. Background Technology

[0002] The estimated coefficient of adhesion (COP) refers to the ability of a wheel to adhere to different road surfaces. The maximum value of the estimated COP is the peak COP. In the field of intelligent driving technology, the transmission of force between the wheel and the road surface is constrained by the peak COP. Therefore, accurate estimation of the peak COP is fundamental to active safety control of vehicles.

[0003] In practice, vehicles can add additional sensors to measure road surface features, thereby determining the road surface type and the corresponding peak coefficient of adhesion. Alternatively, vehicles can estimate the peak coefficient of adhesion by measuring and analyzing the response state after the interaction between the wheels and the road surface, such as acoustic state, deformation state, and motion state.

[0004] However, when vehicles use sensors to measure road surface features, the reliability of estimating the peak coefficient of adhesion (PCI) is affected by the high requirements of the optical operating environment for these sensors. Furthermore, when estimating PCI based on the wheel's response to road forces, the vehicle requires high accuracy in detecting the wheel's response, necessitating the minimization of interference from environmental or other factors. Therefore, accurately estimating PCI is a key research issue. Summary of the Invention

[0005] This application provides a method for detecting peak road adhesion coefficient, a device for detecting peak road adhesion coefficient, a vehicle control system, and a computer-readable storage medium. It can improve the detection accuracy of peak road adhesion coefficient, while expanding the range of vehicle driving conditions for detecting peak road adhesion coefficient. It is low in cost, simple to operate, and highly applicable.

[0006] In a first aspect, this application provides a method for detecting the peak road adhesion coefficient, the method comprising: obtaining the longitudinal slip ratio of a wheel based on the driving state parameters of a vehicle; determining that the wheel is in a first working state based on the longitudinal slip ratio of the wheel; obtaining at least one road surface estimated adhesion coefficient when the wheel is in the first working state, and determining the maximum value among the at least one road surface estimated adhesion coefficient as the peak road adhesion coefficient.

[0007] Secondly, this application also provides a device for detecting the peak adhesion coefficient of a road surface, the device comprising:

[0008] The acquisition module is used to obtain the longitudinal slip ratio of the wheels based on the vehicle's driving state parameters;

[0009] The working state determination module is used to determine that the wheel is in a first working state based on the longitudinal slip ratio of the wheel.

[0010] The adhesion coefficient determination module is used to obtain at least one road surface estimated adhesion coefficient when the wheel is in the first working state, and to determine the maximum value among the at least one road surface estimated adhesion coefficient as the road surface peak adhesion coefficient.

[0011] The aforementioned working state determination module is also used to determine that the wheel is in a second working state based on the longitudinal slip ratio of the wheel.

[0012] The aforementioned acquisition module is also used to acquire the vertical force of the aforementioned wheels based on the aforementioned vehicle's driving state parameters;

[0013] The aforementioned adhesion coefficient determination module is also used to determine the peak road adhesion coefficient of the aforementioned wheel based on the wheel's longitudinal stiffness, longitudinal slip ratio, and vertical force.

[0014] Thirdly, this application also provides a vehicle control system, the system including a processor, a display, and a road surface peak adhesion coefficient detection device provided in the second aspect; the processor is used to generate a safe braking distance based on the road surface peak adhesion coefficient output by the detection device, and transmit the safe braking distance to the display for display.

[0015] Fourthly, this application also provides a computer-readable storage medium storing a computer program adapted to be loaded and executed by a processor, so that a computer device having the processor performs the method provided in the first aspect.

[0016] Fifthly, this application also provides a vehicle, which includes a brake controller, wheel speed sensors, and the road surface peak adhesion coefficient detection device as described in the second aspect above; or, the vehicle includes a brake controller, wheel speed sensors, and a vehicle control system as described in the third aspect above; wherein the brake controller and the wheel speed sensors are used to collect the driving state parameters of the vehicle.

[0017] The method for detecting the peak road adhesion coefficient provided in this application determines whether the wheel is in the first working zone based on the wheel's longitudinal slip ratio. When the wheel is in the first working zone, the maximum value among multiple estimated road adhesion coefficients of the wheel is determined as the peak road adhesion coefficient of the wheel. This method can accurately obtain the peak road adhesion coefficient of the wheel in the first working zone, and it is simple to implement and highly accurate. Attached Figure Description

[0018] Figure 1 A schematic diagram of a system framework for a vehicle provided in an embodiment of this application;

[0019] Figure 2 A schematic diagram of a system framework for a road surface peak adhesion coefficient detection device provided in an embodiment of this application;

[0020] Figure 3 A schematic flowchart of a method for detecting the peak adhesion coefficient of a road surface provided in an embodiment of this application;

[0021] Figure 4 A schematic diagram of a curve provided for an embodiment of this application;

[0022] Figure 5 Another schematic diagram of the method for detecting the peak adhesion coefficient of the road surface provided in the embodiments of this application;

[0023] Figure 6 A schematic diagram of a device for detecting the peak adhesion coefficient of a road surface provided in an embodiment of this application;

[0024] Figure 7 A schematic diagram of the structure of a vehicle control system provided in an embodiment of this application;

[0025] Figure 8 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] The following sections will provide detailed explanations.

[0028] The terms "first," "second," "third," and "fourth," etc., used in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] The method for detecting peak road adhesion coefficient provided in this application can be applied to vehicles. By executing the method for detecting peak road adhesion coefficient, the peak road adhesion coefficient of the vehicle's wheels can be detected. The specific implementation is illustrated in the following examples.

[0031] See Figure 1 , Figure 1 This is a schematic diagram of a system framework for a vehicle provided in an embodiment of this application. Figure 1 As shown, the wheels of vehicle 10 include a left front wheel 1011, a right front wheel 1012, a left rear wheel 1013, and a right rear wheel 1014. For ease of understanding, Figure 1 The vehicle shown has four directions: front, back, left, and right. The left front wheel 1011 is located at the front left of the vehicle, the right front wheel 1012 is located at the front right of the vehicle, the left rear wheel 1013 is located at the rear left of the vehicle, and the right rear wheel 1014 is located at the rear right of the vehicle.

[0032] The vehicle 10 also includes multiple wheel speed sensors. Wheel speed sensor 1021 is connected to the left front wheel 1011 and can detect the rotational speed of the left front wheel 1011. Wheel speed sensor 1022 is connected to the right front wheel 1012 and can detect the rotational speed of the right front wheel 1012. Wheel speed sensor 1023 is connected to the left rear wheel 1013 and can detect the rotational speed of the left rear wheel 1013. Wheel speed sensor 1024 is connected to the right rear wheel 1014 and can detect the rotational speed of the right rear wheel 1014.

[0033] The vehicle 10 also includes a peak road adhesion coefficient detection device 103 and multiple signal harnesses. The peak road adhesion coefficient detection device 103 is connected to wheel speed sensor 1021 via signal harness 1041, to wheel speed sensor 1022 via signal harness 1042, to wheel speed sensor 1023 via signal harness 1043, and to wheel speed sensor 1024 via signal harness 1044. The peak road adhesion coefficient detection device 103 receives the rotational speeds of the left front wheel 1011, right front wheel 1012, left rear wheel 1013, and right rear wheel 1014 detected by the multiple wheel speed sensors via the corresponding signal harnesses. When executing the detection method provided in this embodiment, the peak road adhesion coefficient detection device 103 can calculate the wheel slip ratio based on the wheel speeds sent by the wheel speed sensors and other vehicle driving state parameters.

[0034] The vehicle 10 also includes multiple output shafts, multiple drive motors, and multiple drive motor controllers. Drive motor 1051 is connected to the left front wheel 1011 via output shaft 1061 and to drive motor controller 1071 via signal harness 1041. Drive motor 1052 is connected to the right front wheel 1012 via output shaft 1062 and to drive motor controller 1072 via signal harness 1042. Drive motor 1053 is connected to the left rear wheel 1013 via output shaft 1063 and to drive motor controller 1073 via signal harness 1043. Drive motor 1054 is connected to the right rear wheel 1014 via output shaft 1064 and to drive motor controller 1074 via signal harness 1044. It is understood that each of the aforementioned drive motor controllers is electrically connected to each drive motor through corresponding signal harnesses, and can control the operation of each drive motor, thereby driving the corresponding left front wheel 1011, right front wheel 1012, left rear wheel 1013 and right rear wheel 1014 to rotate respectively.

[0035] Furthermore, each of the aforementioned drive motor controllers is equipped with a motor torque sensor. The motor torque sensor can detect the first torque of the drive motor when the corresponding drive motor is driving the wheel to rotate, and send the detected first torque to the road surface peak adhesion coefficient detection device 103. When executing the detection method provided in this embodiment, the road surface peak adhesion coefficient detection device 103 can obtain the motor torque based on the first torque sent by the motor torque sensor, and obtain the longitudinal force of the wheel based on the motor torque and other vehicle driving state parameters.

[0036] The vehicle 10 also includes a steering controller 109, a brake controller 110, and multiple communication buses. The aforementioned peak road adhesion coefficient detection device 103 can be connected to the drive motor controller 1071 via communication bus 1081, to the drive motor controller 1072 via communication bus 1082, to the drive motor controller 1073 via communication bus 1083, to the drive motor controller 1074 via communication bus 1084, to the steering controller 109 via communication bus 1085, and to the brake controller 110 via communication bus 1086.

[0037] Furthermore, the aforementioned steering controller may include a wheel steering angle sensor. The wheel steering angle sensor can acquire the steering angle of the steering wheel and output it to the road surface peak adhesion coefficient detection device for processing.

[0038] Furthermore, the aforementioned brake controller may include a hydraulic brake torque sensor and a vehicle speed sensor. The hydraulic brake torque sensor detects a second torque from the drive motor and sends this detected second torque to the road surface peak adhesion coefficient detection device for processing. This second torque represents the torque exerted by the drive motor when braking the wheels. The vehicle speed estimator detects the vehicle speed and sends it to the road surface peak adhesion coefficient detection device for processing.

[0039] It is understood that when the vehicle provided in this application embodiment executes the detection method provided in this application embodiment, the road surface peak adhesion coefficient detection device can calculate the longitudinal slip ratio of the wheel based on the wheel steering angle sent by the steering angle sensor, the wheel speed sent by the wheel speed sensor, and the vehicle speed sent by the vehicle speed estimator. Similarly, the road surface peak adhesion coefficient detection device can also calculate the longitudinal force of the wheel based on the motor torque sent by the motor torque sensor, the braking torque sent by the hydraulic brake controller, and the wheel speed sent by the wheel speed sensor.

[0040] In this embodiment, the vehicle is a distributed wheel-side motor electric drive vehicle. It is understood that in other possible embodiments, the vehicle may also be a distributed hub motor electric drive vehicle, and the vehicle speed sensor may also be installed in the road surface peak adhesion coefficient detection device. This application does not limit the type of vehicle or the installation of the vehicle speed sensor.

[0041] The vehicle provided in this application embodiment can acquire its driving state parameters through conventional sensors and controllers. Furthermore, the peak road adhesion coefficient of the wheels can be obtained based on the vehicle's driving state parameters. It is understood that the vehicle provided in this application embodiment does not require the installation of additional sensors and controllers, thus reducing hardware costs.

[0042] In some feasible implementations, this application also provides a road surface peak adhesion coefficient detection device, which can be used to execute the road surface peak adhesion coefficient detection method provided in this application to detect the road surface peak adhesion coefficient of the wheel. The specific implementation is described in the following embodiments.

[0043] See Figure 2 , Figure 2 This is a schematic diagram of a system framework for a road surface peak adhesion coefficient detection device provided in an embodiment of this application. Figure 2As shown, the road surface peak adhesion coefficient detection device includes a wheel longitudinal force estimation module 201, a wheel vertical force estimation module 202, a wheel longitudinal slip ratio estimation module 203, an inertial measurement module 204, and a road surface peak adhesion coefficient estimation module 205. It is understood that the road surface peak adhesion coefficient detection device 20 provided in this application embodiment can be understood as described above. Figure 1 Peak road adhesion coefficient detection device 103 in vehicles.

[0044] The wheel longitudinal force estimation module 201 is connected to the vehicle's drive motor controller 21, brake controller 22, and wheel speed sensor 23. The drive motor controller 21 may include a motor torque sensor 211. When the drive motor controller 21 controls the drive motor to drive the corresponding wheels (e.g., the left front wheel, right front wheel, left rear wheel, and right rear wheel as described above), the motor torque sensor 211 detects the first torque of the drive motor and sends this detected first torque to the wheel longitudinal force estimation module 201 of the road surface peak adhesion coefficient detection device 20. The first torque can be understood as the torque when the drive motor drives the wheel to rotate. The wheel speed sensor 23 detects the wheel speed and sends it to the wheel longitudinal force estimation module 201.

[0045] It is understood that the brake controller 22 may include a hydraulic brake torque sensor 221 and a vehicle speed estimator 222. When the brake controller 22 brakes the corresponding wheels, such as the aforementioned left front wheel, right front wheel, left rear wheel, and right rear wheel, the hydraulic brake torque sensor 221 detects a second torque from the drive motor and sends the detected second torque to the wheel longitudinal force estimation module 201 of the road surface peak adhesion coefficient detection device 20. The second torque represents the torque of the drive motor when braking the wheel. It is understood that the vehicle speed estimator 222 can detect the vehicle speed and send the vehicle speed to the wheel longitudinal slip ratio estimation module 203 of the road surface peak adhesion coefficient detection device 20.

[0046] Furthermore, when the road surface peak adhesion coefficient detection device provided in this application embodiment executes the detection method provided in this application embodiment, the wheel longitudinal force can be calculated by the wheel longitudinal force estimation module 201 based on the first torque and second torque of the received drive motor and the wheel speed.

[0047] The inertial measurement module 204 is connected to the wheel vertical force estimation module 202 and the wheel longitudinal slip ratio estimation module 203, respectively. The inertial measurement module 204 measures the vehicle's longitudinal acceleration, lateral acceleration, and yaw rate and transmits them to the aforementioned wheel vertical force estimation module 202 and wheel longitudinal slip ratio estimation module 203.

[0048] The wheel longitudinal slip ratio estimation module 203 is connected to the vehicle speed estimator 222, the wheel steering angle sensor 241 and wheel speed sensor 23 in the steering controller 24, and the inertial measurement module 204, respectively. The wheel steering angle sensor 241 can detect the steering angle of the wheels. For example, when the vehicle's steering angle is that of the front wheels and the right front wheel, the wheel steering angle sensor 241 detects the steering angles of the left front wheel and the right front wheel, and sends the detected wheel steering angles to the wheel longitudinal slip ratio estimation module 203 of the road surface peak adhesion coefficient detection device 20.

[0049] Furthermore, when the road surface peak adhesion coefficient detection device provided in this application embodiment executes the detection method provided in this application embodiment, the wheel longitudinal slip ratio estimation module 203 can calculate the wheel slip ratio based on the received steering angle, vehicle speed, vehicle longitudinal acceleration, vehicle lateral acceleration, vehicle yaw rate and wheel speed.

[0050] The wheel vertical force estimation module 202 is connected to the inertial measurement module 204. When the road peak adhesion coefficient detection device provided in this application embodiment executes the detection method provided in this application embodiment, it can obtain the wheel vertical force based on the vehicle longitudinal acceleration and vehicle lateral acceleration output by the inertial measurement module 204, as well as the preset vehicle mass, center of gravity height, front axle track, rear axle track, and front and rear axle distance.

[0051] It is understood that the peak road adhesion coefficient estimation module 205 is connected to the aforementioned wheel longitudinal force estimation module 201, wheel vertical force estimation module 202, and wheel longitudinal slip ratio estimation module 203, respectively. When executing the detection method provided in this embodiment, the peak road adhesion coefficient detection device 20 can determine the wheel's peak road adhesion coefficient based on the longitudinal force output by the wheel longitudinal force estimation module 201, the vertical force output by the wheel vertical force estimation module 202, and the longitudinal slip ratio of the wheel longitudinal slip ratio estimation module 203.

[0052] In this embodiment, the road surface peak adhesion coefficient detection device, when executing the detection method provided in this embodiment, can receive vehicle driving state parameters transmitted by the drive motor controller, brake controller, speed sensor, and steering controller, and obtain the road surface peak adhesion coefficient of each wheel under different working states based on the vehicle driving state parameters. The road surface peak adhesion coefficient detection device provided in this embodiment can obtain the road surface peak adhesion coefficient of the wheel under different working states by using corresponding calculation methods when it is determined that the wheel is in a first working state or a second working state. It has high accuracy and is easy to implement, enabling active safety control of the vehicle and ensuring driving safety.

[0053] Based on the description of the road surface peak adhesion coefficient detection device and vehicle above, this application embodiment also provides a method for detecting the road surface peak adhesion coefficient. The aforementioned road surface peak adhesion coefficient detection device and vehicle can achieve accurate detection of the road surface peak adhesion coefficient of the wheels in the first working area by executing the implementation methods provided in the detection method of this application embodiment. The road surface peak adhesion coefficient detection method provided in this application embodiment can improve the detection accuracy of the road surface peak adhesion coefficient, while expanding the range of vehicle driving conditions for detecting the road surface peak adhesion coefficient. It is low in cost, simple to operate, and highly applicable.

[0054] The implementation of the technical solution of this application will be further described in detail below with reference to the accompanying drawings.

[0055] See Figure 3 , Figure 3 This is a schematic flowchart of a method for detecting the peak adhesion coefficient of road surface provided in an embodiment of this application. Figure 3 The detection method shown can be performed by a road surface peak adhesion coefficient detection device or a vehicle control system, and the method includes:

[0056] Step S101: Obtain the longitudinal slip ratio of the wheels based on the vehicle's driving state parameters.

[0057] It's important to explain that the peak coefficient of friction (PFF) is the maximum value of the road surface adhesion coefficient, representing the maximum longitudinal force the road surface can provide to the wheel. The higher the PFF, the less likely the vehicle is to slip. The wheel's coefficient of friction, on the other hand, refers to the ratio of the wheel's longitudinal force to its vertical force, and it characterizes the wheel's adhesion to the road surface. A higher coefficient of friction indicates a greater longitudinal force exerted by the road surface on the wheel. The longitudinal force of the wheel can be understood as the force exerted by the road surface on the wheel's longitudinal direction (i.e., the direction of the wheel's movement).

[0058] The peak coefficient of adhesion (PCI) of a wheel varies depending on its operating condition. Therefore, before measuring the PCI, the wheel's operating condition should be determined first. Then, based on this operating condition, appropriate calculation methods can be used to measure the PCI, thus improving accuracy.

[0059] In some feasible implementations, the wheel's operating state is related to its longitudinal slip ratio. For details, please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a schematic diagram of a curve provided for an embodiment of this application. For example... Figure 4As shown, when the longitudinal slip ratio is small, the wheel operates in the third working state. The longitudinal force of the wheel (which can be understood as friction) is less than the maximum longitudinal force that the road surface can provide. Therefore, the peak coefficient of adhesion (COP) cannot be calculated based on the wheel's longitudinal force. Furthermore, as the wheel speed increases, the longitudinal force also increases, and the vehicle only experiences slight slippage or no slippage. When the longitudinal slip ratio continues to increase, the wheel operates in the second working state. At this point, the wheel's longitudinal force is close to the maximum longitudinal force that the road surface can provide, but the COP calculated based on the wheel's longitudinal force is not equal to the peak COP at this time. Furthermore, as the wheel speed increases, the vehicle's longitudinal force also increases, and the vehicle begins to slip. Further, when the longitudinal slip ratio continues to increase, the wheel operates in the first working state, where the wheel's longitudinal force is equal to or exceeds the maximum longitudinal force that the road surface can provide. At this point, the COP calculated based on the wheel's longitudinal force is approximately equal to the peak COP. Furthermore, as the wheel speed increases, the vehicle's longitudinal force also increases, and the vehicle experiences severe slippage.

[0060] Therefore, the working state of the wheel can be determined based on the longitudinal slip ratio of the wheel, and according to the working characteristics of the wheel in different working states, a highly accurate method can be used to obtain the peak road adhesion coefficient of the wheel.

[0061] It should be understood that the longitudinal slip ratio of a wheel refers to the relative slippage between the wheel and the road surface when a vehicle skids. The degree of slippage between the wheel and the road surface can be expressed by the longitudinal slip ratio. For example, when a vehicle is traveling at a constant speed, the actual speed of the vehicle and the speed of its wheels are the same. When the driver applies the brake pedal to reduce the wheel speed, the circumferential speed of the wheel (i.e., the speed at which the tire surface moves on the road surface) also decreases. However, due to the overall inertia of the vehicle, the actual speed of the vehicle and the speed of the wheels are no longer equal, creating a speed difference between the vehicle speed and the wheel rotation speed. The greater the speed difference, the higher the wheel slip ratio, and consequently, the greater the coefficient of friction between the wheel and the road surface.

[0062] In some feasible implementations, the longitudinal slip ratio of the wheels can be obtained based on the vehicle's driving state parameters. Specifically, as mentioned above, the longitudinal slip ratio of the wheels can be understood as the difference between the vehicle's speed and the speed of the wheels in the vehicle's speed direction. Therefore, the speed of the wheels in the vehicle's speed direction can first be obtained based on the vehicle's driving state parameters, and then the longitudinal slip ratio can be calculated based on the speed of the wheels in the vehicle's speed direction and the vehicle's speed.

[0063] In some feasible implementations, the aforementioned driving state parameters may include the vehicle's yaw rate, wheel steering angle, rotational speed, and roll radius. The detection method provided in this application calculates the wheel's velocity in the vehicle's speed direction based on the aforementioned driving state parameters and the following formulas (1) to (4):

[0064]

[0065]

[0066]

[0067]

[0068] Among them, V fl V fr V rl V rr These represent the velocities of the left front wheel, right front wheel, left rear wheel, and right rear wheel in the direction of the vehicle's velocity, respectively; ω fl ω fr ω rl ω rr γ represents the rotational speeds of the vehicle's left front wheel, right front wheel, left rear wheel, and right rear wheel (unit: meters per second); γ represents the vehicle's yaw rate; δ represents the yaw rate of the vehicle's body. fl δ fr These represent the steering angles of the left and right front wheels, respectively.

[0069] It should be explained that, normally, a vehicle steers by rotating its left and right front wheels, while the rear wheels do not rotate. In this embodiment, because the left and right front wheels have steering angles, their velocity directions (i.e., the direction of their forward movement) may differ from the vehicle's speed direction. Therefore, it is necessary to correct the velocity directions of the left and right front wheels to the vehicle's speed direction based on their steering angles. For example, ω fl Let R be the rotational speed of the left front wheel. e ω fl Let d be the linear velocity of the left front wheel over its effective rolling radius. f γ / 2 is the linear velocity of the yaw rate of the front axle track of the vehicle body. The sum of γ / 2 is the velocity of the left front wheel in the forward direction. Furthermore, based on the vehicle body yaw rate, the velocity of the left front wheel in the forward direction can be mapped to the vehicle's speed direction; that is, the velocity of the left front wheel is corrected to the vehicle's speed direction to obtain the velocity of the left front wheel in the vehicle's speed direction. Similarly, the principle of correcting the velocity of the right front wheel to the vehicle's speed direction to obtain the velocity of the right front wheel in the vehicle's speed direction is described above and will not be repeated here.

[0070] In this embodiment, since the left and right rear wheels do not usually have a steering angle, their speed direction is in the direction of the vehicle's speed. Therefore, as shown in formulas (3) and (4), the speed of the left and right rear wheels in the direction of the vehicle's speed does not need to be corrected according to the steering angle.

[0071] In some feasible implementations, the detection method provided in this application embodiment can be achieved through the above-described... Figure 1 The vehicle speed is obtained by the vehicle speed estimator of the brake controller 110 of the vehicle 10, the steering angle of the steering wheel is obtained by the wheel steering angle sensor of the steering controller 109 of the vehicle 10, the wheel speed is obtained by the wheel speed sensor of the vehicle 10, and the inertial measurement module (i.e., the peak road adhesion coefficient estimation device 103 of the vehicle 10) is used to obtain the vehicle speed. Figure 2 The inertial measurement module 204 shown acquires the vehicle's yaw rate. Furthermore, the detection method provided in this application embodiment can be achieved through the above... Figure 2 The wheel slip ratio estimation module 203 in the road surface peak adhesion coefficient estimation device 20 obtains the speed in the vehicle speed direction based on the above driving state parameters.

[0072] Furthermore, after obtaining the wheel's velocity in the vehicle's velocity direction based on the above, the longitudinal slip ratio S of the wheel can be calculated using the following formula (5) based on the wheel's velocity in the vehicle's velocity direction and the vehicle's speed. ij :

[0073]

[0074] Where ij respectively include fl, fr, rl, rr, i.e., S fl S represents the longitudinal slip ratio of the left front wheel. fr S represents the longitudinal slip ratio of the right front wheel. rl S represents the longitudinal slip ratio of the left rear wheel. rr S represents the longitudinal slip ratio of the right rear wheel. ij V represents the longitudinal slip ratio of the corresponding wheel. ij This represents the velocity of the corresponding wheel in the direction of the vehicle's speed, i.e., V. fl V fr V rl V rr V represents the velocities of the left front wheel, right front wheel, left rear wheel, and right rear wheel in the direction of vehicle speed, respectively; ref The vehicle speed is represented by max(V). ij V ref This indicates the larger of the wheel's velocity in the direction of vehicle speed and the vehicle's speed.

[0075] It needs to be explained that the longitudinal slip ratio of a wheel refers to the slippage between the tire mark and the road surface when the wheel brakes or accelerates while traveling straight. According to the above formula (5), if the ratio of the difference between the wheel's corrected speed in the direction of the vehicle's speed and the vehicle's speed is greater than the larger value between the wheel's corrected speed in the direction of the vehicle's speed and the vehicle's speed, that is, the greater the difference between the wheel's corrected speed in the direction of the vehicle's speed and the vehicle's speed, then the longitudinal slip ratio of the wheel is higher, and the wheel is more prone to slippage.

[0076] In some feasible implementations, the detection method provided in this application embodiment can be achieved through the above-described... Figure 2 The wheel slip ratio estimation module 203 in the road surface peak adhesion coefficient estimation device 20 calculates the longitudinal slip ratio of the wheel based on the above driving state parameters.

[0077] In some feasible implementations, the wheel's operating state is related not only to the aforementioned longitudinal slip ratio but also to the road surface adhesion coefficient. For example... Figure 4 As shown, the coefficient of friction (COP) varies with the longitudinal slip ratio depending on the wheel's operating state. Specifically, in the third operating state, the COP increases linearly with the increase of the longitudinal slip ratio, indicating a linear positive correlation. In the second operating state, the COP curve rises with the increase of the longitudinal slip ratio, indicating a non-linear positive correlation. In the first operating state, the COP initially increases briefly with the increase of the longitudinal slip ratio, reaches a maximum value, and then gradually decreases with further increases in the longitudinal slip ratio. This is because the sliding friction coefficient between the wheel and the road surface is less than the static friction coefficient, thus the COP gradually decreases after reaching its maximum value. Therefore, the operating state of the wheel is related to both the wheel's longitudinal slip ratio and the COP.

[0078] Therefore, in order to accurately determine the working state of the wheel, the embodiments of this application can obtain the road surface adhesion coefficient and longitudinal slip ratio of the wheel, and determine the working state of the wheel based on the road surface adhesion coefficient and longitudinal slip ratio of the wheel.

[0079] In some feasible implementations, the estimated road adhesion coefficient of the wheels can be obtained based on the vehicle's driving state parameters, and this estimated road adhesion coefficient can be used as the aforementioned road adhesion coefficient. As can be seen from the above, the estimated road adhesion coefficient of the wheels refers to the ratio of the longitudinal force to the vertical force of the wheels. Therefore, the embodiments of this application can first obtain the longitudinal force and vertical force of the wheels based on the vehicle's driving state parameters.

[0080] Specifically, the detection method provided in this application embodiment calculates the longitudinal force F of the wheel based on the wheel's motor torque, braking torque, rolling radius, moment of inertia, rotational speed, and the following formula (6). x :

[0081]

[0082] Among them, T E T represents the motor torque of the wheel. B J represents the braking torque. w Let ω represent the moment of inertia of the wheel, ω represent the rotational speed of the wheel (unit: radians / second), and dω / dt represent the acceleration of the wheel. R represents the angular acceleration of the wheel. e This indicates the rolling radius of the wheel.

[0083] It needs to be explained that the motor torque of the wheel can generate rotational force, thus providing power for the wheel to rotate. The motor torque, by overcoming the braking force generated by the wheel's braking torque and the longitudinal force provided by the road surface, produces a net external torque, causing the wheel to rotate. By analyzing the various torques of the wheel in the longitudinal direction, the longitudinal torque of the wheel can be calculated, and the longitudinal force of the wheel corresponding to this longitudinal torque can be calculated based on the wheel's rolling radius.

[0084] In some feasible implementations, the detection method provided in this application embodiment can be achieved through the above-described... Figure 1 The drive motor controller of vehicle 10 acquires the motor torque via a motor torque sensor, and the brake controller 110 of vehicle 10 acquires the second torque of the drive motor via a hydraulic brake torque sensor, determining the detected second torque as the aforementioned brake torque. The wheel speed is then acquired via a wheel speed sensor of vehicle 10. Furthermore, the detection method provided in this application embodiment can utilize the above-described... Figure 2 The wheel longitudinal force estimation module 201 in the road surface peak adhesion coefficient estimation device 20 obtains the longitudinal force of the vehicle based on the above driving state parameters.

[0085] Specifically, the detection method provided in this application embodiment calculates the vertical force of the wheels based on the vehicle's mass, center of gravity height, front axle track width, rear axle track width, wheelbase, distance from the front axle to the vehicle's center of gravity, distance from the rear axle to the vehicle's center of gravity, longitudinal acceleration of the vehicle body, and lateral acceleration of the vehicle body, as well as the following formulas (7) to (10):

[0086]

[0087]

[0088]

[0089]

[0090] Among them, F zfl F zfr F zrl F zrr Let represent the vertical forces on the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively; m represent the mass of the vehicle; g represent the acceleration due to gravity; a represent the distance from the front axle to the vehicle's center of gravity; b represent the distance from the rear axle to the vehicle's center of gravity; L represent the wheelbase; H represent the height of the vehicle's center of gravity; and d represent the vertical forces on the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively. f d r These represent the front axle track and the rear axle track, respectively. x a represents the longitudinal acceleration of the vehicle body. y This indicates the lateral acceleration of the vehicle body.

[0091] It should be explained that the vertical force of a vehicle refers to the supporting force that the wheel experiences perpendicularly to the ground. During the vehicle's movement, the force exerted on each wheel by the vehicle body may be different, influenced by the vehicle body's longitudinal acceleration and lateral acceleration. For example, when the vehicle accelerates forward, the forces exerted on the left and right rear wheels by the vehicle body are greater than those exerted on the left and right front wheels; when the vehicle accelerates to the left, the forces exerted on the left front and left rear wheels by the vehicle body are greater than those exerted on the right front and right rear wheels. Therefore, according to the formulas (7) to (10) above, the forces exerted on each wheel by the vehicle body can be calculated separately. Then, based on the characteristic that the vertical force of the wheel is equivalent to the force exerted on each wheel by the vehicle body, the vertical force of each wheel can be obtained.

[0092] In some feasible implementations, the detection method provided in this application embodiment can be achieved through the above-described... Figure 2 The wheel vertical force estimation module 202, which estimates the peak road adhesion coefficient 20, obtains the wheel vertical force. Specifically, the vehicle's longitudinal acceleration, lateral acceleration, and preset vehicle mass, center of gravity height, front axle track width, rear axle track width, and front and rear axle widths can be obtained through the inertial measurement module 204, which estimates the peak road adhesion coefficient 20. Furthermore, the detection method provided in this application embodiment can utilize the above-described... Figure 2 The wheel vertical force estimation module 202 in the road surface peak adhesion coefficient estimation device 20 obtains the wheel vertical force based on the vehicle longitudinal acceleration and vehicle lateral acceleration output by the aforementioned inertial measurement module 204, as well as the preset vehicle mass, center of gravity height, front axle track, rear axle track, and front and rear axle distance.

[0093] It is understandable that after obtaining the longitudinal and vertical forces of the wheel based on the above, the road surface adhesion coefficient of the wheel can be estimated based on the ratio of the longitudinal force to the vertical force. Specifically, the road surface adhesion coefficient μ1 of the wheel can be obtained based on the following formula (11):

[0094]

[0095] Where μ1 represents the estimated road adhesion coefficient, F x F represents the longitudinal force of the wheel. z This represents the vertical force on the wheel.

[0096] It needs to be explained that during the vehicle's movement, since the vehicle's longitudinal force can be understood as the frictional force provided by the road surface to the vehicle, the road surface estimated adhesion coefficient can be understood as the road surface sliding friction coefficient. Moreover, the magnitude of the vehicle's longitudinal force is inversely proportional to the vehicle's vertical force. Therefore, based on the characteristics that the longitudinal force of the wheel is equal to the road surface frictional force received by the wheel, and the vertical force of the wheel is equal to the force applied by the vehicle body to each wheel, the road surface estimated adhesion coefficient (i.e., sliding friction coefficient) of the wheel can be calculated according to the above formula (11).

[0097] In some feasible implementations, the detection method provided in this application embodiment can be achieved through the above-described... Figure 2 The peak adhesion coefficient estimation module 205 in the road surface peak adhesion coefficient estimation device 20 can, according to... Figure 2 The wheel longitudinal force output by the wheel longitudinal force estimation module 201, the wheel vertical force output by the wheel vertical force estimation module 202, and the wheel longitudinal slip ratio output by the vehicle longitudinal slip ratio estimation module 203 are used to calculate the estimated road adhesion coefficient of the wheel.

[0098] Step S102: Determine that the wheel is in the first working state based on the longitudinal slip ratio of the wheel.

[0099] As can be seen from the above, the working state of a wheel is related to its longitudinal slip ratio. When the wheel is in the third working state, the slip ratio is very small, and the estimated road adhesion coefficient is random and uncertain. However, when the wheel is in the first working state, the slip ratio is large, and the estimated road adhesion coefficient is approximately equal to the peak road adhesion coefficient. Therefore, this embodiment can determine whether the wheel is in the first working state based on its longitudinal slip ratio, thereby detecting the peak road adhesion coefficient of the wheel in the first working state.

[0100] In some feasible implementations, when the longitudinal slip ratio of the wheel meets condition ①: the absolute value of the longitudinal slip ratio is greater than or equal to a first preset absolute value threshold, the wheel is in a first working state.

[0101] It needs to be explained that, such as Figure 4 As shown, when the longitudinal slip ratio of the wheel is small, the wheel is in the third working state. As the longitudinal slip ratio of the wheel gradually increases, the wheel can transition from the third working state to the second working state. When the longitudinal slip ratio of the wheel continues to increase, the wheel can transition from the second working state to the first working state. Therefore, the working state of the wheel can be determined based on the magnitude of its longitudinal slip ratio.

[0102] It is understood that the first preset absolute value threshold in condition ① of this application embodiment can be interpreted as the absolute value of the longitudinal slip ratio corresponding to the wheel transitioning from the second working state to the first working state. Therefore, when the longitudinal slip ratio of the wheel satisfies condition ①, that is, when the absolute value of the longitudinal slip ratio of the wheel is greater than or equal to the first preset absolute value threshold, the wheel is in the first working state.

[0103] For example, such as Figure 4 As shown, when the longitudinal slip ratio of the wheel is greater than 0.12, the estimated road adhesion coefficient briefly rises to its maximum value and then gradually decreases as the longitudinal slip ratio increases. That is, the wheel is in its first working state when the longitudinal slip ratio is greater than 0.12. Therefore, a first preset absolute value threshold of 0.12 can be obtained. Furthermore, when the absolute value of the longitudinal slip ratio of the wheel is greater than or equal to 0.12, the wheel is in its first working state.

[0104] In some feasible implementations, when the longitudinal slip ratio of the wheel meets condition ②: the rate of change of the absolute value of the longitudinal slip ratio is greater than or equal to the first preset rate of change threshold, the wheel is in the first working state.

[0105] It needs to be explained that the absolute value of the wheel's longitudinal slip ratio differs depending on the wheel's operating state, and the rate of change of this absolute value also differs. The rate of change of the absolute value of the wheel's longitudinal slip ratio can be understood as the difference between the absolute value of the wheel's longitudinal slip ratio at the current moment and the absolute value at the previous moment. When the wheel is in the first operating state, as mentioned above, the wheel is in a state of severe slippage, and at this time, the wheel's longitudinal slip ratio changes constantly. Therefore, the wheel can be determined to be in the first operating state if the rate of change of the absolute value of the wheel's longitudinal slip ratio is greater than or equal to 0; that is, the first preset rate of change threshold can be set to 0.

[0106] In some feasible implementations, as can be seen from the above, the embodiments of this application can also determine the first working state of the wheel based on the longitudinal slip ratio of the wheel and the road surface to estimate the adhesion coefficient.

[0107] In some feasible implementations, when the longitudinal slip ratio of the wheel and the estimated road surface adhesion coefficient meet condition ③: the ratio of the estimated road surface adhesion coefficient of the wheel to the longitudinal slip ratio is less than or equal to a first preset ratio threshold, the wheel is in the first working state.

[0108] Specifically, the ratio of the estimated road adhesion coefficient to the longitudinal slip ratio of the aforementioned wheel can be understood as: Figure 4 The secant slope of the curve, i.e., the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio, can be understood as the secant slope at a point on the curve corresponding to the wheel's longitudinal slip ratio. Furthermore, the aforementioned ratio K of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio... s The following formula (12) can be used for calculation:

[0109]

[0110] Where μ1 represents the estimated road adhesion coefficient of the wheel, and s represents the longitudinal slip ratio of the wheel.

[0111] It needs to be explained that, such as Figure 4 As shown, the secant slope of the curve differs depending on the wheel's operating state, indicating that the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio varies. When the wheel is in the third operating state, the secant slope of the corresponding curve is assumed to be the third secant slope. It can be seen that the third secant slope is relatively large and does not change with the wheel's longitudinal slip ratio. When the wheel is in the second operating state, the secant slope of the corresponding curve is assumed to be the second secant slope. It can be seen that the second secant slope is smaller than the third secant slope and changes slightly with the wheel's longitudinal slip ratio. When the wheel is in the first operating state, the secant slope of the corresponding curve is assumed to be the first secant slope. It can be seen that the first secant slope is smaller than the second secant slope and changes significantly with the wheel's longitudinal slip ratio. Therefore, the wheel's operating state can be determined based on the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio, i.e., the aforementioned secant slope.

[0112] For example, such as Figure 4 As shown, when the wheel is in the first working state, the slope of the secant of the corresponding curve is less than or equal to 10, so the first preset ratio threshold can be set to 10. When the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio is less than or equal to 10, the wheel is in the first working state.

[0113] In some feasible implementations, when the longitudinal slip ratio of the wheel and the estimated road surface adhesion coefficient meet condition ④: the ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is less than or equal to a first preset differential threshold, the wheel is in the first working state.

[0114] It should be explained that the detection method provided in this application can acquire the estimated road surface adhesion coefficient and longitudinal slip ratio of the wheel at different times. After acquiring the estimated road surface adhesion coefficient and longitudinal slip ratio of the wheel at multiple times, the change in the estimated road surface adhesion coefficient can be determined based on the difference between the estimated road surface adhesion coefficient of the wheel at any current time and the estimated road surface adhesion coefficient of the wheel at the previous time, i.e., the difference calculation result of the estimated road surface adhesion coefficient. Similarly, the change in the longitudinal slip ratio can be determined based on the difference between the longitudinal slip ratio of the wheel at any current time and the longitudinal slip ratio of the wheel at the previous time, i.e., the difference calculation result of the longitudinal slip ratio.

[0115] Furthermore, the ratio of the change in the estimated road adhesion coefficient at any of the above moments to the change in the longitudinal slip ratio at the same moment can be understood as: Figure 4 The tangent slope of the curve, which is the ratio of the change in the estimated road adhesion coefficient at any given moment to the change in the longitudinal slip ratio at the same moment, can be understood as the tangent slope of a point on the curve corresponding to the longitudinal slip ratio of the wheel.

[0116] Furthermore, the ratio K of the change in the estimated road adhesion coefficient at any of the above moments to the change in the longitudinal slip ratio at the same moment is... t The following formula (13) can be used for calculation:

[0117]

[0118] Where Δμ1 represents the change in the estimated road adhesion coefficient μ1 of the wheel (differential calculation result), and Δ|s| represents the change in the absolute value of the longitudinal slip ratio s of the wheel (differential calculation result).

[0119] It needs to be explained that, such as Figure 4 As shown, the tangent slope of the curve differs depending on the wheel's operating state; that is, the ratio of the change in the estimated road adhesion coefficient to the change in the longitudinal slip ratio at any given moment varies. When the wheel is in the third operating state, the tangent slope of the corresponding curve is assumed to be the third tangent slope. It can be seen that the third tangent slope is relatively large and does not change with the wheel's longitudinal slip ratio. When the wheel is in the second operating state, the tangent slope of the corresponding curve is assumed to be the second tangent slope. It can be seen that the second tangent slope is smaller than the third tangent slope and gradually decreases with the change in the wheel's longitudinal slip ratio. When the wheel is in the first operating state, the tangent slope of the corresponding curve is assumed to be the first tangent slope. It can be seen that the first tangent slope is smaller than the second tangent slope and decreases significantly with the change in the wheel's longitudinal slip ratio. Therefore, the wheel's operating state can be determined based on the ratio of the change in the estimated road adhesion coefficient to the change in the longitudinal slip ratio at any given moment, i.e., the aforementioned tangent slope.

[0120] For example, such as Figure 4 As shown, when the wheel is in the first working state, the slope of the tangent line of the corresponding curve is less than or equal to 0, so the first preset difference threshold can be set to 0. When the ratio of the change in the estimated road surface adhesion coefficient at any given time to the change in the longitudinal slip ratio at the same time is less than or equal to 0, the wheel is in the first working state.

[0121] In some feasible implementations, in order to accurately determine whether the wheel is in the first working state, the wheel can be determined to be in the first working state when at least two of the above conditions ① to ④ are met simultaneously, based on the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface.

[0122] In some feasible implementations, the detection method provided in this application can obtain the ratio of the estimated road adhesion coefficient to the longitudinal slip ratio of the wheel (i.e., the secant slope mentioned above) and the ratio of the change in the estimated road adhesion coefficient at any given time to the change in the longitudinal slip ratio at the same time (i.e., the tangent slope mentioned above) based on the recursive least squares (RLS) method. The secant slope or tangent slope mentioned above can be calculated based on the following formulas (14) to (17):

[0123]

[0124] e(n)=d(n)-w(n-1)u(n) Formula (15)

[0125] w(n)=w(n-1)+k H (n)e(n) Formula (16)

[0126] P(n)=λ -1 P(n-1)-λ -1 k(n)u H (n)P(n-1) Formula (17)

[0127] Where n represents the current time sequence number; u(n) represents the input parameters at different times, which can be the absolute value of the longitudinal slip ratio of the wheel |s|, or the rate of change of the absolute value of the longitudinal slip ratio of the wheel |s| Δ|s|; P(n) represents the covariance matrix; k(n) represents the gain matrix; w represents the weight vector, i.e., the secant slope or tangent slope; e(n) represents the prior estimation error; d(n) represents the target parameter, which can be the road surface estimated adhesion coefficient μ1 of the wheel, or the rate of change of the road surface estimated adhesion coefficient of the wheel Δμ1; λ is the forgetting factor, which is generally less than and close to 1, usually taken as 0.95.

[0128] For example, in the embodiments of this application, the weight vector w of the filter can be adjusted and updated using the RLS algorithm through the RLS adaptive filter. That is, the weight vector w of the adaptive filter is the time-varying coefficient updated by the RLS algorithm.

[0129] When the RLS adaptive filter obtains the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio (i.e., the secant slope) based on the aforementioned RLS algorithm, the absolute value of the wheel's longitudinal slip ratio can be used as the input parameter u(n) of the RLS adaptive filter, and the wheel's estimated road surface adhesion coefficient can be determined as the target parameter d(n) of the RLS adaptive filter. Specifically, the RLS adaptive filter can obtain the wheel's estimated road surface adhesion coefficient and longitudinal slip ratio at multiple times, and use the absolute value of the wheel's longitudinal slip ratio at any given time as u(n), and perform calculations based on the aforementioned formulas (17) and (14) to update the covariance matrix P(n) and gain matrix k(n) of the RLS adaptive filter. Furthermore, when the RLS adaptive filter receives the estimated road surface adhesion coefficient d(n) at any given time, it can calculate the difference between the estimated road surface adhesion coefficient at the current time and the product of the secant slope and the absolute value of the wheel's longitudinal slip ratio at the previous time based on the aforementioned formula (15), thereby obtaining the prior estimation error e(n) of the secant slope at the previous time. It is understandable that after calculating the prior estimation error e(n) above, the RLS adaptive filter can output the tangent slope w(n) obtained at the current time based on the secant slope w(n-1) of the previous time in formula (16) and the updated gain matrix k(n), which is the ratio of the road surface estimated adhesion coefficient of the wheel to the longitudinal slip ratio at the current time.

[0130] Similarly, embodiments of this application can obtain the ratio of the change in the estimated adhesion coefficient of the road surface at any given time to the change in the longitudinal slip ratio at the same time, i.e., the aforementioned tangent slope, based on the above content. Further details will not be elaborated upon here.

[0131] It is understood that the embodiments of this application use the aforementioned RLS adaptive filter to obtain the ratio of the change in the estimated road surface adhesion coefficient to the change in the longitudinal slip ratio at any given time, or the ratio of the estimated road surface adhesion coefficient to the longitudinal slip ratio of the wheel. The RLS adaptive filter can filter out noise when there is noise in the changes in the wheel's longitudinal slip ratio, the estimated road surface adhesion coefficient, the estimated road surface adhesion coefficient, or the longitudinal slip ratio, thereby obtaining a more stable secant slope or tangent slope and ensuring the accuracy of the calculation results.

[0132] Step S103: Obtain at least one road surface estimated adhesion coefficient when the wheel is in the first working state, and determine the maximum value among the at least one road surface estimated adhesion coefficient as the road surface peak adhesion coefficient.

[0133] In some feasible implementations, as can be seen from the above, when the wheel is in the first working state, the wheel slips severely. At this time, the estimated road surface adhesion coefficient of the wheel is approximately equal to the peak road surface adhesion coefficient of the wheel. Therefore, after determining that the wheel is in the first working state, this embodiment of the application can acquire and record at least one estimated road surface adhesion coefficient of the wheel during the first working state, and determine the maximum value among the at least one estimated road surface adhesion coefficient as the peak road surface adhesion coefficient of the wheel in the first working state.

[0134] It is understandable that when the wheel is in its first working state, the road surface adhesion coefficient of the wheel can be estimated based on the ratio of the longitudinal force to the vertical force of the wheel. Specifically, the implementation method for obtaining at least one road surface adhesion coefficient of the wheel can refer to the implementation method of step S101 above, which will not be elaborated here.

[0135] This application embodiment determines the wheel's first working state based on the wheel's longitudinal slip ratio and the road surface estimated adhesion coefficient. When the wheel is in the first working state, the peak road surface adhesion coefficient is determined based on the maximum value among at least one obtained road surface estimated adhesion coefficient. This can improve the accuracy of detecting the peak road surface adhesion coefficient of the wheel in the first working state, and is easy to implement and highly adaptable.

[0136] In some feasible implementations, see Figure 5 , Figure 5 This is another schematic flowchart of the method for detecting the peak adhesion coefficient of road surface provided in the embodiments of this application. Figure 5 The specific implementation methods of steps S201-S203 shown can be referred to the specific implementation methods of steps S101-S103 above, and will not be repeated here. Figure 5 As shown, the process also includes:

[0137] Step S204: Determine that the wheel is in the second working state based on the longitudinal slip ratio of the wheel.

[0138] As described above, the working state of a wheel is related to its longitudinal slip ratio. When the wheel is in its third working state, the slip ratio is very small, and the estimated road adhesion coefficient is random and uncertain. When the wheel is in its first working state, the slip ratio is large, and the estimated road adhesion coefficient is approximately equal to the peak road adhesion coefficient. However, when the wheel is in its second working state, the slip ratio is relatively large, and the estimated road adhesion coefficient is not equal to the peak road adhesion coefficient. Therefore, the method for obtaining the peak road adhesion coefficient can differ depending on the wheel's working state. This embodiment of the application can determine whether the wheel is in its second working state based on its longitudinal slip ratio, and then detect the peak road adhesion coefficient of the wheel in the second working state using a corresponding detection method.

[0139] In some feasible implementations, when the longitudinal slip ratio of the wheel meets condition ⑤: the absolute value of the longitudinal slip ratio is greater than or equal to the second preset absolute value threshold, the wheel is in the second working state.

[0140] It needs to be explained that, such as Figure 4 As shown, when the longitudinal slip ratio of the wheel is small, the wheel is in the third working state. As the longitudinal slip ratio of the wheel gradually increases, the wheel can transition from the third working state to the second working state. When the longitudinal slip ratio of the wheel continues to increase, the wheel can transition from the second working state to the first working state. Therefore, the working state of the wheel can be determined based on the magnitude of its longitudinal slip ratio.

[0141] It is understood that the second preset absolute value threshold in condition ⑤ of this application embodiment can be interpreted as the absolute value of the longitudinal slip ratio corresponding to the wheel transitioning from the third working state to the second working state. Therefore, when the longitudinal slip ratio of the wheel satisfies condition ⑤, that is, when the absolute value of the longitudinal slip ratio of the wheel is greater than or equal to the second preset absolute value threshold, the wheel is in the second working state.

[0142] For example, such as Figure 4 As shown, when the wheel's longitudinal slip ratio is greater than 0.03, the estimated road adhesion coefficient is no longer linearly correlated with the longitudinal slip ratio. As the longitudinal slip ratio increases, the increase in the estimated road adhesion coefficient gradually decreases. That is, when the wheel's longitudinal slip ratio is greater than 0.03, the wheel is in its second working state. Therefore, a second preset absolute value threshold of 0.03 can be obtained. Furthermore, when the absolute value of the wheel's longitudinal slip ratio is greater than or equal to 0.03, the wheel is in its second working state.

[0143] In some feasible implementations, when the longitudinal slip ratio of the wheel meets condition ⑥: the rate of change of the absolute value of the longitudinal slip ratio is greater than or equal to the second preset rate of change threshold, the wheel is in the second working state.

[0144] It needs to be explained that the absolute value of the wheel's longitudinal slip ratio differs depending on the wheel's operating state, and the rate of change of this absolute value also differs. The rate of change of the absolute value of the wheel's longitudinal slip ratio can be understood as the difference between the absolute value of the wheel's longitudinal slip ratio at the current moment and the absolute value at the previous moment. When the wheel is in the second operating state, as mentioned above, the wheel is in a state where slippage has begun, and the change in the wheel's longitudinal slip ratio is significant. Therefore, the wheel can be determined to be in the second operating state if the rate of change of the absolute value of the wheel's longitudinal slip ratio is greater than or equal to 0.1; that is, the second preset rate of change threshold can be set to 0.1.

[0145] In some feasible implementations, in order to accurately determine whether the wheel is in the second working state, the wheel can be determined to be in the second working state when the longitudinal slip ratio of the wheel simultaneously meets the above conditions ⑤ and ⑥.

[0146] In some feasible implementations, as can be seen from the above, the embodiments of this application can also determine that the wheel is in a second working state based on the longitudinal slip ratio of the wheel and the road surface to estimate the adhesion coefficient.

[0147] In some feasible implementations, when the longitudinal slip ratio of the wheel and the estimated road surface adhesion coefficient meet condition ⑦: the ratio of the estimated road surface adhesion coefficient of the wheel to the longitudinal slip ratio is greater than or equal to a second preset ratio threshold, the wheel is in a second working state.

[0148] It needs to be explained that, such as Figure 4 As shown, the secant slope of the curve differs depending on the wheel's operating state, indicating that the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio varies. When the wheel is in the third operating state, the secant slope of the corresponding curve is assumed to be the third secant slope. It can be seen that the third secant slope is relatively large and does not change with the wheel's longitudinal slip ratio. When the wheel is in the second operating state, the secant slope of the corresponding curve is assumed to be the second secant slope. It can be seen that the second secant slope is smaller than the third secant slope and changes slightly with the wheel's longitudinal slip ratio. When the wheel is in the first operating state, the secant slope of the corresponding curve is assumed to be the first secant slope. It can be seen that the first secant slope is smaller than the second secant slope and changes significantly with the wheel's longitudinal slip ratio. Therefore, the wheel's operating state can be determined based on the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio, i.e., the aforementioned secant slope.

[0149] For example, such as Figure 4As shown, when the wheel is in the second working state, if the slope of the secant line of the corresponding curve is greater than or equal to 10, then the above-mentioned second preset ratio threshold can be set to 22. When the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio is greater than or equal to 22, the wheel is in the second working state.

[0150] In some feasible implementations, when the longitudinal slip ratio of the wheel and the estimated road surface adhesion coefficient meet condition ⑧: the ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is greater than or equal to the second preset differential threshold, the wheel is in the second working state.

[0151] It needs to be explained that, such as Figure 4 As shown, the tangent slope of the curve differs depending on the wheel's operating state; that is, the ratio of the change in the estimated road adhesion coefficient to the change in the longitudinal slip ratio at any given moment varies. When the wheel is in the third operating state, the tangent slope of the corresponding curve is assumed to be the third tangent slope. It can be seen that the third tangent slope is relatively large and does not change with the wheel's longitudinal slip ratio. When the wheel is in the second operating state, the tangent slope of the corresponding curve is assumed to be the second tangent slope. It can be seen that the second tangent slope is smaller than the third tangent slope and gradually decreases with the change in the wheel's longitudinal slip ratio. When the wheel is in the first operating state, the tangent slope of the corresponding curve is assumed to be the first tangent slope. It can be seen that the first tangent slope is smaller than the second tangent slope and decreases significantly with the change in the wheel's longitudinal slip ratio. Therefore, the wheel's operating state can be determined based on the ratio of the change in the estimated road adhesion coefficient to the change in the longitudinal slip ratio at any given moment, i.e., the aforementioned tangent slope.

[0152] For example, such as Figure 4 As shown, when the wheel is in the second working state, if the slope of the tangent line of the corresponding curve is greater than or equal to 20, then the second preset difference threshold can be set to 20. When the ratio of the change in the estimated road surface adhesion coefficient at any given time to the change in the longitudinal slip ratio at the same time is greater than or equal to 20, the wheel is in the second working state.

[0153] In some feasible implementations, when the longitudinal slip ratio of the wheel and the estimated road surface adhesion coefficient meet the condition ⑨: the rate of change of the ratio of the estimated road surface adhesion coefficient of the wheel to the longitudinal slip ratio is greater than or equal to the first preset ratio change rate threshold and less than or equal to the second preset ratio change rate threshold, the wheel is in the second working state.

[0154] It needs to be explained that, such as Figure 4As shown, the rate of change of the secant slope of the corresponding curve, i.e., the rate of change of the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio, varies depending on the wheel's operating state. Specifically, the rate of change of the secant slope of the corresponding curve is greater when the wheel is in the second operating state than when it is in the third operating state, but smaller than when it is in the first operating state. Therefore, the operating state of the wheel can be determined based on the rate of change of the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio.

[0155] For example, such as Figure 4 As shown, when the wheel is in the second working state, if the rate of change of the secant slope of the corresponding curve is greater than or equal to -1 and less than or equal to -0.05, then the aforementioned first preset ratio change rate threshold can be set to -1 and the aforementioned first preset ratio change rate threshold can be set to -0.05. When the rate of change of the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio is greater than or equal to -1 and less than or equal to -0.05, the wheel is in the second working state.

[0156] In some feasible implementations, when the longitudinal slip ratio of the wheel and the estimated road surface adhesion coefficient meet condition 10: the rate of change of the ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is greater than or equal to the first preset differential rate of change threshold and less than or equal to the second preset differential rate of change threshold, the wheel is in the second working state.

[0157] It should be explained that, after obtaining the ratio of the change in the estimated road adhesion coefficient at any given time to the change in the longitudinal slip ratio at the same time based on the above content, further, the rate of change of the ratio of the change in the estimated road adhesion coefficient at any given time to the change in the longitudinal slip ratio at the same time can be obtained by taking the difference between the ratio of the ratio of the change in the estimated road adhesion coefficient at any given time to the change in the longitudinal slip ratio at the same time and the ratio of the ratio of the change in the estimated road adhesion coefficient at the previous time to the change in the longitudinal slip ratio at the same time.

[0158] Furthermore, such as Figure 4 As shown, the rate of change of the tangent slope of the corresponding curve, i.e., the rate of change of the ratio of the change in the estimated road surface adhesion coefficient to the change in the longitudinal slip ratio at any given moment, varies depending on the wheel's operating state. Specifically, when the wheel is in the second operating state, the rate of change of the secant slope of the corresponding curve is greater than that when the wheel is in the third operating state, but smaller than that when the wheel is in the first operating state. Therefore, the operating state of the wheel can be determined based on the rate of change of the ratio of the estimated road surface adhesion coefficient to the longitudinal slip ratio.

[0159] For example, such as Figure 4 As shown, when the wheel is in the second working state, if the rate of change of the tangent slope of the corresponding curve is greater than or equal to -1 and less than or equal to -0.05, then the first preset differential rate of change threshold can be set to -1, and the second preset differential rate of change threshold can be set to -0.05. When the rate of change of the ratio of the wheel's estimated road surface adhesion coefficient to its longitudinal slip ratio is greater than or equal to -1 and less than or equal to -0.05, the wheel is in the second working state.

[0160] In some feasible implementations, in order to accurately determine whether the wheel is in the second working state, the wheel can be determined to be in the second working state when at least two of the above conditions ⑤ to ⑩ are met simultaneously, based on the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface.

[0161] It is understood that the embodiments of this application can obtain the ratio of the change in the estimated road surface adhesion coefficient to the change in the longitudinal slip ratio at any given time, or the ratio of the estimated road surface adhesion coefficient to the longitudinal slip ratio of the wheel, by using the aforementioned RLS adaptive filter. Specifically, refer to the detailed implementation of step S102 above; this embodiment will not elaborate further here. It is understood that the RLS adaptive filter can filter out the influence of noise when there is noise in the change in the wheel's longitudinal slip ratio, the change in the estimated road surface adhesion coefficient, the estimated road surface adhesion coefficient, or the longitudinal slip ratio, thereby obtaining a more stable secant slope or tangent slope and ensuring the accuracy of the calculation results.

[0162] Step S205: Obtain the vertical force of the wheels based on the vehicle's driving state parameters.

[0163] Understandably, in order to accurately obtain the peak road adhesion coefficient of the wheel in the second working state, the peak road adhesion coefficient of the wheel in the second working state can be calculated based on the nonlinear identification part of the Dugoff tire model according to the vertical force of the wheel, as well as the wheel's longitudinal stiffness and longitudinal slip ratio. Therefore, after determining that the wheel is in the second working state, the detection method provided in this application embodiment can obtain the vertical force of the wheel based on the vehicle's driving state parameters.

[0164] The specific implementation method for obtaining the vertical force of the wheel based on the vehicle's driving state parameters in this embodiment can refer to the specific implementation method of step S101 above, and will not be repeated here.

[0165] Step S206: Determine the peak road adhesion coefficient of the wheel based on the wheel's longitudinal stiffness, longitudinal slip ratio, and vertical force.

[0166] Understandably, after obtaining the vertical force, longitudinal stiffness, and longitudinal slip ratio of the wheel, the peak road adhesion coefficient μ2 of the wheel can be calculated further according to the following formula (18) of the Dugoff tire model:

[0167]

[0168] Among them, C x F represents the longitudinal stiffness of the wheel. z represents the vertical force of the wheel, and s represents the longitudinal slip ratio of the wheel.

[0169] It should be explained that wheel longitudinal stiffness refers to the stiffness characteristics of a wheel in the longitudinal direction. It describes the stability and grip of the wheel during acceleration and braking. For example, the greater the wheel longitudinal stiffness, the smaller the deformation of the wheel during acceleration and braking, and the better the vehicle's stability and braking performance.

[0170] Step S207: Update the road surface adhesion coefficient of the wheels.

[0171] In some feasible implementations, as described above, when the wheel is in the first working state, the peak road adhesion coefficient of the wheel in the first working state can be obtained and stored based on step S203. Further, if the wheel transitions from the first working state to the second working state, at the instant the wheel enters the second working state, the peak road adhesion coefficient of the wheel in the second working state can be obtained based on steps S204 to S206, and the stored peak road adhesion coefficient can be updated. It is understood that when the wheel transitions from the second working state to the first working state, after obtaining the peak road adhesion coefficient of the wheel in the first working state, the stored peak road adhesion coefficient can be updated. The vehicle can obtain an accurate safe braking distance based on the real-time updated peak road adhesion coefficient.

[0172] This application embodiment also determines that the wheel is in a second working state by estimating the adhesion coefficient based on the longitudinal slip ratio of the wheel and the road surface, and determines the peak road surface adhesion coefficient of the wheel when the wheel is in the second working state, which can effectively expand the range of vehicle driving conditions for detecting the peak road surface adhesion coefficient of the wheel.

[0173] In some feasible implementations, to avoid detection errors when the vehicle's driving conditions do not meet the detection range of the peak road adhesion coefficient, this application can determine whether the vehicle meets preset enabling conditions before determining whether the wheel is in a first or second working state based on the wheel's longitudinal slip coefficient. Only when the vehicle meets any one or more of the preset enabling conditions is the wheel determined to be in a first or second working state based on the wheel's longitudinal slip ratio.

[0174] In some feasible implementations, when the vehicle meets the preset enabling condition ①: the vehicle speed is greater than or equal to the preset speed threshold, the wheel is determined to be in the first working state or the second working state based on the longitudinal slip ratio of the wheel.

[0175] For example, when the vehicle speed is greater than or equal to a preset speed threshold (assuming the preset speed threshold is 1 m / s), the wheel is determined to be in either a first or second operating state based on the longitudinal slip ratio. This avoids detecting the peak road adhesion coefficient of the wheel during the vehicle's initial acceleration phase when the speed is low, thus preventing a decrease in accuracy.

[0176] In some feasible implementations, when the vehicle meets the preset enabling condition ②: the steering angle of the vehicle's steering wheel is less than or equal to a preset steering angle threshold, the wheel is determined to be in a first working state or a second working state based on the longitudinal slip ratio of the wheel.

[0177] For example, when the steering angle of the steering wheel is less than or equal to a preset steering angle threshold (assuming the preset steering angle threshold is 5 degrees), the wheel is determined to be in either a first or second operating state based on the longitudinal slip ratio of the wheel. This avoids detecting the peak road adhesion coefficient of the wheel when the vehicle is not moving longitudinally, thus preventing a reduction in accuracy.

[0178] The steering angle of a vehicle's steering wheels can be obtained based on the average of the steering angles of multiple steering wheels. For example, assuming the vehicle's steering wheels are the left front wheel and the right front wheel, the steering angle of the vehicle's steering wheels can be obtained based on the average of the steering angles of the left front wheel and the right front wheel.

[0179] In some feasible implementations, when the vehicle meets the preset enabling condition ③: the longitudinal slip ratio of the wheel is greater than or equal to the preset slip ratio threshold, the wheel is determined to be in the first working state or the second working state based on the longitudinal slip ratio of the wheel.

[0180] For example, when the longitudinal slip ratio of the wheel is greater than or equal to a preset slip ratio threshold (assuming the preset slip ratio threshold is 0.001), the wheel is determined to be in either a first or second working state based on the longitudinal slip ratio. This avoids detecting the peak road adhesion coefficient of the wheel when the vehicle is not slipping, thus preventing a reduction in accuracy.

[0181] In some feasible implementations, after obtaining the peak road surface adhesion coefficient of the wheels, this application can obtain the vehicle's safe braking distance based on the peak road surface adhesion coefficient of the wheels. Furthermore, the vehicle's safe braking distance can be used as a warning message to enable the driver to maintain driving safety in a timely manner based on the vehicle's safe braking distance.

[0182] Based on the description of the above embodiments of the method for detecting the peak adhesion coefficient of a road surface, this application also discloses a device for detecting the peak adhesion coefficient of a road surface. This device for detecting the peak adhesion coefficient of a road surface can be applied to... Figure 3 as well as Figure 5 In the method for detecting the peak road adhesion coefficient of the illustrated embodiment, the steps in the method for detecting the peak road adhesion coefficient are used to perform the above-described steps. Here, the device for detecting the peak road adhesion coefficient can be the one described above. Figure 3 as well as Figure 5 The embodiment shown illustrates the execution entity of the method for detecting the peak adhesion coefficient of the road surface. Please refer to [link / reference needed]. Figure 6 , Figure 6 This is a schematic diagram of a road surface peak adhesion coefficient detection device provided in an embodiment of this application. In this embodiment, the device 60 can operate the following modules:

[0183] The acquisition module 601 is used to acquire the longitudinal slip ratio of the wheels based on the vehicle's driving state parameters;

[0184] The working state determination module 602 is used to determine that the wheel is in a first working state based on the longitudinal slip ratio of the wheel.

[0185] The adhesion coefficient determination module 603 is used to obtain at least one road surface estimated adhesion coefficient when the wheel is in the first working state, and to determine the maximum value among the at least one road surface estimated adhesion coefficient as the road surface peak adhesion coefficient.

[0186] The aforementioned working state determination module 602 is further used to determine that the wheel is in a second working state based on the longitudinal slip ratio of the wheel.

[0187] The aforementioned acquisition module 601 is also used to acquire the vertical force of the wheels based on the driving state parameters of the vehicle.

[0188] The aforementioned adhesion coefficient determination module 603 is also used to determine the peak road adhesion coefficient of the wheel based on the wheel's longitudinal stiffness, longitudinal slip ratio, and vertical force.

[0189] The acquisition module 601 is further configured to acquire the road surface estimated adhesion coefficient of the wheel based on the vehicle's driving state parameters; the working state determination module 602 is further configured to determine that the wheel is in a first working state based on the longitudinal slip ratio of the wheel and the road surface estimated adhesion coefficient.

[0190] The aforementioned working state determination module 602 is also used to determine that the wheel is in a second working state based on the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface.

[0191] The aforementioned working status determination module 602 includes:

[0192] The first determination unit 6021 is used to determine that the wheel is in a first working state when the longitudinal slip ratio of the wheel satisfies at least one of the following conditions:

[0193] The absolute value of the aforementioned longitudinal slip ratio is greater than or equal to the first preset absolute value threshold;

[0194] The rate of change of the absolute value of the aforementioned longitudinal slip ratio is greater than or equal to the first preset rate of change threshold.

[0195] The aforementioned working status determination module also includes:

[0196] The second judgment unit 6022 is used to determine that the wheel is in a first working state when the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface meet at least one of the following conditions:

[0197] The ratio of the estimated road surface adhesion coefficient of the aforementioned wheel to the aforementioned longitudinal slip ratio is less than or equal to a first preset ratio threshold.

[0198] The estimated road adhesion coefficient and longitudinal slip ratio of the aforementioned wheel at multiple times are obtained. The ratio of the change in the estimated road adhesion coefficient at any given time to the change in the longitudinal slip ratio at the same time is less than or equal to a first preset difference threshold. The change in the estimated road adhesion coefficient is the difference between the estimated road adhesion coefficient of the aforementioned wheel at any given time and the estimated road adhesion coefficient of the aforementioned wheel at the previous time. The change in the longitudinal slip ratio is the difference between the longitudinal slip ratio of the aforementioned wheel at any given time and the longitudinal slip ratio of the aforementioned wheel at the previous time.

[0199] The first judgment unit 6021 is further configured to determine that the wheel is in a second working state when the longitudinal slip ratio of the wheel meets at least one of the following conditions:

[0200] The absolute value of the aforementioned longitudinal slip ratio is greater than or equal to the second preset absolute value threshold;

[0201] The rate of change of the absolute value of the aforementioned longitudinal slip ratio is greater than or equal to the second preset rate of change threshold.

[0202] The second determination unit 6022 is further configured to determine that the wheel is in a second working state when the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface satisfy at least one of the following conditions:

[0203] The ratio of the estimated road surface adhesion coefficient of the aforementioned wheel to the aforementioned longitudinal slip ratio is greater than or equal to the second preset ratio threshold.

[0204] The estimated road surface adhesion coefficient and longitudinal slip ratio of the above wheel at multiple times are obtained. The ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is greater than or equal to a second preset difference threshold. The change in the estimated road surface adhesion coefficient is the difference between the estimated road surface adhesion coefficient of the above wheel at any time and the estimated road surface adhesion coefficient of the above wheel at the previous time. The change in the longitudinal slip ratio is the difference between the longitudinal slip ratio of the above wheel at any time and the longitudinal slip ratio of the above wheel at the previous time.

[0205] The rate of change of the ratio of the road surface estimated adhesion coefficient of the above-mentioned wheel to the longitudinal slip ratio is greater than or equal to the first preset ratio change rate threshold and less than or equal to the second preset ratio change rate threshold.

[0206] The estimated road surface adhesion coefficient and longitudinal slip ratio of the above wheels at multiple times are obtained. The rate of change of the ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is greater than or equal to the first preset differential rate of change threshold and less than or equal to the second preset differential rate of change threshold.

[0207] The aforementioned road surface peak adhesion coefficient detection device 60 further includes:

[0208] Filtering module 604 is used to obtain the road surface estimated adhesion coefficient and longitudinal slip ratio of the aforementioned wheel at multiple times; and to update the gain matrix k of the aforementioned wheel based on the road surface estimated adhesion coefficient of the aforementioned wheel at the current time. H (n); According to e(n)=d(n)-w(n-1)u(n), the prior estimation error e(n) of the road surface estimated adhesion coefficient d(n) of the above wheel at the current moment is obtained, where w(n-1) is the ratio of the road surface estimated adhesion coefficient of the above wheel at the previous moment to the longitudinal slip ratio at the previous moment, and u(n) is the longitudinal slip ratio of the above wheel at the current moment; according to w(n=w(n-1)+k H (n)e(n) obtains the ratio w(n) of the road surface estimated adhesion coefficient of the above wheel at the current moment to the longitudinal slip ratio at the same moment.

[0209] The filtering module 604 is further configured to acquire the road surface estimated adhesion coefficient and longitudinal slip ratio of the wheel at multiple times; and update the gain matrix k of the wheel based on the change in the road surface estimated adhesion coefficient of the wheel at the current time. H(n); According to e(n)=d(n)-w(n-1)u(n), the prior estimation error e(n) of the change in the road surface estimated adhesion coefficient of the above-mentioned wheel at the current moment is obtained, where w(n-1) is the ratio of the change in the road surface estimated adhesion coefficient of the above-mentioned wheel at the previous moment to the change in the longitudinal slip ratio at the previous moment, and u(n) is the change in the longitudinal slip ratio of the above-mentioned wheel at the current moment; according to w(n=w(n-1)+k H (n)e(n) obtains the ratio w(n) of the change in the road surface estimated adhesion coefficient of the above wheel at the current moment to the change in the longitudinal slip ratio at the same moment.

[0210] The aforementioned road surface peak adhesion coefficient detection device 60 further includes:

[0211] The enable determination module 605 is used to determine that the wheel is in a first working state based on the longitudinal slip ratio of the wheel when the vehicle meets the preset enable conditions according to the driving state parameters of the vehicle. The preset enable conditions include any one or more of the following conditions:

[0212] The speed of the aforementioned vehicles is greater than or equal to a preset speed threshold.

[0213] The steering angle of the steering wheels of the above-mentioned vehicles is less than or equal to a preset steering angle threshold;

[0214] The longitudinal slip ratio of the aforementioned wheels is greater than or equal to the preset slip ratio threshold.

[0215] The aforementioned acquisition module 601 includes:

[0216] The slip ratio acquisition unit 6011 is used to acquire the speed of the wheel in the vehicle speed direction based on the vehicle body yaw rate, the steering angle, rotation speed and rolling radius of the wheel; and to acquire the longitudinal slip ratio of the wheel based on the speed of the wheel in the vehicle speed direction and the vehicle speed.

[0217] The aforementioned acquisition module 601 further includes:

[0218] The road surface adhesion coefficient acquisition unit 6012 is used to acquire the longitudinal force of the wheel based on the motor torque, braking torque, rolling radius, moment of inertia, and rotational speed of the wheel; and to acquire the vertical force of the wheel based on the vehicle's mass, center of gravity height, front axle track width, rear axle track width, wheelbase, distance from the front axle to the vehicle's center of gravity, distance from the rear axle to the vehicle's center of gravity, longitudinal acceleration of the vehicle body, and lateral acceleration of the vehicle body; and to acquire the road surface adhesion coefficient of the wheel based on the ratio of the longitudinal force of the wheel to the vertical force of the wheel.

[0219] The aforementioned road surface peak adhesion coefficient detection device 60 further includes:

[0220] Processing module 606 is used to obtain the safe braking distance of the vehicle based on the peak road adhesion coefficient of the wheels.

[0221] The road surface peak adhesion coefficient detection device provided in this application determines whether the wheel is in the first working zone based on the wheel's longitudinal slip ratio. When the wheel is in the first working zone, the maximum value among multiple estimated road surface adhesion coefficients of the wheel is determined as the road surface peak adhesion coefficient of the wheel. This device can accurately obtain the road surface peak adhesion coefficient of the wheel in the first working zone, and its implementation is simple and highly accurate.

[0222] In the embodiments of this application, the modules in the device shown in the figures above can be individually or entirely combined into one or more other modules, or some of the modules can be further divided into multiple functionally smaller modules. This achieves the same operation without affecting the technical effect of the embodiments of this application. The above modules are based on logical function division. In practical applications, the function of one module can be implemented by multiple modules, or the function of multiple modules can be implemented by one module. In other feasible implementations of this application, the device may also include other modules. In practical applications, these functions can also be implemented with the assistance of other modules, and can be implemented collaboratively by multiple modules, without limitation.

[0223] See Figure 7 , Figure 7 This is a schematic diagram of a vehicle control system provided in an embodiment of this application. Figure 7 The vehicle control system shown includes a device for detecting the peak coefficient of adhesion of the road surface, a processor, and a display.

[0224] The device for detecting the peak road adhesion coefficient can detect multiple estimated road adhesion coefficients of the wheel at different times. Furthermore, the device can detect at least one estimated road adhesion coefficient when the wheel is in a first working state, and determine the maximum value among the at least one estimated road adhesion coefficient as the peak road adhesion coefficient of the wheel in the first working state. The specific implementation of the device for detecting the peak road adhesion coefficient can refer to the specific implementation of the device for detecting the peak road adhesion coefficient described above, and will not be repeated here. Furthermore, the beneficial effects of using the same method will not be repeated here either.

[0225] The processor can obtain the vehicle's safe braking distance based on the peak road adhesion coefficient of the wheels in the first working state and transmit it to the display to provide the vehicle driver with a warning information on the safe braking distance.

[0226] The vehicle control system provided in this application embodiment can accurately obtain the peak road adhesion coefficient corresponding to the wheel in the first working zone through the road peak adhesion coefficient detection device, and determine the safe braking distance of the vehicle at this time based on the peak road adhesion coefficient corresponding to the wheel in the first working zone. It has high accuracy and ensures driving safety and vehicle performance.

[0227] For further details, please refer to Figure 8 , Figure 8 This is a schematic diagram of a computer device provided for an embodiment of this application. For example... Figure 8 As shown, the computer device 100 includes a display 103, a processor 101, a memory 104, and a communication module 102; wherein the processor 101 is connected to the display 103, the memory 104, and the communication module 102. The communication module 102 provides data communication functionality. The communication module 102 can control the switching of its communication state under the control instructions of the processor 101. The communication module 102 is also used to send data and to receive and parse data. For example, when the computer device 100 acquires the communication state between the chip and the computer device 100, the chip returns communication parameters to the computer device 100. The communication module receives and parses these communication parameters so that the computer device 100 can acquire the communication state between the chip and the computer device 100. Furthermore, the memory 104 stores program code, the display 103 displays the object operation interface, and the processor 101 calls the program code to execute the detection method corresponding to any of the above embodiments.

[0228] It should be understood that the computer device 100 described in the embodiments of this application can perform the foregoing... Figure 3 as well as Figure 5 The description of the detection method in the corresponding embodiments can also be performed as described above. Figure 1 The description of the vehicle in the corresponding embodiment can also be executed as described above. Figure 2 as well as Figure 6 The description of the detection device in the corresponding embodiments will not be repeated here. Furthermore, the beneficial effects of using the same method will also not be repeated.

[0229] This application also provides a computer-readable storage medium storing a computer program, the computer program including program instructions that are executed by a processor. Figure 3 as well as Figure 5 For details of the detection methods provided in each step, please refer to the above. Figure 3 as well as Figure 5 The implementation methods provided for each step will not be elaborated here. Furthermore, the beneficial effects of using the same method will also not be described in detail.

[0230] The aforementioned computer-readable storage medium can be the internal storage unit of the detection device provided in any of the foregoing embodiments or the computer device, such as the hard disk or memory of the computer device. The computer-readable storage medium can also be an external storage device of the computer device, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., provided on the computer device. Furthermore, the computer-readable storage medium can include both internal storage units and external storage devices of the computer device. The computer-readable storage medium is used to store the computer program and other programs and data required by the computer device. The computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

[0231] The terms "first," "second," etc., in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the term "comprising," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product, or device that includes a series of steps or units is not limited to the listed steps or modules, but may optionally include steps or modules not listed, or may optionally include other step units inherent to these processes, methods, apparatuses, products, or devices.

[0232] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0233] The methods and related apparatuses provided in this application are described with reference to the method flowcharts and / or structural diagrams provided in this application. Specifically, each block of the method flowchart and / or structural diagram, as well as combinations of blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to create a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, generate instructions for implementing the process. Figure 1 A schematic diagram of one or more processes and / or structures. Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 A schematic diagram of one or more processes and / or structures. Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 A process or multiple processes and / or structures illustrate the steps of the functions specified in one or more boxes.

[0234] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with the claims of this application shall still fall within the scope of this application.

Claims

1. A method for detecting the peak adhesion coefficient of road surfaces, characterized in that, The method includes: The longitudinal slip ratio of the wheels is obtained based on the vehicle's driving state parameters; The wheel is determined to be in a first working state based on the longitudinal slip ratio of the wheel; Obtain at least one road surface estimated adhesion coefficient when the wheel is in a first working state, and determine the maximum value among the at least one road surface estimated adhesion coefficient as the road surface peak adhesion coefficient; Wherein, when the wheel is in the first working state, the longitudinal force of the wheel is greater than or equal to the maximum longitudinal force; the longitudinal force of the wheel is the force exerted by the road surface on the wheel in the forward direction; the peak adhesion coefficient of the road surface characterizes the maximum longitudinal force provided by the road surface to the wheel.

2. The method according to claim 1, characterized in that, The method further includes: The wheel is determined to be in a second working state based on the longitudinal slip ratio of the wheel; The vertical force of the wheel is obtained based on the vehicle's driving state parameters; The peak road adhesion coefficient of the wheel is determined based on the wheel's longitudinal stiffness, longitudinal slip ratio, and vertical force.

3. The method according to claim 1, characterized in that, The method further includes: The road adhesion coefficient of the wheels is estimated based on the vehicle's driving state parameters. Determining that the wheel is in a first working state based on the longitudinal slip ratio of the wheel includes: The wheel is determined to be in its first working state based on the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface.

4. The method according to claim 2, characterized in that, The method further includes: The road adhesion coefficient of the wheels is estimated based on the vehicle's driving state parameters. Determining that the wheel is in a second working state based on the longitudinal slip ratio of the wheel includes: The wheel is determined to be in a second working state based on the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface.

5. The method according to claim 1, characterized in that, Determining that the wheel is in a first working state based on the longitudinal slip ratio of the wheel includes: The wheel is in a first working state when its longitudinal slip ratio meets at least one of the following conditions: The absolute value of the longitudinal slip ratio is greater than or equal to a first preset absolute value threshold; The rate of change of the absolute value of the longitudinal slip ratio is greater than or equal to the first preset rate of change threshold.

6. The method according to claim 3, characterized in that, The determination of the wheel being in a first working state based on the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface includes: The wheel is in a first working state when the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface meet at least one of the following conditions: The ratio of the estimated road surface adhesion coefficient of the wheel to the longitudinal slip ratio is less than or equal to a first preset ratio threshold. The estimated road surface adhesion coefficient and longitudinal slip ratio of the wheel are obtained at multiple times. The ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is less than or equal to a first preset difference threshold. The change in the estimated road surface adhesion coefficient is the difference between the estimated road surface adhesion coefficient of the wheel at any time and the estimated road surface adhesion coefficient of the wheel at the previous time, and the change in the longitudinal slip ratio is the difference between the longitudinal slip ratio of the wheel at any time and the longitudinal slip ratio of the wheel at the previous time.

7. The method according to claim 2, characterized in that, The determination of the wheel being in a second working state based on the wheel's longitudinal slip ratio includes: The wheel is in a second operating state when its longitudinal slip ratio meets at least one of the following conditions: The absolute value of the longitudinal slip ratio is greater than or equal to the second preset absolute value threshold; The rate of change of the absolute value of the longitudinal slip ratio is greater than or equal to the second preset rate of change threshold.

8. The method according to claim 4, characterized in that, The determination that the wheel is in the second working state based on the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface includes: The wheel is in a second working state when the longitudinal slip ratio of the wheel and the estimated adhesion coefficient of the road surface meet at least one of the following conditions: The ratio of the estimated road surface adhesion coefficient of the wheel to the longitudinal slip ratio is greater than or equal to a second preset ratio threshold. The estimated road surface adhesion coefficient and longitudinal slip ratio of the wheel at multiple times are obtained. The ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is greater than or equal to a second preset difference threshold. The change in the estimated road surface adhesion coefficient is the difference between the estimated road surface adhesion coefficient of the wheel at any time and the estimated road surface adhesion coefficient of the wheel at the previous time. The change in the longitudinal slip ratio is the difference between the longitudinal slip ratio of the wheel at any time and the longitudinal slip ratio of the wheel at the previous time. The rate of change of the ratio of the estimated road surface adhesion coefficient of the wheel to the longitudinal slip ratio is greater than or equal to a first preset ratio change rate threshold and less than or equal to a second preset ratio change rate threshold. The estimated road surface adhesion coefficient and longitudinal slip ratio of the wheel at multiple times are obtained. The rate of change of the ratio of the change in the estimated road surface adhesion coefficient at any time to the change in the longitudinal slip ratio at the same time is greater than or equal to a first preset differential rate of change threshold and less than or equal to a second preset differential rate of change threshold.

9. The method according to claim 6, characterized in that, The method further includes: The road surface adhesion coefficient and longitudinal slip ratio of the wheel are estimated at multiple times. Update the wheel's gain matrix based on the wheel's longitudinal slip ratio at the current moment. ; according to Obtain the road surface estimated adhesion coefficient of the wheel at the current moment. Prior estimation error ,in, The ratio of the road surface adhesion coefficient of the wheel at the previous moment to the longitudinal slip ratio at the previous moment. The longitudinal slip ratio of the wheel at the current moment; according to Obtain the ratio of the estimated road adhesion coefficient of the wheel at the current moment to the longitudinal slip ratio at the same moment. .

10. The method according to claim 6, characterized in that, The method further includes: The road surface adhesion coefficient and longitudinal slip ratio of the wheel are estimated at multiple times. The gain matrix of the wheel is updated based on the change in the longitudinal slip ratio of the wheel at the current moment. ; according to Obtain the change in the estimated road surface adhesion coefficient of the wheel at the current moment. Prior estimation error ,in, The ratio of the change in the coefficient of friction of the wheel on the road surface at the previous moment to the change in the longitudinal slip ratio at the previous moment. This represents the change in the longitudinal slip ratio of the wheel at the current moment; according to Obtain the ratio of the change in the estimated road adhesion coefficient of the wheel at the current moment to the change in the longitudinal slip ratio at the same moment. .

11. The method according to claim 1, characterized in that, Before determining that the wheel is in its first working state based on the wheel's longitudinal slip ratio, the method further includes: If the vehicle meets the preset enabling conditions based on the vehicle's driving state parameters, the wheel is determined to be in a first working state based on the longitudinal slip ratio of the wheel. The preset enabling conditions include any one or more of the following conditions: The vehicle's speed is greater than or equal to a preset speed threshold. The steering angle of the vehicle's steering wheels is less than or equal to a preset steering angle threshold; The longitudinal slip ratio of the wheel is greater than or equal to a preset slip ratio threshold.

12. The method according to claim 1, characterized in that, The driving status parameters include the vehicle speed, body yaw rate, wheel steering angle, rotational speed, and rolling radius. The process of obtaining the longitudinal slip ratio of the wheels based on the vehicle's driving state parameters includes: The speed of the wheel in the direction of the vehicle's speed is obtained based on the vehicle's yaw rate, the wheel's steering angle, rotational speed, and rolling radius. The longitudinal slip ratio of the wheel is obtained based on the speed of the wheel in the direction of the vehicle's speed and the vehicle's speed.

13. The method according to claim 1, characterized in that, The driving state parameters include the motor torque, braking torque, rolling radius, moment of inertia, and rotational speed of the wheels; the mass, center of gravity height, front axle track, rear axle track, wheelbase, distance from the front axle to the vehicle's center of gravity, distance from the rear axle to the vehicle's center of gravity, longitudinal acceleration of the vehicle body, and lateral acceleration of the vehicle body. The method of obtaining the wheel's road surface adhesion coefficient based on the vehicle's driving state parameters includes: The longitudinal force of the wheel is obtained based on the motor torque, braking torque, rolling radius, moment of inertia, and rotational speed of the wheel. The vertical force of the wheels is obtained based on the vehicle's mass, center of gravity height, front axle track, rear axle track, wheelbase, distance from the front axle to the vehicle's center of gravity, distance from the rear axle to the vehicle's center of gravity, longitudinal acceleration of the vehicle body, and lateral acceleration of the vehicle body. The road surface adhesion coefficient of the wheel is estimated based on the ratio of the longitudinal force to the vertical force of the wheel.

14. The method according to any one of claims 1-13, characterized in that, The method further includes: The safe braking distance of the vehicle is obtained based on the peak road adhesion coefficient of the wheels.

15. A device for detecting the peak adhesion coefficient of a road surface, characterized in that, The device includes: The acquisition module is used to obtain the longitudinal slip ratio of the wheels based on the vehicle's driving state parameters; The working state determination module is used to determine that the wheel is in a first working state based on the longitudinal slip ratio of the wheel; The adhesion coefficient determination module is used to obtain at least one road surface estimated adhesion coefficient when the wheel is in a first working state, and to determine the maximum value among the at least one road surface estimated adhesion coefficient as the road surface peak adhesion coefficient. Wherein, when the wheel is in the first working state, the longitudinal force of the wheel is greater than or equal to the maximum longitudinal force; the longitudinal force of the wheel is the force exerted by the road surface on the wheel in the forward direction; the peak adhesion coefficient of the road surface characterizes the maximum longitudinal force provided by the road surface to the wheel.

16. The apparatus according to claim 15, characterized in that, The working state determination module is also used to determine that the wheel is in a second working state based on the longitudinal slip ratio of the wheel; The acquisition module is also used to acquire the vertical force of the wheel based on the vehicle's driving state parameters; The adhesion coefficient determination module is also used to determine the peak road adhesion coefficient of the wheel based on the wheel's longitudinal stiffness, longitudinal slip ratio, and vertical force.

17. A vehicle control system, characterized in that, The system includes a processor, a display, and a detection device for the peak adhesion coefficient of the road surface as described in any one of claims 15-16; The processor is used to generate a safe braking distance based on the peak road adhesion coefficient output by the detection device, and transmit the safe braking distance to the display for display.

18. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program adapted to be loaded and executed by a processor to cause a computer device having the processor to perform the method of any one of claims 1-14.

19. A vehicle, characterized in that, The vehicle includes a brake controller, wheel speed sensors, and a detection device for peak road adhesion coefficient as described in any one of claims 15 to 16; or, the vehicle includes a brake controller, wheel speed sensors, and a vehicle control system as described in claim 17; wherein the brake controller and the wheel speed sensors are used to collect the driving state parameters of the vehicle.

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