Method for determining road adhesion coefficient

Abstract

The application relates to a road surface adhesion coefficient determination method. The method comprises the following steps: determining the utilization adhesion coefficients of each tire of a target vehicle on a to-be-tested road surface at multiple time points according to a three-degree-of-freedom vehicle model and a tire model of the target vehicle; determining the slip rates of each tire at the multiple time points according to the vehicle speed, the angular velocity of each tire and the tire radius of the target vehicle; and determining the road surface adhesion coefficients of each tire on the to-be-tested road surface according to the utilization adhesion coefficients and the slip rates of each tire at the multiple time points. The method can improve the accuracy of the determined road surface adhesion coefficients of the tires of the target vehicle on the to-be-tested road surface.

Description

Technical Field

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

[0002] The coefficient of friction, also known as the peak coefficient of friction, represents the ability of a vehicle's tires to grip the road surface under different conditions. The value of the coefficient of friction depends primarily on the characteristics of the road surface and the tires, such as tire construction and road materials. The tire coefficient of friction is a crucial input parameter for control systems such as anti-lock braking systems (ABS) and traction control systems (TCS), and is also a vital basis for decision-making and planning in autonomous driving technologies. Therefore, obtaining accurate, real-time coefficients of friction is essential for the active safety control of vehicles.

[0003] Traditional techniques primarily rely on a vehicle dynamics model to determine the coefficient of adhesion (μ) and slip ratio (s) of the target vehicle's tires on the test surface at multiple time points. Based on these coefficients of adhesion and slip ratios at each time point, a μ-s curve for the test surface is determined. The least squares method is then used to fit the μ-s curves of each tire of the target vehicle on the test surface. Finally, based on the slope of the μ-s curve of the test surface, the μ-s curve with the closest slope is determined, and the road adhesion coefficient of this curve is taken as the road adhesion coefficient of each tire of the target vehicle on the test surface.

[0004] However, because the road adhesion coefficient of the target vehicle on the test road surface is an approximation, the accuracy of the road adhesion coefficient of the target vehicle on the test road surface determined by traditional technology is low. Summary of the Invention

[0005] Therefore, it is necessary to provide a method for determining the road adhesion coefficient that can improve the accuracy of the determined road adhesion coefficient of the road surface to be tested, in order to address the above-mentioned technical problems.

[0006] Firstly, this application provides a method for determining the road surface adhesion coefficient. The method includes:

[0007] Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0008] Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point.

[0009] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the road adhesion coefficient of each tire on the test road surface is determined.

[0010] In one embodiment, determining the road adhesion coefficient of each tire on the test road surface based on the adhesion coefficient and slip ratio of each tire at each time point includes:

[0011] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the target curve for each tire is determined; the target curve is the coefficient of adhesion-slip ratio curve.

[0012] Based on the target curve corresponding to each tire and multiple preset curves, the road adhesion coefficient of each tire on the test road surface is determined; the preset curve is a preset adhesion coefficient-slip ratio curve.

[0013] In one embodiment, determining the road adhesion coefficient of each tire on the test road surface based on the target curve corresponding to each tire and a plurality of preset curves includes:

[0014] Determine the target coordinate point on the target curve corresponding to each tire;

[0015] Based on the target slip ratio at the target coordinate point, determine the target preset curve from each of the preset curves;

[0016] Based on the adhesion coefficient corresponding to the target slip ratio on the target preset curve and the road adhesion coefficient corresponding to the target preset curve, the road adhesion coefficient of each tire on the test road surface is determined.

[0017] In one embodiment, determining the target preset curve from the preset curves based on the target slip ratio at the target coordinate point includes:

[0018] Determine each candidate adhesion coefficient; each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on each preset curve, or each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on the preset curve corresponding to the target adhesion degree type; the target adhesion degree type is determined according to the road surface type of the road surface to be tested.

[0019] Based on the adhesion coefficient of each candidate and the adhesion coefficient of the target at the target coordinate point, the target preset curve is determined from each preset curve.

[0020] In one embodiment, the method further includes:

[0021] Obtain the image of the road surface to be tested;

[0022] Based on the image to be identified, determine the target road surface type of the road surface to be tested;

[0023] Based on the first preset correspondence, the target road surface adhesion coefficient range corresponding to the target road surface type is determined; the first preset correspondence includes the correspondence between different road surface types and different road surface adhesion coefficient ranges;

[0024] Based on the second preset correspondence and the target road surface adhesion coefficient range, the target adhesion degree type corresponding to the road surface type is determined from a plurality of preset adhesion degree types; the second preset correspondence includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types.

[0025] In one embodiment, determining the target preset curve from each preset curve based on each candidate adhesion coefficient and the target adhesion coefficient at the target coordinate point includes:

[0026] Determine the difference between the adhesion coefficient of each candidate and the adhesion coefficient of the target;

[0027] Based on the differences in the adhesion coefficients of each candidate curve, a target preset curve is determined from the preset curves.

[0028] In one embodiment, the method further includes:

[0029] Obtain the number of unbraked driven wheels;

[0030] The initial speed of the target vehicle is determined based on the number of unbraked driven wheels.

[0031] Determine the speed of the target vehicle based on its initial speed.

[0032] In one embodiment, determining the initial vehicle speed based on the number of unbraked driven wheels includes:

[0033] If the number is one, the wheel speed of the unbraked driven wheel will be used as the initial speed value of the target vehicle.

[0034] In one embodiment, determining the speed of the target vehicle based on the number of unbraked driven wheels includes:

[0035] If this number is the same as the total number of driven wheels of the target vehicle, then the average wheel speed of each unbraked driven wheel is taken as the initial speed of the target vehicle.

[0036] In one embodiment, determining the initial vehicle speed based on the number of unbraked driven wheels includes:

[0037] If the quantity is zero, the maximum wheel speed among the wheel speeds of the driven wheels of the target vehicle is taken as the initial speed value of the target vehicle.

[0038] In one embodiment, determining the speed of the target vehicle based on its initial speed value includes:

[0039] The initial speed of the target vehicle is filtered using an adaptive Kalman filter to determine the vehicle's speed.

[0040] Secondly, this application also provides a device for determining the road surface adhesion coefficient. The device includes:

[0041] The first determining module is used to determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface based on the three-degree-of-freedom vehicle model and tire model of the target vehicle.

[0042] The second determining module is used to determine the slip ratio of each tire at each time point based on the vehicle speed of the target vehicle, the angular velocity of each tire and the tire radius.

[0043] The third determining module is used to determine the road adhesion coefficient of each tire on the test road surface based on the utilization adhesion coefficient and slip ratio of each tire at each time point.

[0044] Thirdly, this application also provides a computer device. The computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to perform the following steps:

[0045] Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0046] Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point.

[0047] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the road adhesion coefficient of each tire on the test road surface is determined.

[0048] Fourthly, this application also provides a computer-readable storage medium. This computer-readable storage medium stores a computer program thereon, which, when executed by a processor, performs the following steps:

[0049] Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0050] Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point.

[0051] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the road adhesion coefficient of each tire on the test road surface is determined.

[0052] Fifthly, this application also provides a computer program product. This computer program product includes a computer program that, when executed by a processor, performs the following steps:

[0053] Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0054] Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point.

[0055] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the road adhesion coefficient of each tire on the test road surface is determined.

[0056] The aforementioned method for determining the road surface adhesion coefficient determines the utilization adhesion coefficient of each tire of the target vehicle at multiple time points on the test road surface based on a three-degree-of-freedom vehicle model and tire model. It then determines the slip ratio of each tire at each time point based on the vehicle speed, angular velocity of each tire, and tire radius. Finally, it determines the road surface adhesion coefficient of each tire on the test road surface based on the utilization adhesion coefficient and slip ratio at each time point. Traditional techniques yield approximate values ​​for the road surface adhesion coefficient of the target vehicle, resulting in low accuracy. In this application, however, the road surface adhesion coefficient of each tire on the test road surface is determined based on the utilization adhesion coefficient and slip ratio at each time point, rather than using approximate values ​​as in traditional techniques. This improves the accuracy of the determined road surface adhesion coefficient of each tire on the test road surface. Furthermore, since this application determines the road surface adhesion coefficient of each tire on the test road surface, the method provided in this application can also improve the accuracy of the road surface adhesion coefficient determined on split road surfaces. Attached Figure Description

[0057] Figure 1 This is an internal structural diagram of the computer device provided in the embodiments of this application;

[0058] Figure 2 One of the flowcharts illustrating the method for determining the road surface adhesion coefficient provided in this application embodiment;

[0059] Figure 3 This is a force analysis diagram of a three-degree-of-freedom vehicle model of a target vehicle provided in an embodiment of this application;

[0060] Figure 4 This is a force analysis diagram of a tire model provided in an embodiment of this application;

[0061] Figure 5 This is the second flowchart illustrating the method for determining the road surface adhesion coefficient provided in the embodiments of this application;

[0062] Figure 6 This is the third flowchart illustrating the method for determining the road surface adhesion coefficient provided in this application embodiment;

[0063] Figure 7 This application provides an embodiment of an adhesion coefficient-slip ratio curve.

[0064] Figure 8 This is one of the flowcharts illustrating the target preset curve determination method provided in the embodiments of this application;

[0065] Figure 9 This is a flowchart illustrating a method for determining the type of target adhesion provided in an embodiment of this application;

[0066] Figure 10 This is a second schematic flowchart of the method for determining a target preset curve provided in the embodiments of this application;

[0067] Figure 11 This is a flowchart illustrating a method for determining the speed of a target vehicle according to an embodiment of this application;

[0068] Figure 12 This is a structural block diagram of a road surface adhesion coefficient determination device provided in an embodiment of this application. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0070] The embodiments provided in this application can be applied to, for example... Figure 1 On the computer device shown, refer to Figure 1 , Figure 1This is an internal structural diagram of a computer device provided in an embodiment of this application. The computer device can be a terminal. The computer device includes a processor, memory, communication interface, display screen, and input device connected via a system bus. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used for wired or wireless communication with external terminals. Wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a resource scaling method. The display screen of the computer device can be a liquid crystal display (LCD) or an e-ink display. The input device of the computer device can be a touch layer covering the display screen, or buttons, a trackball, or a touchpad mounted on the computer device casing, or an external keyboard, touchpad, or mouse, etc.

[0071] Those skilled in the art will understand that Figure 1 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0072] In one embodiment, such as Figure 2 As shown, Figure 2 One of the flowcharts illustrating the method for determining the road surface adhesion coefficient provided in this application embodiment is used in the application of this method. Figure 1 Taking a computer device as an example, the following steps may be included:

[0073] S201, based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0074] Among them, the three-degree-of-freedom vehicle model represents the model composed of the vehicle's lateral motion, yaw motion, and longitudinal motion; the tire model represents the dynamic model of the vehicle's four tires, and the tire model is divided into the braking tire model under vehicle braking conditions and the driving tire model under vehicle driving conditions.

[0075] Figure 3 This is a force analysis diagram of a three-degree-of-freedom vehicle model of a target vehicle provided in an embodiment of this application, such as... Figure 3 As shown, fl, fr, rl, and rr represent the left front tire, right front tire, left rear tire, and right rear tire of the target vehicle, respectively; Fx Indicates the longitudinal force of the tire, F y Indicates the lateral force of the tire; I z Let represent the moment of inertia about the center of mass; δ represent the steering angle of the front wheel; M represent the mass of the target vehicle; and a represent the rotational inertia about the center of mass. x Let a be the longitudinal acceleration of the target vehicle. y ω represents the lateral acceleration of the target vehicle. r B represents the yaw rate of the target vehicle; F B is the track width between the front wheels. R L is the track width between the rear wheels. F L is the distance from the front axle to the center of gravity. R This is the distance from the rear axle to the center of mass.

[0076] according to Figure 3 The dynamic equations of the target vehicle can be obtained as follows:

[0077] Ma x =(F xfl +F xfr )cosδ-(F yfl +F yfr )sinδ+F xrl +F xrr

[0078] Ma y =(F xfl +F xfr )sinδ+(F yfl +F yfr cosδ+F yrl +F yrr

[0079]

[0080] The expression for the vertical load of each tire of the target vehicle is:

[0081]

[0082]

[0083]

[0084]

[0085] Among them, F Zfl This represents the vertical force on the left front wheel, F. Zfr This represents the vertical force on the right front tire, F. Zrl This represents the vertical force on the left rear tire, F. ZrrThis represents the vertical force of the right rear wheel; h is the height of the target vehicle's center of gravity from the ground; Φ is the roll angle of the target vehicle.

[0086] Based on the dynamic equations of the target vehicle and the expression for the vertical load of the tires, the vertical force of each tire is determined. These vertical forces are then substituted into the tire model to determine the coefficient of adhesion for each tire. The specific process is as follows:

[0087] Figure 4 This is a force analysis diagram of a tire model provided in an embodiment of this application. Figure 4 In the diagram, the left side shows the force analysis of the tires during vehicle braking, and the right side shows the force analysis of the tires during vehicle actuation; ω represents the angular velocity of the tire, and T... b T is the braking torque of the tire. d F is the driving torque of the tire. x F is the longitudinal force of the tire. z This is the vertical force on the tire. According to... Figure 4 The equations for the tire model of the target vehicle during braking can be obtained as follows:

[0088]

[0089] Where, μ r Let J be the coefficient of adhesion of the tire under braking conditions, J be the moment of inertia of the tire, ω be the angular velocity of the tire, and F be the coefficient of friction. z T is the vertical force on the tire. b The braking torque of the tire is T, which can be obtained from the wheel cylinder pressure. f Let be the rolling resistance torque of the tire. Substituting the vertical force of each tire into the equations of the tire model during braking, the coefficient of adhesion for each tire under braking conditions is determined.

[0090] according to Figure 4 The equations for the tire model of the target vehicle during driving can be obtained as follows:

[0091]

[0092] Where, μ d T represents the coefficient of adhesion of a tire under driving conditions. d The driving torque of the tire is given by the value of the motor torque, which can be obtained from the motor power and speed. The vertical force of each tire is then substituted into the equations of the tire model under driving conditions to determine the coefficient of adhesion for each tire.

[0093] S202, based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point.

[0094] For example, the formula for calculating tire slip ratio is as follows:

[0095]

[0096] Where ω is the angular velocity of the tire; R is the tire radius; and v is the speed of the target vehicle.

[0097] The s obtained above can be i The slip ratio of each tire of the target vehicle on the test road surface; optionally, the s obtained above can also be used as the slip ratio of each tire of the target vehicle on the test road surface. i The product obtained by multiplying by the first preset coefficient is used as the slip ratio of each tire of the target vehicle on the test road surface.

[0098] In this embodiment, the average wheel speed of each tire can be used as the speed of the target vehicle. Alternatively, the maximum wheel speed among the wheel speeds of each tire can be used as the speed of the target vehicle.

[0099] S203, based on the utilization adhesion coefficient and slip ratio of each tire at each time point, determine the road adhesion coefficient of each tire on the test road surface.

[0100] Each time point refers to the time when the target vehicle was traveling on the road surface to be tested.

[0101] Based on the above examples, after determining the coefficient of adhesion μ and slip ratio s for each tire at each time point, curve fitting software is used to fit the coefficient of adhesion μ and slip ratio s for each tire at each time point to obtain a target curve. The target curve is the μ-s curve of each tire on the test road surface. The slope k of the target curve is determined. Based on the difference between the slope k of the target curve and a preset slope, a first preset curve and a second preset curve are determined from multiple preset curves. The preset curves are the known μ-s curves of each tire on various road surface types in the database. The difference between the slope of the first preset curve and the second preset curve and k is less than the preset slope difference. Then, based on the target curve, the first preset curve, and the second preset curve, the road adhesion coefficient of each tire on the test road surface is determined using interpolation.

[0102] In the aforementioned method for determining the road surface adhesion coefficient, the utilization adhesion coefficient of each tire of the target vehicle at multiple time points on the test road surface is determined based on the three-degree-of-freedom vehicle model and tire model of the target vehicle. Furthermore, the slip ratio of each tire at each time point is determined based on the vehicle speed, the angular velocity of each tire, and the tire radius. Finally, the road surface adhesion coefficient of each tire on the test road surface is determined based on the utilization adhesion coefficient and slip ratio of each tire at each time point. The road surface adhesion coefficient of the target vehicle determined using traditional techniques is an approximation with low accuracy. However, in this application, since the road surface adhesion coefficient of each tire on the test road surface is determined based on the utilization adhesion coefficient and slip ratio of each tire at each time point, rather than estimating the road surface adhesion coefficient based on an approximate value of the slope as in traditional techniques, the accuracy of the determined road surface adhesion coefficient of each tire of the target vehicle on the test road surface is improved.

[0103] Figure 5 This is the second flowchart illustrating the method for determining the road surface adhesion coefficient provided in this application. This embodiment relates to a possible implementation of how to determine the road surface adhesion coefficient of each tire on the test road surface based on the adhesion coefficient and slip ratio of each tire at each time point. Based on the above embodiment, such as... Figure 5 As shown, the above S203 may include:

[0104] S501, based on the coefficient of adhesion and slip ratio of each tire at each time point, determine the target curve for each tire; the target curve is the coefficient of adhesion-slip ratio curve.

[0105] For example, after determining the coefficient of adhesion μ and slip ratio s of each tire at each time point, fitting software on a computer device is used to fit μ and s of each tire at each time point to determine the target curve.

[0106] S502, based on the target curve corresponding to each tire and multiple preset curves, determine the road adhesion coefficient of each tire on the test road surface; the preset curve is a preset curve using adhesion coefficient-slip ratio.

[0107] The preset curve can be the adhesion coefficient-slip ratio curve corresponding to each road surface type stored in the database.

[0108] A target coordinate point can be arbitrarily selected on the target curve. Based on the slip ratio, the coefficient of adhesion, and a first preset difference at the target coordinate point, a first coordinate point and a second coordinate point are determined from multiple preset curves. The preset curves to which the first and second coordinate points belong are different. Specifically, the slip ratios of the first and second coordinate points are equal to the slip ratio of the target coordinate point. The first difference between the coefficient of adhesion at the first coordinate point and the coefficient of adhesion at the target coordinate point is less than the first preset difference. The second difference between the coefficient of adhesion at the second coordinate point and the coefficient of adhesion at the target coordinate point is less than the first preset difference. The average of the first road surface adhesion coefficient in the preset curve corresponding to the first coordinate point and the second road surface adhesion coefficient in the preset curve corresponding to the second coordinate point is taken as the road surface adhesion coefficient of each tire on the test road surface.

[0109] In this embodiment, the target curve corresponding to each tire is determined based on the coefficient of adhesion and slip ratio of each tire at each time point. Based on the target curve corresponding to each tire and multiple preset curves, the road adhesion coefficient of each tire on the test road surface is determined, thereby improving the accuracy of determining the adhesion coefficient of each tire on the test road surface.

[0110] Figure 6 This is the third flowchart illustrating the method for determining the road surface adhesion coefficient provided in this application. This embodiment relates to a possible implementation of determining the road surface adhesion coefficient of each tire on the test road surface based on the target curve corresponding to each tire and multiple preset curves. Based on the above embodiments, such as... Figure 6 As shown, the above S502 may include:

[0111] S601, determine the target coordinate points on the target curve corresponding to each tire.

[0112] S602, determine the target preset curve from each preset curve based on the target slip ratio in the target coordinate point.

[0113] S603, based on the utilization adhesion coefficient corresponding to the target slip ratio on the target preset curve and the road surface adhesion coefficient corresponding to the target preset curve, determine the road surface adhesion coefficient of each tire on the test road surface.

[0114] The target coordinate point is a coordinate point within a linear interval on the target curve.

[0115] Because the fitted target curve may contain intervals without linear relationships, when selecting target coordinate points, it is necessary to choose a coordinate point within a linear interval on the target curve as the target coordinate point. From multiple preset curves, a first coordinate point and a second coordinate point are determined, wherein the slip ratios of the first and second coordinate points are equal to the slip ratio of the target coordinate point, the first difference between the coefficient of adhesion used by the first coordinate point and the coefficient of adhesion used by the target coordinate point is less than a first preset difference, and the second difference between the coefficient of adhesion used by the second coordinate point and the coefficient of adhesion used by the target coordinate point is less than a first preset difference; the preset curves corresponding to the first and second coordinate points are then used as the target preset curves.

[0116] Let's take the left front tire of the target vehicle as an example. Figure 7 As shown, Figure 7 This application provides an embodiment of a method utilizing the adhesion coefficient-slip ratio curve. Figure 7 The target curves are the coefficient of friction-slip ratio curves for dry asphalt pavement and the coefficient of friction-slip ratio curves for wet asphalt pavement. An arbitrary target coordinate point (s, μ) is selected on the target curves, where μ1 represents the coefficient of friction of the tire on dry asphalt pavement when the slip ratio is s, and μ2 represents the coefficient of friction of the tire on wet asphalt pavement when the slip ratio is s. max1 The coefficient of friction between a tire and a dry asphalt surface, μ max2 The coefficient of adhesion of a tire on a wet asphalt surface can be expressed by the following method using interpolation:

[0117]

[0118] μ is calculated using the above expression. max , will μ max As the road adhesion coefficient of the left front tire on the test road surface, the road adhesion coefficients of the other tires on the test road surface can be obtained by analogy.

[0119] Alternatively, μ can also be max The product obtained by multiplying by the second preset coefficient is used as the road adhesion coefficient of the left front tire on the test road surface.

[0120] Optionally, after the target preset curve is initially determined, when determining the road surface adhesion coefficient again, it can be directly judged whether the adhesion coefficients μ and μ1, μ2 of the target coordinate points on the road surface to be tested satisfy the following relationship:

[0121]

[0122] If the above relationship is satisfied, it can be determined that the road surface adhesion coefficient has not changed abruptly. Then, the previously determined target preset curve is used as the target preset curve required this time, and the road surface adhesion coefficient is further calculated using an interpolation algorithm. There is no need to determine the target preset curve again from multiple preset curves.

[0123] Optionally, in determining the road surface adhesion coefficient, the actual environment affects the acquisition of known parameters. Noise points may exist during parameter acquisition, reducing the accuracy of the determined road surface adhesion coefficient and causing significant fluctuations. Therefore, the recursive least squares method is used to fit the data, and the interpolation algorithm formula is rewritten as follows:

[0124] μ 1max (μ2-μ1)+(μ-μ1)(μ 2max -μ 1max )=μ max (μ2-μ1)

[0125] The recursive form of the least squares method is:

[0126]

[0127] The observation information output by the system is y. t =μ 1max (μ2-μ1)+(μ-μ1)(μ 2max -μ 1max The system input information is θ(t) = μ2 - μ1, and the parameters to be identified are... By identifying parameters Estimate the road surface adhesion coefficient.

[0128] The calculation steps of recursive least squares are as follows:

[0129] (1) Initialize parameters θ(0) and P(0), and forgetting factor λ;

[0130] (2) Measurement system output y t Calculate the regression matrix

[0131] (3) Calculate the estimation error:

[0132] (4) Calculate the gain matrix:

[0133] (5) Calculate the covariance matrix:

[0134] (6) Update the estimated parameter vector: θ(t) = θ(t-1) + K(t)e(t);

[0135] (7) Repeat steps (2)-(6) until the road surface adhesion coefficient with a relatively large error is eliminated.

[0136] In the embodiments of the present application, target coordinate points are determined on the target curve corresponding to each tire; then, a target preset curve is determined from each preset curve according to the target slip ratio in the target coordinate points, and the road surface adhesion coefficient of each tire on the road surface to be measured is determined according to the utilized adhesion coefficient corresponding to the target slip ratio on the target preset curve and the road surface adhesion coefficient corresponding to the target preset curve. The accuracy of the determined road surface adhesion coefficient of each tire on the road surface to be measured is improved.

[0137] Figure 8 is one of the schematic flow diagrams of the target preset curve determination method provided in the embodiments of the present application. This embodiment relates to a possible implementation manner of how to determine the target preset curve from each preset curve according to the target slip ratio in the target coordinate points. On the basis of the above embodiments, as Figure 7 shown, the above S602 may include:

[0138] S801: Determine each candidate utilized adhesion coefficient; each candidate utilized adhesion coefficient includes the utilized adhesion coefficient corresponding to the target slip ratio on each preset curve, or each candidate utilized adhesion coefficient includes the utilized adhesion coefficient corresponding to the target slip ratio on the preset curve corresponding to the target adhesion degree type; the target adhesion degree type is determined according to the road surface type of the road surface to be measured.

[0139] Wherein, the target adhesion degree type is the adhesion degree type to which the road surface type of the road surface to be measured belongs, and the road surface adhesion degree type is determined according to the magnitude of the road surface adhesion coefficient corresponding to each road surface type.

[0140] Exemplarily, according to the slip ratio s in the target coordinate point, the utilized adhesion coefficient corresponding to s in each preset curve is determined as the candidate utilized adhesion coefficient.

[0141] S802: Determine the target preset curve from each preset curve according to each candidate utilized adhesion coefficient and the target utilized adhesion coefficient in the target coordinate point.

[0142] In this embodiment, the target preset curve may be determined from each preset curve according to the difference between each candidate utilized adhesion coefficient and the target utilized adhesion coefficient. Specifically, if there are 4 candidate utilized adhesion coefficients in total, which are (μ1, μ2, μ3, μ4) respectively, the differences (d1, d2, d3, d4) between each candidate utilized adhesion coefficient and the target utilized adhesion coefficient are calculated. If the relationship between the differences is: d1<d1<d2<d4, the preset curves corresponding to the candidate utilized adhesion coefficients corresponding to d1 and d2 are taken as the target preset curves.

[0143] In this embodiment, by determining the adhesion coefficient of each candidate, and then determining the target preset curve from each preset curve based on the adhesion coefficient of each candidate and the target adhesion coefficient in the target coordinate point, the efficiency of determining the target preset curve is improved.

[0144] Figure 9 This is a flowchart illustrating a method for determining the type of target adhesion provided in an embodiment of this application. This embodiment relates to a possible implementation of how to determine the type of target adhesion corresponding to the road surface type to be tested. Based on the above embodiment, such as... Figure 9 As shown, the above method also includes:

[0145] S901, acquire the image of the road surface to be identified.

[0146] S902, based on the image to be identified, determine the target road surface type of the road surface to be tested.

[0147] S903, determine the target road surface adhesion coefficient range corresponding to the target road surface type according to the first preset correspondence; the first preset correspondence includes the correspondence between different road surface types and different road surface adhesion coefficient ranges.

[0148] S904, based on the second preset correspondence and the target road surface adhesion coefficient range, determine the target adhesion degree type corresponding to the road surface type from a plurality of preset adhesion degree types; the second preset correspondence includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types.

[0149] For example, a convolutional neural network (CNN) model can be used to determine the type of target adhesion. Specifically, image samples of known road surface types are used as a training set to train an initial CNN model. The model parameters are continuously adjusted based on the mean squared error to obtain a target CNN model. An image of the road surface to be identified is acquired using a vehicle-mounted camera. This image is then input into the target CNN model, which outputs the target road surface type corresponding to the image.

[0150] After determining the target pavement type, the target pavement adhesion coefficient range corresponding to the target pavement type is determined according to the first preset correspondence. Then, based on the second preset correspondence and the target pavement adhesion coefficient range, the target adhesion degree type corresponding to the target pavement type is determined from a set of preset adhesion degree types. For example, if the target pavement type is cement pavement, assuming the target pavement adhesion coefficient range for cement pavement is (0.06-0.09), and its corresponding adhesion degree type is high adhesion pavement type, then the target adhesion degree type is determined to be high adhesion pavement type.

[0151] In this embodiment, an image of the road surface to be tested is acquired, and then, based on the image, the target road surface type is determined. According to a first preset correspondence, the range of target road surface adhesion coefficients corresponding to the target road surface type is determined. Further, based on a second preset correspondence and the range of target road surface adhesion coefficients, a target adhesion degree type corresponding to the road surface type is determined from a set of preset adhesion degree types. By determining the target road surface type of the road surface to be tested, and then determining the target adhesion degree type corresponding to the road surface type from a set of preset adhesion degree types, the efficiency of determining the target preset curve is improved, thereby improving the real-time performance of the determined road surface adhesion coefficient. Furthermore, by introducing a convolutional neural network model to determine the road surface type of the road surface to be tested, when it is difficult to calculate the road surface adhesion coefficient, the road surface adhesion coefficient of each tire of the target vehicle on the road surface to be tested can be directly determined based on the road surface type, improving the accuracy of determining the road surface adhesion coefficient of each tire on the road surface to be tested.

[0152] Figure 10 This is a second flowchart illustrating the method for determining a target preset curve provided in this application. This embodiment relates to a possible implementation of how to determine a target preset curve from various preset curves based on the adhesion coefficients of each candidate curve and the target adhesion coefficient at the target coordinate point. Based on the above embodiment, as follows... Figure 10 As shown, the above S802 includes:

[0153] S1001, determine the difference between the adhesion coefficient of each candidate and the adhesion coefficient of the target.

[0154] S1002, Based on the differences in the adhesion coefficients of each candidate curve, determine the target preset curve from the preset curves.

[0155] To illustrate with the example above, if there are a total of 4 candidate adhesion coefficients, namely (μ1, μ2, μ3, μ4), the difference between each candidate adhesion coefficient and the target adhesion coefficient is calculated as (d1, d2, d3, d4). Let d1 = 0.01, d2 = 0.02, d3 = 0.04, d4 = 0.05. Set the preset difference to 0.03. The preset curves corresponding to the candidate adhesion coefficients with differences less than the preset difference are taken as the target preset curves. Since d1 < 0.03 and d2 < 0.03, the preset curves corresponding to μ1 and μ2 are taken as the target preset curves.

[0156] In this embodiment, the difference between each candidate adhesion coefficient and the target adhesion coefficient is determined, and then a target preset curve is determined from each preset curve based on the difference corresponding to each candidate adhesion coefficient. Determining the target preset curve through the difference provides a prerequisite for determining the road adhesion coefficient of each tire on the test road surface.

[0157] Figure 11 This is a flowchart illustrating a method for determining the speed of a target vehicle according to an embodiment of this application. Based on the above embodiment, as follows... Figure 11 As shown, the above method for determining the road surface adhesion coefficient also includes:

[0158] S1101, obtain the number of unbraked driven wheels.

[0159] S1102, determine the initial speed of the target vehicle based on the number of unbraked driven wheels.

[0160] S1103, Determine the speed of the target vehicle based on its initial speed value.

[0161] The initial speed of the target vehicle can be a measured value of the target vehicle's speed.

[0162] Because of the influence of various factors in the actual environment, such as changes in acceleration and friction between tires and the road surface, the speed of the target vehicle cannot be directly obtained. Therefore, it is necessary to determine the initial speed value of the target vehicle based on the wheel speeds of the driven wheels, and then determine the target vehicle's speed based on the initial speed value. In this embodiment, the number of unbraked driven wheels is first obtained. If there are more than two unbraked driven wheels, the average wheel speed of the unbraked driven wheels can be used as the initial speed value of the target vehicle. The product of the initial speed value of the target vehicle and a third preset coefficient is then used as the target vehicle's speed.

[0163] In this embodiment, the number of unbraked driven wheels is obtained, and the initial vehicle speed is determined based on this number. Furthermore, the vehicle speed is determined based on this initial speed. This provides the prerequisite for determining the slip ratio of each tire at each time point.

[0164] In one embodiment, the above-mentioned S1102, which determines the initial vehicle speed value of the target vehicle based on the number of unbraked driven wheels, can be implemented in the following way:

[0165] If there is only one vehicle, the speed of the unbraked driven wheel will be used as the initial speed of the target vehicle.

[0166] Specifically, if there is only one unbraked driven wheel, the wheel speed of the unbraked driven wheel is taken as the initial speed of the target vehicle.

[0167] Alternatively, the initial speed of the target vehicle can be obtained by multiplying the speed of the unbraked driven wheel by a fourth preset coefficient.

[0168] In one embodiment, the above-mentioned S1102, which determines the initial vehicle speed value of the target vehicle based on the number of unbraked driven wheels, can also be implemented in the following way:

[0169] If the number is the same as the total number of driven wheels of the target vehicle, then the average wheel speed of each unbraked driven wheel is taken as the initial speed of the target vehicle.

[0170] If the number of unbraked driven wheels is the same as the total number of driven wheels of the target vehicle, then the average wheel speed of each unbraked driven wheel is taken as the initial speed of the target vehicle.

[0171] Alternatively, the product of the average wheel speed of each unbraked driven wheel multiplied by a fourth preset coefficient can be used as the initial speed value of the target vehicle.

[0172] In one embodiment, the above-mentioned S1102, which determines the initial vehicle speed value of the target vehicle based on the number of unbraked driven wheels, can also be implemented in the following way:

[0173] If the quantity is zero, the maximum wheel speed among the wheel speeds of the target vehicle's driven wheels will be used as the initial speed value of the target vehicle.

[0174] If the number of unbraked driven wheels is not zero, the maximum wheel speed among the wheel speeds of the target vehicle's driven wheels will be used as the initial vehicle speed.

[0175] Alternatively, the product of the maximum wheel speed of each driven wheel of the target vehicle and a fourth preset coefficient can be used as the initial vehicle speed value.

[0176] In one embodiment, the above-described S1103, determining the speed of the target vehicle based on the initial speed value of the target vehicle, can be implemented in the following manner:

[0177] The initial speed value of the target vehicle is filtered using an adaptive Kalman filter to determine the target vehicle's speed.

[0178] The initial speed of the target vehicle is filtered using an adaptive Kalman filter to determine the target vehicle's speed. The specific process is as follows:

[0179] First, determine the state-space model for vehicle speed estimation:

[0180]

[0181] In the formula, V nLet a be the speed of the target vehicle at time n. n Let Δa be the acceleration of the target vehicle at time n. n Let n be the change in the target vehicle's acceleration at time n.

[0182] Since the acceleration of the target vehicle changes very little during actual driving, the change in acceleration can be regarded as process noise.

[0183]

[0184] The covariance matrix of the process noise is Q k .

[0185] The model for measuring vehicle speed is as follows:

[0186]

[0187] In the formula, r n This represents measurement noise.

[0188] Because the noise characteristics of the system measurements vary with road conditions, using Kalman filtering will introduce some bias. To perform fusion filtering on vehicle speed using Kalman filtering, the system state-space equations first need to be discretized:

[0189]

[0190] P k|k-1 =ΦP k-1 Φ T +Q k-1

[0191] In the formula, This is the posterior estimate of the state matrix at time k; Φ is the prior estimate of the state matrix at time k; Φ is the one-step state transition matrix; q k-1 P is the mean of the process noise at time k-1; k|k-1 P is the prior estimate of the error covariance at time k; k-1 Q is the posterior estimate of the error covariance at time k-1; k-1 Let be the covariance matrix of the process noise at time k-1.

[0192] Introducing intermediate variables:

[0193]

[0194] d k = (1-b) / (1-b) k )

[0195] Among them, V k For the residual, Z kLet H be the observation value at time k, and H be the observation matrix. Let d be the mean of the observed noise at time k-1. k is the weighting coefficient, and b is the forgetting factor.

[0196] The adaptive Kalman filter algorithm for the covariance matrix K k State matrix x k The update equation for the gain matrix is:

[0197] K k =P k / k-1 H T HP k / k-1 H T +R k-1 ) -1

[0198] x k =x k|k-1 +K k V k

[0199] P k =(IK k H)P k|k-1

[0200] process noise mean Covariance matrix of process noise Measuring the mean noise The covariance matrix R of measurement noise k The update equation is:

[0201]

[0202]

[0203]

[0204] The speed of the target vehicle is determined by filtering the initial vehicle speed value using an adaptive Kalman filter algorithm.

[0205] In this embodiment, an adaptive Kalman filter algorithm is used to filter the initial speed value of the target vehicle to determine its speed. By introducing the adaptive Kalman filter algorithm to filter the initial speed value, the influence of noise signals in the initial speed value is removed, improving the accuracy of determining the target vehicle's speed.

[0206] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0207] Based on the same inventive concept, this application also provides a road surface adhesion coefficient determining device for implementing the road surface adhesion coefficient determining method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more embodiments of the road surface adhesion coefficient determining device provided below can be found in the limitations of the road surface adhesion coefficient determining method described above, and will not be repeated here.

[0208] In one embodiment, such as Figure 12 As shown, a road surface adhesion coefficient determining device 1200 is provided, including: a first determining module 1201, a second determining module 1202, and a third determining module 1203, wherein:

[0209] The first determining module 1201 is used to determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface based on the three-degree-of-freedom vehicle model and tire model of the target vehicle.

[0210] The second determining module 1202 is used to determine the slip ratio of each tire at each time point based on the vehicle speed of the target vehicle, the angular velocity of each tire and the tire radius.

[0211] The third determining module 1203 is used to determine the road adhesion coefficient of each tire on the test road surface based on the utilization adhesion coefficient and slip ratio of each tire at each time point.

[0212] In one embodiment, the third determining module 1203 includes:

[0213] The first determining unit is used to determine the target curve for each tire based on the coefficient of adhesion and slip ratio at each time point; the target curve is the coefficient of adhesion-slip ratio curve.

[0214] The second determining unit is used to determine the road adhesion coefficient of each tire on the test road surface based on the target curve corresponding to each tire and multiple preset curves; the preset curve is a preset curve using adhesion coefficient-slip ratio.

[0215] In one embodiment, the second determining unit is specifically used to determine target coordinate points on the target curve corresponding to each tire, determine target preset curves from each preset curve based on the target slip ratio in the target coordinate points, and determine the road adhesion coefficient of each tire on the test road surface based on the adhesion coefficient corresponding to the target slip ratio on the target preset curve and the road adhesion coefficient corresponding to the target preset curve.

[0216] In one embodiment, the second determining unit is specifically used to determine each candidate adhesion coefficient; each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on each preset curve, or each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on a preset curve corresponding to the target adhesion degree type; the target adhesion degree type is determined according to the road surface type of the road surface to be tested. Based on each candidate adhesion coefficient and the target adhesion coefficient at the target coordinate point, a target preset curve is determined from each preset curve.

[0217] In one embodiment, the second determining unit is specifically configured to acquire a to-be-identified image of the road surface to be tested; determine the target road surface type based on the to-be-identified image; and determine the target road surface adhesion coefficient range corresponding to the target road surface type based on a first preset correspondence relationship; the first preset correspondence relationship includes the correspondence between different road surface types and different road surface adhesion coefficient ranges. Based on a second preset correspondence relationship and the target road surface adhesion coefficient range, a target adhesion degree type corresponding to the road surface type is determined from a plurality of preset adhesion degree types; the second preset correspondence relationship includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types.

[0218] In one embodiment, the second determining unit is specifically used to determine the difference between each candidate adhesion coefficient and the target adhesion coefficient, and to determine the target preset curve from each preset curve based on the difference corresponding to each candidate adhesion coefficient.

[0219] In one embodiment, the road surface adhesion coefficient determining device 1200 may further include:

[0220] The acquisition module is used to obtain the number of unbraked driven wheels;

[0221] The fourth determining module is used to determine the initial speed of the target vehicle based on the number of unbraked driven wheels;

[0222] The fifth determining module is used to determine the speed of the target vehicle based on its initial speed value.

[0223] In one embodiment, the fourth determining module is specifically used to determine, if the number is one, the wheel speed of the unbraked driven wheel as the initial vehicle speed value of the target vehicle.

[0224] In one embodiment, the fourth determining module is specifically used to take the average wheel speed of each unbraked driven wheel as the initial vehicle speed value if the number is the same as the total number of driven wheels of the target vehicle.

[0225] In one embodiment, the fourth determining module is specifically used to take the maximum wheel speed among the wheel speeds of each driven wheel of the target vehicle as the initial vehicle speed value if the quantity is zero.

[0226] In one embodiment, the fifth determining module is specifically used to take the maximum wheel speed among the wheel speeds of each driven wheel of the target vehicle as the initial vehicle speed value if the quantity is zero.

[0227] The various modules in the aforementioned road surface adhesion coefficient determining device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0228] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0229] Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0230] Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point;

[0231] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the road adhesion coefficient of each tire on the test road surface is determined.

[0232] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0233] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the target curve for each tire is determined; the target curve is the coefficient of adhesion-slip ratio curve.

[0234] Based on the target curve corresponding to each tire and multiple preset curves, the road adhesion coefficient of each tire on the test road surface is determined; the preset curve is a preset curve using the adhesion coefficient-slip ratio.

[0235] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0236] Determine the target coordinate points on the target curve corresponding to each tire;

[0237] Based on the target slip ratio at the target coordinate point, determine the target preset curve from each preset curve;

[0238] Based on the coefficient of adhesion corresponding to the target slip ratio on the target preset curve and the road surface adhesion coefficient corresponding to the target preset curve, the road surface adhesion coefficient of each tire on the test road surface is determined.

[0239] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0240] Determine each candidate adhesion coefficient; each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on each preset curve, or each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on the preset curve corresponding to the target adhesion degree type; the target adhesion degree type is determined according to the road surface type of the road surface to be tested.

[0241] Based on the adhesion coefficient of each candidate and the adhesion coefficient of the target at the target coordinate point, the target preset curve is determined from each preset curve.

[0242] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0243] Acquire the image of the road surface to be tested for identification;

[0244] Based on the image to be identified, determine the target road surface type of the road surface to be tested;

[0245] Based on the first preset correspondence, the target road surface adhesion coefficient range corresponding to the target road surface type is determined; the first preset correspondence includes the correspondence between different road surface types and different road surface adhesion coefficient ranges.

[0246] Based on the second preset correspondence and the target road surface adhesion coefficient range, the target adhesion degree type corresponding to the road surface type is determined from multiple preset adhesion degree types; the second preset correspondence includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types.

[0247] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0248] Determine the difference between the adhesion coefficient of each candidate and the target adhesion coefficient;

[0249] Based on the differences in the adhesion coefficients of each candidate curve, the target preset curve is determined from the preset curves.

[0250] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0251] Obtain the number of unbraked driven wheels;

[0252] Determine the initial speed of the target vehicle based on the number of unbraked driven wheels;

[0253] Determine the target vehicle's speed based on its initial speed.

[0254] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0255] If there is only one vehicle, the speed of the unbraked driven wheel will be used as the initial speed of the target vehicle.

[0256] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0257] If the number is the same as the total number of driven wheels of the target vehicle, then the average wheel speed of each unbraked driven wheel is taken as the initial speed of the target vehicle.

[0258] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0259] If the quantity is zero, the maximum wheel speed among the wheel speeds of the target vehicle's driven wheels will be used as the initial speed value of the target vehicle.

[0260] In one embodiment, the processor, when executing a computer program, also performs the following steps:

[0261] The initial speed value of the target vehicle is filtered using an adaptive Kalman filter algorithm to determine the target vehicle's speed.

[0262] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, the computer program performing the following steps when executed by a processor:

[0263] Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0264] Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point;

[0265] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the road adhesion coefficient of each tire on the test road surface is determined.

[0266] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0267] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the target curve for each tire is determined; the target curve is the coefficient of adhesion-slip ratio curve.

[0268] Based on the target curve corresponding to each tire and multiple preset curves, the road adhesion coefficient of each tire on the test road surface is determined; the preset curve is a preset curve using the adhesion coefficient-slip ratio.

[0269] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0270] Determine the target coordinate points on the target curve corresponding to each tire;

[0271] Based on the target slip ratio at the target coordinate point, determine the target preset curve from each preset curve;

[0272] Based on the coefficient of adhesion corresponding to the target slip ratio on the target preset curve and the road surface adhesion coefficient corresponding to the target preset curve, the road surface adhesion coefficient of each tire on the test road surface is determined.

[0273] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0274] Determine each candidate adhesion coefficient; each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on each preset curve, or each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on the preset curve corresponding to the target adhesion degree type; the target adhesion degree type is determined according to the road surface type of the road surface to be tested.

[0275] Based on the adhesion coefficient of each candidate and the adhesion coefficient of the target at the target coordinate point, the target preset curve is determined from each preset curve.

[0276] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0277] Acquire the image of the road surface to be tested for identification;

[0278] Based on the image to be identified, determine the target road surface type of the road surface to be tested;

[0279] Based on the first preset correspondence, the target road surface adhesion coefficient range corresponding to the target road surface type is determined; the first preset correspondence includes the correspondence between different road surface types and different road surface adhesion coefficient ranges.

[0280] Based on the second preset correspondence and the target road surface adhesion coefficient range, the target adhesion degree type corresponding to the road surface type is determined from multiple preset adhesion degree types; the second preset correspondence includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types.

[0281] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0282] Determine the difference between the adhesion coefficient of each candidate and the target adhesion coefficient;

[0283] Based on the differences in the adhesion coefficients of each candidate curve, the target preset curve is determined from the preset curves.

[0284] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0285] Obtain the number of unbraked driven wheels;

[0286] Determine the initial speed of the target vehicle based on the number of unbraked driven wheels;

[0287] Determine the target vehicle's speed based on its initial speed.

[0288] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0289] If there is only one vehicle, the speed of the unbraked driven wheel will be used as the initial speed of the target vehicle.

[0290] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0291] If the number is the same as the total number of driven wheels of the target vehicle, then the average wheel speed of each unbraked driven wheel is taken as the initial speed of the target vehicle.

[0292] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0293] If the quantity is zero, the maximum wheel speed among the wheel speeds of the target vehicle's driven wheels will be used as the initial speed value of the target vehicle.

[0294] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0295] The initial speed value of the target vehicle is filtered using an adaptive Kalman filter algorithm to determine the target vehicle's speed.

[0296] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, performs the following steps:

[0297] Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, determine the adhesion coefficients of each tire of the target vehicle at multiple time points on the test road surface.

[0298] Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point;

[0299] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the road adhesion coefficient of each tire on the test road surface is determined.

[0300] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0301] Based on the coefficient of adhesion and slip ratio of each tire at each time point, the target curve for each tire is determined; the target curve is the coefficient of adhesion-slip ratio curve.

[0302] Based on the target curve corresponding to each tire and multiple preset curves, the road adhesion coefficient of each tire on the test road surface is determined; the preset curve is a preset curve using the adhesion coefficient-slip ratio.

[0303] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0304] Determine the target coordinate points on the target curve corresponding to each tire;

[0305] Based on the target slip ratio at the target coordinate point, determine the target preset curve from each preset curve;

[0306] Based on the coefficient of adhesion corresponding to the target slip ratio on the target preset curve and the road surface adhesion coefficient corresponding to the target preset curve, the road surface adhesion coefficient of each tire on the test road surface is determined.

[0307] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0308] Determine each candidate adhesion coefficient; each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on each preset curve, or each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on the preset curve corresponding to the target adhesion degree type; the target adhesion degree type is determined according to the road surface type of the road surface to be tested.

[0309] Based on the adhesion coefficient of each candidate and the adhesion coefficient of the target at the target coordinate point, the target preset curve is determined from each preset curve.

[0310] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0311] Acquire the image of the road surface to be tested for identification;

[0312] Based on the image to be identified, determine the target road surface type of the road surface to be tested;

[0313] Based on the first preset correspondence, the target road surface adhesion coefficient range corresponding to the target road surface type is determined; the first preset correspondence includes the correspondence between different road surface types and different road surface adhesion coefficient ranges.

[0314] Based on the second preset correspondence and the target road surface adhesion coefficient range, the target adhesion degree type corresponding to the road surface type is determined from multiple preset adhesion degree types; the second preset correspondence includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types.

[0315] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0316] Determine the difference between the adhesion coefficient of each candidate and the target adhesion coefficient;

[0317] Based on the differences in the adhesion coefficients of each candidate curve, the target preset curve is determined from the preset curves.

[0318] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0319] Obtain the number of unbraked driven wheels;

[0320] Determine the initial speed of the target vehicle based on the number of unbraked driven wheels;

[0321] Determine the target vehicle's speed based on its initial speed.

[0322] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0323] If there is only one vehicle, the speed of the unbraked driven wheel will be used as the initial speed of the target vehicle.

[0324] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0325] If the number is the same as the total number of driven wheels of the target vehicle, then the average wheel speed of each unbraked driven wheel is taken as the initial speed of the target vehicle.

[0326] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0327] If the quantity is zero, the maximum wheel speed among the wheel speeds of the target vehicle's driven wheels will be used as the initial speed value of the target vehicle.

[0328] In one embodiment, when the computer program is executed by a processor, it also performs the following steps:

[0329] The initial speed value of the target vehicle is filtered using an adaptive Kalman filter algorithm to determine the target vehicle's speed.

[0330] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0331] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0332] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0333] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for determining the road surface adhesion coefficient, characterized in that, The method includes: Based on the three-degree-of-freedom vehicle model and tire model of the target vehicle, the utilization adhesion coefficient of each tire of the target vehicle at multiple time points on the test road surface is determined; the tire model includes a tire model during braking and a tire model during driving. The vertical force of each tire is substituted into the tire model during braking to determine the utilization adhesion coefficient of each tire under braking conditions, or the vertical force of each tire is substituted into the tire model during driving to determine the utilization adhesion coefficient of each tire under driving conditions. Based on the target vehicle's speed, the angular velocity of each tire, and the tire radius, determine the slip ratio of each tire at each time point; Based on the utilization coefficient of each tire and the slip ratio at each time point, the road adhesion coefficient of each tire on the test road surface is determined, including determining the target curve of each tire based on the utilization coefficient of each tire and the slip ratio at each time point; the target curve is the utilization coefficient of adhesion-slip ratio curve. Determine the target coordinate points on the target curves of each tire; Determine each candidate adhesion coefficient; each candidate adhesion coefficient includes the adhesion coefficient corresponding to the target slip ratio on a preset curve of the target adhesion degree type; the preset curve is a preset adhesion coefficient-slip ratio curve; determining the target adhesion degree type includes: Based on the acquired image to be identified, the target road surface type is determined; the target road surface adhesion coefficient range of the target road surface type is determined according to a first preset correspondence; the target adhesion degree type is determined according to a second preset correspondence and the target road surface adhesion coefficient range; the first preset correspondence includes the correspondence between different road surface types and different road surface adhesion coefficient ranges; the second preset correspondence includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types. The difference between each candidate utilization adhesion coefficient and the target utilization adhesion coefficient is determined; based on the difference corresponding to each candidate utilization adhesion coefficient, a target preset curve is determined from each preset curve; based on the utilization adhesion coefficient corresponding to the target slip ratio on the target preset curve and the road surface adhesion coefficient of the target preset curve, the road surface adhesion coefficient of each tire on the test road surface is determined.

2. The method according to claim 1, characterized in that, The method further includes: Obtain the number of unbraked driven wheels; The initial speed of the target vehicle is determined based on the number of unbraked driven wheels. The speed of the target vehicle is determined based on its initial speed value.

3. The method according to claim 2, characterized in that, Determining the initial vehicle speed based on the number of unbraked driven wheels includes: If the quantity is one, the wheel speed of the unbraked driven wheel is taken as the initial vehicle speed of the target vehicle.

4. The method according to claim 2, characterized in that, Determining the initial vehicle speed based on the number of unbraked driven wheels includes: If the number is the same as the total number of driven wheels of the target vehicle, then the average wheel speed of each of the unbraked driven wheels is taken as the initial speed of the target vehicle.

5. The method according to claim 2, characterized in that, Determining the initial vehicle speed based on the number of unbraked driven wheels includes: If the quantity is zero, the maximum wheel speed among the wheel speeds of the driven wheels of the target vehicle is taken as the initial vehicle speed value.

6. The method according to any one of claims 2-5, characterized in that, Determining the speed of the target vehicle based on its initial speed value includes: The initial speed value of the target vehicle is filtered using an adaptive Kalman filter algorithm to determine the speed of the target vehicle.

7. A device for determining the road surface adhesion coefficient, characterized in that, The device includes: The first determining module is used to determine the utilization adhesion coefficient of each tire of the target vehicle at multiple time points on the test road surface based on the three-degree-of-freedom vehicle model and tire model of the target vehicle; the tire model includes a tire model during braking and a tire model during driving, and the vertical force of each tire is substituted into the tire model during braking to determine the utilization adhesion coefficient of each tire under braking conditions, or the vertical force of each tire is substituted into the tire model during driving to determine the utilization adhesion coefficient of each tire under driving conditions. The second determining module is used to determine the slip ratio of each tire at each time point based on the vehicle speed of the target vehicle, the angular velocity of each tire, and the tire radius. The third determining module is used to determine the road adhesion coefficient of each tire on the test road surface based on the utilization adhesion coefficient and slip ratio of each tire at each time point; it includes a first determining unit used to determine the target curve of each tire based on the utilization adhesion coefficient and slip ratio of each tire at each time point; the target curve is the utilization adhesion coefficient-slip ratio curve; The second determining unit is used to determine target coordinate points on the target area line of each tire. The second determining unit is further configured to determine each candidate adhesion coefficient, wherein each candidate adhesion coefficient includes an adhesion coefficient corresponding to the target slip ratio on a preset curve of the target adhesion degree type; the preset curve is a preset adhesion coefficient-slip ratio curve; determining the target adhesion degree type includes: determining the target road surface type based on the acquired image to be identified; determining the target road surface adhesion coefficient range of the target road surface type based on a first preset correspondence; determining the target adhesion degree type based on a second preset correspondence and the target road surface adhesion coefficient range; the first preset correspondence includes the correspondence between different road surface types and different road surface adhesion coefficient ranges; the second preset correspondence includes the correspondence between different road surface adhesion coefficient ranges and different adhesion degree types; The second determining unit is further configured to determine the difference between each of the candidate utilization adhesion coefficients and the target utilization adhesion coefficient; determine a target preset curve from each of the preset curves based on the difference corresponding to each of the candidate utilization adhesion coefficients; and determine the road surface adhesion coefficient of each tire on the test road surface based on the utilization adhesion coefficient corresponding to the target slip ratio on the target preset curve and the road surface adhesion coefficient of the target preset curve.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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