Wheel slip rate calculation method, device, electronic device and storage medium

Abstract

The present invention discloses a wheel slip calculation method, device, electronic device and storage medium. The method comprises: calculating the absolute speed of the physical wheel relative to the reference wheel in the X and Y directions of the vehicle body based on the component speeds of the reference wheel center translation speed in the X and Y directions of the vehicle body and the component speeds of the relative linear speed of the physical wheel relative to the reference wheel caused by rigid body rotation in the X and Y directions of the vehicle body; calculating the maximum and minimum values ​​of the absolute speeds of the physical wheel relative to all reference wheels in the rotational direction based on the absolute speeds of the physical wheel relative to the reference wheel in the X and Y directions of the vehicle body; and calculating the real-time slip rate of the wheel based on the maximum and minimum values ​​of the absolute speeds of the physical wheel center and the rotational direction of the physical wheel relative to all reference wheels. The algorithm has high versatility and can ensure the normal implementation of the vehicle's anti-skid and anti-lock braking functions, thereby improving the vehicle's driving safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle braking, and more specifically, relates to a wheel slip rate calculation method, device, electronic equipment and storage medium. Background Art

[0002] Whether it's a traditional fuel-powered vehicle or a new energy electric vehicle, chassis anti-skid and anti-lock braking systems are crucial safety features. Accurate calculation of each wheel's slip ratio is fundamental to the safety of these features. Inaccurate slip ratio calculation can lead to false or ineffective triggering of these features, or even abnormal torque control after triggering. These can significantly impact vehicle safety. Therefore, accurate slip ratio calculation is fundamental to safe driving.

[0003] Existing slip calculation methods simply divide each wheel's speed by the vehicle's center speed. This solution only works when the vehicle is in straight-line driving. If the vehicle is turning, the actual wheel speed differs significantly from the center speed. This discrepancy is particularly pronounced when the vehicle is making large turns with a small radius. This can lead to inaccurate or erroneous slip calculations, potentially causing erroneous or non-functional triggering of anti-skid and anti-lock braking systems, or even abnormal torque control on each wheel after triggering, seriously impacting vehicle safety.

[0004] Therefore, there is an urgent need for a wheel slip calculation method that can be used for both mechanically steered vehicles and vehicles without steering structures that achieve vehicle steering through differentials, and that can also be used for vehicles with any number of axles, without any restrictions or requirements on the vehicle chassis configuration, and with a highly versatile algorithm. Summary of the Invention

[0005] In response to the above-mentioned defects or improvement needs in the prior art, the present invention provides a wheel slip rate calculation method, device, electronic device and storage medium, which calculate the theoretical speed of each wheel based on the yaw angular velocity, and calculate the slip rate of each wheel on this basis; it is not only applicable to vehicles with mechanical Ackerman steering, but also to vehicles without steering structure that achieve vehicle steering through differential speed, and it is also applicable to vehicles with any number of axles. There are no restrictions or requirements on the vehicle chassis configuration. The algorithm is highly versatile and can accurately calculate the slip rate of each wheel, which can ensure the normal implementation of the vehicle's anti-skid and anti-lock braking functions, thereby improving the vehicle's driving safety.

[0006] To achieve the above object, one aspect of the present invention provides a method for calculating wheel slip rate, comprising the following steps:

[0007] ≤1: Calculate the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X and Y directions based on the components of the translational velocity of the reference wheel center on the reference axle in the X and Y directions of the vehicle body, and the components of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle due to the rigid body rotational motion in the X and Y directions of the vehicle body.

[0008] ≤2: Based on the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the body, calculate the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction;

[0009] S3: Calculate the real-time slip rate of the wheel based on the maximum and minimum values ​​of the translational velocity of the physical wheel center and the absolute velocity of the physical wheel in the rotational direction relative to the reference wheels on all reference axles.

[0010] Furthermore, the component velocity of the translation velocity of the reference wheel center on the reference axle in the X-direction of the vehicle body in step ≤1 is expressed by equation (1):

[0011] VX kt =V kt *cosθ kt (1)

[0012] Where f is the number of the left or right reference wheel, t∈{1,2}, where t=1 indicates the left reference wheel and t=2 indicates the right reference wheel; k is the serial number of the reference axles starting from the front of the vehicle, k∈[1,n], H is the total number of reference axles; V kt is the translational velocity of the left or right reference wheel center of the kth reference axle; θ kt is the angle between the left or right reference wheel of the kth reference axle and the vehicle body in the X direction, If the wheel deviates to the right side of the vehicle, it is positive, and if it deviates to the left side of the vehicle, it is negative; VX kt is the component of the translational velocity of the left or right reference wheel center of the k-th reference axle in the X direction of the vehicle body;

[0013] The component velocity of the translation velocity of the reference wheel center on the reference axle in the Y direction of the vehicle body in step S1 is expressed by formula (2):

[0014] VY kt =V kt *sinθ kt (2)

[0015] Among them, VY kt is the component of the translational velocity of the left or right reference wheel center of the k-th reference axle in the Y direction of the vehicle body.

[0016] Furthermore, the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotation in step S1 is calculated by formula (5):

[0017] V ij(kt) =w*l ij(kt) (5)

[0018] Wherein, j is the number of the left or right physical wheel, where 1 represents the left wheel and 2 represents the right wheel; i is the serial number of the vehicle axle starting from the front of the vehicle; V ij(kt) is the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel of the k-th reference axle caused by the rigid body rotation; w is the yaw angular velocity of the vehicle rotation, obtained by the angular velocity sensor installed at the center of the vehicle, with positive value for counterclockwise rotation and negative value for clockwise rotation; l ij(kt) is the distance between the left or right physical wheel of the i-th axle and the left or right reference wheel of the k-th reference axle;

[0019] In step S1, the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotation motion is calculated by formula (8) in the X direction and the Y direction of the body:

[0020]

[0021] Among them: VX ij(kt) VY is the component of the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the X direction of the vehicle body caused by the rigid body rotation; ij(kt) is the component of the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the Y direction of the vehicle body caused by the rigid body rotation; ij(kt) is the angle between the line vector connecting the left or right physical wheel of the i-th axle and the left or right reference wheel of the k-th reference axle and the X direction of the vehicle body, α ij(kt) ∈[-π,π].

[0022] Furthermore, in step S1, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body is calculated by formula (10):

[0023]

[0024] Among them: VX1 ij(kt) VY1 is the absolute total velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the X-direction of the vehicle body; ij(kt) is the absolute total velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the Y direction of the vehicle body.

[0025] Furthermore, in step S2, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotation direction is calculated by formula (11):

[0026] V1 ij(kt) =|VX1 ij(kt) *cosθ ij +VY1 ij(kt) *sinθ ij | (11)

[0027] Among them: V1 ij(kt) is the absolute speed of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the rotation direction; θ ij The angle between the left or right physical wheel of the i-th axle and the vehicle body in the X direction, If the wheel deflects to the right side of the vehicle, it is positive, and if it deflects to the left side of the vehicle, it is negative.

[0028] For vehicles without mechanical steering structure, θ kt =0 and θ ij =0.

[0029] Furthermore, in step S2, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotation direction are calculated by formula (12):

[0030]

[0031] Where: Vmin ij Vmax is the minimum absolute speed of the left or right physical wheel of the i-th axle when all wheels of the vehicle are used as reference wheels; ij The maximum absolute speed of the left or right physical wheel of the i-th axle when all wheels of the vehicle are used as reference wheels.

[0032] Furthermore, the real-time slip rate of the wheel in step S3 is calculated by formula (13):

[0033]

[0034] Where: S ij is the slip rate of the left or right physical wheel of the i-th axle; β is the state of vehicle braking or driving; V ij is the translational velocity of the left or right physical wheel center of the i-th axle, which is calculated based on the wheel speed and is related to V kt It is essentially a variable with different numbers; V1 is the closing speed threshold of the dynamic calculation of the slip rate; V2 is the opening speed threshold of the dynamic calculation, and V2>V1; V2 and V1 are calibrable and changeable parameters;

[0035] If the vehicle is in braking state, the wheel speed in the unlocked state is the largest, then Vmax ij Valid, β takes the value of 1;

[0036] If the vehicle is in driving state and the wheel speed is minimum in the non-slip state, then Vmin ij Valid, β is -1.

[0037] A second aspect of the present invention provides a wheel slip ratio calculation device, comprising:

[0038] a first calculation module for calculating the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X and Y directions of the vehicle body based on the component velocities of the translation velocity of the reference wheel center on the reference axle in the X and Y directions of the vehicle body and the component velocities of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in the X and Y directions of the vehicle body;

[0039] a second calculation module, calculating, based on the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction;

[0040] The third calculation module calculates the real-time slip rate of the wheel according to the maximum and minimum values ​​of the translation speed of the center of the physical wheel and the absolute speed of the physical wheel in the rotation direction relative to the reference wheels on all reference axles.

[0041] A third aspect of the present invention provides an electronic device, comprising a processor and a memory, wherein the processor and the memory are connected to each other;

[0042] The memory is used to store computer programs;

[0043] The processor is configured to execute the above-mentioned wheel slip ratio calculation method when calling the computer program.

[0044] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program is executed by a processor to implement the above-mentioned wheel slip ratio calculation method.

[0045] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0046] A wheel slip calculation method of the present invention calculates the theoretical speed of each wheel based on the yaw angular velocity, and calculates the slip rate of each wheel based on this; specifically, according to the component velocities of the translational velocity of the reference wheel center on the reference axle in the X direction and the Y direction of the vehicle body, and the component velocities of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in the X direction and the Y direction of the vehicle body, the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body is calculated; according to the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body, the rotational direction of the physical wheel relative to the reference wheel on the reference axle is calculated. The present invention calculates the real-time slip rate of each wheel based on the maximum and minimum values ​​of the absolute upward speed and the absolute speed of the physical wheel relative to all reference wheels on the reference axles in the rotational direction; the real-time slip rate of the wheel is calculated based on the translational speed of the physical wheel center and the maximum and minimum values ​​of the absolute speed of the physical wheel relative to all reference wheels on the reference axles in the rotational direction; the present invention calculates the theoretical speed of each wheel based on the yaw angular velocity, and calculates the slip rate of each wheel based on this; regardless of whether the vehicle is in a straight-line or turning state, or in extreme operating conditions such as understeer or oversteer, as long as the yaw angular velocity of the vehicle is obtained in real time and combined with the vehicle size, the slip rate of each wheel can still be accurately calculated. The present invention has a wide range of applicability and is applicable to vehicles with any chassis configuration. Obtaining the slip ratio through kinematic calculation can be applicable to vehicles that do not have a mechanical steering structure but steer through differential speed, can also be applicable to vehicles with a mechanical steering structure, and can also be applicable to vehicles with multiple axles or different wheelbases; it can solve the problem that the existing slip ratio calculation method only uses the wheel speed divided by the speed at the center of the vehicle to obtain the slip ratio, which can only be applied when the vehicle is in a straight-line driving condition. If the vehicle is in a turning driving state, the actual wheel speed of each wheel differs greatly from the speed at the center of the vehicle, resulting in inaccurate or erroneous calculation of the slip ratio of each wheel, which may cause the drive anti-skid and brake anti-lock braking to be falsely triggered or unable to be triggered normally, or the torque control of each wheel after triggering is abnormal, seriously affecting the driving safety of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of a flow chart of a method for calculating wheel slip rate according to an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of the speed geometry relationship of a vehicle using differential steering without a mechanical steering structure in accordance with a wheel slip ratio calculation method according to an embodiment of the present invention;

[0049] Figure 3 This is a schematic structural diagram of a wheel slip ratio calculation device according to an embodiment of the present invention;

[0050] Figure 4 FIG. 4 is a schematic diagram of the physical structure of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0052] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified 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 of the steps in the flowcharts of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0053] Accurately calculating the slip ratio is fundamental to safe vehicle operation. Existing methods for calculating slip ratios simply divide each wheel speed by the vehicle's center speed. This solution only works when the vehicle is in a straight-line driving condition. If the vehicle is turning, the actual wheel speed of each wheel differs significantly from the speed at the vehicle's center. This discrepancy is particularly significant when the vehicle is in a large turning radius. This can lead to inaccurate or erroneous slip ratio calculations for each wheel, potentially causing the drive anti-skid and anti-lock braking systems to be falsely or improperly triggered, or even abnormal torque control on each wheel after triggering, seriously impacting vehicle safety.

[0054] In response to the problems existing in the above-mentioned related technologies, an embodiment of the present invention provides a method for calculating the wheel slip rate, which can be applied to a server, a terminal, or a system including a terminal and a server, and is implemented through the interaction between the terminal and the server. The server can be implemented as an independent server or a server cluster composed of multiple servers. The terminal can be, but is not limited to, various personal computers, laptops, smart phones, tablet computers, Internet of Things devices and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart car-mounted devices, etc. Portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. It should be noted that the quantities of "multiple" and the like mentioned in the embodiments of this application all refer to the quantity of "at least two", for example, "multiple" refers to "at least two".

[0055] Before describing the specific implementation of the present invention, we will first describe the main application scenarios of the present invention. This embodiment provides a wheel slip calculation method that is applicable not only to vehicles with mechanical Ackerman steering but also to vehicles without steering mechanisms that achieve steering through differentials. Furthermore, this method is applicable to vehicles with any number of axles and has no restrictions or requirements on vehicle chassis configurations. The algorithm is highly versatile and can ensure the proper implementation of drive anti-skid and anti-lock braking functions, thereby improving vehicle driving safety.

[0056] It should be noted that the body X direction mentioned in the text refers to the direction along the longitudinal center axis of the vehicle; the body Y direction refers to the direction along the lateral center axis of the vehicle.

[0057] like Figure 1 As shown, one aspect of the present invention provides a method for calculating a wheel slip rate. This embodiment uses the method applied to a server as an example for illustration. The method includes the following steps:

[0058] S1: Calculate the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X and Y directions based on the components of the translation velocity of the reference wheel center on the reference axle in the X and Y directions of the vehicle body and the components of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle due to the rigid body rotational motion in the X and Y directions of the vehicle body;

[0059] S2: Calculate the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction, based on the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body;

[0060] S3: Calculate the real-time slip rate of the wheel based on the maximum and minimum values ​​of the translational velocity of the center of the physical wheel and the absolute velocity of the physical wheel in the rotational direction relative to the reference wheels on all reference axles.

[0061] Furthermore, in an embodiment of the present invention, the translational velocity of the reference wheel center on the reference axle in step S1 is calculated based on the actual rotational speed of each reference wheel; the component velocity of the translational velocity of the reference wheel center on the reference axle in step S1 in the X direction of the vehicle body is expressed by formula (1):

[0062] VX kt =V kt *cosθ kt (1)

[0063] Where t is the number of the left or right reference wheel on the reference axle, t∈{1,2}, where t=1 indicates the left reference wheel and t=2 indicates the right reference wheel; k is the serial number of the reference axles starting from the front of the vehicle, k∈[1,n], where n is the total number of reference axles; V kt is the translational velocity of the left or right reference wheel center of the kth reference axle; θ kt is the angle between the left or right reference wheel of the kth reference axle and the vehicle body in the X direction, If the wheel deviates to the right side of the vehicle, it is positive, and if it deviates to the left side of the vehicle, it is negative; VX kt is the component of the translational velocity of the left or right reference wheel center of the k-th reference axle in the X direction of the vehicle body;

[0064] The component velocity of the translation velocity of the reference wheel center on the reference axle in the Y direction of the vehicle body in step S1 is expressed by formula (2):

[0065] VY kt =V kt *sinθ kt (2)

[0066] Among them, VY kt is the component of the translational velocity of the left or right reference wheel center of the k-th reference axle in the Y direction of the vehicle body.

[0067] Furthermore, since the tire pressures of the reference wheels are inconsistent, resulting in different radii of the reference wheels, the radius of each reference wheel needs to be corrected according to the tire pressure of each reference wheel. Therefore, the translation speed of the reference wheel center is equal to the reference wheel speed multiplied by the reference wheel correction radius. The translation speed of the reference wheel center on the reference axle in step S1 is expressed by formula (3):

[0068] V kt =w kt *τ kt (3)

[0069] Where: w kt is the rotational speed of the left or right reference wheel of the kth reference axle, acquired through sensor acquisition; τ kt is the correction radius of the left or right reference wheel of the kth reference axle;

[0070] The correction radius of the reference wheel on the reference axle is calculated by formula (4):

[0071]

[0072] Where: τ kt rmax is the correction radius of the left or right reference wheel of the kth reference axle; ktis the maximum tire radius of the left or right reference wheel of the kth reference axle; p kt is the actual tire pressure of the left or right reference wheel of the kth reference axle, obtained through the tire pressure sensor; pmin kt The minimum permissible tire pressure of the left or right reference wheel of the kth reference axle; pmax kt The maximum permissible tire pressure of the left or right reference wheel of the kth reference axle; rmin kt is the minimum tire radius of the left or right reference wheel of the kth reference axle;

[0073] If the actual tire pressure of the left or right reference wheel of the kth reference axle is equal to the maximum allowable tire pressure, then the correction radius of the reference wheel is equal to the maximum tire radius of the wheel; that is: if p kt =pmax kt , then T kt = rmax kt ;

[0074] If the actual tire pressure of the left or right reference wheel of the kth reference axle is equal to the minimum allowable tire pressure, then the correction radius of the reference wheel is equal to the minimum tire radius of the wheel; that is: if p kt =pmin kt , then τ kt = rmin kt ;

[0075] If the actual tire pressure of the left or right reference wheel of the kth reference axle is greater than or equal to the minimum allowable tire pressure and less than or equal to the maximum allowable tire pressure, then the corrected radius of the reference wheel is greater than or equal to the minimum tire radius of the wheel and less than or equal to the maximum tire radius of the wheel;

[0076] That is: if pmin kt ≤p kt ≤pmax kt , then rmin kt ≤τ kt ≤rmax kt .

[0077] Furthermore, in an embodiment of the present invention, the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in step ≤1 is calculated by formula (5):

[0078] V ij(kt) ==w*l ij(kt) (5)

[0079] Wherein, j is the number of the left or right physical wheel, where 1 represents the left wheel and 2 represents the right wheel; i is the serial number of the axle starting from the front of the vehicle; V ij(kt)is the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel of the k-th reference axle caused by the rigid body rotation; w is the yaw angular velocity of the vehicle rotation, obtained by the angular velocity sensor installed at the center of the vehicle, with positive value for counterclockwise rotation and negative value for clockwise rotation; l ij (kt) is the distance between the left or right physical wheel of the i-th axle and the left or right reference wheel of the k-th reference axle;

[0080] Furthermore, when the vehicle is traveling in a straight line, if there is no rotational motion, the yaw angular velocity w of the vehicle's rotation is equal to 0; when the vehicle is turning left, the yaw angular velocity w of the vehicle's rotation is less than 0; when the vehicle is turning right, the yaw angular velocity w of the vehicle's rotation is greater than 0.

[0081] Furthermore, the yaw rate of the vehicle's rotation is very important and is obtained through an angular velocity sensor. Due to vibration during vehicle movement and sensor accuracy issues, a sliding mean filter is required to ensure the smoothness of the yaw rate of the vehicle's rotation.

[0082] The sliding mean filtering process of the yaw rate of vehicle rotation is expressed by equation (6):

[0083]

[0084] Where: w(a) is the ath value of the yaw angle velocity of m vehicle rotations continuously collected by the angular velocity sensor; The minimum value of the yaw angle velocity of the vehicle rotation continuously collected by the angle sensor; The angle sensor continuously collects the maximum value of the yaw angle velocity of the vehicle rotation;

[0085] Furthermore, the distance l between the left or right physical wheel of the i-th axle and the left or right reference wheel on the k-th reference axle is ij(kt) Calculated by formula (7):

[0086]

[0087] Where: d i is the wheelbase on the i-th axle; d k is the wheelbase on the kth reference axle; d ik is the wheelbase between the i-th axle and the k-th reference axle;

[0088] Furthermore, if the physical wheel on the i-th axle and the reference wheel on the k-th reference axle are wheels on the same side, then |jt|=0 or ||jt|-1|=1; if the physical wheel on the i-th axle and the reference wheel on the k-th reference axle are wheels on opposite sides, then |jt|=1 or ||jt|-1|=0.

[0089] Furthermore, if Figure 2 As shown, in the embodiment of the present invention, the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in step S1 is calculated by formula (8) in the X direction and the Y direction of the vehicle body:

[0090]

[0091] Among them: VX ij(kt) VY is the component of the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the X direction of the vehicle body caused by the rigid body rotation; ij(kt) is the component of the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the Y direction of the vehicle body caused by the rigid body rotation; ij(kt) is the angle between the line vector connecting the left or right physical wheel of the i-th axle and the left or right reference wheel of the k-th reference axle and the X direction of the vehicle body, α ij(kt) ∈[-π,π].

[0092] Furthermore, according to the geometric position relationship of the wheel installation, it can be known that the angle α between the line vector connecting the left or right physical wheel of the i-th axle and the left or right reference wheel of the k-th reference axle and the X direction of the vehicle body is ij(kt) It is expressed by formula (9):

[0093] α ij(kt) =π-α kt(ij) (9).

[0094] Furthermore, in an embodiment of the present invention, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body in step S1 is calculated by formula (10):

[0095]

[0096] Among them: VX1 ij(kt) VY1 is the absolute total velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the X-direction of the vehicle body; ij(kt) VX is the absolute total velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the Y direction of the vehicle body; ij(kt) VX is the component of the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the X direction of the vehicle body caused by the rigid body rotation; kt VY is the component velocity of the translation velocity of the left or right reference wheel center on the kth reference axle in the X direction of the vehicle body; ij(kt)VY is the component of the relative linear velocity of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the Y direction of the vehicle body caused by the rigid body rotation; kt is the component of the translational velocity of the reference wheel center on the kth reference axle in the Y direction of the vehicle body.

[0097] Furthermore, in an embodiment of the present invention, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotation direction in step S2 is calculated by formula (11):

[0098] V1 ij(kt) =|VX1 ij(kt) *cosθ ij +VY1 ij(kt) *sinθ ij | (11)

[0099] Among them: V1 ij(kt) is the absolute speed of the left or right physical wheel of the i-th axle relative to the left or right reference wheel on the k-th reference axle in the rotation direction; θ ij The angle between the left or right physical wheel of the i-th axle and the vehicle body in the X direction, If the wheel deflects to the right side of the vehicle, it is positive, and if it deflects to the left side of the vehicle, it is negative; ij and θ kt Same angle, different numbers.

[0100] Furthermore, in an embodiment of the present invention, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotation direction in step S2 are calculated by formula (12):

[0101]

[0102] Where: Vmin ij Vmax is the minimum absolute speed of the left or right physical wheel of the i-th axle when all wheels of the vehicle are used as reference wheels; ij The maximum absolute speed of the left or right physical wheel of the i-th axle when all wheels of the vehicle are used as reference wheels.

[0103] Furthermore, in an embodiment of the present invention, the real-time slip rate of the wheel in step S3 is calculated by formula (13):

[0104]

[0105] Where: S ij is the slip rate of the left or right physical wheel of the i-th axle; β is the state of vehicle braking or driving; V ijis the translational velocity of the left or right physical wheel center of the i-th axle, which is calculated based on the wheel speed and is related to V kt It is essentially a variable with different numbers; V1 is the closing speed threshold of the dynamic calculation of the slip rate; V2 is the opening speed threshold of the dynamic calculation, and V2>V1; V2 and V1 are calibrable and changeable parameters.

[0106] That is, when the translation speed of the physical wheel center is less than or equal to the closing speed threshold of the dynamic calculation of the slip rate, the real-time slip rate of the wheel is zero;

[0107] When the translation speed of the physical wheel center is greater than or equal to the speed threshold for the dynamic calculation of the slip rate, the real-time slip rate of the wheel is:

[0108]

[0109] Furthermore, due to the inconsistency of the tire pressure of each wheel, the radius of each wheel is different, and the radius of each wheel needs to be corrected according to the tire pressure of each wheel. Therefore, the translation speed of the left or right physical wheel center of the i-th axle is equal to the left or right physical wheel speed of the i-th axle multiplied by the corrected radius of the left or right physical wheel of the i-th axle. That is, the translation speed of the physical wheel center is expressed by formula (14):

[0110] V ij =w ij *τ ij (14)

[0111] Where: Vx j is the translational velocity of the left or right physical wheel center of the i-th axle; w ij is the rotation speed of the left or right physical wheel of the i-th axle, acquired through sensor acquisition; τ ij The corrected radius of the left or right physical wheel of the i-th axle.

[0112] Furthermore, if the vehicle is in a braking state and the wheel speed in the unlocked state is the largest, then Vmax il If the vehicle is in driving state and the wheel speed is minimum without slipping, then Vmin ij Valid, β is -1.

[0113] Furthermore, when the vehicle speed is at the left or right physical wheel of the i-th axle, the minimum value ymin of the absolute speed when all wheels of the vehicle are used as reference wheels ij and the maximum value ymax ij When switching between acceleration and deceleration, the slope process control is used to avoid drastic changes in slip rate caused by switching between rapid acceleration and deceleration.

[0114] Furthermore, for a vehicle without mechanical steering structure, let θ kt =0 and θ ij =0, and put it into formulas (12) to (13) to calculate, the slip rate can be accurately calculated during the turning or straight driving process.

[0115] The present invention provides a wheel slip rate calculation method, which calculates the theoretical speed of each wheel based on the yaw angular velocity, and calculates the slip rate of each wheel based on this. The method is applicable not only to vehicles with mechanical Ackerman steering, but also to vehicles without a steering structure that achieve vehicle steering through differential speed. It is also applicable to vehicles with any number of axles, has no restrictions or requirements on the vehicle chassis configuration, and has a high algorithm versatility. The present invention can ensure that the vehicle's drive anti-skid and brake anti-lock functions are normally implemented, thereby improving vehicle driving safety. It can solve the problem that the existing slip rate calculation method only uses the wheel speed divided by the vehicle center speed to obtain the value, which can only be applied when the vehicle is in a straight-line driving condition. If the vehicle is in a turning driving state, the actual driving wheel speed of each wheel differs significantly from the vehicle center speed, resulting in inaccurate or erroneous calculation of the slip rate of each wheel, which may cause the drive anti-skid and brake anti-lock to be erroneously triggered or unable to be triggered normally, or abnormal torque control of each wheel after triggering, seriously affecting the vehicle's driving safety.

[0116] like Figure 3 As shown, the second aspect of the present invention provides a device for calculating wheel slip rate, comprising a first calculation module, a second calculation module and a third calculation module.

[0117] a first calculation module for calculating the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X and Y directions of the vehicle body based on the component velocities of the translation velocity of the reference wheel center on the reference axle in the X and Y directions of the vehicle body and the component velocities of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in the X and Y directions of the vehicle body;

[0118] a second calculation module, calculating, based on the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction;

[0119] The third calculation module calculates the real-time slip rate of the wheel according to the maximum and minimum values ​​of the translation speed of the center of the physical wheel and the absolute speed of the physical wheel in the rotation direction relative to the reference wheels on all reference axles.

[0120] It should be noted that the wheel slip rate calculation device provided in the embodiment of the present invention can be a computer program running in a computer device, including program code, for example, the wheel slip rate calculation device is an application software; the wheel slip rate calculation device can be used to execute the corresponding steps in the above method provided in the embodiment of the present invention.

[0121] In some feasible implementations, the wheel slip rate calculation device provided in this embodiment can be implemented by a combination of software and hardware. As an example, the wheel slip rate calculation device in the embodiment of the present application can be a processor in the form of a hardware decoding processor, which is programmed to execute the wheel slip rate calculation method provided in the embodiment of the present application. For example, the processor in the form of a hardware decoding processor can adopt one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs) or other electronic components.

[0122] In some feasible implementations, the wheel slip rate calculation device provided in this embodiment can be implemented in software, which can be software in the form of programs and plug-ins, and include a series of modules to implement the control method provided in the embodiment of the present invention.

[0123] The wheel slip calculation device provided in this embodiment calculates the theoretical speed of each wheel based on the yaw angular velocity, and calculates the slip rate of each wheel on this basis; specifically, according to the component velocities of the translational velocity of the reference wheel center on the reference axle in the X direction and the Y direction of the vehicle body, and the component velocities of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in the X direction and the Y direction of the vehicle body, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body is calculated; according to the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction are calculated; according to the translational velocity of the physical wheel center, the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction The real-time slip rate of the wheel is calculated by using the maximum and minimum values ​​of the absolute speed in the turning direction; the method is applicable not only to vehicles with mechanical Ackerman steering, but also to vehicles without steering structure that achieve vehicle steering through differential speed, and also to vehicles with any number of axles, without any restrictions and requirements on the vehicle chassis configuration, the algorithm has high versatility, can ensure the normal implementation of the vehicle's drive anti-skid and brake anti-lock functions, and thus can improve the vehicle's driving safety; it can solve the problem that the existing slip rate calculation method only uses the wheel speed of each wheel divided by the speed at the center of the vehicle to obtain the value, which can only be applied when the vehicle is in a straight-line driving condition. If the vehicle is in a turning driving state, the actual wheel speed of each wheel is significantly different from the speed at the center of the vehicle, resulting in inaccurate or erroneous calculation of the slip rate of each wheel, which may cause the drive anti-skid and brake anti-lock to be triggered incorrectly or not to be triggered normally, or the torque control of each wheel after triggering is abnormal, seriously affecting the vehicle's driving safety.

[0124] The method for calculating the wheel slip rate provided by the first aspect of the present invention is implemented by relying on electronic equipment, such as Figure 4 As shown, the third aspect of the present invention provides an electronic device, which includes: at least one processor, a communication interface, at least one memory and a communication bus, wherein the at least one processor, the communication interface and the at least one memory communicate with each other through the communication bus; at least one processor can call the logic instructions in at least one memory to execute all or part of the steps of the method provided by the aforementioned method embodiments; that is, the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the wheel slip rate calculation method provided by any one of the various implementation methods of the first aspect.

[0125] The logic instructions in the at least one memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the fourth aspect of the present invention provides a non-transitory computer-readable storage medium, which is used to store computer instructions. The computer instructions enable a computer to execute the wheel slip rate calculation method provided by any of the various implementation methods of the first aspect of the present invention. The technical solution of the present invention, or the part that contributes to the existing technology, or the part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each method embodiment of the present invention. The aforementioned storage medium includes: a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc., various media that can store program code.

[0126] The computer-readable storage medium provided by the embodiment of the present invention calculates the theoretical speed of each wheel based on the yaw angular velocity, and calculates the slip rate of each wheel on this basis; specifically, according to the component velocities of the translational velocity of the reference wheel center on the reference axle in the X direction and the Y direction of the body, and the component velocities of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in the X direction and the Y direction of the body, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the body is calculated; according to the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the body, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction are calculated; according to the translational velocity of the physical wheel center, the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the X direction and the Y direction of the body, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction are calculated. The maximum and minimum values ​​of the absolute speed in the rotational direction are used to calculate the real-time slip rate of the wheel; the method is applicable not only to vehicles with mechanical Ackerman steering, but also to vehicles without steering structure that achieve vehicle steering through differential speed, and also to vehicles with any number of axles, without any restrictions or requirements on the vehicle chassis configuration, and the algorithm has high versatility, which can ensure the normal implementation of the vehicle's drive anti-skid and brake anti-lock functions, thereby improving the vehicle's driving safety; the method can solve the problem that the existing slip rate calculation method only uses the wheel speed of each wheel divided by the speed at the center of the vehicle to obtain the value, which can only be applied when the vehicle is in a straight-line driving condition. If the vehicle is in a turning driving state, the actual wheel speed of each wheel is significantly different from the speed at the center of the vehicle, resulting in inaccurate or erroneous calculation of the slip rate of each wheel, which may cause the drive anti-skid and brake anti-lock to be triggered incorrectly or not to be triggered normally, or the torque control of each wheel after triggering is abnormal, seriously affecting the vehicle's driving safety.

[0127] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for calculating wheel slip rate, characterized in that: The steps include: S1: Calculate the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X and Y directions based on the components of the translation velocity of the reference wheel center on the reference axle in the X and Y directions of the vehicle body and the components of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle due to the rigid body rotational motion in the X and Y directions of the vehicle body; S2: Calculate the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction, based on the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body; S3: Calculate the real-time slip rate of the wheel based on the maximum and minimum values ​​of the translational velocity of the physical wheel center and the absolute velocity of the physical wheel in the rotational direction relative to the reference wheels on all reference axles; The real-time slip rate of the wheel in step S3 is calculated by formula (13): （13） in: For the The slip rate of the physical wheel on the left or right side of the axle; The state of the vehicle being braked or driven; For the The translational speed of the physical wheel center on the left or right side of the axle, which is calculated based on the wheel speed. The essence is a variable with different numbers; For the The minimum absolute speed of the physical wheel on the left or right side of the axle when all wheels of the vehicle are used as reference wheels; For the The maximum absolute speed of the physical wheel on the left or right side of the axle when all wheels of the vehicle are used as reference wheels; a closing speed threshold dynamically calculated for the slip ratio; is the dynamically calculated opening speed threshold, and ; 、 The parameters can be calibrated and changed; If the vehicle is in braking state and the wheel that is not locked has the highest speed, then efficient, The value is 1; If the vehicle is in driving state and the wheel speed is minimum in the non-slip state, then efficient, The value is -1.

2. The wheel slip ratio calculation method according to claim 1, characterized in that: The component velocity of the translation velocity of the reference wheel center on the reference axle in the X-direction of the vehicle body in step S1 is expressed by equation (1): （1） in, is the number of the left or right reference wheel, ,in, 1 indicates the left reference wheel, 2 indicates the right reference wheel; The reference axles are numbered sequentially starting from the front of the vehicle. , is the total number of reference axles; For the Translational velocity of the reference wheel center to the left or right of the reference axle; For the The angle between the left or right reference wheel of the reference axle and the vehicle body in the X direction, , it is positive if the wheel deviates to the right side of the vehicle body, and negative if it deviates to the left side of the vehicle body; For the The component of the translational velocity of the left or right reference wheel center of the reference axle in the X direction of the vehicle body; The component velocity of the translation velocity of the reference wheel center on the reference axle in the Y direction of the vehicle body in step S1 is expressed by formula (2): （2） in, For the The component of the translational velocity of the reference wheel center on the left or right side of the reference axle in the Y direction of the vehicle body.

3. The wheel slip ratio calculation method according to claim 2, characterized in that: The relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotation in step S1 is calculated by formula (5): （5） in, The number of the left or right wheel on the same axle, where 1 represents the left wheel and 2 represents the right wheel; The vehicle axles are numbered sequentially starting from the front of the vehicle; The rigid body rotation causes The left or right physical wheel of the axle is relative to the The relative linear speed of the reference wheel on the left or right side of the reference axle; The yaw rate of the vehicle is obtained by the angular velocity sensor installed at the center of the vehicle. The yaw rate is positive when the vehicle rotates counterclockwise and negative when it rotates clockwise. For the The left or right physical wheel of the axle is connected to the The distance between the reference wheels to the left or right of the reference axis; The relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotation in step S1 is calculated by formula (8) in the X direction and the Y direction of the body: （8） in: The rigid body rotation causes The left or right physical wheel of the axle is relative to the The component of the relative linear velocity of the left or right reference wheel of the reference axle in the X direction of the vehicle body; The rigid body rotation causes The left or right physical wheel of the axle is relative to the The component of the relative linear velocity of the left or right reference wheel on the reference axle in the Y direction of the vehicle body; For the The left or right physical wheel of the axle is connected to the The angle between the left or right reference wheel line vector of the reference axle and the X direction of the vehicle body, .

4. The wheel slip ratio calculation method according to claim 3, characterized in that: In step S1, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body is calculated by formula (10): （10） in: For the The left or right physical wheel of the axle is relative to the The absolute net velocity of the left or right reference wheel on the reference axle in the X-direction of the vehicle body; For the The left or right physical wheel of the axle is relative to the The absolute net velocity of the left or right reference wheel on the reference axle in the Y direction of the vehicle body.

5. The wheel slip ratio calculation method according to claim 4, characterized in that: In step S2, the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotation direction is calculated by formula (11): （11） in: For the The left or right physical wheel of the axle is relative to the The absolute speed of the left or right reference wheel on the reference axle in the direction of rotation; No. The angle between the left or right physical wheel of the axle and the body in the X direction, , it is positive if the wheel deviates to the right side of the vehicle body, and negative if it deviates to the left side of the vehicle body; For vehicles without mechanical steering structure, and .

6. The wheel slip ratio calculation method according to claim 5, characterized in that: In step S2, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotation direction are calculated using formula (12): （12） in: For the The minimum absolute speed of the physical wheel on the left or right side of the axle when all wheels of the vehicle are used as reference wheels; For the The maximum absolute speed of the left or right physical wheel of the axle when all wheels of the vehicle are used as reference wheels.

7. A wheel slip ratio calculation device, characterized in that: include: a first calculation module for calculating the absolute velocity of the physical wheel relative to the reference wheel on the reference axle in the X and Y directions of the vehicle body based on the component velocities of the translation velocity of the reference wheel center on the reference axle in the X and Y directions of the vehicle body and the component velocities of the relative linear velocity of the physical wheel relative to the reference wheel on the reference axle caused by the rigid body rotational motion in the X and Y directions of the vehicle body; a second calculation module, calculating, based on the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the X direction and the Y direction of the vehicle body, the maximum and minimum values ​​of the absolute speed of the physical wheel relative to the reference wheel on the reference axle in the rotational direction and the absolute speed of the physical wheel relative to the reference wheels on all reference axles in the rotational direction; The third calculation module calculates the real-time slip rate of the wheel according to the maximum and minimum values ​​of the translation speed of the center of the physical wheel and the absolute speed of the physical wheel in the rotation direction relative to the reference wheels on all reference axles.

8. An electronic device, characterized in that: comprising a processor and a memory, wherein the processor and the memory are connected to each other; The memory is used to store computer programs; The processor is configured to execute the wheel slip ratio calculation method according to any one of claims 1 to 6 when calling the computer program.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the wheel slip ratio calculation method according to any one of claims 1 to 6.

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