Vehicle Anti-slip control

Abstract

A vehicle anti-slip control method and system, a vehicle and a storage medium, relating to the technical field of vehicles. The method comprises: acquiring an actual rotating speed of a motor in a vehicle; determining a target rotating speed of the motor; on the basis of a rotating speed deviation value, generating a torque adjustment signal; when the frequency of the torque adjustment signal is greater than or equal to a safety frequency, inputting the rotating speed deviation value into a notch filter to obtain a corrected rotating speed deviation value; and on the basis of the corrected rotating speed deviation value, generating an updated torque adjustment signal, and when the frequency of the updated torque adjustment signal is smaller than the safety frequency, adjusting the actual rotating speed of the motor to the target rotating speed. Therefore, the smoothness of a vehicle is improved.

Description

Vehicle anti-skid control

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 8, 2023, with application number 202311490176.5, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The embodiments of the present disclosure relate to, but are not limited to, the field of vehicle technology, and more particularly to, but are not limited to, a vehicle anti-skid control method, system, vehicle, and storage medium. Background Art

[0004] When a vehicle enters a low-adhesion road surface while driving, the wheels are prone to excessive slip or skidding, which will greatly affect the stability and safety of the vehicle, and at the same time affect the vehicle's acceleration performance and deceleration and braking capabilities.

[0005] Summary of the Invention

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims. The present disclosure provides a vehicle anti-skid control method, system, vehicle, and storage medium.

[0007] According to a first aspect of an embodiment of the present disclosure, there is provided a vehicle anti-skid control method, comprising:

[0008] Obtaining an actual rotational speed of a motor in the vehicle;

[0009] determining a target speed of the motor, the target speed being a motor speed corresponding to when a slip ratio of the vehicle's wheels on a current road surface reaches an optimal slip ratio;

[0010] generating a torque adjustment signal according to a speed deviation value, wherein the speed deviation value is a difference between the actual speed and the target speed;

[0011] When the frequency of the torque adjustment signal is greater than or equal to the safety frequency, the speed deviation value is input into a notch filter to obtain a corrected speed deviation value, and the center frequency of the notch filter is the frequency of the torque adjustment signal;

[0012] An updated torque adjustment signal is generated according to the corrected speed deviation value, so as to adjust the actual speed of the motor to the target speed at a frequency lower than the safety frequency.

[0013] In some embodiments, the method further comprises:

[0014] The frequency of the torque regulation signal is calculated according to the duration of the interval between adjacent peaks in the torque regulation signal; or the frequency of the torque regulation signal is calculated according to the duration of the interval between adjacent troughs in the torque regulation signal.

[0015] In some embodiments, the notch filter is further configured with a gain coefficient, and the method further comprises:

[0016] According to the difference between adjacent peaks and troughs in the torque regulation signal, the gain coefficient of the notch filter is calculated to control the degree of suppression of the motor speed deviation value.

[0017] In some embodiments, determining the target speed of the motor includes:

[0018] Get the vehicle's body speed;

[0019] determining an actual slip ratio of the vehicle according to an actual rotation speed of the motor and a vehicle body speed;

[0020] Obtaining the utilization adhesion coefficient of the vehicle;

[0021] determining an optimal slip rate of the wheels of the vehicle on the current road surface according to the actual slip rate and the utilized adhesion coefficient;

[0022] The target rotational speed of the motor is determined according to an optimal slip ratio of the wheels of the vehicle on the current road surface.

[0023] In some embodiments, determining an optimal slip rate of the vehicle wheels on the current road surface based on the actual slip rate and the utilized adhesion coefficient includes:

[0024] comparing the actual slip ratio and the usable adhesion coefficient with the optimal slip ratios and standard usable adhesion coefficients corresponding to a plurality of pre-stored standard road surfaces, and determining the similarity between the plurality of standard road surfaces and the current road surface;

[0025] The optimal slip ratio of the vehicle wheels on the current road surface is determined based on the similarities between the multiple standard road surfaces and the current road surface and in combination with the optimal slip ratio corresponding to each standard road surface.

[0026] In some embodiments, after determining the target speed of the motor, the method further includes:

[0027] determining a speed correction amount for the target speed based on the product of a rate of change of the driving torque of the motor and a deformation coefficient of the transmission system of the vehicle;

[0028] A corrected target speed of the vehicle is determined based on the target speed and the speed correction amount.

[0029] In some embodiments, the torque adjustment signal is used to adjust the driving torque of the motor to the target torque, so as to adjust the actual speed of the motor to the target speed of the motor;

[0030] The target torque of the motor is determined by:

[0031] determining a slip state of the vehicle based on the speed deviation value and a rate of change of the speed deviation value;

[0032] determining a torque adjustment amount of the motor according to a slip state of the vehicle;

[0033] The minimum value of the sum of the driving torque of the motor and the torque adjustment amount and the driving torque is used as the target torque.

[0034] According to a second aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, on which a program is stored. When the program is executed by a processor, the vehicle anti-skid control method according to the first aspect is implemented.

[0035] According to a third aspect of an embodiment of the present disclosure, there is provided a vehicle anti-skid control system, comprising: one or more processors for implementing the vehicle anti-skid control method of the first aspect.

[0036] According to a fourth aspect of an embodiment of the present disclosure, a vehicle is provided, comprising: a vehicle anti-skid control system as described in the third aspect.

[0037] The technical solutions provided by the embodiments of the present disclosure may have the following beneficial effects:

[0038] The vehicle anti-skid control method provided by the embodiment of the present disclosure can generate a torque regulation signal at the current moment based on the speed deviation value at the current moment. When the frequency of the torque regulation signal at the current moment is greater than or equal to the safety frequency, the speed deviation value can be input into the notch filter to obtain a corrected speed deviation value. Thus, a torque regulation signal is generated based on the corrected speed deviation value to adjust the actual speed of the motor to the target speed at a frequency less than the safety frequency. Among them, the center frequency of the notch filter is the frequency of the torque regulation signal at the current moment, and the notch filter can eliminate signal fluctuations greater than or equal to the safety frequency, thereby controlling the frequency of the torque regulation signal within a certain range. The solution provided by the embodiment of the present disclosure can adaptively eliminate frequency fluctuations in the torque regulation signal while performing anti-skid control on the vehicle, thereby improving driving safety and comfort.

[0039] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. Other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a schematic flow chart showing a vehicle anti-skid control method according to an embodiment of the present disclosure.

[0041] FIG2 is a flow chart showing a method for calculating a target speed of a motor according to an embodiment of the present disclosure.

[0042] FIG3 is a schematic flow chart showing a method for calculating an optimal slip ratio in an embodiment of the present disclosure.

[0043] FIG4A is a flow chart showing a method for correcting a target speed of a motor according to an embodiment of the present disclosure.

[0044] FIG4B is a flow chart showing a method for calculating a target torque in an embodiment of the present disclosure.

[0045] FIG5 is a schematic diagram showing a vehicle slip state curve in an embodiment of the present disclosure.

[0046] FIG6 shows a schematic structural diagram of a vehicle anti-skid control system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0047] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0048] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0049] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining."

[0050] When a vehicle enters a low-adhesion road surface while driving, it is easy for the wheels to excessively slip or skid, which will greatly affect the stability and safety of the vehicle, and also affect the vehicle's acceleration performance and deceleration braking capabilities. In the related art, although it is possible to control the torque of the motor by outputting a torque adjustment signal, thereby preventing the vehicle from skidding to a certain extent, due to the elastic deformation of the vehicle's transmission system, the noise and errors caused by these elastic deformations will eventually be transmitted to the torque adjustment signal, causing fluctuations in the torque control, and even worsening to cause high-frequency resonance, resulting in uneven driving and reducing the comfort and safety of the entire vehicle.

[0051] First, an embodiment of the present disclosure provides a vehicle anti-skid control method, which can be executed by a vehicle or a server communicatively connected to the vehicle.

[0052] Specifically, FIG1 shows a flow chart of a vehicle anti-skid control method according to an embodiment of the present disclosure, including steps S110 to S150 .

[0053] S110: Acquire the actual rotational speed of the motor in the vehicle.

[0054] It should be noted that the actual speed of the motor can be obtained through a sensor, which is not described in detail in the embodiment of the present disclosure.

[0055] S120, determining a target speed of the motor.

[0056] It should be noted that the target speed is the motor speed corresponding to the vehicle's wheel slip ratio on the current road surface reaching the optimal slip ratio. The optimal slip ratio refers to the slip ratio at which the vehicle achieves optimal braking performance, and the optimal slip ratio varies for different road surfaces.

[0057] For example, Figure 2 shows a flow chart of a method for calculating a target speed of a motor according to an embodiment of the present disclosure. As shown in Figure 2, the target speed of the motor according to an embodiment of the present disclosure can be calculated as follows.

[0058] S121, obtaining the vehicle body speed.

[0059] It should be noted that the vehicle body speed can be calculated using any calculation method in the relevant technology, or can be collected by installing sensors in the vehicle.

[0060] For example, the vehicle body speed may be calculated in real time based on the speed of the vehicle wheels, the acceleration of the vehicle body, and the steering wheel angle.

[0061] S122: Determine the actual slip rate of the vehicle based on the actual rotational speed of the motor and the vehicle body speed.

[0062] It should be noted that the actual slip ratio can indicate the degree of slippage of the vehicle's wheels relative to the current road surface. The slip ratio measures the degree of slippage of the vehicle's wheels relative to the current road surface. A larger slip ratio indicates greater slippage of the vehicle's wheels relative to the current road surface, while a smaller slip ratio indicates less slippage of the vehicle's wheels relative to the current road surface.

[0063] In some embodiments, the actual slip ratio of the vehicle may be determined based on a ratio of the actual rotational speed of the motor to the product of the vehicle body speed and the transmission ratio of the vehicle transmission system.

[0064] For example, the actual slip ratio λ(t) is expressed by the following equation (1):

[0065] Among them, λ(t) is used to represent the actual slip rate of the vehicle; ω m (t) is used to indicate the actual speed of the motor; V b (t) is used to indicate the vehicle's body speed; i g Used to indicate the transmission ratio of a vehicle's transmission system; t is used to indicate time.

[0066] With this arrangement, the actual slip ratio λ(t) of the vehicle can be determined quickly and accurately using the above formula (1).

[0067] S123: Obtain the vehicle's utilization adhesion coefficient.

[0068] In some embodiments, the vehicle's utilization adhesion coefficient is obtained by the ratio of the vehicle's current longitudinal driving force to the vertical load. The utilization adhesion coefficient can be expressed by the following formula (2):

[0069] Among them, μ(t) is used to represent the vehicle's utilization adhesion coefficient; F z (t) is used to represent the current vertical load force of the vehicle; F x (t) is used to represent the current longitudinal driving force of the vehicle.

[0070] In this embodiment, the vehicle's current vertical load refers to the vertical force acting on the vehicle's wheels, also known as wheel force. It is determined by the vehicle's own weight and other wheel parameters. The vehicle's current longitudinal driving force refers to the force acting in the longitudinal direction of the vehicle's length, which propels the vehicle forward or restrains it from moving backward. Longitudinal driving force has a significant impact on the vehicle's acceleration, deceleration, and traction capabilities.

[0071] In this embodiment, F z (t) represents the current vertical load force of the vehicle, expressed as F x (t) represents the current longitudinal driving force of the vehicle. x(t) is expressed by the following formula (3):

[0072] Among them, F x (t) is used to represent the current longitudinal driving force of the vehicle; T m Used to indicate the driving torque of the vehicle motor; J m Used to represent the moment of inertia of the vehicle motor; ω m It is used to indicate the actual speed of the vehicle motor; Δt is used to indicate the unit time; Used to indicate the rate of change of the vehicle motor speed, that is, the motor acceleration; i g Used to indicate the transmission ratio of the vehicle transmission system; T f Used to express the rolling resistance torque of vehicle wheels; J w Used to represent the moment of inertia of the vehicle wheels; R w Used to indicate the rolling radius of a vehicle's wheels.

[0073] With this configuration, the vehicle's utilization adhesion coefficient can be adjusted based on the actual speed of the vehicle's motor ω m , the motor acceleration of the vehicle motor and the rolling resistance torque T of the vehicle's wheels f Sure.

[0074] S124: Determine the optimal slip rate of the vehicle wheels on the current road surface based on the actual slip rate and the utilized adhesion coefficient.

[0075] For example, Figure 3 shows a flow chart of a method for calculating an optimal slip ratio in an embodiment of the present disclosure. As shown in Figure 3, the optimal slip ratio of the motor in an embodiment of the present disclosure can be calculated as follows.

[0076] S1241 , comparing the actual slip rate and the utilized adhesion coefficient with the optimal slip rates and standard utilized adhesion coefficients corresponding to various pre-stored standard road surfaces, and determining the similarities between the various standard road surfaces and the current road surface.

[0077] In some embodiments, before executing S1241 , the actual slip rate may be judged according to a preset slip rate threshold to determine whether the vehicle needs to perform anti-skid control.

[0078] For example, if the actual slip rate is less than a preset slip rate threshold, the vehicle is considered to be at the optimal slip rate, and anti-skid control is not required. For example, the actual slip rate λ(t) of the current road surface may be very small, for example, λ(t) < 3%. In such a small slip rate, the difference in the applied adhesion coefficient between different road surfaces is small, making it difficult to distinguish between different road surfaces, and slip rate control intervention is not required. In other words, when λ(t) < 3%, the vehicle's slip rate can be considered to be at the optimal slip rate, and anti-skid control is not required.

[0079] If the actual slip ratio is greater than or equal to a preset slip ratio threshold (e.g., greater than 3%), the vehicle is deemed to be not at the optimal slip ratio, and steps S1241 to S1242 may be executed to determine the optimal slip ratio for the vehicle on the current road surface. For example, when the actual slip ratio λ(t) is ≥ 3%, the actual slip ratio and usable adhesion coefficient of the vehicle's wheels on the current road surface are compared with the optimal slip ratios and standard usable adhesion coefficients corresponding to various pre-stored standard road surfaces to determine the similarity between the various standard road surfaces and the current road surface.

[0080] For example, when the actual slip rate is significantly larger, for example, λ(t) ≥ 3%, the actual slip rate and utilization adhesion coefficient corresponding to the current road surface can be compared with the optimal slip rate and standard utilization adhesion coefficient of the pre-stored standard road surface to calculate the weight coefficient between the current road surface and multiple standard road surfaces. The weight coefficient is used to represent the similarity between the current road surface and multiple standard road surfaces.

[0081] The weight coefficient can be expressed as follows:

[0082] Among them, ε i (t) is the weight coefficient of the current road surface compared with the i-th standard road surface at the current time t; μ(t) is the utilization adhesion coefficient of the current road surface at the current time t; μ i (t) is the utilized adhesion coefficient on the i-th standard road surface under the actual slip rate input on the current road surface at the current time t; i is the type number of the pre-configured standard road surface; δ is an extremely small positive number to avoid the denominator being zero.

[0083] With this configuration, the actual slip rate and the utilized adhesion coefficient can be compared with the optimal slip rates and standard utilized adhesion coefficients corresponding to various pre-stored standard road surfaces, and the similarities between the various standard road surfaces and the current road surface can be determined respectively.

[0084] S1242: Determine the optimal slip rate of the vehicle wheels on the current road surface based on the similarity between each standard road surface and the current road surface and the optimal slip rate of each standard road surface.

[0085] In some embodiments, the optimal slip ratio of the vehicle on the current road surface can be determined based on the weight coefficients between the current road surface and the multiple standard road surfaces calculated above. The optimal slip ratio can be expressed as follows:

[0086] Among them, λ opt (t) is used to represent the optimal slip rate of the vehicle's wheels on the current road surface; ∑ε i (t)λ′ opt (i) is used to represent the sum of the products of the optimal slip rate of each standard road surface among multiple standard road surfaces and the weight coefficient corresponding to the standard road surface, where i is the type number of the pre-configured standard road surface; ∑ε i (t) is used to represent the sum of multiple weight coefficients of the current road surface relative to the standard road surface.

[0087] With this setting, the optimal slip rate of the vehicle's wheels on the current road surface is determined as the ratio of the sum of the products of the optimal slip rate of each standard road surface and the weight coefficient corresponding to the standard road surface to the sum of multiple weight coefficients of the current road surface relative to the standard road surface, which can make the determined optimal slip rate more accurate.

[0088] S125 , determining a target speed of the motor according to the optimal slip ratio of the vehicle.

[0089] In some embodiments, the motor target speed refers to the motor speed corresponding to the wheel speed when the vehicle's wheels are in an optimal slip state. The motor target speed is expressed by the following equation (6):

[0090] in, Used to indicate the target speed of the vehicle motor; opt (t) is used to represent the optimal slip rate of the vehicle's wheels on the current road surface; V b (t) is used to indicate the vehicle's body speed; i g Used to indicate the gear ratio of a vehicle's drivetrain.

[0091] Since the power transmission between the vehicle's motor and wheels is not completely rigidly connected, it is necessary to consider the speed error caused by the elastic deformation of the transmission system's shaft system during torque loading. Therefore, this embodiment also provides a motor target speed correction method.

[0092] Exemplarily, FIG4A shows a flow chart of a method for correcting a motor target speed in an embodiment of the present disclosure. As shown in FIG4A , the method for correcting a motor target speed provided in an embodiment of the present disclosure includes steps S126 to S127.

[0093] S126 , determining a speed correction amount for the target speed based on the product of the rate of change of the driving torque of the motor and the distortion coefficient of the vehicle's transmission system.

[0094] In some embodiments, when correcting the motor target speed, the correction can be made for the motor torque loading process and the process in which the motor torque maintains a stable value. During the motor torque loading process and the stable output process, the rate of change of the driving torque output by the motor is multiplied by the deformation coefficient of the transmission system as the correction amount for the motor target speed. The correction amount for the motor target speed can be expressed by the following formula (7):

[0095] Among them, ω offset (t) is used to represent the correction value of the target speed of the vehicle motor; T m (t) is used to represent the driving torque of the vehicle motor; LPF (T m (t)) is used to indicate the m (t) is subjected to first-order low-pass filtering; ΔT is used to represent the time constant of the first-order low-pass filtering; K is used to represent the deformation coefficient of the vehicle transmission system, which can be obtained through actual vehicle calibration when applied in actual vehicles.

[0096] S127 , determining a corrected target speed of the vehicle motor according to the motor target speed and the motor target speed correction amount.

[0097] For example, the corrected target speed of the vehicle motor can be expressed by the following expression (8):

[0098] That is, equation (6) and equation (7) are superimposed.

[0099] With such an arrangement, a corrected target speed can be determined based on the target speed of the motor and the correction amount of the target speed, so that the obtained target speed of the motor is more accurate.

[0100] S130: Generate a torque adjustment signal according to the speed deviation value.

[0101] It should be noted that the speed deviation value is the difference between the actual speed and the target speed.

[0102] For example, the speed deviation of the motor can be calculated by the following formula (9):

[0103] Where e(t) is used to represent the speed deviation between the actual motor speed and the target speed at time t; ω m (t) is used to indicate the actual speed of the vehicle motor; Used to indicate the target speed of the motor after vehicle correction.

[0104] Based on the speed deviation, the motor's target torque, or torque adjustment signal, is calculated. The torque adjustment signal carries the target torque corresponding to the target speed. In other words, the torque adjustment signal adjusts the motor's driving torque to the target torque, thereby adjusting the motor's actual speed to the target speed.

[0105] For example, FIG4B shows a flow chart of a target torque calculation method in an embodiment of the present disclosure. As shown in FIG4B , the target torque calculation method provided in the embodiment of the present disclosure includes steps S131 to S133.

[0106] S131 , determining the slip state of the vehicle on the current road surface based on the speed deviation value of the motor and the rate of change of the speed deviation value.

[0107] In some embodiments, the rate of change of the motor speed deviation value is expressed by the following equation (10):

[0108] in, It is used to indicate the rate of change of the motor speed deviation at time t; e(t) is used to indicate the speed deviation between the actual motor speed and the target speed at time t; LPF(e(t)) is used to indicate the first-order low-pass filtering of e(t); ΔT is used to indicate the time constant of the first-order low-pass filter.

[0109] In this way, based on the calculated speed deviation value e(t) and the rate of change of the speed deviation value The vehicle's slip state at the current time t can be determined. The specific correspondence between the slip state, the motor speed deviation value, and the motor speed deviation value change rate is shown in the following table:

[0110] Table 1: Correspondence between slip state, speed deviation value, and speed deviation value change rate

[0111] FIG5 shows a schematic diagram of a vehicle slip state curve in an embodiment of the present disclosure.

[0112] 5 and Table 1, when the speed deviation value of the vehicle motor is greater than 0 and the rate of change of the motor speed deviation value is greater than or equal to 0, it can be determined that the slip state of the vehicle wheel on the current road surface is an aggravated slip state.

[0113] When the speed deviation value of the vehicle motor is greater than 0 and the rate of change of the motor speed deviation value is less than 0, it is determined that the slip state of the vehicle wheel on the current road surface is a slip callback state.

[0114] When the speed deviation value of the vehicle motor is less than 0 and the rate of change of the motor speed deviation value is greater than 0, it is determined that the slip state of the vehicle wheel on the current road surface is a slip-up state.

[0115] When the speed deviation value of the vehicle motor is less than 0, and the rate of change of the motor speed deviation value is less than or equal to 0, it is determined that the slip state of the vehicle wheel on the current road surface is an insufficient slip state.

[0116] When the speed deviation value of the vehicle motor is equal to 0, and the rate of change of the motor speed deviation value is an arbitrary value, it is determined that the slip state of the vehicle wheel on the current road surface is the optimal slip state.

[0117] S132: Determine the torque adjustment amount of the motor according to the slip state of the vehicle on the current road surface.

[0118] In some embodiments, when the actual motor speed exceeds the target speed, it indicates that the vehicle is experiencing excessive slip. In this case, intervention is required to reduce the motor's drive torque to prevent further slippage, which could affect vehicle stability and safety.

[0119] In order to achieve a fast and stable active anti-slip control effect, the embodiment of the present disclosure can adopt a segmented PI (Proportional-Integral) control algorithm, calling different PI parameters based on different slip states, so as to quickly and accurately determine the torque adjustment amount of the motor.

[0120] The slip-ratio-adhesion coefficient curve shows that the utilization adhesion coefficient first increases and then decreases with slip. In engineering, this can be simplified into two segments: one segment from 0 to the optimal slip ratio, and another segment from the optimal slip ratio to 1. In other words, while the slip-ratio-utilization adhesion coefficient function is a nonlinear function, it can be simplified in engineering to a nonlinear function composed of two linear segments. This allows segmented PI control to achieve the same control performance while significantly simplifying parameter calibration in practical applications compared to nonlinear control.

[0121] For example, the torque adjustment amount can be expressed by the following formula (11):

[0122] Among them, Tq adj (t) is the torque adjustment amount; P is the proportional coefficient; I is the integral coefficient; e(t) is used to represent the speed deviation between the actual motor speed and the target speed at time t; different slip states correspond to different P and I values.

[0123] S133 , taking the minimum value of the sum of the motor's driving torque and the torque adjustment amount and the driving torque as the target torque.

[0124] It should be noted that vehicle anti-skid is essentially about reducing the motor's drive torque, thereby controlling the motor's speed. Therefore, the target torque can be used to adjust the actual motor speed to the target by taking the minimum of the sum of the motor's drive torque, the torque adjustment amount, and the drive torque.

[0125] For example, the target torque of the motor can be expressed as follows:

[0126] Among them, Tq int (t) is used to represent the target torque of the vehicle motor; Tq rep (t) is used to represent the driving torque given by the vehicle controller and can be controlled by the driver through the accelerator pedal; e(t) is used to represent the speed deviation between the actual motor speed and the target speed at time t; P is the proportional coefficient; I is the integral coefficient; min is the minimum operation function.

[0127] In some embodiments, in order to ensure the smoothness of torque output when the vehicle switches between different slip states and avoid sudden changes or steps in torque due to the selection of different P and I parameters when switching between slip states during torque adjustment, the I item needs to be assigned an initial value when switching the slip state to ensure smooth connection of torque commands when switching between different slip states.

[0128] Therefore, the discretization of the above formula (12) can be expressed by the following formula (13):

[0129] Among them, I0 is used to represent the initial value of the I item. When the slip state remains unchanged, this value remains unchanged. When the slip state switches, the initial value I0 of the I item is reset to ensure smooth connection of the torque output.

[0130] The initial value I0 of the I term can be expressed by the following formula (14): I0 = Tq int (t-1)-Tq req (t)-P×e(t) (14)

[0131] Among them, Tq int (t-1) is used to represent the target torque before the slip state is switched; Tq req (t) is used to represent the motor driving torque at the moment of slip state switching; e(t) is used to represent the motor speed deviation value at the moment of slip state switching; P is the proportional coefficient; I0 ​​is the initial value of the integral coefficient I.

[0132] By actively adjusting the electric drive torque output and controlling the actual speed of the motor to the target speed, the wheels can be kept running at the optimal slip rate state, so that the vehicle can achieve the best anti-skid effect under the current road surface.

[0133] In some embodiments, when the target torque Tq of the vehicle motor before the vehicle switches to the slip state int (t) is less than or equal to the motor drive torque Tq req (t), and the slip state is not in the slip aggravation state or the slip callback state, it indicates that the vehicle no longer needs to be anti-skid controlled at this time, and there is no need to generate a torque adjustment signal.

[0134] At this point, the disclosed embodiment can determine the slip state of the vehicle's wheels on the current road surface based on the actual motor speed and the motor target speed. Based on the actual motor speed and the motor target speed, active anti-skid control is implemented, thereby achieving optimal slip rate control. According to the above settings, the signal transmission link of the vehicle's active anti-skid control is short, the control adjustment cycle is short, and a better anti-skid control effect can be achieved. And based on the slip state, a segmented PI algorithm is adopted to adjust the motor drive torque, which can quickly and stably control the wheels to achieve the optimal slip rate. The motor drive torque responds quickly. When the motor-driven vehicle slips, the wheel slip is suppressed by reducing the motor drive torque, and the anti-skid control effect is better. A better anti-skid control effect can be obtained, while ensuring the power of the vehicle, while improving the stability and safety of the vehicle.

[0135] S140 , when the frequency of the torque adjustment signal is greater than or equal to the safety frequency, inputting the speed deviation value into a notch filter to obtain a corrected speed deviation value.

[0136] It should be noted that when a vehicle slips while driving, the controller needs to quickly reduce the torque to prevent further aggravation of the slip, which may cause a decrease in the lateral adhesion of the tires and lead to side slip and other events that affect vehicle safety.

[0137] However, the inventors discovered that a rapid reduction in torque can cause oscillations in the motor speed. The transmission system from the motor rotor shaft, through the reducer, differential, and half-axle to the wheel can be considered as a long transmission shaft. During the loading and unloading of torque, the transmission shaft generates a certain amount of elastic deformation. The rapid unloading of torque causes the elastic deformation of the transmission shaft to cause oscillations in the transmission shaft, so that the speed deviation value e(t) of the motor calculated above includes the oscillations of this part of the transmission shaft. When the target torque of the motor is calculated using e(t) including the oscillations of this part of the transmission shaft, the calculated target torque will also include the oscillations of this part of the transmission shaft, thereby causing oscillations in the adjustment torque, further worsening the oscillation amplitude of the motor speed signal, and causing driving safety issues.

[0138] Specifically, when the motor is not oscillating, the frequency of the pure torque regulation signal will be below 3Hz. However, when the elastic deformation of the drive shaft causes oscillation, the oscillation frequency generated on the motor side will be greater than or equal to 5Hz, so the frequency of the converted torque regulation signal will also be greater than or equal to 5Hz. Therefore, when the frequency of the torque regulation signal is detected to be greater than or equal to 5Hz, it is assumed that the oscillation on the motor side is caused by the elastic deformation of the drive shaft. At this time, the notch filter can be activated to filter the speed deviation value e(t) on the motor side.

[0139] That is to say, the safe frequency in the embodiment of the present disclosure can be understood as the frequency of the pure torque regulation signal. When the frequency of the torque regulation signal is greater than or equal to the safe frequency, it is considered that there is oscillation caused by the motor-side drive shaft in the torque regulation signal. At this time, the speed deviation value can be input into the notch filter to eliminate the oscillation in the output torque regulation signal. The electronic control unit of the automobile is a discrete control system. For the current vehicle anti-skid control method, the electronic control unit of the automobile calculates the target torque once at regular intervals (for example, a scheduling cycle) to generate a torque regulation signal and performs torque adjustment. At this time, the frequency of the torque adjustment will be judged. If it is determined that the frequency of the torque adjustment is too large, it is necessary to turn on the filtering of the speed deviation value, and turn on the notch filtering of the speed deviation value e(t) in the next scheduling cycle, so as to calculate the speed deviation value e'(t) after the notch filtering, and then calculate the target torque Tq of the motor based on e'(t). int (t), which is the updated torque regulation signal. That is, Tq is calculated based on e(k), e(k+1)…, e(t-1) int (k), Tq int (k+1)……Tq int (t-1); based on Tq int (k), Tq int (k+1)……Tq int (t-1) Determine whether it is necessary to enable notch filtering for the speed deviation value; if necessary, enable notch filtering at time t.

[0140] It should be noted that the working principle of the notch filter is to form a blocking band near a specific frequency (center frequency) so that the signals near the frequency are suppressed. Its main function is to suppress or eliminate the signal of a specific frequency.

[0141] In some embodiments, the center frequency of the notch filter is the frequency of the torque regulation signal at the current moment. In other words, the notch filter can suppress motor-side signals greater than or equal to the safe frequency, thereby controlling the frequency of the output torque regulation signal to within the safe frequency range.

[0142] For example, the frequency of the torque regulation signal can be determined by calculating the frequency of the torque regulation signal based on the duration of intervals between adjacent peaks in the torque regulation signal, or by calculating the frequency of the torque regulation signal based on the duration of intervals between adjacent troughs in the torque regulation signal.

[0143] In some embodiments, the torque adjustment signal is Tq int (k), which is calculated by the vehicle controller in real time in each scheduling cycle based on the speed deviation value. According to the duration dt of each scheduling cycle, Tq can be calculated int (k) rate of change, which can be obtained by the following formula:

[0144] Among them, by calculating Tq int (t) The zero crossing point of the rate of change, that is, the duration between adjacent peaks in the torque regulation signal, or the duration between adjacent troughs, can be used to calculate Tq int (t) adjustment frequency f; Tq int The time interval between two consecutive zero crossings of the (t) change rate is the adjustment period T of the torque adjustment signal.

[0145] In some embodiments, the notch filter is further configured with a gain coefficient. The gain coefficient reflects the degree of suppression of the motor-side signal (i.e., the speed deviation value) by the notch filter. The gain coefficient determines the attenuation of the signal at the notch frequency. The greater the degree of suppression, the smaller the gain coefficient, and the better the suppression effect on the specific frequency signal to be eliminated. In other words, the more significant the signal attenuation at this frequency, the smaller the gain coefficient, the greater the degree of suppression of the frequency portion to be eliminated of the speed deviation value, and the smaller the frequency portion to be eliminated contained in the speed deviation value.

[0146] Exemplarily, the gain coefficient of the torque regulation signal can be determined as follows: The gain coefficient of the notch filter is calculated based on the difference between adjacent peaks and troughs in the torque regulation signal. In some embodiments, the gain coefficient can be obtained by actual vehicle calibration based on the difference between adjacent peaks and troughs in the torque regulation signal.

[0147] For example, the input and output of the notch filter can be expressed by the following equation (15): y(t)=a0×x(t)+a1×x(t-1)+a2×x(t-2)-b1×y(t-1)-b2×y(t-2) (15)

[0148] Where x(t) is the input value of the notch filter at the current sampling time t; x(t-1) is the input value of the notch filter at the previous sampling time; x(t-2) is the input value of the notch filter at the previous two sampling times; y(t) is the output value of the notch filter at the current sampling time; y(t-1) is the output value of the notch filter at the previous sampling time; y(t-2) is the output value of the notch filter at the previous two sampling times; a0, a1, a2, b1, and b2 are all coefficients in the notch filter, and the determination method of each coefficient is as follows:

[0149] Where: ΔT is the call period of the designed filter; T is the period value corresponding to the center frequency to be suppressed by the notch filter, that is, the period value corresponding to the frequency of the torque control signal at the current moment; the reciprocal of T is the center frequency to be suppressed by the notch filter; g is the gain coefficient.

[0150] It is understood that both the input and output of the notch filter are speed deviation values. In other words, x and y are used to indicate the speed deviation value, i.e., x(t) is the original input e(t) at the current moment, and y(t) is the corrected e′(t) output by the notch filter at the current moment. This disclosure does not elaborate on this.

[0151] S150 , generating an updated torque adjustment signal according to the corrected speed deviation value, so as to adjust the actual speed of the motor to the target speed at a frequency lower than the safety frequency.

[0152] It should be noted that, based on the same inventive concept as described above in steps S131 to S133, a torque adjustment signal within a safe frequency range can be generated based on the corrected speed deviation value, thereby avoiding safety hazards caused by excessive torque adjustment due to signal oscillation. The corrected speed deviation value is the speed deviation value obtained by filtering out motor signal oscillations through a notch filter.

[0153] The adaptive torque regulation control method designed in this disclosure can adaptively filter out the oscillation frequency portion of the motor speed signal (speed deviation value), eliminating the error portion of the input signal during the target torque calculation process, avoiding errors in the torque regulation calculation, and thus avoiding frequency fluctuations in the torque regulation signal, as well as the torque unevenness caused by fluctuations or the driving discomfort caused by high-frequency regulation. The method provided in the embodiment of this disclosure ensures the smoothness of torque regulation during vehicle anti-skid control by adaptively controlling the output frequency of the torque regulation signal, thereby improving driving comfort and user experience.

[0154] The present disclosure also provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, the vehicle anti-skid control method shown in the embodiments of Figures 1 to 4B described above is implemented. In some embodiments, the computer-readable storage medium can be an internal storage unit of the aforementioned vehicle, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device of the vehicle, such as a plug-in hard disk, a smart media card (SMC), an SD card, a flash card, etc. equipped on the device. Furthermore, the computer-readable storage medium can also include both an internal storage unit of the vehicle and an external storage device. The computer-readable storage medium is used to store computer programs and other programs and data required by the vehicle, and can also be used to temporarily store data that has been output or is about to be output. From a hardware perspective, as shown in Figure 6, a hardware structure diagram of a vehicle in which the processor of the present disclosure is located is shown. In addition to the processor 601, memory 602, network interface 603, and non-volatile memory 604 shown in Figure 6, the vehicle in which the projection system is located in the embodiment can generally include other hardware based on the actual function of the vehicle, which will not be described in detail.

[0155] The present disclosure also provides a vehicle anti-skid control system, comprising: one or more processors for implementing a vehicle anti-skid control method as in any one of the above-mentioned embodiments. For the system embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to the partial description of the method embodiments. The system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the technical solution of the present disclosure. Those skilled in the art can understand and implement the technical solution of the present disclosure without paying any creative work.

[0156] Based on the same inventive concept, embodiments of the present disclosure also provide a vehicle including a vehicle anti-skid control system. This vehicle anti-skid control system can implement the vehicle anti-skid control method described in the embodiments of Figures 1 to 4B . While providing anti-skid control for the vehicle, the disclosed embodiments can also adaptively eliminate fluctuations in the torque regulation signal, thereby improving driving safety and comfort.

[0157] Since the principles of solving the problems in the embodiments of the present disclosure are similar to those in the above method embodiments, the implementation of the embodiments of the present disclosure may refer to the implementation of the above method embodiments, and repeated details will not be repeated.

[0158] The above descriptions are only some embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A vehicle anti-skid control method, comprising: Obtaining an actual rotation speed of a motor in the vehicle; Determining a target speed of the motor, the target speed being a motor speed corresponding to when a slip rate of the wheels of the vehicle on a current road surface reaches an optimal slip rate; generating a torque adjustment signal according to a speed deviation value, wherein the speed deviation value is a difference between the actual speed and the target speed; When the frequency of the torque regulation signal is greater than or equal to the safety frequency, the rotation speed deviation value is input into a notch filter to obtain a corrected rotation speed deviation value, and the center frequency of the notch filter is the frequency of the torque regulation signal; An updated torque adjustment signal is generated according to the corrected speed deviation value, so as to adjust the actual speed of the motor to the target speed at a frequency lower than the safety frequency.

2. The method according to claim 1, further comprising: Calculating the frequency of the torque regulation signal according to the duration of intervals between adjacent peaks in the torque regulation signal; or The frequency of the torque regulation signal is calculated according to the duration of intervals between adjacent troughs in the torque regulation signal.

3. The method according to claim 1 or 2, wherein: The notch filter is also configured with a gain coefficient, and the method further comprises: According to the difference between adjacent peaks and troughs in the torque regulation signal, the gain coefficient of the notch filter is calculated to control the signal attenuation at the notch frequency.

4. The vehicle anti-skid control method according to any one of claims 1 to 3, wherein: Determining the target speed of the motor includes: Obtaining the body speed of the vehicle; determining an actual slip rate of the vehicle according to an actual rotation speed of the motor and a vehicle body speed; Obtaining the utilization adhesion coefficient of the vehicle; Determining an optimal slip rate of the vehicle on the current road surface according to the actual slip rate and the utilized adhesion coefficient; The target rotation speed of the motor is determined according to the optimal slip ratio of the vehicle on the current road surface.

5. The vehicle anti-skid control method according to claim 4, wherein: The step of determining the optimal slip rate of the wheel of the vehicle on the current road surface according to the actual slip rate and the utilized adhesion coefficient includes: The actual slip ratio, the utilized adhesion coefficient and the optimal slip ratio corresponding to the pre-stored multiple standard road surfaces are compared. The rate and the standard adhesion coefficient are compared to determine the similarity between the multiple standard road surfaces and the current road surface respectively; According to the similarities between the multiple standard road surfaces and the current road surface, combined with the optimal slip rate corresponding to each standard road surface, the optimal slip rate of the wheel of the vehicle on the current road surface is determined.

6. The vehicle anti-skid control method according to any one of claims 1 to 5, wherein: After determining the target speed of the motor, the method further includes: determining a speed correction amount of the target speed according to a product of a rate of change of the driving torque of the motor and a deformation coefficient of a transmission system of the vehicle; A corrected target speed of the vehicle is determined based on the target speed and the speed correction amount.

7. The vehicle anti-skid control method according to any one of claims 1 to 6, wherein: The torque adjustment signal is used to adjust the driving torque of the motor to the target torque, so as to adjust the actual speed of the motor to the target speed of the motor; The target torque of the motor is determined by: Determining a slip state of the vehicle according to the speed deviation value and a rate of change of the speed deviation value; determining a torque adjustment amount of the motor according to a slip state of the vehicle; The minimum value of the sum of the driving torque of the motor and the torque adjustment amount and the driving torque is used as the target torque.

8. A computer-readable storage medium, wherein: A program is stored thereon, and when the program is executed by a processor, the vehicle anti-skid control method as claimed in any one of claims 1 to 7 is implemented.

9. A vehicle anti-skid control system, wherein: include: One or more processors, used to implement the vehicle anti-skid control method as claimed in any one of claims 1 to 7.

10. A vehicle, wherein: include: The vehicle anti-skid control system as claimed in claim 9.

Images