Wheel anti-lock braking method based on wheel deceleration and motor torque control

Abstract

The present invention discloses a wheel anti-lock braking method based on wheel deceleration and motor torque control, the method comprising: estimating a road adhesion coefficient (1), estimating a maximum road adhesion coefficient #imgabs0# (112); calculating an ideal wheel deceleration (2) for determining an ideal wheel deceleration α id (210); Target wheel deceleration calculation (3) wheel deceleration α required according to the current vehicle state p (301) and the ideal wheel deceleration α id (210), used to determine the target wheel deceleration α g (302); Design of wheel deceleration dynamic controller u k (σ k )(4) According to the actual motion state information of the electric vehicle and the target wheel deceleration α g (302) is used to determine the control rate u of the controller k (σ k )(413); Based on the wheel deceleration dynamic control rate parameter setting u k (5) is used to optimize the control rate parameter σ (409); the motor controller (6) obtains the control rate u according to the optimization k (509) outputs the required motor torque; the power system (7) is used to output the actual motion state information of the current electric vehicle, including the wheel deceleration α of the electric vehicle i (701), vehicle speed v (702) and wheel angular velocity ω i (703); The method can effectively solve the problem of wheel locking caused by motor regenerative braking during emergency braking of an electric vehicle, and improve the stability of the electric vehicle during braking.

Description

Technical Field

[0001] The invention relates to the technical field of emergency brake control of electric vehicles and discloses a wheel anti-lock method based on wheel deceleration and motor torque control. Background Art

[0002] An anti-lock braking system (ABS) is a safety device installed in vehicles. During braking, the ABS prevents wheel slip, reduces braking distance, and ensures braking stability. Traditional hydraulic ABS require multiple hydraulic actuators to implement the braking function, while electric motor ABS (Electric Motor Anti-lock Braking System) achieves braking control without any additional actuators. During braking in electric vehicles, using only the electric motor as the single brake actuator allows precise control of braking torque, improving vehicle braking stability. Currently, electric motor ABS systems primarily utilize a logic threshold control strategy based on slip ratio and wheel acceleration and deceleration. However, this approach is complex to debug and requires extensive validation under various road conditions. Some ABS control strategies use the longitudinal wheel slip ratio as the system state variable and achieve satisfactory control results. However, the slip ratio cannot be directly measured and can only be estimated based on vehicle speed.

[0003] The patent with application number CN202110178471.1 and invention name "A method for implementing ABS braking in electric vehicles" provides an anti-lock braking logic method for electric vehicles. This patent implements wheel anti-lock control based on the wheel slip rate and vehicle speed. It sets a slip rate threshold and uses a motor speed control method to adjust the braking torque of the motor. Although this method can increase the energy recovery of the entire vehicle, the slip rate and motor speed need to be calculated and estimated and cannot be directly measured. In actual engineering applications, the estimated data is not accurate enough, which is not conducive to controller control. In addition, the patent sets a large number of thresholds and there is no definite calculation method, which makes debugging difficult in actual applications.

[0004] Patent application number CN201310230834.7, entitled "Control Method for an Anti-lock Braking System of an Electric Vehicle Driven by Four-Wheel Hub Motors without Hydraulic Braking," implements wheel anti-lock control using a logic threshold control method based on wheel slip rate. By adjusting the motor's reverse braking torque and drive torque, the slip rate during braking of the electric vehicle is ensured to fluctuate around the optimal slip rate. Although this patent maximizes the use of the ground adhesion coefficient, the slip rate must be estimated by calculating the vehicle speed, which in turn must be estimated by calculating the wheel speed. Neither of these can be directly measured, resulting in inaccurate estimates in actual engineering applications, hindering controller control. Furthermore, the patent establishes four slip rate thresholds, making parameter calibration difficult and lacking a theoretical basis. A large amount of experimental data is required to verify the control effect, resulting in extremely high R&D costs.

[0005] Therefore, the common motor brake anti-lock control methods in the prior art have their own limitations, and the wheel anti-lock braking method lacks easily measurable control variables, making it difficult to be widely used in the anti-lock braking system of electric vehicles. Summary of the Invention

[0006] To address the inability to achieve high brake energy recovery efficiency and wheel locking during braking in existing electric vehicles, this paper proposes a wheel anti-lock braking method based on wheel deceleration and motor torque control. A controller is designed and its parameters are optimized to improve brake energy recovery efficiency and range in electric vehicles. This controller utilizes wheel deceleration as the system's control target to control motor anti-lock braking, while addressing the inability to accurately calculate slip ratios in most current anti-lock braking methods. This improves braking stability and safety in electric vehicles, achieving wheel anti-lock braking.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] A wheel anti-lock braking method based on wheel deceleration and motor torque control, characterized by:

[0009] The method includes the estimation of road adhesion coefficient (1), calculation of ideal wheel deceleration (2), calculation of target wheel deceleration (3), design of wheel deceleration dynamics controller u k (σ k (4) Adjustment of the wheel deceleration dynamic control rate parameter u k (5), motor controller (6), power system (7), etc.;

[0010] Road adhesion coefficient estimation (1) According to the wheel braking torque T bi (102) and wheel angular velocity ω i (705), using the observer, the maximum road adhesion coefficient is estimated

[0011] Ideal wheel deceleration calculation (2) is used to determine the ideal wheel deceleration α id (210);

[0012] Target wheel deceleration calculation (3) According to the wheel deceleration α required by the current vehicle state p (301) and the ideal wheel deceleration α id (210), used to determine the target wheel deceleration α g (302);

[0013] Design of wheel deceleration dynamics controller based on u k (σ k )(4) According to the actual motion state information of the electric vehicle and the target wheel deceleration α g (302) is used to determine the control rate u of the controller k (σ k )(413);

[0014] Based on the wheel deceleration dynamics control rate parameter tuning u k (5) is used to optimize the control rate parameter σ(409) and obtain the optimal control rate u k (509);

[0015] The motor controller (6) obtains the control rate u according to the optimization k (509) outputs the required motor torque and inputs it to the power system (7);

[0016] The power system (7) is used to output the actual motion state information of the current electric vehicle, including the wheel deceleration α of the electric vehicle i (701), vehicle speed v (702) and wheel angular velocity ω i (703).

[0017] The method includes the following steps:

[0018] Step 1: Estimation of the road adhesion coefficient (1) is performed to obtain the maximum road adhesion coefficient during the braking process of the electric vehicle based on the wheel angular velocity.

[0019] Step 2: Design the target wheel deceleration calculation logic, based on the wheel deceleration α required by the current vehicle state p (301) and the ideal wheel deceleration α id (210), determine the target wheel deceleration α g (302);

[0020] Step 3: Establish a dynamic model based on wheel deceleration and obtain the state equation of the electric vehicle braking process;

[0021] Step 4: Design a controller based on wheel deceleration dynamics;

[0022] Step 5: Optimize the parameter σ (409) by using a control algorithm based on the wheel deceleration dynamics parameter tuning;

[0023] Step 6: Calculate the control rate u after optimizing the control algorithm based on the wheel deceleration dynamics parameter tuning k (509), and finally the optimal wheel braking torque T during the braking process of the electric vehicle is obtained bi，k (601);

[0024] According to the above six steps, the control rate u after optimization of the control algorithm based on the wheel deceleration dynamic parameter tuning during the braking process of the electric vehicle is obtained using equations (4.6) and (5.3). k (509),

[0025]

[0026] In formula (5.4): d k (405) is the disturbance of the control system at the current k moment, (508) is the value of the optimal control rate parameter at the current time k, s k (408) is the wheel deceleration error at the current time k, η (410) is the convergence factor, and b (403) is the coefficient of the control system input.

[0027] The road adhesion coefficient estimation (1) is based on the wheel angular velocity to obtain an estimated value of the road adhesion coefficient during the braking process of the electric vehicle:

[0028]

[0029] In formula (1.2): (106) is the estimated value of the road adhesion coefficient, κ p (107) is the proportional gain, κ i (108) is the integral gain, ω i (703) is the wheel angular velocity, ε(109) is the switch gain, I ωi (101) is the moment of inertia of the wheel, (110) is the estimated value of wheel braking torque, T bi (102) is the measured value of the wheel braking torque, (111) is the difference between the estimated and measured wheel angular velocity values, i (105) represents the signs of the four wheels of the vehicle, and i = fl represents the left front wheel of the vehicle, i = fr represents the right front wheel of the vehicle, i = rl represents the left rear wheel of the vehicle, and i = rr represents the right rear wheel of the vehicle. The following expressions of this method are the same;

[0030] When the actual wheel slip rate is equal to the optimal slip rate of the current road surface, the estimated road adhesion coefficient is (106) is equal to the maximum adhesion coefficient of the current road surface (112).

[0031] The wheel deceleration dynamics model (8):

[0032]

[0033] In formula (4.1): α i (701) is the wheel deceleration, m (401) is the total mass of the car, r (103) is the wheel rolling radius, v (702) is the car speed, F xi (104) is the ground braking force.

[0034] The wheel deceleration dynamic control rate parameter setting u k The cost function J(Δσ) of the parameter tuning control algorithm during the braking process of the electric vehicle constructed in (5) k )(501):

[0035]

[0036] In formula (5.1): (502) is the estimated value of the control system output variable of the electric vehicle during braking at the current time k, y k (503) is the measured value of the control system output variable at the current time k during the braking process of the electric vehicle, Δσ k (504) is the control increment of the control rate parameter σ (409) at the current time k during the braking process of the electric vehicle, and β (505) is the weight coefficient;

[0037] According to formula (5.1), the control increment of the optimal control rate parameter σ(409) at the current time k is constructed (506),

[0038]

[0039] In formula (5.2),

[0040]

[0041] (507) is the sampling time;

[0042] The optimal control rate parameter at the current k moment during the braking process of the electric vehicle is obtained by using backward difference (508),

[0043]

[0044] In formula (5.3), σ k-1 is the value of the control rate parameter σ(409) at time k-1 during the braking process of the electric vehicle.

[0045] The beneficial effects of the present invention are:

[0046] 1. The present invention uses wheel deceleration as the control target. In actual engineering applications, wheel deceleration can be accurately measured, effectively solving the problem that the slip rate cannot be measured in some wheel anti-lock braking control methods and can only be estimated by vehicle speed.

[0047] 2. This invention designs a wheel anti-lock braking controller that uses a parameter tuning control algorithm to obtain optimal control rate parameters. These optimized parameters are then substituted into the control rate to achieve the optimal motor braking torque during electric vehicle braking. This invention ensures smooth operation during emergency braking of electric vehicles, effectively resolving the issue of motor regenerative braking during emergency braking, improving the braking energy recovery efficiency and braking stability of electric vehicles, extending driving range, and reducing braking distance and time.

[0048] 3. The present invention designs a wheel anti-lock braking controller that does not require setting thresholds in the control strategy. It is relatively simple to debug in actual applications, does not require a large number of road tests, and has low development costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Table 1 is a comparison table of the meanings of the sequence numbers of the present invention;

[0050] Figure 1 This is a logical relationship diagram of a wheel anti-lock braking method based on wheel deceleration and motor torque control according to the present invention;

[0051] Figure 2 This is a system architecture diagram of a wheel anti-lock braking method based on wheel deceleration and motor torque control according to the present invention;

[0052] Figure 3 It is a schematic diagram of the force on the wheels of the automobile during the braking process of the present invention;

[0053] Figure 4 is a flow chart of the present invention using a road adhesion coefficient observer;

[0054] The technical features indicated by the reference numerals in the figure are shown in Table 1.

[0055] Table 1 Comparison table of serial number meanings

[0056]

[0057]

[0058] DETAILED DESCRIPTION

[0059] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] Table 1 is a comparison table of the meaning of the serial numbers of the present invention, which is divided into four parts: serial number, symbol, symbol definition and unit. Figure 1 The road adhesion coefficient in [ 1 ] is estimated; Serial number 101 represents the slip rate; all representations in this table are the same as this one. All symbols and contents in the patent can be found in Table 1.

[0061] Figure 1 The present invention is a wheel anti-lock braking method based on wheel deceleration and motor torque control, characterized in that the method includes road adhesion coefficient estimation (1), ideal wheel deceleration calculation (2), target wheel deceleration calculation (3), wheel deceleration dynamics controller design u k (σ k (4) Adjustment of the wheel deceleration dynamic control rate parameter u k (5), motor controller (6), power system (7); road adhesion coefficient estimation (1) according to wheel braking torque T bi (102) and wheel angular velocity ω i (705), using the observer, the maximum road adhesion coefficient is estimated (112); Ideal wheel deceleration calculation (2) is used to determine the ideal wheel deceleration α id (210); Target wheel deceleration calculation (3) wheel deceleration α required according to the current vehicle state p (301) and the ideal wheel deceleration α id (210), used to determine the target wheel deceleration α g (302); Design of wheel deceleration dynamic controller u k (σ k )(4) According to the actual motion state information of the electric vehicle and the target wheel deceleration α g (302) is used to determine the control rate u of the controller k (σ k )(413); Based on the wheel deceleration dynamic control rate parameter setting u k (5) is used to optimize the control rate parameter σ(409) and obtain the optimal control rate u k (509); The motor controller (6) obtains the control rate u according to the optimization k(509) outputs the required motor torque and inputs it to the power system (7); the power system (7) is used to output the current actual motion state information of the electric vehicle, including the wheel deceleration α of the electric vehicle i (701), vehicle speed v (702) and wheel angular velocity ω i (703).

[0062] Figure 2 The present invention is a system architecture diagram of a wheel anti-lock braking method based on wheel deceleration and motor torque control, the system comprising an accelerator pedal (9), a brake pedal (10), a vehicle controller (11), a motor controller (6) and a power battery (12). During the braking process of an electric vehicle, the driver steps on the brake pedal (10), and a brake pedal opening analog signal enters the vehicle controller (11); the wheel anti-lock braking control algorithm of the present invention is integrated into the vehicle controller (11), and the control algorithm solves and obtains the optimal control rate u k (509); Based on the obtained optimal control rate u k (509), the vehicle controller (11) inputs the required braking torque to the motor controller (6); the motor controller (6) controls the drive motor to output the optimal wheel braking torque T bi，k (601).

[0063] Figure 3 This is a schematic diagram of the force on the wheels of an electric vehicle during braking. The present invention uses a single wheel model, F xi (104) is the ground braking force, F zi (116) is the normal reaction force of the ground on the wheel, ω i (703) is the wheel angular velocity, T bi (102) is the wheel braking torque, v (702) is the longitudinal speed of the vehicle, and r (103) is the wheel rolling radius. In order to solve the problem of wheel locking during braking of electric vehicles, a wheel dynamics model during braking is established based on the single-wheel model of electric vehicles.

[0064] Figure 4 This is a flow chart of the present invention's use of a road adhesion coefficient observer. During electric vehicle braking, the road adhesion coefficient used by the wheels is an unmeasurable variable. Using the observer, an estimate of the road adhesion coefficient used during braking is obtained based on the wheel angular velocity. An estimate of the wheel angular velocity is then obtained based on the error between the measured and estimated wheel braking torque.

[0065] The specific steps of this method are as follows:

[0066] Step 1: Design a road adhesion coefficient observer;

[0067] Step 1.1, according to Figure 3The electric vehicle single wheel model establishes the wheel dynamics model during braking:

[0068]

[0069] In formula (1.1): I ωi (101) is the moment of inertia of the wheel, ω i (703) is the wheel angular velocity, T bi (102) is the wheel braking torque, r(103) is the wheel rolling radius, F xi (104) is the ground braking force, i (105) represents the four wheels of the car, and i = fl represents the left front wheel of the car, i = fr represents the right front wheel of the car, i = rl represents the left rear wheel of the car, and i = rr represents the right rear wheel of the car. The following expressions of this method are the same;

[0070] Step 1.2: According to formula (1.1), the estimated value of the road adhesion coefficient during the braking process of the electric vehicle is obtained based on the wheel angular velocity:

[0071]

[0072] In formula (1.2): (106) is the estimated value of the road adhesion coefficient, κ p (107) is the proportional gain, κ i (108) is the integral gain, ε(109) is the switching gain, (110) is the estimated value of the wheel braking torque, (111) is the difference between the estimated and measured wheel angular velocity;

[0073] When the actual wheel slip rate is equal to the optimal slip rate of the current road surface, the estimated road adhesion coefficient is (106) is equal to the maximum adhesion coefficient of the current road surface (112);

[0074] Step 2: Establishing an ideal wheel deceleration curve during braking of the electric vehicle;

[0075] Step 2.1. Define the wheel slip rate during braking of an electric vehicle:

[0076]

[0077] In formula (2.1): i (201) is the wheel slip rate, v(702) is the vehicle speed;

[0078] According to the fact that wheel speed is equal to the product of wheel angular velocity and wheel rolling radius, and the derivative of equation (2.1) with respect to time, we can obtain:

[0079]

[0080] Step 2.2: Derive the relationship between wheel deceleration and slip rate based on equation (2.2):

[0081] α i =a v (1-λ i ) (2.3)

[0082] In formula (2.3): α i (701) is the wheel deceleration, a v (202) is the longitudinal acceleration of the vehicle;

[0083] Step 2.3: Establish the slip rate calculation equation based on the estimated maximum road adhesion coefficient:

[0084]

[0085] In formula (2,4): opt (203) is the optimal slip ratio, μ max (204) is the peak road adhesion coefficient;

[0086] Step 2.4: Based on equations (2.3) and (2.4), establish the equation for calculating the wheel deceleration during the braking process of an electric vehicle:

[0087]

[0088] In formula (2.5): g(205) is the acceleration due to gravity, α fi (206) is the calculated wheel deceleration;

[0089] Step 2.5: Use equation (2.5) to fit the ideal wheel deceleration curve of the wheel according to the wheel deceleration calculation equation during the braking process of the electric vehicle:

[0090]

[0091] In formula (2.6), p1(207), p2(208), and p3(209) are the parameters of the ideal wheel deceleration curve obtained by fitting during the braking process of the electric vehicle, α id (210) is the ideal wheel deceleration;

[0092] Step 3: Design the target wheel deceleration calculation logic;

[0093] The wheel deceleration α required according to the current vehicle state p (301) and the ideal wheel deceleration α id (210), determine the target wheel deceleration α g (302):

[0094]

[0095] In formula (3.1), the wheel deceleration α required by the current vehicle state is p (301) is less than the ideal wheel deceleration α id (210), α g =α p ; Wheel deceleration α required by the current vehicle state p (301) is greater than or equal to the ideal wheel deceleration α id (210), α g =α id ;

[0096] Step 4: Establish a dynamic model based on wheel deceleration and obtain the state equation of the electric vehicle braking process;

[0097] Step 4.1: Establish the dynamic model (8) based on wheel deceleration according to equations (1.1) and (2.2):

[0098]

[0099] In formula (4.1): m(401) is the total mass of the vehicle;

[0100] Step 4.2: Establish the state equation of the electric vehicle braking process according to formula (4.1):

[0101]

[0102] y=x (4.3)

[0103] In formula (4.2), x (402) is the state variable of the control system, b (403) is the coefficient of the control system input, u (404) is the input of the control system, d (405) is the disturbance of the control system, and x = α i ,for In formula (4.3): y(406) is the output of the control system;

[0104] Step 5: Design a controller based on wheel deceleration dynamics;

[0105] Step 5.1: Design the dynamic sliding surface S (407) based on the wheel deceleration:

[0106] S=s+σ∫s (4.4)

[0107] In formula (4.4): s (408) is the wheel deceleration error, σ (409) is the control rate parameter;

[0108] Step 5.2: According to equation (4.4), use the constant velocity convergence law to solve:

[0109]

[0110] In formula (4.5): η(410) is the convergence factor;

[0111] Step 5.3: Solve the controller control rate u(σ)(411) according to equations (4.2) and (4.5):

[0112]

[0113] Step 6: Optimize the control rate parameter σ (409) using a control algorithm based on the wheel deceleration dynamics parameter tuning;

[0114] Step 6.1: Construct the cost function J(Δσ) of the parameter tuning control algorithm during the braking process of the electric vehicle k )(501):

[0115]

[0116] In formula (5.1): (502) is the estimated value of the control system output variable of the electric vehicle during braking at the current time k, k (503) is the measured value of the control system output variable of the electric vehicle during braking at the current time k, Δσ k (504) is the control increment of the control rate parameter σ (409) at the current time k during the braking process of the electric vehicle, and β (505) is the weight coefficient;

[0117] Step 6.2: By solving the cost function of the parameter tuning control algorithm, the optimal control rate parameter at the current k moment is obtained. (506):

[0118]

[0119] In formula (5.2): (507) is the sampling time;

[0120] Step 6.3: Use backward difference to obtain the optimal control rate parameter at the current k moment during the braking process of the electric vehicle. (508):

[0121]

[0122] Step 7: Calculate the control rate u after optimizing the control algorithm based on the wheel deceleration dynamics parameter tuning k (509), and finally the optimal wheel braking torque T during the braking process of the electric vehicle is obtainedbi，k (601);

[0123] Step 7.1: According to equations (4.6) and (5.3), the control rate u after optimization of the control algorithm based on the wheel deceleration dynamic parameters in the braking process of the electric vehicle is obtained. k (509):

[0124]

[0125] Step 7.2: According to formula (5.4), the optimal wheel braking torque T during the braking process of the electric vehicle is obtained. bi，k (601):

[0126]

[0127] In summary, the present invention has the following advantages:

[0128] 1. The present invention uses wheel deceleration as the control target. In actual engineering applications, wheel deceleration can be accurately measured, effectively solving the problem that the slip rate cannot be measured in some wheel anti-lock braking control methods and can only be estimated by vehicle speed.

[0129] 2. This invention designs a wheel anti-lock braking controller that uses a parameter tuning control algorithm to obtain optimal control rate parameters. These optimized parameters are then substituted into the control rate to achieve the optimal motor braking torque during electric vehicle braking. This invention ensures smooth operation during emergency braking of electric vehicles, effectively resolving the issue of motor regenerative braking during emergency braking, improving the braking energy recovery efficiency and braking stability of electric vehicles, extending driving range, and reducing braking distance and time.

[0130] 3. The present invention designs a wheel anti-lock braking controller that does not require setting thresholds in the control strategy. It is relatively simple to debug in actual applications, does not require a large number of road tests, and has low development costs.

Claims

1. A wheel anti-lock braking method based on wheel deceleration and motor torque control, characterized by: The method includes the estimation of road adhesion coefficient (1), calculation of ideal wheel deceleration (2), calculation of target wheel deceleration (3), design of wheel deceleration dynamics controller u k (σ k (4) Adjustment of the wheel deceleration dynamic control rate parameter u k (5), motor controller (6), power system (7); Road adhesion coefficient estimation (1) According to the wheel braking torque T bi (102) and wheel angular velocity ω i (705), using the observer, the maximum road adhesion coefficient is estimated Ideal wheel deceleration calculation (2) is used to determine the ideal wheel deceleration α id (210); Target wheel deceleration calculation (3) According to the wheel deceleration α required by the current vehicle state p (301) and the ideal wheel deceleration α id (210), used to determine the target wheel deceleration α g (302); Design of wheel deceleration dynamics controller based on u k (σ k )(4) According to the actual motion state information of the electric vehicle and the target wheel deceleration α g (302) is used to determine the control rate u of the controller k (σ k )(413); Based on the wheel deceleration dynamics control rate parameter tuning u k (5) is used to optimize the control rate parameter σ(409) and obtain the optimal control rate u k (509); The motor controller (6) obtains the control rate u according to the optimization k (509) outputs the required motor torque and inputs it to the power system (7); The power system (7) is used to output the actual motion state information of the current electric vehicle, including the wheel deceleration α of the electric vehicle i (701), vehicle speed v (702) and wheel angular velocity ω i (703); The method comprises the following steps, Step 1: Estimation of the road adhesion coefficient (1) is performed to obtain the maximum road adhesion coefficient during the braking process of the electric vehicle based on the wheel angular velocity. Step 2: Design the target wheel deceleration calculation logic, based on the wheel deceleration α required by the current vehicle state p (301) and the ideal wheel deceleration α id (210), determine the target wheel deceleration α g (302), Step 3: Establish a dynamic model based on wheel deceleration and obtain the state equation of the electric vehicle braking process. Step 4: Design a controller based on wheel deceleration dynamics. Step 5: Optimize the parameter σ(409) by using the control algorithm based on the wheel deceleration dynamic parameter tuning. Step 6: Calculate the control rate u after optimizing the control algorithm based on the wheel deceleration dynamics parameter tuning k (509), and finally the optimal wheel braking torque T during the braking process of the electric vehicle is obtained bi，k (601); According to the above six steps, the control rate u after optimization of the control algorithm based on the wheel deceleration dynamic parameter tuning during the braking process of the electric vehicle is obtained using equations (4.6) and (5.3). k (509), In formula (5.4), u(σ) (411) is the control rate of the controller, d (405) is the disturbance of the control system, σ (409) is the control rate parameter, s (408) is the wheel deceleration error, S (407) is the dynamic sliding surface, σ k-1 is the value of the control rate parameter σ(409) at time k-1 during the braking process of the electric vehicle, is the control increment of the optimal control rate parameter at the current k moment, d k is the value of the disturbance d(405) of the control system during the braking process of the electric vehicle at the current time k, is the value of the optimal control rate parameter at the current k moment, s k is the value of the wheel deceleration error s(408) at the current time k during the braking process of the electric vehicle, S k is the value of the dynamic sliding surface S (407) at the current time k during the braking process of the electric vehicle, η (410) is the convergence factor, and b (403) is the coefficient of the control system input.

2. The wheel anti-lock braking method based on wheel deceleration and motor torque control according to claim 1, characterized in that: The estimated value of the road adhesion coefficient during braking of electric vehicles is obtained based on the wheel angular velocity. In formula (1.2): To use the estimated value of the road adhesion coefficient, κ p (107) is the proportional gain, κ i (108) is the integral gain, ω i (703) is the wheel angular velocity, ε(109) is the switch gain, I ωi (101) is the moment of inertia of the wheel, is the estimated value of wheel braking torque, T bi (102) is the wheel braking torque measurement value, is the difference between the estimated and measured wheel angular velocity values, i(105) represents the signs of the four wheels of the vehicle, and i=fl represents the left front wheel of the vehicle, i=fr represents the right front wheel of the vehicle, i=rl represents the left rear wheel of the vehicle, and i=rr represents the right rear wheel of the vehicle. The above i has the same meaning below; When the actual wheel slip rate is equal to the optimal slip rate of the current road surface, the estimated road adhesion coefficient is Equal to the maximum adhesion coefficient of the current road surface 3. The wheel anti-lock braking method based on wheel deceleration and motor torque control according to claim 1, characterized in that: Establish the wheel deceleration dynamic model (8): In formula (4.1): α i (701) is the wheel deceleration, m (401) is the total mass of the car, r (103) is the wheel rolling radius, v (702) is the car speed, F xi (104) is the ground braking force.

4. The wheel anti-lock braking method based on wheel deceleration and motor torque control according to claim 1, characterized in that: The cost function J(Δσ k )(501), In formula (5.1): is the estimated value of the control system output variable of the electric vehicle during braking at the current time k, y k (503) is the measured value of the control system output variable at the current time k during the braking process of the electric vehicle, Δσ k (504) is the control increment of the control rate parameter σ (409) at the current time k during the braking process of the electric vehicle, and β (505) is the weight coefficient; According to formula (5.1), the control increment of the optimal control rate parameter σ(409) at the current time k is constructed In formula (5.2), T(507) is the sampling time, x id (511) is the ideal state variable value of the control system during the braking process of the electric vehicle, x k-1 is the value of the state variable x(402) of the control system during the braking process of the electric vehicle at time k-1, y k (503) is the measured value of the control system output variable at the current time k during the braking process of the electric vehicle, s k-1 is the value of the wheel deceleration error s(408) at time k-1 during the braking process of the electric vehicle, d k-1 is the value of the disturbance d(405) of the control system during the braking process of the electric vehicle at time k-1; The optimal control rate parameter at the current k moment during the braking process of the electric vehicle is obtained by using backward difference In formula (5.3), σ k-1 is the value of the control rate parameter σ(409) at time k-1 during the braking process of the electric vehicle.

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