Vehicle braking control method, device and equipment and storage medium

Abstract

The invention discloses a vehicle braking control method and device and related equipment which are applied to the technical field of vehicle control. According to the method, based on an obtained brake fault signal of a target wheel, it is determined that an actuator of the target wheel breaks down, and the numerical value of the longitudinal force of the target wheel is set to be 0. And determining the target rear wheel turning angle and the longitudinal force of each controllable wheel by using the total constraint condition and the speed change condition. Through the rear wheel steering system, the angle of the rear wheel is adjusted based on the target rear wheel steering angle, so that the transverse deviation of the vehicle posture is reduced, and the transverse stability of the vehicle is guaranteed. And on the basis of the longitudinal force of the controllable wheels, brake control is conducted on the other three wheels with the actuators not broken down, the problem that the brake effect is reduced due to the fact that the target wheel breaks down is solved, and longitudinal speed control over the vehicle is achieved. In this way, effective braking control in the transverse direction and the longitudinal direction can be achieved, and the driving requirement is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle control, in particular to a vehicle braking control method, device, equipment and storage medium. BACKGROUND

[0002] An Electro-Mechanical Brake (EMB) system is a relatively advanced vehicle braking system. The EMB system mainly includes an electronic brake pedal, an upper controller and four actuators located at the wheel end. During driving, when the driver steps on the electronic brake pedal, the pedal stroke sensor collects the pedal stroke and sends the pedal stroke to the upper controller. The pedal stroke is used to represent the braking intention of the driver. The upper controller generates a vehicle braking force request based on the pedal stroke, and distributes the vehicle braking force request to the clamping force request of the four wheel-end actuators. Finally, the clamping force corresponding to the clamping force request is generated by the motor inside the actuator, and the mechanical clamping brake caliper is clamped, thereby generating a vehicle deceleration. The EMB system no longer uses a hydraulic system for brake force transmission, but uses four independently controllable actuators to generate braking force, which can achieve faster brake torque response and more secure redundancy mechanism.

[0003] However, in the actual use process of the EMB system, a problem of failure of an actuator may occur. The failed actuator cannot generate the clamping force corresponding to the clamping force request, and thus cannot control the braking of the vehicle wheel, resulting in insufficient braking force of the entire vehicle, which not only causes the overall deceleration of the vehicle to fail to reach the control expectation of the driver, but also may cause the vehicle to yaw.

[0004] At present, there is a lack of a method for effectively controlling vehicle braking in the case of failure of an actuator in an EMB system. SUMMARY

[0005] Therefore, the present application provides a vehicle braking control method, device and related equipment, which can effectively control vehicle braking in the case of failure of an actuator in an EMB system.

[0006] The technical scheme provided by the present application is as follows:

[0007] In a first aspect, the present application provides a vehicle braking control method, which is applied to a vehicle configured with an Electro-Mechanical Brake (EMB) system and a rear wheel steering system, the EMB system includes an upper controller, the upper controller is connected with the rear wheel steering system, and the method comprises the following steps:

[0008] In response to obtaining a braking failure signal of a target vehicle wheel, the upper controller sets a value of a longitudinal force of the target vehicle wheel to 0;

[0009] The upper controller acquires total constraint conditions, the total constraint conditions including vehicle lateral stability constraint conditions and vehicle longitudinal deceleration constraint conditions;

[0010] The upper controller determines target rear wheel steering angles and longitudinal forces of controllable wheels of the vehicle, the controllable wheels being three wheels of the vehicle except the target wheels, the target rear wheel steering angles satisfying the total constraint conditions and speed change conditions, the speed change conditions being that a difference between a rate of change of a longitudinal speed of the vehicle and a rate of change of the longitudinal speed of the vehicle in normal times is minimum;

[0011] The upper controller controls the controllable wheels according to the longitudinal forces of the controllable wheels, and sends the target rear wheel steering angles to the rear wheel steering system, so that the rear wheel steering system controls rear wheel angles of the vehicle according to the target rear wheel steering angles.

[0012] In a possible implementation, the total constraint conditions further include wheel adhesion limit constraint conditions, the wheel adhesion limit constraint conditions being that a sum of squares of the longitudinal forces of the wheels and squares of lateral forces of the wheels is less than a product of a ground adhesion coefficient and a square of a dynamic vertical load of the wheel.

[0013] In a possible implementation, the sending of the target rear wheel steering angles to the rear wheel steering system, so that the rear wheel steering system controls the rear wheel angles of the vehicle according to the target rear wheel steering angles, includes:

[0014] The target rear wheel steering angles and a fault signal are sent to the rear wheel steering system, so that the rear wheel steering system controls the rear wheel angles of the vehicle according to the target rear wheel steering angles in response to acquisition of the fault signal.

[0015] In a possible implementation, the vehicle lateral stability constraint conditions and the vehicle longitudinal deceleration constraint conditions are obtained in the following manner:

[0016] Whole vehicle parameters, state variables, steering variables and lateral forces of four wheels of the vehicle are acquired, the whole vehicle parameters including a front half track, a rear half track, a track, a wheel track, a whole vehicle mass and a yaw moment of inertia of the vehicle, the state variables including a vehicle yaw rate, a vehicle center of mass side slip angle and a vehicle longitudinal speed, the steering variables including longitudinal forces of the four wheels, a front wheel steering angle and a rear wheel steering angle;

[0017] A first lateral and longitudinal dynamics model of the vehicle is constructed by using the whole vehicle parameters, the state variables, the steering variables and the lateral forces of the four wheels, the first lateral and longitudinal dynamics model including an expression describing a yaw moment, an expression describing a rate of change of a vehicle center of mass side slip angle and an expression describing a whole vehicle longitudinal force;

[0018] According to a corresponding relationship between the lateral forces of the four wheels, the cornering stiffness coefficients of the wheels, the vehicle parameters, the state variables, and the steering variables, the lateral forces of the four wheels in the first lateral and longitudinal dynamics model are replaced by the cornering stiffness coefficients of the wheels, the vehicle parameters, the state variables, and the steering variables to obtain a second lateral and longitudinal dynamics model;

[0019] The rate of change of the vehicle yaw rate and the rate of change of the vehicle mass center side slip angle are set to 0, and the second lateral and longitudinal dynamics model includes an expression describing the yaw moment and an expression describing the rate of change of the vehicle mass center side slip angle to form the vehicle lateral stability constraint condition;

[0020] The expression describing the vehicle longitudinal dynamics included in the second lateral and longitudinal dynamics model is used as the vehicle longitudinal deceleration constraint condition.

[0021] In a possible implementation, the expression describing the vehicle longitudinal dynamics includes a sine value of a front wheel angle, a cosine value of the front wheel angle, a sine value of a rear wheel angle, and a cosine value of the rear wheel angle, the sine value of the front wheel angle is replaced by a front wheel angle, the cosine value of the front wheel angle is replaced by 1, the sine value of the rear wheel angle is replaced by a rear wheel angle, and the cosine value of the rear wheel angle is replaced by 1.

[0022] In a second aspect, the application provides a vehicle brake control device, which is applied to a vehicle configured with an electronic mechanical brake system and a rear wheel steering system, the electronic mechanical brake system includes an upper controller, the upper controller is connected with the rear wheel steering system, the device is applied to the upper controller, and the device includes:

[0023] The setting unit is configured to set a value of a longitudinal force of a target wheel to 0 in response to obtaining a brake fault signal of the target wheel.

[0024] The obtaining unit is configured to obtain total constraint conditions, the total constraint conditions including vehicle lateral stability constraint conditions and vehicle longitudinal deceleration constraint conditions.

[0025] The determining unit is configured to determine a target rear wheel angle and longitudinal forces of controllable wheels of the vehicle that satisfy the total constraint conditions and a speed change condition, the speed change condition being that a difference between a rate of change of a vehicle longitudinal speed and a rate of change of a normal vehicle longitudinal speed is minimum, and the controllable wheels being three wheels of the vehicle except the target wheel.

[0026] The control unit is configured to control the controllable wheels according to the longitudinal forces of the controllable wheels, and send the target rear wheel angle to the rear wheel steering system so that the rear wheel steering system controls a rear wheel angle of the vehicle according to the target rear wheel angle.

[0027] In a possible implementation, the vehicle lateral stability constraint condition and the vehicle longitudinal deceleration constraint condition are obtained in the following manner:

[0028] obtaining a whole vehicle parameter, a state variable, a steering variable and lateral forces of four wheels of the vehicle, the whole vehicle parameter comprising a front half track, a rear half track, a track, a wheel track, a whole vehicle mass and a yaw moment of inertia of the vehicle, the state variable comprising a vehicle yaw rate, a vehicle side slip angle and a vehicle longitudinal speed, the steering variable comprising longitudinal forces of the four wheels, a front wheel steering angle and a rear wheel steering angle;

[0029] constructing a first lateral and longitudinal dynamics model of the vehicle by using the whole vehicle parameter, the state variable, the steering variable and the lateral forces of the four wheels, the first lateral and longitudinal dynamics model comprising an expression describing a yaw moment, an expression describing a rate of change of the vehicle side slip angle and an expression describing a whole vehicle longitudinal dynamics;

[0030] replacing the lateral forces of the four wheels in the first lateral and longitudinal dynamics model by using a side slip stiffness coefficient of the wheels, the whole vehicle parameter, the state variable and the steering variable according to a corresponding relationship between the lateral forces of the four wheels, the side slip stiffness coefficient of the wheels, the whole vehicle parameter, the state variable and the steering variable, to obtain a second lateral and longitudinal dynamics model;

[0031] setting the rate of change of the vehicle yaw rate and the rate of change of the vehicle side slip angle to 0, and constructing the vehicle lateral stability constraint condition by using the expression describing the yaw moment and the expression describing the rate of change of the vehicle side slip angle comprised in the second lateral and longitudinal dynamics model;

[0032] taking the expression describing the whole vehicle longitudinal dynamics comprised in the second lateral and longitudinal dynamics model as the vehicle longitudinal deceleration constraint condition.

[0033] In a possible implementation, the expression describing the whole vehicle longitudinal dynamics comprises a sine value of the front wheel steering angle, a cosine value of the front wheel steering angle, a sine value of the rear wheel steering angle and a cosine value of the rear wheel steering angle, the sine value of the front wheel steering angle is replaced by the front wheel steering angle, the cosine value of the front wheel steering angle is replaced by 1, the sine value of the rear wheel steering angle is replaced by the rear wheel steering angle, and the cosine value of the rear wheel steering angle is replaced by 1.

[0034] In a possible implementation, the total constraint condition further comprises a wheel adhesion limit constraint condition, and the wheel adhesion limit constraint condition is that a sum of a square of a longitudinal force of a wheel and a square of a lateral force of the wheel is less than a product of a ground adhesion coefficient and a square of a dynamic vertical load of the wheel.

[0035] In a possible implementation, the control unit is configured to send a target rear wheel steering angle to the rear wheel steering system, so that the rear wheel steering system controls the rear wheel angle of the vehicle according to the target rear wheel steering angle, including:

[0036] The control unit is configured to send a target rear wheel steering angle and a fault signal to the rear wheel steering system, so that the rear wheel steering system controls the rear wheel angle of the vehicle according to the target rear wheel steering angle in response to obtaining the fault signal.

[0037] In a third aspect, the present application provides a device, including: a processor, a memory, a system bus;

[0038] The processor and the memory are connected through the system bus;

[0039] The memory is configured to store one or more programs, the one or more programs including instructions that, when executed by the processor, cause the processor to perform the method of the first aspect.

[0040] In a fourth aspect, the present application provides a computer-readable storage medium, the computer-readable storage medium storing instructions, when the instructions run on a terminal device, cause the terminal device to perform the method of the first aspect.

[0041] Therefore, the present application has the following beneficial effects:

[0042] The present application provides a vehicle braking control method, device and related equipment which can be applied to a vehicle configured with an electronic mechanical braking system and a rear wheel steering system. In the method, based on obtaining a braking fault signal of a target wheel, it is determined that the actuator of the target wheel is faulty, and the value of the longitudinal force of the target wheel is set to 0, so as to realize braking control of the vehicle in the case that the actuator of the target wheel cannot brake the target vehicle. The target rear wheel steering angle and the longitudinal force of each controllable wheel are determined by using a total constraint condition and a speed change condition. The total constraint condition includes a vehicle lateral stability constraint condition and a vehicle longitudinal deceleration constraint condition, which respectively meet the stability demand of the vehicle in the lateral direction and the deceleration demand of the vehicle in the longitudinal direction. The speed change condition is used to meet the demand that the speed change rate of the vehicle is relatively stable, so as to realize a relatively stable braking process in the case of fault. By using the rear wheel steering system, the angle of the rear wheel is adjusted based on the target rear wheel steering angle, so as to reduce the lateral deviation of the vehicle attitude and ensure the stability of the vehicle in the lateral direction. Based on the longitudinal force of the controllable wheel, the three wheels whose actuators are not faulty are controlled to brake, so as to compensate for the problem of reduced braking effect caused by the fault of the target wheel, and realize the speed control of the vehicle in the longitudinal direction. In this way, the vehicle with the rear wheel steering system can be adapted to realize effective braking control in the lateral and longitudinal directions, and meet the driving demand. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 A scene schematic diagram of a vehicle braking control method provided for an embodiment of the present application;

[0044] Figure 2 A flowchart schematic diagram of a vehicle braking control method provided for an embodiment of the present application;

[0045] Figure 3 A schematic diagram of a vehicle's longitudinal and lateral dynamics model provided for an embodiment of the present application;

[0046] Figure 4 A structural schematic diagram of a vehicle braking control device provided for an embodiment of the present application. DETAILED DESCRIPTION

[0047] In order to facilitate understanding and explaining the technical solutions provided by the embodiments of the present application, the background art of the present application will be described first.

[0048] The EMB system realizes independent control for the wheel end by configuring four independently controllable actuators at the wheel end, improves the response speed of braking and the safety of braking. However, when the actuator fails, the EMB system cannot effectively control the braking of the wheel corresponding to the failed actuator during the execution of the braking control. In the case of failure of an actuator, the failed actuator cannot normally execute the clamping of the wheel, and the braking control of the wheel is lacking. When one wheel cannot be effectively braked, the vehicle as a whole cannot achieve the braking control expected by the driver or the automatic driving system, which may cause the braking distance to exceed the expected distance and affect the driving safety. Moreover, in the case that the other three actuators normally execute the clamping of the wheel, the motion of the wheel that cannot be effectively braked will affect the posture of the vehicle as a whole, and lateral yaw may occur.

[0049] At present, there are two control methods for the failure of the EMB system actuator. The first one is for vehicles equipped with a distributed drive system, which generates a counter driving force on the wheel with a failed actuator to compensate for the insufficient braking force of the actuator on the wheel. However, the distributed drive system has a high cost and is basically configured on high-end vehicles, which cannot achieve universal application for vehicles. In addition, the second one is for vehicles equipped with a front wheel steer-by-wire system, which compensates for the vehicle's yaw angle by adding front wheel steering angle to realize the control of the vehicle's posture. However, this control method cannot reduce the vehicle's longitudinal driving speed, and will also interfere with the driver's driving intention, which cannot meet the braking demand.

[0050] Based on this, the embodiment of the application provides a vehicle braking control method. In response to obtaining a brake fault signal of a target wheel, it is determined that a fault occurs in an actuator of the target wheel, and the value of the longitudinal force of the target wheel is set to 0 to trigger the braking control of the vehicle in the case where the fault occurs in the actuator of the target wheel. The target rear wheel steering angle and the longitudinal force of each controllable wheel are determined by using a total constraint condition and a speed change condition. The total constraint condition includes a vehicle lateral stability constraint condition and a vehicle longitudinal deceleration constraint condition, which respectively meet the stability requirements of the vehicle in the lateral direction and the deceleration requirements of the vehicle in the longitudinal direction. The speed change condition is used to meet the requirement that the speed change rate of the vehicle is relatively stable, so that the braking process is relatively smooth in the case where the fault occurs. Through the rear wheel steering system, the angle of the rear wheel is adjusted based on the target rear wheel steering angle to reduce the lateral deviation of the vehicle posture and ensure the stability of the vehicle in the lateral direction. Based on the longitudinal force of the controllable wheel, the braking control is performed on the three wheels whose actuators do not have faults, so as to compensate for the problem of reduced braking effect caused by the fault of the target wheel, and to realize the speed control of the vehicle in the longitudinal direction. In this way, the vehicle with a more popular rear wheel steering system can realize effective braking control in the lateral and longitudinal directions in the case where the actuator of the EMB fails, and the driving requirements can be met.

[0051] First of all, it should be pointed out that the vehicle braking control method provided by the embodiment of the application is applied to a vehicle configured with a rear wheel steering (RWS) system. The rear wheel steering system is used to generate a rear wheel steering angle, which can reduce the excessive steering generated by the vehicle when turning at high speed, and can also compensate for the problem of insufficient steering, thereby improving the flexibility and safety of vehicle driving.

[0052] Referring to Figure 1 As shown in the figure, the figure is a scene schematic diagram of a vehicle braking control method provided by the embodiment of the application. The vehicle is configured with an EMB system and an RWS system. The EMB system includes an upper controller and four actuators located at the wheel end. The four actuators located at the wheel end include an actuator of wheel A, an actuator of wheel B, an actuator of wheel C and an actuator of wheel D. The four actuators located at the wheel end include a lower controller. The lower controller is connected with the upper controller. The upper controller of the EMB system is also connected with the RWS system.

[0053] The lower controller of the actuator of the EMB system performs fault detection of the actuator. When the lower controller of the actuator of a certain wheel, for example, wheel A, detects that the actuator fails, a brake fault signal is generated. The lower controller of the actuator of wheel A sends the brake fault signal to the upper controller of the EMB system. The upper controller of the EMB system acquires the brake fault signal of the actuator of wheel A, and determines that the value of the longitudinal force of wheel A is 0. That is, the actuator of wheel A cannot provide the longitudinal force to wheel A. The upper controller of the EMB system acquires the total constraint condition. The total constraint condition includes a vehicle lateral stability constraint condition and a vehicle longitudinal deceleration constraint condition. The vehicle lateral stability constraint condition is used to ensure the stability of the lateral state of the vehicle. The vehicle longitudinal deceleration constraint condition is used to describe the deceleration of the longitudinal speed of the vehicle. The upper controller of the EMB system determines the target rear wheel steering angle and the longitudinal force of each controllable wheel that satisfies the total constraint condition and the speed change condition. The controllable wheels are wheel B, wheel C, and wheel D. The upper controller of the EMB system sends the target rear wheel steering angle to the RWS system. The RWS system adjusts the angle of the rear wheel of the vehicle according to the target rear wheel steering angle. The upper controller of the EMB system sends the longitudinal force of wheel B to the actuator of wheel B, sends the longitudinal force of wheel C to the actuator of wheel C, and sends the longitudinal force of wheel D to the actuator of wheel D. The actuator of wheel B, the actuator of wheel C, and the actuator of wheel D control the wheels based on the acquired longitudinal force.

[0054] In this way, the longitudinal force of the actuator that does not fail can be adjusted, the adjustment of the longitudinal speed can be realized, the angle of the rear wheel can be adjusted by using the more common rear wheel steering system of the vehicle configuration, the stability of the lateral direction of the vehicle can be ensured, and the effective control of the vehicle braking in the case of the failure of the actuator of the EMB system can be realized.

[0055] In order to facilitate the understanding of the technical solutions provided by the embodiments of the present application, the vehicle braking control method provided by the embodiments of the present application will be described below in conjunction with the drawings.

[0056] Referring to Figure 2 As shown in the figure, the figure is a flowchart of a vehicle braking control method provided by an embodiment of the present application. As Figure 2 As shown in the figure, the vehicle braking control method provided by the embodiments of the present application includes S201-S204.

[0057] S201: The upper controller sets the value of the longitudinal force of the target wheel to 0 in response to acquiring the brake fault signal of the target wheel.

[0058] The brake fault signal of the target wheel is used to indicate that the actuator of the target wheel is faulty. As an example, the brake fault signal of the target wheel includes a fault identifier and a wheel identifier of the target wheel. The fault identifier is used to indicate that the actuator is faulty. The wheel identifier of the target wheel is used to indicate the target wheel. The embodiments of the present application do not limit the position of the target wheel on the vehicle, and the target wheel can be a front right wheel, a front left wheel, a rear right wheel, and a rear left wheel. That is, the detection of brake faults and the corresponding compensation control can be performed for any wheel on the vehicle where the actuator is faulty.

[0059] The brake fault signal of the target wheel is generated by the actuator of the EMB system configured at the wheel. As an example, the actuator includes a lower controller. The lower controller is used to control the actuator. The lower controller monitors the actuator. When the actuator is faulty, the brake fault signal of the target wheel is generated.

[0060] The longitudinal force of the wheel is the force determined by the upper controller of the EMB system to control the actuator of the wheel. The actuator applies the longitudinal force to the wheel, that is, the clamping force to the wheel, according to the longitudinal force issued by the upper controller, to realize the brake control of the wheel.

[0061] After obtaining the brake fault signal of the target wheel, the upper controller of the EMB system determines that the actuator of the target wheel cannot apply the longitudinal force to the target wheel, and stops the brake control strategy of the actuator under normal circumstances. The strategy of compensation control for actuator failure is started. Specifically, the upper controller of the EMB system sets the value of the longitudinal force of the target wheel to 0. It should be noted that after setting the value of the longitudinal force of the target wheel to 0, the value of the longitudinal force of the target wheel remains unchanged during the subsequent execution of S202 and S203 to determine the target rear wheel angle and the longitudinal force of each controllable wheel. Until the upper controller obtains the brake recovery signal of the target wheel, or obtains the reset signal triggered after excluding the brake fault.

[0062] S202: The upper controller obtains the total constraint condition.

[0063] The total constraint condition is a condition for ensuring the lateral stability and longitudinal speed control of the vehicle. The total constraint condition includes a vehicle lateral stability constraint condition and a vehicle longitudinal deceleration constraint condition. The total constraint condition can be pre-configured in the upper controller or in other modules connected to the upper controller for calling by the upper controller.

[0064] In some possible implementations, the total constraint condition can be described using an expression. As an example, the vehicle lateral stability constraint condition is expressed by formula (1) and formula (2):

[0065]

[0066] wherein a is the front half track, b is the rear half track, and β is the vehicle yaw angle. ′ is the vehicle yaw rate. sp is the vehicle yaw rate. sp is calculated according to the front wheel angle and the rear wheel angle at the normal time of the vehicle. ′ x is the vehicle longitudinal speed at the current time. r is the rear wheel angle. T is the wheel track of the vehicle. m is the mass of the vehicle. f is the front wheel cornering stiffness coefficient. r is the rear wheel cornering stiffness coefficient. xfl , F xfr , F xrl , F xrr respectively represent the longitudinal force of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel. Among them, the longitudinal force of the target wheel is 0.

[0067] As an example, the target wheel is the left front wheel, that is, the actuator of the left front wheel fails, then F xfl = 0. The above formula (1) can be simplified as formula (3):

[0068]

[0069] The vehicle longitudinal deceleration constraint condition is expressed by formula (4):

[0070]

[0071] wherein, is the rate of change of the vehicle longitudinal speed.

[0072] The total constraint condition of the above formula (1), formula (2) and formula (4) can be determined according to the lateral and longitudinal dynamics model of the vehicle. The present embodiment provides a possible implementation manner for determining the total constraint condition, please refer to the following.

[0073] In addition, in addition to the above vehicle lateral stability constraint condition and vehicle longitudinal deceleration constraint condition, the total constraint condition also includes the wheel adhesion limit constraint condition. The wheel adhesion limit constraint condition is used to ensure that the wheel cannot exceed the adhesion limit of the wheel and will not lose the grip.

[0074] As an example, the wheel adhesion limit constraint condition is that the sum of the square of the longitudinal force of the wheel and the square of the lateral force of the wheel is less than the product of the ground adhesion coefficient and the square of the dynamic vertical load of the wheel. Specifically, the wheel adhesion limit constraint condition is expressed by formula (5):

[0075]

[0076] wherein μ denotes the ground adhesion coefficient, F z denotes the dynamic vertical load of the wheel. F zfl denotes the dynamic vertical load of the wheel. F zfr denotes the dynamic vertical load of the wheel. F zrl denotes the dynamic vertical load of the wheel. F zrr denotes the dynamic vertical load of the wheel. F xfl denotes the dynamic vertical load of the wheel. F xfr denotes the dynamic vertical load of the wheel. F xrl denotes the dynamic vertical load of the wheel. F xrr denotes the longitudinal force of the wheel. F yfl denotes the longitudinal force of the wheel. F yfr denotes the longitudinal force of the wheel. F yrl denotes the longitudinal force of the wheel. F yrr denotes the lateral force of the wheel.

[0077] Taking the above target wheel as the left front wheel for example, that is, the actuator of the left front wheel fails, then F xfl = 0. The above formula (5) can be simplified as formula (6):

[0078]

[0079] S203: The upper layer controller determines the target rear wheel steering angle and the longitudinal forces of the controllable wheels that satisfy the total constraint condition and the speed change condition.

[0080] The speed change condition is that the difference between the rate of change of the longitudinal speed of the vehicle and the rate of change of the longitudinal speed of the vehicle under normal conditions is minimum.

[0081] Taking the target wheel as the left front wheel for example, the speed change condition can be expressed by formula (7):

[0082]

[0083] wherein is the rate of change of the longitudinal speed of the vehicle under normal conditions. δ r is the target rear wheel steering angle to be determined, F xfr is the longitudinal force of the right front wheel, F xrl is the longitudinal force of the left rear wheel, and F xrr is the longitudinal force of the right rear wheel.

[0084] The speed change condition can ensure that the longitudinal speed of the vehicle changes relatively stably, satisfying the driving demand of the driver. The speed change condition is also the target to be achieved by the brake control.

[0085] The upper controller determines the target rear wheel steering angle and the longitudinal force of each controllable wheel according to the total constraint condition and the speed variation condition. The target rear wheel steering angle is the angle of the rear wheel adjusted by the rear wheel steering system. The controllable wheel is the other three wheels except the target wheel which can normally realize braking.

[0086] Taking the left front wheel as the target wheel, the target rear wheel steering angle and the longitudinal force of each controllable wheel are determined according to formula (1), formula (3) and formula (4) with formula (7) as the target when the total constraint condition includes the vehicle lateral stability constraint condition and the vehicle longitudinal deceleration constraint condition. The target rear wheel steering angle and the longitudinal force of each controllable wheel are determined according to formula (1), formula (3), formula (4) and formula (6) with formula (7) as the target when the total constraint condition includes the vehicle lateral stability constraint condition, the vehicle longitudinal deceleration constraint condition and the wheel adhesion limit constraint condition.

[0087] S204: The upper controller controls the controllable wheel according to the longitudinal force of the controllable wheel, and sends the target rear wheel steering angle to the rear wheel steering system so that the rear wheel steering system controls the rear wheel steering of the vehicle according to the target rear wheel steering angle.

[0088] The upper controller controls the controllable wheel according to the determined longitudinal force of the controllable wheel. Specifically, the upper controller sends the longitudinal force of each controllable wheel to the actuator of the controllable wheel. The actuator controls the braking of the wheel according to the obtained longitudinal force.

[0089] The upper controller sends the target rear wheel steering angle to the rear wheel steering system. The rear wheel steering system adjusts the angle of the rear wheel of the vehicle based on the obtained target rear wheel steering angle. As an example, the upper controller sends the target rear wheel steering angle to the rear wheel steering system, so that the rear wheel steering system adjusts the angle of the rear wheel at the current time to the target rear wheel steering angle. As another example, the upper controller determines the difference between the target rear wheel steering angle and the angle of the rear wheel at the current time. The upper controller sends the difference to the rear wheel steering system so that the rear wheel steering system adjusts the rear wheel angle based on the difference. In a possible implementation, the upper controller sends the target rear wheel steering angle and a fault signal to the rear wheel steering system. The fault signal is used to indicate that the vehicle braking is in a fault state, triggering the rear wheel steering system to control the angle of the rear wheel. The rear wheel steering system adjusts the angle of the rear wheel according to the target rear wheel steering angle in response to obtaining the fault signal. Triggering the rear wheel steering system to adjust the angle of the rear wheel by using the fault signal can realize the adjustment of the angle of the rear wheel in the case of actuator failure, prevent the false influence on the normal control of the angle of the rear wheel by the rear wheel steering system in other cases, and improve the safety of adjusting the angle of the rear wheel by the rear wheel steering system.

[0090] Based on the related content of S201-S204, for the single-wheel actuator fault of the EMB system, the rear wheel angle adjustment for compensation is performed by using the rear wheel steering system which is more commonly equipped in vehicles, the lateral stability of the vehicle during braking is ensured, and higher adaptability is achieved. Moreover, when it is determined that the single-wheel actuator fails, the longitudinal forces of the remaining three normally operating actuators are adjusted, the demand for longitudinal speed control of the vehicle is considered on the premise of ensuring the lateral stability of the vehicle, effective braking control is achieved, the safety of vehicle driving is improved, the fault-tolerant control mechanism of the single-wheel actuator of the EMB system is realized, and the driving intention is met.

[0091] In a possible implementation, the embodiment of the present application provides a possible implementation of determining the total constraint condition according to the lateral and longitudinal dynamics model of the vehicle. It should be noted that the implementation of determining the total constraint condition can be performed by an upper controller or other modules, and the embodiment of the present application does not limit this. The possible implementation of determining the total constraint condition includes the following steps:

[0092] A1: obtaining the vehicle parameters, state variables, steering variables and lateral forces of the four wheels of the vehicle.

[0093] The vehicle parameters include the front half track, the rear half track, the track, the wheel track, the vehicle mass and the yaw moment of inertia of the vehicle. The state variables include the vehicle yaw rate, the vehicle mass side slip angle and the vehicle longitudinal speed. The steering variables include the longitudinal forces of the four wheels, the front wheel steering angle and the rear wheel steering angle.

[0094] The vehicle parameters are fixed values of the vehicle and can be determined in advance. The state variables and the steering variables are variable quantities determined based on the current state of the vehicle. The state variables and the steering variables can be obtained by sensors, computing modules and other devices in the vehicle system.

[0095] A2: constructing a first lateral and longitudinal dynamics model of the vehicle by using the vehicle parameters, the state variables, the steering variables and the lateral forces of the four wheels.

[0096] The first lateral and longitudinal dynamics model includes an expression describing the yaw moment, an expression describing the rate of change of the vehicle mass side slip angle, and an expression describing the longitudinal dynamics of the vehicle.

[0097] As an example, the embodiment of the present application provides a first lateral and longitudinal dynamics model. The first lateral and longitudinal dynamics model is expressed by formula (8):

[0098]

[0099] Wherein, a is the front half track, b is the rear half track, L is the track, T is the wheel track, m is the vehicle mass, I zis the yaw rotational inertia of the vehicle. γ is the vehicle yaw angular velocity, β is the vehicle mass center side slip angle, v x is the vehicle longitudinal velocity, δ f is the front wheel steering angle, δ r is the rear wheel steering angle. F xfl , F xfr , F xrl , F xrr respectively represent the longitudinal force of the left front wheel, the longitudinal force of the right front wheel, the longitudinal force of the left rear wheel and the longitudinal force of the right rear wheel. F yfl , F yfr , F yrl , F yrr respectively represent the lateral force of the left front wheel, the lateral force of the right front wheel, the lateral force of the left rear wheel and the lateral force of the right rear wheel.

[0100] Figure 3 is a schematic diagram of a vehicle longitudinal and lateral dynamics model provided by an embodiment of the present application, the meanings of various parameters and variables please refer to Figure 3 .

[0101] Further, for the above formula (8), in order to facilitate calculation, the calculation process of the sine value and the cosine value in formula (8) is simplified. In the process of driving, the steering angles of the front wheel and the rear wheel are small. The sine value of the front wheel steering angle is replaced by the front wheel steering angle, the cosine value of the front wheel steering angle is replaced by 1, the sine value of the rear wheel steering angle is replaced by the rear wheel steering angle, and the cosine value of the rear wheel steering angle is replaced by 1.

[0102] The formula (8) is simplified and calculated, so that sinδ f = δ f , cosδ f = 1, sinδ r = δ r , cosδ r = 1, and formula (9) is obtained.

[0103]

[0104] By utilizing the small steering angle of the wheel, the trigonometric function is simplified and calculated, which can reduce the calculation cost on the basis of ensuring the calculation result is relatively accurate and effective, and is helpful to improve the calculation speed of the target rear wheel steering angle and the longitudinal force of each controllable wheel, and realize the rapid response of the vehicle braking control.

[0105] A3: According to the corresponding relationship between the lateral force of the four wheels, the wheel side slip stiffness coefficient, the vehicle parameter, the state variable and the steering variable, the lateral force of the four wheels in the first longitudinal and lateral dynamics model is replaced by the wheel side slip stiffness coefficient, the vehicle parameter, the state variable and the steering variable, and the second longitudinal and lateral dynamics model is obtained.

[0106] The first lateral dynamics model includes four wheel lateral forces which can be replaced by other parameters. The correspondence between the four wheel lateral forces, the wheel cornering stiffness coefficients, the vehicle parameters, the state variables and the steering variables. The correspondence can be determined based on the vehicle kinematic geometry principles.

[0107] The correspondence between the correspondence between the four wheel lateral forces, the wheel cornering stiffness coefficients, the vehicle parameters, the state variables and the steering variables, includes a first relationship between the front wheel lateral forces, the wheel cornering stiffness coefficients, the vehicle center of mass side slip angle, the front half track, the vehicle yaw rate, the vehicle longitudinal speed and the front wheel steering angle, and a second relationship between the rear wheel lateral forces, the wheel cornering stiffness coefficients, the vehicle center of mass side slip angle, the rear half track, the vehicle yaw rate, the vehicle longitudinal speed and the rear wheel steering angle.

[0108] According to the first relationship, the front wheel lateral forces are replaced by the wheel cornering stiffness coefficients, the vehicle center of mass side slip angle, the front half track, the vehicle yaw rate, the vehicle longitudinal speed and the front wheel steering angle. The front wheel includes the left front wheel and the right front wheel.

[0109] Similarly, according to the second relationship, the rear wheel lateral forces are replaced by the wheel cornering stiffness coefficients, the vehicle center of mass side slip angle, the rear half track, the vehicle yaw rate, the vehicle longitudinal speed and the rear wheel steering angle. The rear wheel includes the left rear wheel and the right rear wheel.

[0110] The first relationship and the second relationship are determined according to the definition of the wheel lateral forces and the relationship between the side slip angle and the vehicle parameters, the state variables and the steering variables.

[0111] In the case that the wheel side slip angle is small, the relationship between the wheel lateral force and the wheel side slip angle can be approximated as a proportional relationship. The proportional relationship between the wheel lateral force and the wheel side slip angle is shown in equation (10) and equation (11).

[0112] F yfl = F yfr = C f α f (10)

[0113] F yrl = F yrr = C r α r (11)

[0114] where C f is the front wheel cornering stiffness coefficient, C r is the rear wheel cornering stiffness coefficient. α f is the front wheel side slip angle, and α r is the rear wheel side slip angle.

[0115] In addition, based on vehicle kinematics, the relationship between the side slip angle of the wheel and the vehicle parameters, state variables and steering variables is determined. The relationship between the side slip angle of the wheel and the vehicle parameters, state variables and steering variables is shown in formula (12) and formula (13).

[0116]

[0117] Substituting formula (12) into formula (10) and formula (13) into formula (11) respectively, formula (14) of the first relationship and formula (15) of the second relationship are obtained.

[0118]

[0119] As an example, substituting formula (14) and formula (15) into the above formula (9) with the simplified first lateral and longitudinal dynamics model formula (9), the second lateral and longitudinal dynamics model, that is, formula (16), is obtained.

[0120]

[0121] In the second lateral and longitudinal dynamics model, the lateral force of the wheel is not included, and the calculation difficulty is reduced and the calculation efficiency is improved without using the lateral force of the wheel which is not easy to obtain.

[0122] A4: The rate of change of the vehicle yaw rate and the rate of change of the vehicle mass center side slip angle are set to 0, and the second lateral and longitudinal dynamics model includes an expression describing the yaw moment and an expression describing the rate of change of the vehicle mass center side slip angle to form a vehicle lateral stability constraint condition.

[0123] Under the condition of maintaining the lateral stability of the vehicle, the rate of change of the vehicle yaw rate and the rate of change of the vehicle mass center side slip angle are 0. The rate of change of the vehicle yaw rate and the rate of change of the vehicle mass center side slip angle are set to 0 to obtain the vehicle lateral stability constraint condition.

[0124] As an example, the above formula (16) is taken as an example, and the first expression and the second expression in the formula (16) are set to 0 to obtain the vehicle lateral stability constraint condition, that is, the above formula (1) and formula (2). and

[0125] A5: The expression describing the longitudinal dynamics of the vehicle included in the second lateral and longitudinal dynamics model is taken as a vehicle longitudinal deceleration constraint condition.

[0126] As an example, the above formula (16) is taken as an example, and the third expression is taken as the vehicle longitudinal deceleration constraint condition, that is, the above formula (4).

[0127] ​In addition, it should be noted that the lateral and longitudinal dynamics model described above is a possible mathematical model for describing vehicle dynamics. Those skilled in the art can construct a lateral and longitudinal dynamics model in other ways, and the embodiments of the present application do not limit this.

[0128] Based on the kinematics principle of the vehicle, a lateral and longitudinal dynamics model of the vehicle is first constructed, and then a lateral stability constraint condition of the vehicle and a longitudinal deceleration constraint condition of the vehicle are generated based on the needs of the vehicle brake control in terms of lateral stability and longitudinal deceleration. In this way, the vehicle can be more accurately and effectively controlled in the lateral and longitudinal directions.

[0129] Based on the vehicle brake control method provided in the above method embodiment, the embodiments of the present application further provide a vehicle brake control device. The vehicle brake control device is applied to a vehicle configured with an electronic mechanical brake system and a rear wheel steering system. The electronic mechanical brake system includes an upper controller. The upper controller is connected with the rear wheel steering system, and the vehicle brake control device is applied to the upper controller.

[0130] The vehicle brake control device will be described below with reference to the accompanying drawings.

[0131] Referring to Figure 4 FIG. 1 is a structural schematic diagram of a vehicle brake control device provided by an embodiment of the present application. As shown in Figure 4 The vehicle brake control device includes:

[0132] The setting unit 401 is configured to set the value of the longitudinal force of the target wheel to 0 in response to obtaining the brake fault signal of the target wheel.

[0133] The obtaining unit 402 is configured to obtain a total constraint condition, wherein the total constraint condition includes a lateral stability constraint condition of the vehicle and a longitudinal deceleration constraint condition of the vehicle.

[0134] The determining unit 403 is configured to determine a target rear wheel steering angle and longitudinal forces of controllable wheels of the vehicle that satisfy the total constraint condition and a speed change condition, wherein the speed change condition is that a difference between a longitudinal speed change rate of the vehicle and a normal longitudinal speed change rate of the vehicle is minimum, and the controllable wheels are three wheels of the vehicle except the target wheel.

[0135] The control unit 404 is configured to control the controllable wheels according to the longitudinal forces of the controllable wheels, and send the target rear wheel steering angle to the rear wheel steering system, so that the rear wheel steering system controls the rear wheel angle of the vehicle according to the target rear wheel steering angle.

[0136] In a possible implementation, the lateral stability constraint condition of the vehicle and the longitudinal deceleration constraint condition of the vehicle are obtained in the following manner:

[0137] obtaining a vehicle parameter, a state variable, a steering variable and lateral forces of four wheels of a vehicle, the vehicle parameter comprising a front half track, a rear half track, a wheel base, a track, a vehicle mass and a yaw moment of inertia of the vehicle, the state variable comprising a vehicle yaw rate, a vehicle center of mass side slip angle and a vehicle longitudinal speed, the steering variable comprising longitudinal forces of the four wheels, a front wheel steering angle and a rear wheel steering angle;

[0138] constructing a first lateral and longitudinal dynamics model of the vehicle by using the vehicle parameter, the state variable, the steering variable and the lateral forces of the four wheels, the first lateral and longitudinal dynamics model comprising an expression describing a yaw moment, an expression describing a rate of change of the vehicle center of mass side slip angle and an expression describing a vehicle longitudinal force;

[0139] replacing the lateral forces of the four wheels in the first lateral and longitudinal dynamics model by using a side slip stiffness coefficient of the wheels, the vehicle parameter, the state variable and the steering variable according to a corresponding relationship between the lateral forces of the four wheels, the side slip stiffness coefficient of the wheels, the vehicle parameter, the state variable and the steering variable, to obtain a second lateral and longitudinal dynamics model;

[0140] setting the rate of change of the vehicle yaw rate and the rate of change of the vehicle center of mass side slip angle to 0, and constructing the vehicle lateral stability constraint condition by using the expression describing the yaw moment and the expression describing the rate of change of the vehicle center of mass side slip angle included in the second lateral and longitudinal dynamics model;

[0141] using the expression describing the vehicle longitudinal force included in the second lateral and longitudinal dynamics model as the vehicle longitudinal deceleration constraint condition.

[0142] In a possible implementation, the expression describing the vehicle longitudinal force comprises a sine value of the front wheel steering angle, a cosine value of the front wheel steering angle, a sine value of the rear wheel steering angle and a cosine value of the rear wheel steering angle, the sine value of the front wheel steering angle is replaced by the front wheel steering angle, the cosine value of the front wheel steering angle is replaced by 1, the sine value of the rear wheel steering angle is replaced by the rear wheel steering angle, and the cosine value of the rear wheel steering angle is replaced by 1.

[0143] In a possible implementation, the total constraint condition further comprises a wheel adhesion limit constraint condition, the wheel adhesion limit constraint condition being that a sum of a square of a longitudinal force of a wheel and a square of a lateral force of the wheel is less than a product of a ground adhesion coefficient and a square of a dynamic vertical load of the wheel.

[0144] In a possible implementation, the control unit 404, configured to send a target rear wheel steering angle to the rear wheel steering system so that the rear wheel steering system controls the rear wheel angle of the vehicle according to the target rear wheel steering angle, comprises:

[0145] The control unit 404 is configured to send a target rear wheel steering angle and a fault signal to the rear wheel steering system, so that the rear wheel steering system controls the rear wheel angle of the vehicle according to the target rear wheel steering angle in response to obtaining the fault signal.

[0146] Based on the vehicle braking control method provided in the above method embodiments, the present application provides an apparatus, comprising: a processor, a memory, a system bus;

[0147] The processor and the memory are connected through the system bus;

[0148] The memory is configured to store one or more programs, the one or more programs comprising instructions that, when executed by the processor, cause the processor to perform the vehicle braking control method described in any of the above embodiments.

[0149] Based on the vehicle braking control method provided in the above method embodiments, the present application provides a computer-readable storage medium, the computer-readable storage medium storing instructions, when the instructions are run on a terminal device, causing the terminal device to perform the vehicle braking control method described in any of the above embodiments.

[0150] It should be noted that the embodiments in the present specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts of each embodiment can be mutually referred to. For the system or device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts are described in the method part.

[0151] It should be understood that in the present application, "at least one" means one or more, and "multiple" means two or more. "And / or" is used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, "A and / or B" can mean: only A, only B, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b or c, can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0152] It is also to be noted that, as used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless otherwise indicated. Furthermore, to the extent that the terms "including," "includes," "having," "has," "with," or "contains" are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term "comprising" as an open transition term without precluding any additional or other elements.

[0153] The embodiments disclosed herein can each be implemented as a method, apparatus, or article of manufacture using programming instructions. The embodiments disclosed herein can be implemented using software, firmware, hardware, or a combination thereof. The embodiments disclosed herein can be implemented in a computer system that includes one or more processors that are configured with instructions that, once implemented in hardware, cause the computer system to carry out the steps described herein. The instructions can be stored on a computer readable medium, such as a floppy disk, a hard disk, a CD-ROM, a DVD, a memory, a solid state drive, or a magnetic tape. The instructions can also be downloaded from the Internet. The instructions can be implemented in a plurality of programming languages.

[0154] The above description of disclosed embodiments is intended to be illustrative and not restrictive. Many embodiments will be apparent to those of skill in the art upon reading and understanding the above description, and it is therefore contemplated to be within the scope of the application to claim any such embodiments. Changes to the described embodiments can be made without departing from the spirit and scope of the application. Accordingly, the application is not to be limited by the above description, but is only limited by the scope of the appended claims.

Claims

1. A vehicle brake control method characterized by, The method is applied to a vehicle configured with an electronic mechanical brake system and a rear wheel steering system, the electronic mechanical brake system comprising an upper controller connected with the rear wheel steering system, the method comprising: in response to obtaining a brake fault signal of a target wheel, the upper controller setting a value of a longitudinal force of the target wheel to 0; the upper controller obtaining total constraints, the total constraints comprising a vehicle lateral stability constraint and a vehicle longitudinal deceleration constraint; the upper controller determining a target rear wheel steering angle and longitudinal forces of controllable wheels of the vehicle, the controllable wheels being three wheels of the vehicle except the target wheel, the target rear wheel steering angle satisfying the total constraints and a speed change condition, the speed change condition being that a difference between a rate of change of a vehicle longitudinal speed and a rate of change of a normal vehicle longitudinal speed is minimum; the upper controller controlling the controllable wheels according to the longitudinal forces of the controllable wheels and sending the target rear wheel steering angle to the rear wheel steering system so that the rear wheel steering system controls angles of rear wheels of the vehicle according to the target rear wheel steering angle.

2. The method of claim 1, wherein, the total constraints further comprising a wheel adhesion limit constraint, the wheel adhesion limit constraint being that a sum of a square of a longitudinal force of a wheel and a square of a lateral force of the wheel is less than a product of a ground adhesion coefficient and a square of a dynamic vertical load of the wheel.

3. The method of claim 1, wherein, the sending the target rear wheel steering angle to the rear wheel steering system so that the rear wheel steering system controls the angles of the rear wheels of the vehicle according to the target rear wheel steering angle comprises: sending the target rear wheel steering angle and a fault signal to the rear wheel steering system so that the rear wheel steering system controls the angles of the rear wheels of the vehicle according to the target rear wheel steering angle in response to obtaining the fault signal.

4. The method according to any one of claims 1 to 3, characterized in that, the vehicle lateral stability constraint and the vehicle longitudinal deceleration constraint are obtained in the following way: obtaining vehicle parameters, state variables, steering variables and lateral forces of four wheels of the vehicle, the vehicle parameters comprising a front half track, a rear half track, a track, a wheel track, a vehicle mass and a yaw moment of inertia of the vehicle, the state variables comprising a vehicle yaw rate, a vehicle center of mass side slip angle and a vehicle longitudinal speed, the steering variables comprising longitudinal forces of the four wheels, a front wheel steering angle and a rear wheel steering angle; constructing a first lateral and longitudinal dynamics model of the vehicle by using the vehicle parameters, the state variables, the steering variables and the lateral forces of the four wheels, the first lateral and longitudinal dynamics model comprising an expression describing a yaw moment, an expression describing a rate of change of the vehicle center of mass side slip angle and an expression describing a vehicle longitudinal dynamics; replacing the lateral forces of the four wheels in the first lateral and longitudinal dynamics model by using wheel side stiffness coefficients, the vehicle parameters, the state variables and the steering variables according to a corresponding relationship between the lateral forces of the four wheels and the wheel side stiffness coefficients, the vehicle parameters, the state variables and the steering variables to obtain a second lateral and longitudinal dynamics model; The rate of change of the vehicle yaw rate and the rate of change of the vehicle mass center side slip angle are set to 0, and a lateral stability constraint condition of the vehicle is constituted by an expression included in the second lateral and longitudinal dynamics model and describing a lateral force and an expression describing the rate of change of the vehicle mass center side slip angle. An expression included in the second lateral and longitudinal dynamics model and describing a longitudinal force of the vehicle is taken as a longitudinal deceleration constraint condition of the vehicle.

5. The method of claim 4, wherein, The expression describing the longitudinal force of the vehicle includes a sine value of a front wheel angle, a cosine value of the front wheel angle, a sine value of a rear wheel angle, and a cosine value of the rear wheel angle, the sine value of the front wheel angle is replaced by a front wheel angle, the cosine value of the front wheel angle is replaced by 1, the sine value of the rear wheel angle is replaced by a rear wheel angle, and the cosine value of the rear wheel angle is replaced by 1.

6. A vehicle brake control device characterized by comprising: The device is applied to a vehicle configured with an electronic mechanical braking system and a rear wheel steering system, the electronic mechanical braking system includes an upper controller connected with the rear wheel steering system, and the device is applied to the upper controller. A setting unit is configured to set a longitudinal force of a target wheel to 0 in response to obtaining a braking fault signal of the target wheel. An obtaining unit is configured to obtain total constraint conditions including a lateral stability constraint condition of the vehicle and a longitudinal deceleration constraint condition of the vehicle. A determining unit is configured to determine a target rear wheel angle and longitudinal forces of controllable wheels of the vehicle, the controllable wheels being three wheels of the vehicle except the target wheel, the target rear wheel angle and the longitudinal forces of the controllable wheels satisfying the total constraint conditions and a speed change condition, the speed change condition being that a difference between a rate of change of a longitudinal speed of the vehicle and a rate of change of a normal longitudinal speed of the vehicle is minimum. A control unit is configured to control the controllable wheels according to the longitudinal forces of the controllable wheels and to send the target rear wheel angle to the rear wheel steering system so that the rear wheel steering system controls a rear wheel angle of the vehicle according to the target rear wheel angle.

7. The apparatus of claim 6, wherein, The total constraint conditions further include a wheel adhesion limit constraint condition, the wheel adhesion limit constraint condition being that a sum of a square of a longitudinal force of a wheel and a square of a lateral force of the wheel is less than a product of a ground adhesion coefficient and a square of a dynamic vertical load of the wheel.

8. The apparatus of claim 6, wherein, The control unit is configured to send the target rear wheel angle to the rear wheel steering system so that the rear wheel steering system controls the rear wheel angle of the vehicle according to the target rear wheel angle, including: The control unit is configured to send the target rear wheel angle and a fault signal to the rear wheel steering system so that the rear wheel steering system controls the rear wheel angle of the vehicle according to the target rear wheel angle in response to obtaining the fault signal.

9. An apparatus, comprising: including: a processor, a memory, and a system bus; the processor and the memory are connected through the system bus; the memory is configured to store one or more programs, the one or more programs including instructions, the instructions, when executed by the processor, causing the processor to execute the method of any one of claims 1-5.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores instructions, and when the instructions run on the terminal device, the terminal device executes the method in any one of claims 1-5.

Images