Brake control method, vehicle, and storage medium

Abstract

This application provides a braking control method, a vehicle, and a storage medium. The method, applied in the field of vehicle technology, includes: acquiring the slip ratio of each wheel of the vehicle during braking; calculating the target braking force for the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force; and controlling the braking mechanism of each wheel to output the corresponding target braking force. This method can calculate the target braking force based on the slip ratio of different wheels and the driver's requested braking force, and control the braking mechanism of each wheel to output the corresponding target braking force. This enables independent control and adjustment of the braking force of each wheel, thereby improving the accuracy and stability of control and resulting in better overall braking performance.

Description

Technical Field

[0001] This application relates to the field of vehicles, and more specifically, to a braking control method, vehicle, and storage medium in the field of vehicle braking. Background Technology

[0002] A vehicle braking system is a series of specialized devices that apply a certain force to the wheels of a vehicle, thereby forcibly braking it to a certain extent. The functions of the braking system are: to force a moving vehicle to decelerate or even stop it as required by the driver; to keep a stopped vehicle stable under various road conditions (including on slopes); and to keep the speed of a vehicle traveling downhill stable.

[0003] Most braking systems in related technologies are hydraulic brakes. They are mainly operated by the driver pressing the brake pedal, which pressurizes the hydraulic lines of the braking system. This causes the front and rear brake calipers to push out pistons and clamp the brake discs under the action of hydraulic pressure. Since the hydraulic lines of the front and rear brake calipers are the same, the clamping force of the front and rear brakes and the hydraulic pressure in the lines have a basically linear relationship. This makes the braking force between different tires consistent during braking. However, due to the limitations of the hydraulic system and the structural parameters of the vehicle, there are problems such as reduced control precision and slow response speed during braking. Summary of the Invention

[0004] This application provides a braking control method, a vehicle, and a storage medium. The method can determine the target braking force based on the slip ratio of different wheels and the driver's requested braking force, and control the braking mechanism of each wheel to output the corresponding target braking force. This enables independent control and adjustment of the braking force of each wheel, thereby improving the accuracy and stability of the control and resulting in better overall braking performance.

[0005] In a first aspect, a braking control method is provided, the method comprising: acquiring the slip ratio of each wheel of a vehicle during braking; calculating a target braking force for the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force; and controlling the braking mechanism of each wheel to output the corresponding target braking force.

[0006] Through the above technical solution, the embodiments of this application can calculate the target braking force of the corresponding wheel according to the slip ratio of different wheels and the driver's requested braking force, so that the braking mechanism can output the corresponding target braking force. This can realize independent control and adjustment of the braking force of each wheel, thereby improving the accuracy and stability of control and the overall braking effect.

[0007] In conjunction with the first aspect, in some possible implementations, controlling the braking mechanism of each wheel to output a corresponding target braking force includes: acquiring the current braking force of each wheel; and controlling the caliper motor in the corresponding braking mechanism to output a target current based on the current braking force of each wheel and the corresponding target braking force.

[0008] Through the above technical solution, the embodiments of this application can achieve vehicle braking by adjusting the output target current of the caliper motor in the braking mechanism according to the current braking force of each wheel and the corresponding target braking force.

[0009] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the step of calculating the target braking force of the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force includes: inputting the slip ratio of each wheel and the driver's requested braking force into a closed-loop processing model, and outputting the target braking force of the corresponding wheel.

[0010] Through the above technical solution, the embodiments of this application can calculate the target braking force of the corresponding wheel based on the closed-loop processing model, so that the subsequent braking mechanism can output the corresponding target braking force.

[0011] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the step of calculating the target braking force of the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force further includes: identifying whether the caliper motor of each wheel has failed; when at least one caliper motor failure is identified, the slip ratio of the wheel corresponding to each non-failed caliper motor and the driver's requested braking force are input into a closed-loop processing model, and the closed-loop processing model outputs the target braking force of the wheel corresponding to each non-failed caliper motor.

[0012] Through the above technical solution, the embodiments of this application can, when the caliper motor fails, input the slip ratio of the wheel corresponding to the non-failed caliper motor and the driver's requested braking force into the closed-loop processing model according to the actual situation, thereby calculating the target braking force of the wheel corresponding to each non-failed caliper motor, so that the subsequent braking mechanism can output the corresponding target braking force.

[0013] In combination with the first aspect and the above implementation methods, in some possible implementation methods, the closed-loop processing model uses a closed-loop processing algorithm for data processing. The closed-loop processing algorithm includes: if the wheel slip ratio is less than or equal to a preset value, then the driver's requested braking force is used as the target braking force for the corresponding wheel; if the wheel slip ratio is greater than the preset value, then when the actual yaw rate of the vehicle is detected and the slip ratio is not a longitudinal slip ratio, the target braking force for the corresponding wheel is calculated based on the difference in angular velocity between the actual yaw rate and the target yaw rate and the driver's requested braking force; otherwise, the target braking force for the corresponding wheel is calculated based on the longitudinal slip ratio and the driver's requested braking force.

[0014] Through the above technical solution, the embodiments of this application can process data based on the closed-loop processing algorithm in the closed-loop processing model, thereby calculating the target braking force of each wheel according to the actual situation, so as to facilitate the subsequent control of the braking force of each wheel.

[0015] In combination with the first aspect and the above implementation methods, in some possible implementation methods, before calculating the target braking force based on the difference between the actual yaw rate and the target yaw rate, the method further includes: obtaining the steering wheel angle and the current vehicle speed of the vehicle; and calculating the target yaw rate based on the steering wheel angle and the current vehicle speed.

[0016] Through the above technical solution, the embodiments of this application can calculate the target yaw rate based on the steering wheel angle, so as to calculate the target braking force based on the difference between the actual yaw rate and the target yaw rate.

[0017] In combination with the first aspect and the above implementation methods, in some possible implementation methods, when any caliper motor failure is detected, the method further includes: obtaining the number and location of caliper motor failures; matching the target speed limit of the vehicle based on the number and / or location of caliper motor failures; and controlling the vehicle speed to be within the target speed limit.

[0018] Through the above technical solution, the embodiments of this application can limit the vehicle speed according to the actual situation when any caliper motor fails, so that the vehicle speed reaches a safe range, thereby improving vehicle safety.

[0019] In combination with the first aspect and the above implementation methods, in some possible implementation methods, obtaining the slip ratio of each wheel of the vehicle during braking further includes: obtaining the actual wheel speed of each wheel; and calculating the slip ratio of the corresponding wheel based on the actual wheel speed of each wheel.

[0020] The above technical solution enables the calculation of the slip ratio of each wheel based on the actual wheel speed of each wheel, so as to calculate the target braking force of the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force.

[0021] Secondly, a braking control device is provided, comprising: an acquisition module for acquiring the slip ratio of each wheel of the vehicle during braking; a calculation module for calculating the target braking force of the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force; and a control module for controlling the braking mechanism of each wheel to output the corresponding target braking force.

[0022] Thirdly, a vehicle is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the braking control method as described in the above embodiments.

[0023] Fourthly, a computer-readable storage medium is provided having a computer program stored thereon, characterized in that the program is executed by a processor to implement the braking control method as described in the above embodiments. Attached Figure Description

[0024] Figure 1 This is a flowchart of the braking control method provided in the embodiments of this application;

[0025] Figure 2 This is a block diagram of the braking control device provided in the embodiments of this application;

[0026] Figure 3 This is a schematic diagram of the vehicle structure provided in the embodiments of this application. Detailed Implementation

[0027] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0028] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0029] The following will combine Figure 1 The braking control method is described in detail.

[0030] Figure 1 This is a flowchart of a braking control method provided in an embodiment of this application.

[0031] For example, such as Figure 1 As shown, the vehicle independently controls each wheel based on an electromechanical braking system, wherein the method includes:

[0032] In step S101, the slip ratio of each wheel of the vehicle during braking is obtained.

[0033] It can be understood that the braking in the embodiments of the present application may refer to the braking triggered by the driver stepping on the brake pedal. In the embodiments of the present application, the slip ratio of each wheel can be obtained when braking is triggered.

[0034] It should be noted that the chassis structure of the vehicle in the embodiments of the present application mainly includes four EMB (Electromechanical Brake System) actuators, which can independently control the four wheels; the EMB is an actuator driven by a caliper motor and is installed on the caliper of the braking mechanism, and it is a device that directly brakes the vehicle without media such as brake fluid; the EMB replaces the traditional hydraulic brake and is used for the main brake, and its application range has been expanded.

[0035] Since relative motion occurs between the wheel and the ground when the wheel generates traction or braking force, and the slip ratio is the proportion of the sliding component in the wheel movement, the formula is defined as follows:

[0036] s=(u - u w ) / u×100%=(u - rω) / u×100%

[0037] Where, u is the vehicle speed; u w is the wheel speed; ω is the wheel rolling angular velocity; r is the wheel radius.

[0038] When the wheel is in pure rolling, u w =u, s = 零; when the wheel is locked and in pure sliding, u w =0, s = 100%; when the wheel is rolling and sliding, u>u w , 0<s<100%; the larger the wheel slip ratio, the greater the proportion of the sliding component in the wheel movement. [[ID=2,7]]

[0039] In the embodiments of the present application, the slip ratio of each wheel of the vehicle can be obtained in real time through a sensor to determine the adhesion coefficient between each wheel and the current driving road surface; or the slip ratio of the wheel can be determined according to the current wheel speed and the current reference vehicle speed of each wheel; or by constructing a wheel dynamics equation including the wheel driving torque and speed to express the adhesion characteristics between the wheel and the road surface, and detecting the wheel slip state by calculating the derivative change, so as to obtain the slip ratio corresponding to the maximum adhesion coefficient, without specific limitation.

[0040] As a possible implementation method, obtaining the slip ratio of each wheel of the vehicle during braking includes: obtaining the actual wheel speed of each wheel; calculating the slip ratio of the corresponding wheel according to the actual wheel speed of each wheel.

[0041] It is understandable that tire parameters such as tire pressure, tire mass, and tire wear directly affect the wheel speed of each wheel. Therefore, the embodiments of this application can calculate the slip ratio based on the wheel speed and then use the slip ratio to achieve accurate control of braking force, thereby effectively overcoming the influence of relevant parameters on braking force.

[0042] In step S102, the target braking force for the corresponding wheel is calculated based on the slip ratio of each wheel and the driver's requested braking force.

[0043] It is understood that since the slip ratio affects the braking effect and the slip ratio of each wheel may be different, the embodiments of this application can combine the slip ratio of each wheel and the driver's requested braking force to calculate the target braking force of the corresponding wheel in order to accurately determine the target braking force of each wheel.

[0044] As one possible approach, the target braking force for the corresponding wheel is calculated based on the slip ratio of each wheel and the driver's requested braking force, including: inputting the slip ratio of each wheel and the driver's requested braking force into a closed-loop processing model, and the closed-loop processing model outputting the target braking force for the corresponding wheel.

[0045] It is understood that the embodiments of this application can input the slip ratio of each wheel and the driver's requested braking force into the closed-loop processing model, thereby outputting the target braking force of the corresponding wheel, so as to facilitate the subsequent control of the braking mechanism of each wheel to output the corresponding target braking force.

[0046] As another possible implementation, the target braking force for the corresponding wheel is calculated based on the slip ratio of each wheel and the driver's requested braking force. This also includes: identifying whether the caliper motor of each wheel has failed; when at least one caliper motor failure is identified, the slip ratio of the wheel corresponding to each non-failed caliper motor and the driver's requested braking force are input into the closed-loop processing model, and the closed-loop processing model outputs the target braking force for the wheel corresponding to each non-failed caliper motor.

[0047] It is understood that, in the embodiments of this application, when the caliper motor fails, the slip ratio of the wheel corresponding to the non-failed caliper motor and the driver's requested braking force are input into the closed-loop processing model to calculate the target braking force of the wheel corresponding to the non-failed caliper motor. This allows the braking mechanism of the wheel corresponding to the non-failed caliper motor to output the target braking force, thereby using the non-failed caliper motor for braking and improving the robustness of braking.

[0048] It should be noted that when the caliper motor of one of the vehicle's wheels fails, the target braking force for the wheel corresponding to the failed caliper motor can be calculated based on the slip ratio of the non-failed wheel and the driver's requested braking force. In addition, when the braking force of the vehicle's caliper motor is insufficient, current compensation can be performed on the non-failed wheel based on the target yaw rate and the actual yaw rate, so that the caliper motor can generate the target braking force.

[0049] In this embodiment of the application, the closed-loop processing model uses a closed-loop processing algorithm for data processing. The closed-loop processing algorithm includes: if the wheel slip ratio is less than or equal to a preset value, then the driver's requested braking force is used as the target braking force of the corresponding wheel; if the wheel slip ratio is greater than or equal to the preset value, then when the actual yaw rate of the vehicle is detected and the slip ratio is not the longitudinal slip ratio, the target braking force of the corresponding wheel is calculated based on the difference between the actual yaw rate and the target yaw rate and the driver's requested braking force; otherwise, the target braking force of the corresponding wheel is calculated based on the longitudinal slip ratio and the driver's requested braking force.

[0050] The preset value can be specifically calibrated according to the actual situation, and the target yaw rate can be calculated based on the vehicle's steering wheel angle and current speed. Yaw rate refers to the vehicle's deflection around its vertical axis. The magnitude of this deflection represents the vehicle's stability. If the yaw rate reaches a threshold, it indicates that the wheels are about to slip or fishtail, which are dangerous conditions.

[0051] It is understood that the embodiments of this application can use a closed-loop processing algorithm to process data and determine the target braking force based on the magnitude of the driver's requested braking force, whether the vehicle generates yaw rate and longitudinal slip rate during braking.

[0052] Specifically, when the wheel slip ratio is small, the vehicle usually won't fishtail, so it can fully respond to the driver's requested braking force. However, when the wheel slip ratio is large, it's necessary to control the vehicle to execute the target braking force based on the actual situation. If the vehicle fully responds to the driver's requested braking force, it can easily lead to vehicle instability. Therefore, this application embodiment also needs to combine the yaw rate and / or longitudinal slip ratio to correct the target braking force, for example:

[0053] (1) When the actual yaw rate is greater than the target yaw rate, obtain the angular velocity difference between the actual yaw rate and the target yaw rate; determine the braking force difference between the left and right wheels based on the angular velocity difference, and calculate the target braking force of the corresponding wheel based on the braking force difference and the driver's requested braking force.

[0054] The braking force difference is the braking force required to keep the vehicle stable. The actual yaw rate has positive and negative values, so the vehicle attitude can be determined based on the sign of the actual yaw rate. For example, a positive actual yaw rate can be pre-calibrated to indicate a tilt to the left, and a negative actual yaw rate can be pre-calibrated to indicate a tilt to the right, etc., which can be specifically calibrated.

[0055] Therefore, in the embodiments of this application, the correspondence between the angular velocity difference and the correction value of the driver's requested braking force can be pre-calibrated. For example, when the angular velocity difference is A, the corresponding correction value of the driver's requested braking force is a N·m. The specific braking force of the vehicle can be determined according to the sign of the actual yaw rate. After correcting the driver's requested braking force based on the correction value, the target braking force can be obtained.

[0056] For example, when a tilt to the left requires correction, the difference in braking force between the left and right wheels can be determined based on the difference in angular velocity. That is, by assigning different target braking forces to the two wheels, the vehicle body can be kept stable. Assuming the driver requests a braking force of 100 N·m and the difference in braking force is 10 N·m, then the target braking force for the left wheel can be 90 N·m, and the target braking force for the right wheel can be 100 N·m, etc. Of course, the braking force for the left wheel can also be appropriately reduced, for example, the target braking force for the left wheel can be 88 N·m, and the target braking force for the right wheel can be 98 N·m, etc.

[0057] (2) The target braking force is corrected based on the longitudinal slip ratio. For example, a larger longitudinal slip ratio indicates a lower lateral adhesion coefficient of the wheel, so the corresponding target braking force needs to be smaller to avoid sideslip; a smaller longitudinal slip ratio indicates a higher lateral adhesion coefficient of the wheel, so the corresponding target braking force can be larger. Therefore, in this embodiment, the correction value of the driver's requested braking force can be determined based on the longitudinal slip ratio, and the target braking force is calculated based on the correction value and the driver's requested braking force.

[0058] Therefore, the embodiments of this application can pre-calibrate the correspondence between the slip ratio and the correction value of the driver's requested braking force. For example, when the slip ratio is B, the corresponding correction value of the driver's requested braking force is bN·m, and the target braking force can be obtained after correcting the driver's requested braking force based on the correction value.

[0059] For example, when the detected current slip ratio is longitudinal slip ratio of 30%, the wheel lateral adhesion coefficient is low, requiring an appropriate reduction in the target braking force. Based on the correspondence table between longitudinal slip ratio and target braking force correction values, the correction value for the target braking force can be determined. For instance, by consulting the table, the correction value for a longitudinal slip ratio of 30% can be determined to be 20. When the detected driver's requested braking force is 100N, due to the large longitudinal slip ratio, the response to the driver's requested braking force needs to be appropriately reduced, resulting in a target braking force of 80N.

[0060] It should be noted that the closed-loop processing algorithm is applicable to situations where there is caliper motor failure or all caliper motors are functioning normally. The following will illustrate this by using the closed-loop processing model to calculate the target braking force of the wheel corresponding to each non-failed caliper motor, as follows:

[0061] If the system detects situations such as the steering wheel consistently turning to one side or the brake disc vibrating during vehicle braking, it can be determined that the caliper motor has failed. When any caliper motor failure is detected, the longitudinal slip ratio of the wheel corresponding to the non-failed caliper motor, the driver's requested braking force, the actual yaw rate, the steering wheel angle, and the current vehicle speed are input into the closed-loop processing model. The target braking force for the corresponding wheel is then output, including the following situations:

[0062] (1) When the steering wheel angle is constant, the driver’s requested braking force is relatively small. The braking force is insufficient to cause the vehicle to yaw or produce longitudinal slip. At this time, the target braking force of the non-failed caliper motor corresponding to the wheel fully responds to the driver’s braking force request.

[0063] (2) When the steering wheel angle is constant, if the driver requests a large braking force, the braking force is sufficient to generate a certain actual yaw rate but will not generate a longitudinal slip rate. The closed-loop processing model calculates the target yaw rate based on the input signals such as the steering wheel angle and the current vehicle speed. When the actual yaw rate is greater than the target yaw rate, the difference between the actual yaw rate and the target yaw rate is used as the control quantity. Based on the angular velocity difference between the actual yaw rate and the target yaw rate and the driver's requested braking force, the target braking force of the wheel corresponding to the caliper motor of the non-failed wheel is calculated. This algorithm has been described in the above method and will not be repeated here to avoid redundancy.

[0064] Specifically, to avoid inaccuracies in calculating the target yaw rate when the vehicle is unstable, this embodiment of the application obtains the deviation-compensated steering wheel angle, current vehicle speed, characteristic vehicle speed, wheelbase, and the steering angle between the steering wheel angle and the wheel angle during the calculation. The target yaw rate is calculated based on these factors, thereby improving the accuracy of the target yaw rate calculation. Furthermore, the calculation method of this embodiment can also be applied to the calculation of the target yaw rate in a stable state, offering better applicability. The formula for the target yaw rate is as follows:

[0065]

[0066] Where w is the target yaw rate, a is the steering wheel angle value after deviation compensation, V1 is the current vehicle speed, V2 is the characteristic vehicle speed, l is the wheelbase, and α is the steering ratio between the steering wheel angle and the wheel angle, i.e., the steering characteristic. The characteristic vehicle speed is a parameter used to describe the vehicle's understeer characteristics. When the vehicle speed reaches a preset value, the vehicle's steady-state angular velocity gain (the ratio of yaw rate to front wheel angle, also known as steering sensitivity) reaches its maximum value.

[0067] 3) When the steering wheel angle is constant, if the driver requests a large braking force, the driver's requested braking force can generate a longitudinal slip ratio. Regardless of whether the vehicle generates a yaw rate, the closed-loop processing model calculates the target braking force of the wheel corresponding to the non-failed caliper motor based on the longitudinal slip ratio of each wheel and the driver's requested braking force.

[0068] In this embodiment of the application, when any caliper motor failure is detected, the method further includes: obtaining the number and location of caliper motor failures; matching the target speed limit of the vehicle based on the number and / or location of caliper motor failures; and controlling the vehicle speed to be within the target speed limit.

[0069] It is understood that the embodiments of this application can limit the vehicle speed according to the actual situation when any caliper motor fails, so that the vehicle speed reaches a safe range, thereby improving vehicle safety.

[0070] Specifically, the system identifies the number of caliper motor failures in the vehicle. When any one caliper motor fails, the vehicle speed is limited to any speed within a first speed range, such as 60 kph. When any two caliper motors fail, the speed is limited to any speed within a second speed range, such as 10 kph, where the maximum value within the second speed range is less than the minimum value within the first speed range. When any three caliper motors fail, the vehicle will brake using only the remaining caliper motor or use regenerative braking to bring it to a stop. Power will be promptly cut off after the vehicle comes to a stop to improve vehicle safety.

[0071] It should be noted that when any caliper motor failure is detected, this embodiment of the application may also display a corresponding speed limit reminder on the vehicle's display screen and / or broadcast a speed limit reminder, such as "Braking malfunction, speed needs to be reduced to 60kph" or "Braking malfunction, please pull over" or other prompts, without making specific limitations here.

[0072] In step S103, the braking mechanism of each wheel is controlled to output the corresponding target braking force.

[0073] The braking mechanism includes a caliper motor and a brake caliper connected to the caliper motor.

[0074] It is understood that the embodiments of this application can achieve independent control and adjustment of the braking force of each wheel by controlling the output of the target braking force of the braking mechanism of each wheel, thereby improving the accuracy and stability of the control.

[0075] In this embodiment of the application, controlling the braking mechanism of each wheel to output the corresponding target braking force includes: acquiring the current braking force of each wheel; and controlling the caliper motor in the corresponding braking mechanism to output the target current based on the current braking force and the corresponding target braking force of each wheel.

[0076] It is understood that, in the embodiments of this application, the output target current of the caliper motor in the corresponding braking mechanism can be controlled according to the current braking force and the corresponding target braking force of each wheel. Specifically, when the target braking force is greater than the current braking force, the target current is increased; when the target braking force is less than the current braking force, the target current is decreased.

[0077] In summary, the embodiments of this application can determine the target braking force based on the slip ratio of different wheels and the driver's requested braking force, and control the braking mechanism of each wheel to output the corresponding target braking force. This enables independent control and adjustment of the braking force of each wheel, thereby improving the accuracy and stability of control and resulting in better overall braking performance.

[0078] The following will illustrate this with specific scenarios. This embodiment of the application takes the braking scenario in rainy weather as an example, as detailed below:

[0079] 1. When a vehicle is in motion, it needs to brake when it encounters a pedestrian crossing, a traffic light, or when the vehicle in front brakes. At this time, the vehicle sensors obtain the slip ratio of each wheel when the vehicle is braking.

[0080] 2. Check if the caliper motor of each wheel is malfunctioning, and / or determine if the slip ratio of all wheels is less than or equal to a preset value (which can be specifically calibrated). Operate according to the actual situation, as follows:

[0081] (1) If the caliper motors of each wheel are not faulty and the slip ratio of all wheels is less than or equal to the preset value, the driver’s requested braking force is taken as the target braking force, and the current braking force of each wheel is obtained. When the target braking force is greater than the current braking force, the target current is increased; when the target braking force is less than the current braking force, the target current is decreased, and the braking mechanism of each wheel is controlled to output the corresponding target braking force.

[0082] (2) If the caliper motors of each wheel are not faulty and at least one wheel has a slip ratio greater than the preset value, then when the actual yaw rate of the vehicle is detected and the slip ratio is not the longitudinal slip ratio, the target braking force is calculated based on the difference between the actual yaw rate and the target yaw rate and the driver's requested braking force. Otherwise, the target braking force is calculated based on the longitudinal slip ratio and the driver's requested braking force.

[0083] Specifically: When the slip ratio of at least one wheel is large, it is necessary to control the vehicle to execute the target braking force according to the actual situation. If the braking force is fully responded to by the driver, it is easy to cause vehicle instability. Therefore, the embodiments of this application also need to combine the yaw rate and / or longitudinal slip ratio to correct the target braking force, for example:

[0084] 1) When the actual yaw rate is greater than the target yaw rate, obtain the angular velocity difference between the actual yaw rate and the target yaw rate; determine the braking force difference between the left and right wheels based on the angular velocity difference, and calculate the target braking force for the corresponding wheel based on the braking force difference and the driver's requested braking force.

[0085] The braking force difference is the braking force required to keep the vehicle stable. The actual yaw rate has positive and negative values, so the vehicle attitude can be determined based on the sign of the actual yaw rate. For example, a positive actual yaw rate can be pre-calibrated to indicate a tilt to the left, and a negative actual yaw rate can be pre-calibrated to indicate a tilt to the right, etc., which can be specifically calibrated.

[0086] For example, when a tilt to the left requires correction, the braking force difference between the left and right wheels can be determined based on the difference in angular velocity. That is, by assigning different target braking forces to the two wheels, the vehicle body can be kept stable. Assuming the driver requests a braking force of 100 N·m and the braking difference is 10 N·m, then the target braking force for the left wheel can be 90 N·m, and the target braking force for the right wheel can be 100 N·m, etc. Of course, the braking force for the left wheel can also be appropriately reduced, for example, the target braking force for the left wheel can be 88 N·m, and the target braking force for the right wheel can be 98 N·m, etc.

[0087] 2) The target braking force is adjusted based on the longitudinal slip ratio. For example, a larger longitudinal slip ratio indicates a lower wheel lateral force adhesion coefficient, thus requiring a smaller target braking force to avoid sideslip; a smaller longitudinal slip ratio indicates a higher wheel lateral force adhesion coefficient, allowing for a larger target braking force. Therefore, in this embodiment, the correction value for the driver's requested braking force can be determined based on the longitudinal slip ratio, and the target braking force is calculated based on the correction value and the driver's requested braking force.

[0088] For example, when the detected current slip ratio is longitudinal slip ratio and the longitudinal slip ratio is 30%, the wheel lateral force adhesion coefficient is low, requiring an appropriate reduction in the target braking force. Based on the correspondence table between longitudinal slip ratio and the driver's requested braking force correction value, the correction value for the driver's requested braking force can be determined. For instance, by consulting the table, it can be determined that the correction value corresponding to a longitudinal slip ratio of 30% is 20. When the detected driver's requested braking force is 100N, the corresponding target braking force is 80N.

[0089] (3) If it is detected that the steering wheel always turns to one side or the brake disc vibrates when the vehicle is braking, it can be determined that the caliper motor has failed; when any caliper motor fails, the target braking force is calculated according to the actual situation, as follows:

[0090] 1) When the steering wheel angle is constant, the driver's requested braking force is relatively small. The driver's requested braking force is insufficient to cause the vehicle to yaw or produce longitudinal slip. At this time, the target braking force of the non-failed caliper motor at the corresponding wheel fully responds to the driver's braking force request.

[0091] 2) When the steering wheel angular velocity is constant, if the driver requests a large braking force, the driver's requested braking force is sufficient to generate a certain actual yaw rate but will not generate a longitudinal slip rate. The closed-loop processing model calculates the target yaw rate based on input signals such as steering wheel angle and current vehicle speed. When the actual yaw rate is greater than the target yaw rate, the difference between the actual yaw rate and the target yaw rate is used as the control variable. The target braking force of the wheel corresponding to the caliper motor of the non-failed wheel is calculated based on the angular velocity difference between the actual yaw rate and the target yaw rate and the driver's requested braking force.

[0092] 3) When the steering wheel angle is constant, if the driver requests a large braking force, the driver's requested braking force can generate a longitudinal slip ratio. Regardless of whether the vehicle generates a yaw rate, the closed-loop processing model calculates the target braking force of the wheel corresponding to the non-failed caliper motor based on the longitudinal slip ratio of each wheel and the driver's requested braking force.

[0093] Based on the target braking force and the current braking force of each wheel, if the target braking force is greater than the current braking force, the target current is increased; if the target braking force is less than the current braking force, the target current is decreased, and the braking mechanism of each wheel is controlled to output the corresponding target braking force.

[0094] 3. During normal driving, if any caliper motor failure is detected, the number of failed caliper motors in the vehicle will be identified. If any one caliper motor fails, the vehicle speed will be limited to any speed within the first speed range, such as 60 kph. If any two caliper motors fail, the vehicle speed will be limited to any speed within the second speed range, such as 10 kph, where the maximum value within the second speed range is less than the minimum value within the first speed range. If any three caliper motors fail, the vehicle will brake using only the remaining caliper motor or use regenerative braking to bring it to a stop. Power will be cut off promptly after the vehicle stops to improve vehicle safety.

[0095] Figure 2 This is a schematic diagram of the braking control device provided in the embodiments of this application.

[0096] For example, such as Figure 2 As shown, the vehicle independently controls each wheel based on an electromechanical braking system. The device 10 may include an acquisition module 110, a calculation module 120, and a control module 130.

[0097] The acquisition module 110 is used to acquire the slip ratio of each wheel of the vehicle during braking; the calculation module 120 is used to calculate the target braking force of the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force; and the control module 130 is used to control the braking mechanism of each wheel to output the corresponding target braking force.

[0098] In this embodiment of the application, the acquisition module 110 is further configured to: acquire the actual wheel speed of each wheel; and calculate the slip ratio of the corresponding wheel based on the actual wheel speed of each wheel.

[0099] In this embodiment of the application, the calculation module 120 is further configured to: input the slip ratio of each wheel and the driver's requested braking force into the closed-loop processing model, and the closed-loop processing model outputs the target braking force of the corresponding wheel.

[0100] In this embodiment of the application, the calculation module 120 is further used to: identify whether the caliper motor of each wheel has failed; when at least one caliper motor has failed, input the slip ratio of the wheel corresponding to each non-failed caliper motor and the driver's requested braking force into the closed-loop processing model, and the closed-loop processing model outputs the target braking force of the wheel corresponding to each non-failed caliper motor.

[0101] In this embodiment of the application, the closed-loop processing model uses a closed-loop processing algorithm for data processing. The closed-loop processing algorithm includes: if the slip ratio of each wheel is less than or equal to a preset value, then the driver's requested braking force is used as the target braking force; if the slip ratio of each wheel is greater than the preset value, then when the actual yaw rate of the vehicle is detected and the slip ratio is not the longitudinal slip ratio, the target braking force is calculated based on the difference between the actual yaw rate and the target yaw rate and the driver's requested braking force; otherwise, the target braking force is calculated based on the longitudinal slip ratio and the driver's requested braking force.

[0102] In this embodiment of the application, the calculation module 120 is further used to: obtain the steering wheel angle and the current vehicle speed; and calculate the target yaw rate based on the steering wheel angle and the current vehicle speed.

[0103] In this embodiment of the application, the device 10 further includes: a speed limiting module, used to obtain the number and location of caliper motor failures; match the target speed limit of the vehicle according to the number and / or location of caliper motor failures; and control the vehicle speed to be within the target speed limit.

[0104] In this embodiment, the control module 130 is further configured to: acquire the current braking force of each wheel; and control the output target current of the caliper motor in the corresponding braking mechanism according to the current braking force of each wheel and the corresponding target braking force.

[0105] It should be noted that the foregoing explanation of the braking control method embodiment also applies to the braking control device of this embodiment, and will not be repeated here.

[0106] In summary, the embodiments of this application can calculate the target braking force of the corresponding wheel by the slip ratio of each wheel and the driver's requested braking force, and can independently control the braking mechanism of each wheel to output the corresponding target braking force, thereby realizing independent control and adjustment of the braking force of each wheel, thereby improving the accuracy and stability of control.

[0107] Figure 3 A schematic diagram of the structure of a vehicle provided in an embodiment of this application. The vehicle may include:

[0108] The memory 301, the processor 302, and the computer program stored on the memory 301 and capable of running on the processor 302.

[0109] When the processor 302 executes the program, it implements the braking control method provided in the above embodiments.

[0110] Furthermore, the vehicle also includes:

[0111] Communication interface 303 is used for communication between memory 301 and processor 302.

[0112] The memory 301 is used to store computer programs that can run on the processor 302.

[0113] The memory 301 may include high-speed RAM (Random Access Memory) memory, and may also include non-volatile memory, such as at least one disk storage.

[0114] If the memory 301, processor 302, and communication interface 303 are implemented independently, then the communication interface 303, memory 301, and processor 302 can be interconnected via a bus to complete communication between them. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus, or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 3 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0115] Optionally, in a specific implementation, if the memory 301, processor 302, and communication interface 303 are integrated on a single chip, then the memory 301, processor 302, and communication interface 303 can communicate with each other through an internal interface.

[0116] Processor 302 may be a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement embodiments of this application.

[0117] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the braking control method described above.

[0118] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0119] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0120] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A braking control method, wherein a vehicle independently controls each wheel based on an electromechanical braking system, characterized in that, The method includes: Obtain the slip ratio of each wheel of the vehicle during braking; The target braking force for the corresponding wheel is calculated based on the slip ratio of each wheel and the driver's requested braking force. Control the braking mechanism of each wheel to output the corresponding target braking force; The step of calculating the target braking force for the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force includes: The slip ratio of each wheel and the driver's requested braking force are input into the closed-loop processing model, and the closed-loop processing model outputs the target braking force for the corresponding wheel. The closed-loop processing model uses a closed-loop processing algorithm for data processing, wherein the closed-loop processing algorithm includes: If the slip ratio of the wheel is less than or equal to a preset value, the driver's requested braking force is taken as the target braking force of the corresponding wheel. If the slip ratio of the wheel is greater than a preset value, then when the actual yaw rate of the vehicle is detected and the slip ratio is not the longitudinal slip ratio, the target braking force of the corresponding wheel is calculated based on the difference in angular velocity between the actual yaw rate and the target yaw rate and the driver's requested braking force; otherwise, the target braking force of the corresponding wheel is calculated based on the longitudinal slip ratio and the driver's requested braking force. Specifically, the target yaw rate is calculated based on the steering wheel angle value after deviation compensation, the current vehicle speed, the characteristic vehicle speed, the wheelbase, and the steering ratio between the steering wheel angle and the wheel angle. The characteristic vehicle speed is a parameter used to describe the understeer characteristics of the vehicle.

2. The method according to claim 1, characterized in that, The braking mechanism that controls each wheel to output the corresponding target braking force includes: Obtain the current braking force for each wheel; The caliper motor in the corresponding braking mechanism is controlled to output the target current based on the current braking force and the corresponding target braking force of each wheel.

3. The method according to claim 1, characterized in that, The step of calculating the target braking force for the corresponding wheel based on the slip ratio of each wheel and the driver's requested braking force further includes: Identify whether the caliper motor of each wheel is malfunctioning; When at least one caliper motor failure is detected, the slip ratio of the wheel corresponding to each non-failed caliper motor and the driver's requested braking force are input into the closed-loop processing model, and the closed-loop processing model outputs the target braking force of the wheel corresponding to each non-failed caliper motor.

4. The method according to claim 3, characterized in that, When any caliper motor failure is detected, the following is also included: Obtain the number and location of caliper motor failures; Match the target speed limit of the vehicle based on the number and / or location of caliper motor failures; The vehicle speed is controlled to be within the target speed limit.

5. The method according to claim 1, characterized in that, The method of obtaining the slip ratio of each wheel of the vehicle during braking also includes: Obtain the actual wheel speed of each wheel; The slip ratio of the corresponding wheel is calculated based on the actual wheel speed of each wheel.

6. A vehicle, characterized in that, The vehicle includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the braking control method as described in any one of claims 1-5.

7. A computer-readable storage medium, characterized in that, It stores a computer program, characterized in that the program is executed by a processor to implement the braking control method as described in any one of claims 1-5.

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