An ABS closed-loop control method for a four-wheel motor-driven vehicle under a split road surface working condition

Abstract

The application provides an ABS closed-loop control method for a four-wheel motor-driven vehicle in a split road surface working condition, and comprises the following steps: in step S1, collecting vehicle running state information; collecting vehicle running parameters in real time through a collecting unit; in step S2, calculating a slip rate difference Delta S and a brake pressure difference Delta P; in step S3, identifying whether the vehicle is in the split road surface working condition; and in step S4, determining a vehicle deflection trend and distributing a reverse driving force. The split road surface identification is more accurate, the control is more direct, the vehicle deviation risk in heavy braking of the split road surface can be significantly reduced, and the braking safety is improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle braking control technology, and in particular to a closed-loop ABS control method for a four-wheel motor driven vehicle under split-road conditions. Background Technology

[0002] In existing technologies, electric vehicles equipped with four-wheel motor drive and electromechanical braking (EMB) often employ open-loop control when applying ABS anti-lock braking on open roads. This type of method typically judges the vehicle's state based on wheel slip ratio, braking pressure, and the yaw moment and steering angle changes calculated from these, and applies a steering force in the opposite direction through a steer-by-wire module to counteract the steering angle change caused by the yaw moment. However, this approach has at least the following drawbacks: First, the ABS braking pressure adjustment accuracy is low, and its anti-interference capability is weak; second, the open-loop judgment of open road conditions mainly relies on slip ratio and braking pressure, which is not direct enough in monitoring the vehicle's yaw state; third, relying on the steer-by-wire module to counteract the yaw moment results in a long control chain, and the vehicle is still prone to veering under strong and heavy braking. Summary of the Invention

[0003] The purpose of this invention is to provide a method for closed-loop ABS control of a four-wheel motor vehicle on a split-road surface, so as to solve the problems of low braking control accuracy, weak anti-interference ability, and easy vehicle deviation during heavy braking in the prior art.

[0004] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution: a method for closed-loop ABS control of a four-wheeled electric vehicle on a split-road surface, comprising the following steps:

[0005] In step S1, vehicle operating status information is collected; vehicle operating parameters are collected in real time through the acquisition unit; the acquisition unit includes a vehicle controller, wheel speed sensors and IMU sensors; the wheel speed sensors collect the wheel speed of each wheel, the IMU sensors collect the lateral acceleration of the vehicle, and the vehicle controller collects and integrates brake pedal displacement, wheel speed, lateral acceleration, longitudinal acceleration, yaw rate, steering wheel angle and actual front wheel angle;

[0006] In step S2, the slip ratio difference ΔS and the braking pressure difference ΔP are calculated. The vehicle controller calculates the slip ratio difference ΔS of the left and right tires and the braking pressure difference ΔP of the corresponding wheels based on the collected yaw rate and wheel speed.

[0007] In step S3, it is identified whether the vehicle is in a split-road condition; the vehicle controller determines whether the absolute values ​​of the slip ratio difference ΔS and the braking pressure difference ΔP obtained in step S2 exceed the preset thresholds respectively; at the same time, it combines the yaw rate to determine whether it is greater than the set threshold for comprehensive judgment. When the above differences are all greater than the threshold, it is determined that the vehicle is traveling on a split-adhesion road surface and enters step S4 to perform stability control.

[0008] In step S4, determining the vehicle yaw tendency and distributing the reverse driving force includes:

[0009] S41: Calculate the reverse driving force: The vehicle controller determines the deflection direction and yaw trend of the vehicle due to uneven adhesion between the left and right front wheels based on the slip ratio difference ΔS and the braking pressure difference ΔP. Combined with the current yaw rate, it calculates and outputs the reverse driving force required by the left and right wheels.

[0010] S42: Distribute reverse driving force: According to the reverse driving force value calculated in step S41, it is applied to the front wheel through the motor drive module to directly adjust the left and right driving torque or braking torque.

[0011] Preferably, the motor drive module is a front wheel motor, which directly adjusts the front wheel drive force.

[0012] Preferably, the calculation objects of the slip ratio difference and braking pressure difference are the left and right front wheels of the vehicle.

[0013] Preferably, the threshold value for the yaw rate is 1 rad / s.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. By using the difference in front wheel slip ratio and braking pressure as the identification conditions for split-road conditions, and simultaneously combining them with the yaw rate for verification, the vehicle's split-road conditions can be identified more accurately.

[0016] 2. By adjusting the front wheel drive force to counteract the wheel steering tendency, the vehicle's attitude can be stabilized without relying on the steer-by-wire module, making the control method more direct;

[0017] 3. Through closed-loop control of yaw rate, the vehicle status can be monitored more accurately and stability adjustments can be made. Under heavy braking conditions on split-road surfaces, the risk of vehicle deviation can be significantly reduced, and vehicle braking safety can be improved. Attached Figure Description

[0018] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0019] Figure 1This is a flowchart of an ABS closed-loop control method for a four-wheel motor driven vehicle under split-road conditions, as described in the embodiment.

[0020] Figure 2 This is a schematic diagram of the vehicle structure in the ABS closed-loop control method for a four-wheel motor driven vehicle under split road conditions described in the embodiment.

[0021] Figure 3 This is a schematic diagram illustrating the operating principle of an ABS closed-loop control method for a four-wheel motor driven vehicle under split-road conditions, as described in the embodiment. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0024] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, all directional indications in this application (such as up, down, left, right, front, back, bottom, etc.) are only used to explain the relative positional relationships and movements between components in a specific orientation (as shown in the figures). If the specific orientation changes, the directional indication will also change accordingly. Furthermore, descriptions involving "first," "second," etc., in this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0025] like Figure 1 - Figure 3 As shown, this embodiment takes a new energy vehicle equipped with four-wheel motor drive and EMB braking as an example to illustrate the ABS closed-loop control method for a four-wheel motor driven vehicle under split-road conditions described in this invention.

[0026] The method specifically includes the following steps:

[0027] In step S1, vehicle operating status information is collected. The acquisition unit collects vehicle operating parameters in real time, providing data support for the vehicle controller to determine the vehicle's driving status, identify road surface adhesion conditions, and execute stability control. The acquisition unit includes the vehicle controller, wheel speed sensors, and inertial measurement unit (IMU) sensors. The wheel speed sensors collect wheel speed signals in real time, the IMU sensors collect lateral acceleration signals, and the vehicle controller collects and integrates information such as brake pedal displacement signals, wheel speed signals, lateral acceleration signals, longitudinal acceleration signals, yaw rate signals, steering wheel angle signals, and the actual steering angle of the front wheels to achieve comprehensive perception of the vehicle's operating status.

[0028] In step S2, the slip ratio difference ΔS and the braking pressure difference ΔP are calculated. The vehicle controller calculates the slip ratio difference ΔS between the left and right tires and the corresponding braking pressure difference ΔP based on the collected yaw rate and wheel speed signals. In this embodiment, the slip ratio difference and braking pressure difference are calculated for the left and right front tires of the vehicle.

[0029] In step S3, it is determined whether the vehicle is in a split-surface road condition. The vehicle controller, based on the slip ratio difference ΔS and braking pressure difference ΔP obtained in step S2, determines whether their absolute values ​​exceed preset thresholds, i.e., |ΔS|>Sth and |ΔP|>Pth, where Sth is the slip ratio difference threshold and Pth is the braking pressure difference threshold. Simultaneously, it combines the yaw rate signal to determine whether it exceeds a set threshold for comprehensive judgment. In this embodiment, the yaw rate threshold is set to 1 rad / s. When all the above differences are greater than the threshold, it is determined that the vehicle is traveling on a split-surface road condition, and step S4 is entered to perform stability control.

[0030] In step S4, the vehicle yaw tendency is determined and a counter-driving force is allocated. The main steps are as follows:

[0031] Step S41: Calculate the reverse driving force: The vehicle controller determines the deflection direction and yaw trend of the vehicle caused by uneven adhesion between the left and right front wheels based on the slip ratio difference ΔS and the braking pressure difference ΔP. Combined with the current yaw rate, it calculates and outputs the reverse driving force required by the left and right wheels.

[0032] Step S42: Distribute Reverse Driving Force: Based on the reverse driving force calculated in step S41, it is applied to the front wheels via the four-wheel motor drive module. This directly adjusts the left and right drive / braking torque, utilizing the motor's rapid torque response to counteract the vehicle's tendency to veer and yaw due to differences in road surface adhesion, suppressing body roll and improving driving stability during ABS operation. Unlike traditional solutions that rely on the steer-by-wire system to apply reverse steering intervention, this embodiment achieves directional stability control by directly adjusting the front wheel motor drive force. This results in faster response and more direct control, effectively improving the vehicle's braking directional stability on split-road surfaces and preventing dangerous conditions such as fishtailing and veering.

[0033] The specific embodiments of the present invention have been described above. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention.

Claims

1. A closed-loop control method for ABS of a four-wheel motor driven vehicle under split-road conditions, characterized in that, Includes the following steps: In step S1, vehicle operating status information is collected; vehicle operating parameters are collected in real time through the acquisition unit; the acquisition unit includes a vehicle controller, wheel speed sensors and IMU sensors; the wheel speed sensors collect the wheel speed of each wheel, the IMU sensors collect the lateral acceleration of the vehicle, and the vehicle controller collects and integrates brake pedal displacement, wheel speed, lateral acceleration, longitudinal acceleration, yaw rate, steering wheel angle and actual front wheel angle; In step S2, the slip ratio difference ΔS and the braking pressure difference ΔP are calculated; The vehicle controller calculates the slip ratio difference ΔS between the left and right tires and the corresponding braking pressure difference ΔP between the wheels based on the collected yaw rate and wheel speed. In step S3, it is identified whether the vehicle is in a split-road condition; the vehicle controller determines whether the absolute values ​​of the slip ratio difference ΔS and the braking pressure difference ΔP obtained in step S2 exceed the preset thresholds respectively; at the same time, it combines the yaw rate to determine whether it is greater than the set threshold for comprehensive judgment. When the above differences are all greater than the threshold, it is determined that the vehicle is traveling on a split-adhesion road surface and enters step S4 to perform stability control. In step S4, determining the vehicle yaw tendency and distributing the reverse driving force includes: S41: Calculate the reverse driving force: The vehicle controller determines the deflection direction and yaw trend of the vehicle due to uneven adhesion between the left and right front wheels based on the slip ratio difference ΔS and the braking pressure difference ΔP. Combined with the current yaw rate, it calculates and outputs the reverse driving force required by the left and right wheels. S42: Distribute reverse driving force: According to the reverse driving force value calculated in step S41, it is applied to the front wheel through the motor drive module to directly adjust the left and right driving torque or braking torque.

2. The ABS closed-loop control method for a four-wheel motor driven vehicle under split-road conditions according to claim 1, characterized in that, The motor drive module is a front wheel motor, which directly adjusts the front wheel drive force.

3. The ABS closed-loop control method for a four-wheel motor driven vehicle under split-road conditions according to claim 1, characterized in that, The calculation objects for the slip ratio difference and braking pressure difference are the left and right front wheels of the vehicle.

4. The ABS closed-loop control method for a four-wheel motor driven vehicle under split-road conditions according to claim 1, characterized in that, The threshold value for the yaw rate is set at 1 rad / s.

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