A vehicle stability control method and control system

Abstract

This invention discloses a vehicle stability control method and system, comprising: acquiring the vehicle's current state; when the vehicle is in a straight-line braking state, acquiring the wheel deceleration and wheel slip ratio of the drive wheels; when the wheel slip ratio of the drive wheels is greater than a first slip ratio threshold but less than an EBD or ABS activation threshold, or when the wheel deceleration is greater than a wheel deceleration threshold, pre-recovering energy from the drive wheel drive motor; when the vehicle is in a turning state, acquiring the vehicle yaw rate and lateral acceleration, and determining whether the vehicle is understeer or oversteer based on the yaw rate; when the vehicle is understeer or oversteer, or when the lateral acceleration is greater than a set acceleration threshold, controlling the torque growth gradient and peak value of the drive motor or engine, and increasing the pressure on the brakes of the corresponding wheels. This ensures smooth vehicle operation.

Description

Technical Field

[0001] This invention relates to the field of vehicle stability control technology, and in particular to a vehicle stability control method and control system. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Currently, most large vans are pure electric vehicles with rear-wheel drive. They transport passengers between cities under complex and varied operating conditions, including slippery roads in rainy or snowy weather, potholes, speed bumps, and other road conditions. During operation, they may also encounter situations requiring emergency obstacle avoidance and braking, which can easily lead to skidding, fishtailing, and rollover, affecting passenger safety and vehicle safety.

[0004] Current vehicle control strategies primarily address the following issues: when driving straight, ABS activation results in significant energy recovery but slow deactivation, leading to vehicle slippage; or when turning, high speeds and rapid steering cause significant yaw and roll, resulting in high drive torque, large brake fluid requirements, slow ESC boost rate, and untimely control, all of which compromise vehicle safety. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a vehicle stability control method and control system. By pre-controlling the energy recovery of the drive motors of the drive wheels before the ABS and VDC functions are activated, and by pre-pressurizing the four brakes before the vehicle accelerates during steering, the response time is shortened, the control accuracy is improved, and the difficulty of subsequent ABS and VDC function control is reduced. This effectively avoids slippage and rollover problems caused by vehicle weight and slow active braking pressurization.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] Firstly, a vehicle stability control method is proposed, including:

[0008] Obtain the vehicle's current status;

[0009] When the vehicle is in a straight-line braking state, the wheel deceleration and wheel slip ratio of the drive wheels are obtained; when the wheel slip ratio of the drive wheels is greater than the first slip ratio threshold and less than the EBD or ABS activation threshold, or when the wheel deceleration is greater than the wheel deceleration threshold, the energy of the drive wheel drive motor is pre-recovered.

[0010] When the vehicle is turning, the yaw rate and lateral acceleration of the vehicle are acquired. Based on the yaw rate, it is determined whether the vehicle is understeer or oversteer. When the vehicle is understeer or oversteer, or the lateral acceleration is greater than the set acceleration threshold, the torque growth gradient and peak value of the drive motor or engine are controlled, and the brakes of the corresponding wheels are pressurized.

[0011] Secondly, a vehicle stability control method is proposed, including:

[0012] The vehicle status monitoring module is used to obtain the vehicle's status.

[0013] The control module is used to acquire the wheel deceleration and wheel slip ratio of the drive wheels when the vehicle is in a straight-line braking state; when the wheel slip ratio of the drive wheels is greater than a first slip ratio threshold but less than the EBD or ABS activation threshold, or when the wheel deceleration is greater than the wheel deceleration threshold, the energy of the drive motor of the drive wheels is pre-recovered; when the vehicle is in a turning state, the module acquires the vehicle yaw rate and lateral acceleration, and determines whether the vehicle is understeer or oversteer based on the vehicle yaw rate; when the vehicle is understeer or oversteer, or when the lateral acceleration is greater than a set acceleration threshold, the module controls the torque growth gradient and peak value of the drive motor or engine, and applies pressure to the brakes of the corresponding wheels.

[0014] Thirdly, an electronic device is proposed, including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, complete the steps described in a vehicle stability control method.

[0015] Fourthly, a computer-readable storage medium is proposed for storing computer instructions, which, when executed by a processor, complete the steps described in a vehicle stability control method.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention calculates the wheel deceleration and wheel slip ratio of the drive wheels when the vehicle brakes under straight-line conditions. When the wheel slip ratio of the drive wheels is greater than the first slip ratio threshold but less than the EBD or ABS activation threshold, or when the wheel deceleration is greater than the wheel deceleration threshold, the energy of the drive motor of the drive wheels is pre-recovered to reduce the drive wheel slip ratio. This solves the problem of large negative torque and slow exit when the energy recovery is activated during EBD or ABS activation, which leads to vehicle slippage.

[0018] 2. In addition, when the vehicle is accelerating while turning, if the vehicle is understeering or oversteering, or if the lateral acceleration is greater than a set acceleration threshold, the invention controls the drive torque and increases the pressure on the brakes of the corresponding wheels to prevent the vehicle speed from rising rapidly and the vehicle from yawing and tilting. This solves the problem of slow vehicle response due to large brake fluid requirements and large vehicle load, thereby improving vehicle stability and safety.

[0019] 3. This invention determines whether the vehicle is understeering or oversteering, or whether the lateral acceleration is greater than a set acceleration threshold, after determining that the wheel slip ratio of the drive wheel is greater than a first slip ratio threshold but less than the EBD or ABS activation threshold, or the wheel deceleration is greater than the wheel deceleration threshold. It also judges whether the vehicle has wheel speed faults, steering angle sensor faults, etc., and determines whether to downgrade EBD and ABS for safety, whether to pre-recover energy from the drive motor of the drive wheel, or control the drive torque, and to increase the pressure on the brakes of the corresponding wheels, so as to prevent the vehicle from being miscontrolled without the detection of vehicle faults, and also to prevent the corresponding control functions from being simply turned off.

[0020] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application.

[0022] Figure 1 The method flowchart is disclosed in the embodiment;

[0023] Figure 2 The system block diagram is disclosed for an embodiment. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Example 1

[0028] In this embodiment, a vehicle stability control method is disclosed, including:

[0029] S1: Obtain the vehicle's current status.

[0030] This embodiment obtains the vehicle steering angle, brake pedal opening, and accelerator pedal opening;

[0031] The vehicle's status and the driver's intentions are determined based on the steering angle, brake pedal opening, and accelerator pedal opening.

[0032] The vehicle's state includes straight-ahead driving, emergency turning, braking, and acceleration.

[0033] Preferably, in this embodiment, the wheel speed of each wheel is obtained through a wheel speed sensor; the yaw rate and lateral acceleration of the vehicle are obtained through a yaw angle sensor; the turning angle of the vehicle is obtained through a steering angle sensor, and the vehicle's straight-ahead or turning state is determined based on the turning angle, and the turning rate of the vehicle is determined based on the turning rate; the brake pedal opening is obtained through a master cylinder pressure sensor; the accelerator pedal opening is obtained through an accelerator pedal status sensor, and the braking state, acceleration state, and driver intention of the vehicle are determined based on the brake pedal opening and the accelerator pedal opening.

[0034] S2: When the vehicle is in a straight-line braking state, the wheel deceleration and wheel slip ratio of the drive wheels are obtained; when the wheel slip ratio of the drive wheels is greater than the first slip ratio threshold but less than the EBD or ABS activation threshold, or when the wheel deceleration is greater than the wheel deceleration threshold, the energy of the drive wheel drive motor is pre-recovered; on the one hand, the peak value of the energy recovery torque is controlled, and on the other hand, the growth gradient of the energy recovery torque is reduced; the slip caused by energy recovery is reduced, and the problem of large energy recovery and slow exit when ABS is activated is solved.

[0035] When the vehicle is turning, the yaw rate and lateral acceleration are acquired. Based on the yaw rate, it is determined whether the vehicle is understeer or oversteer. When the vehicle is understeer or oversteer, or when the lateral acceleration exceeds the set acceleration threshold, the torque growth gradient and peak value of the drive motor or engine are controlled to prevent the driver from continuously pressing the accelerator pedal, which could lead to vehicle acceleration instability. At the same time, the brakes of the corresponding wheels are pressurized to eliminate disc-pad gaps, so that the friction pads and brake discs generate a small braking torque. This solves the problem of high brake fluid requirements and slow ESC active pressurization when VDC is activated, which makes vehicle control difficult.

[0036] This embodiment also obtains the vehicle speed and the rotational speed of each wheel;

[0037] The wheel deceleration of the drive wheel is calculated based on the current speed of the drive wheel and the speed of the drive wheel at the previous moment.

[0038] The wheel slip ratio λ of the drive wheels is calculated based on the drive wheel rotation speed and vehicle speed, using the following formula:

[0039]

[0040] In the formula, λ is the slip ratio, and V vec V is the vehicle speed. wheel This refers to the wheel rotation speed.

[0041] like Figure 1 As shown, in order to ensure the accuracy of the various data obtained and to prevent the data from being faulty and causing misjudgment of the vehicle status, and thus miscontrolling the vehicle, this embodiment also judges the vehicle fault and determines whether to perform vehicle stability function control based on the vehicle fault judgment result.

[0042] Specifically, when the deceleration of the drive wheel is greater than the deceleration threshold, or the wheel slip ratio of the drive wheel is greater than the first slip ratio threshold but less than the EBD or ABS activation threshold, it is determined whether a wheel speed fault or a steering angle sensor fault has occurred. When there is no wheel speed fault or steering angle sensor fault, the energy of the drive wheel drive motor is pre-recovered according to preset values. When a single wheel speed fault occurs, the ABS and VDC are downgraded by estimating the wheel speed of the faulty vehicle, reducing the control range of the slip ratio, reducing the peak value of the energy recovery torque, and ensuring vehicle stability. When two or more wheel speed faults or two or more steering angle sensor faults occur, the energy recovery and EBD and ABS functions are directly turned off to avoid large slippage and miscontrol.

[0043] When the vehicle is determined to be understeer or oversteer, or the lateral acceleration exceeds the set acceleration threshold, it is checked whether there is a wheel speed fault or a steering angle sensor fault. If there is no wheel speed fault or steering angle sensor fault, the torque increase gradient and peak value of the drive motor or engine are controlled to prevent the driver from continuously pressing the accelerator pedal, which could lead to vehicle acceleration instability. At the same time, the brakes of the corresponding wheels are pressurized to eliminate disc-pad gaps and generate a small braking torque between the friction pads and brake discs, solving the problem of large brake fluid requirements and slow ESC active pressurization when VDC is activated, which makes vehicle control difficult. When the steering angle sensor is faulty, if there is only a large deviation in the zero angle position, the VDC function is downgraded to reduce the peak value of the vehicle's self-centering torque and the brake strength. If the steering angle value exceeds the tolerance or is completely faulty, the VDC function is turned off.

[0044] Specifically, when the current of the wheel speed sensor is greater than the current threshold but less than or equal to the limit operating current, and this continues for a set time; or when the current of the wheel speed sensor is greater than the limit operating current, the wheel speed of that wheel is determined to be faulty.

[0045] When the accelerator pedal opening is less than the set opening threshold, the wheel speed of an individual wheel is much higher than that of other wheels and exceeds the set wheel speed threshold, indicating a wheel speed fault in that wheel.

[0046] When the vehicle is running at high speed, if the vehicle speed is greater than the speed set value, and the wheel speed of one wheel is always lower than the wheel speed of the other wheels and the wheel speed difference reaches the set threshold, it is determined that the vehicle tire has a low tire pressure fault. When the ABS is activated, it can perform function degradation control according to the slip ratio to avoid braking deviation and slippage caused by the difference in braking force of the left rear wheel. The TCS (Traction Control System) braking function should be avoided from being mistakenly activated.

[0047] When there is a difference in wheel speed between the two wheels of the vehicle, and this difference is greater than or equal to a set threshold, and the vehicle steering angle obtained by the steering angle sensor does not change, the steering angle sensor is determined to be faulty.

[0048] The main functional degradation strategies are as follows:

[0049] When only a single wheel speed failure occurs, the vehicle's turning radius and the difference between the turning radii of the inner and outer wheels can be calculated by referring to the normal wheel speed on the same axle and based on the turning angle signal. This allows for compensation estimation of the faulty wheel speed, safety downgrading of the vehicle's ABS (Anti-lock Braking System) and VDC (Vehicle Dynamics Control System) functions, reducing energy recovery intensity and torque gradient, avoiding simple disengagement of functions, and improving vehicle safety.

[0050] When the vehicle is traveling straight and a large deviation of the steering angle sensor occurs, it is necessary to learn the deviation between the actual steering angle of the vehicle and the steering angle output by the steering angle sensor, and to safely downgrade the VDC function, reduce the return torque and wheel brake strength, avoid simply disengaging the function, and improve vehicle safety.

[0051] This embodiment discloses a method that, when a vehicle is traveling straight, calculates the wheel deceleration and wheel slip ratio of the drive wheels during braking under straight-traffic conditions. When the wheel slip ratio of the drive wheels is greater than a first slip ratio threshold but less than the EBD or ABS activation threshold, or when the wheel deceleration is greater than the wheel deceleration threshold, the energy of the drive wheel drive motor is pre-recovered to reduce the drive wheel slip ratio. This solves the problem of large negative torque and slow exit when energy recovery is activated during EBD or ABS activation, which leads to vehicle slippage. When the vehicle is accelerating while turning, if the vehicle understeers or oversteers, or the lateral acceleration is greater than a set acceleration threshold, the drive torque is controlled, and the brakes of the corresponding wheels are pressurized to avoid rapid speed increases and increased vehicle yaw and tilt. This solves the problem of slow vehicle response due to large brake fluid requirements and large vehicle load, thus improving vehicle stability and safety.

[0052] This embodiment determines whether the vehicle is understeering or oversteering, or whether the lateral acceleration is greater than a set acceleration threshold, after determining that the wheel slip ratio of the drive wheel is greater than a first slip ratio threshold but less than the EBD or ABS activation threshold, or the wheel deceleration is greater than the wheel deceleration threshold. It also judges whether the vehicle has wheel speed faults, low air pressure faults, or steering angle sensor faults. Based on the judgment, it determines whether to downgrade the safety of EBD and ABS, whether to pre-recover the energy of the drive motor of the drive wheel, or control the drive torque, and to increase the pressure of the brakes of the corresponding wheels. This prevents the vehicle from being miscontrolled without the detection of vehicle faults, and also prevents the corresponding control functions from being simply turned off.

[0053] Example 2

[0054] In this embodiment, a vehicle stability control method is disclosed, including:

[0055] The vehicle status monitoring module is used to obtain the vehicle's status.

[0056] The control module is used to acquire the wheel deceleration and wheel slip ratio of the drive wheels when the vehicle is in a straight-line braking state; when the wheel slip ratio of the drive wheels is greater than a first slip ratio threshold but less than the EBD or ABS activation threshold, or when the wheel deceleration is greater than the wheel deceleration threshold, the energy of the drive motor of the drive wheels is pre-recovered; when the vehicle is in a turning state, the module acquires the vehicle yaw rate and lateral acceleration, and determines whether the vehicle is understeer or oversteer based on the vehicle yaw rate; when the vehicle is understeer or oversteer, or when the lateral acceleration is greater than a set acceleration threshold, the module controls the torque growth gradient and peak value of the drive motor or engine, and applies pressure to the brakes of the corresponding wheels.

[0057] like Figure 2As shown, the vehicle status detection module includes wheel speed sensors, yaw angle sensors, steering angle sensors, master cylinder pressure sensors, accelerator pedal status sensors, brake pedal status sensors, and a status determination module.

[0058] Wheel speed sensors are used to acquire the wheel speed of each wheel; yaw angle sensors are used to acquire the yaw rate of the vehicle; steering angle sensors are used to acquire the steering angle of the vehicle; master cylinder pressure sensors are used to acquire the brake pedal opening; accelerator pedal status sensors are used to acquire the accelerator pedal status; brake pedal status sensors are used to acquire the brake pedal opening; and a status determination module is used to determine the vehicle's status and the driver's intention based on the steering angle, brake pedal opening, and accelerator pedal opening.

[0059] Example 3

[0060] In this embodiment, an electronic device is disclosed, including a memory and a processor, as well as computer instructions stored in the memory and running on the processor. When the processor executes the computer instructions, it completes the steps described in the vehicle stability control method disclosed in Embodiment 1.

[0061] Example 4

[0062] In this embodiment, a computer-readable storage medium is disclosed for storing computer instructions, which, when executed by a processor, complete the steps of the vehicle stability control method disclosed in Embodiment 1.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A vehicle body stability control method, characterized in that, include: Obtain the vehicle's steering angle, brake pedal opening, and accelerator pedal opening; determine the vehicle's current state based on these parameters. When the vehicle is in a straight-line braking state, the wheel deceleration and wheel slip ratio of the drive wheels are obtained. When it is determined that the wheel deceleration of the drive wheels is greater than the wheel deceleration threshold, or the wheel slip ratio of the drive wheels is greater than the first slip ratio threshold but less than the EBD or ABS activation threshold, it is determined whether there is a wheel speed fault or a steering angle sensor fault. When there is no wheel speed fault or steering angle sensor fault, the energy of the drive wheel drive motor is pre-recovered according to the preset value. When a single wheel speed failure occurs, the ABS and VDC are downgraded by estimating the wheel speed of the faulty vehicle, reducing the control range of slip ratio and reducing the peak value of energy recovery torque; when two or more wheel speed failures or two or more steering angle sensor failures occur, energy recovery, EBD, and ABS functions are directly turned off. When the vehicle is turning, the yaw rate and lateral acceleration of the vehicle are obtained. Based on the yaw rate, it is determined whether the vehicle is understeering or oversteering. When the vehicle understeers or oversteers, or when the lateral acceleration exceeds the set acceleration threshold, it determines whether there is a wheel speed fault or a steering angle sensor fault. When there is no wheel speed fault or steering angle sensor fault, it controls the torque growth gradient and peak value of the drive motor or engine, and simultaneously increases the pressure on the brakes of the corresponding wheels. When the steering angle sensor fault is only a large deviation in the zero angle position, it downgrades the VDC function, reduces the peak value of the vehicle's self-centering torque and the brake strength. When the steering angle sensor fault is an out-of-tolerance or complete failure of the steering angle value, it shuts down the VDC function.

2. The vehicle stability control method as described in claim 1, characterized in that, When the current of the wheel speed sensor is greater than the current threshold but less than or equal to the limit operating current, and this continues for a set time; or when the current of the wheel speed sensor is greater than the limit operating current, the wheel speed of that wheel is determined to be faulty. When the accelerator pedal opening is less than the set opening threshold, the wheel speed of an individual wheel is much higher than that of other wheels and exceeds the set wheel speed threshold, indicating a wheel speed fault in that wheel.

3. The vehicle stability control method as described in claim 1, characterized in that, When there is a difference in wheel speed between the two wheels of the vehicle, and this difference is greater than or equal to a set threshold, and the vehicle steering angle obtained by the steering angle sensor does not change, the steering angle sensor is determined to be faulty.

4. The vehicle stability control method as described in claim 1, characterized in that, It also obtains the vehicle speed and the rotational speed of each wheel; calculates the wheel deceleration of the drive wheels based on the current and previous drive wheel rotational speeds; and calculates the wheel slip ratio of the drive wheels based on the drive wheel rotational speeds and the vehicle speed.

5. A vehicle body stability control method, characterized in that, include: The vehicle status monitoring module is used to acquire the vehicle's steering angle, brake pedal opening, and accelerator pedal opening; and to determine the vehicle's status based on these parameters. The control module is used to acquire the wheel deceleration and wheel slip ratio of the drive wheels when the vehicle is in a straight-moving braking state; when it is determined that the wheel deceleration of the drive wheels is greater than the wheel deceleration threshold, or the wheel slip ratio of the drive wheels is greater than the first slip ratio threshold but less than the EBD or ABS activation threshold, it determines whether there is a wheel speed fault or a steering angle sensor fault; when there is no wheel speed fault or steering angle sensor fault, it performs pre-recovery of energy from the drive motor of the drive wheels according to preset values. When a single wheel speed failure occurs, the ABS and VDC are downgraded by estimating the wheel speed of the faulty vehicle, reducing the control range of slip ratio and the peak value of energy recovery torque; when two or more wheel speed failures or two or more steering angle sensor failures occur, energy recovery, EBD, and ABS functions are directly turned off; when the vehicle is in a turning condition, the vehicle yaw rate and lateral acceleration are acquired, and the vehicle understeer or oversteer is determined based on the vehicle yaw rate. When the vehicle understeers or oversteers, or when the lateral acceleration exceeds the set acceleration threshold, it determines whether there is a wheel speed fault or a steering angle sensor fault. When there is no wheel speed fault or steering angle sensor fault, it controls the torque growth gradient and peak value of the drive motor or engine, and simultaneously increases the pressure on the brakes of the corresponding wheels. When the steering angle sensor fault is only a large deviation in the zero angle position, it downgrades the VDC function, reduces the peak value of the vehicle's self-centering torque and the brake strength. When the steering angle sensor fault is an out-of-tolerance or complete failure of the steering angle value, it shuts down the VDC function.

6. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, complete the steps of the vehicle stability control method according to any one of claims 1-4.

7. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, complete the steps of the vehicle stability control method according to any one of claims 1-4.

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