Driving anti-skid control method for electric automobile

Abstract

The invention specifically discloses a driving anti-slip control method for an electric vehicle, which comprises the following steps: acquiring a vehicle state signal and judging whether a creeping function flag bit is activated or not, if so, entering a creeping control mode, and if not, outputting a final torque TqOut which is equal to 0; according to a brake pedal of the vehicle, the steering angle of a steering wheel and the gradient of a road surface on which the vehicle runs, a corresponding basic torque TqBase, a crawling auxiliary torque TqClimb and a steering wheel angle correction coefficient XSteer required by crawling are obtained; according to the formula TqOut = XSteer * (TqBase + TqClimb), the final torque TqOut is obtained through calculation, and the calculated final torque TqOut is supplied to a torque executing mechanism for crawling control. According to the method, the running stability of the electric automobile in the crawling mode and the participation degree of a driver can be improved, and the adaptability to complex working conditions is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle control, and more specifically, to a driving anti-skid control method for an electric vehicle. Background Art

[0002] With the increasing attention paid to energy-saving and environmental protection policies around the world, electric vehicles, with their zero-emission, low-noise and high-efficiency characteristics, have gradually become an important direction for future transportation development. Electric vehicles achieve stable driving of vehicles under different working conditions by precisely controlling the torque and speed of the motor. However, the driving state of electric vehicles is affected by many factors, such as slope, road conditions, etc. The creep control of electric vehicles, as one of its basic driving control modes, has a wide range of application scenarios, such as vehicle starting and slow following. Existing creep control mostly uses PID control. If the parameter setting is unreasonable, it will lead to problems such as large torque fluctuations and poor stability under conditions such as slope starting and complex road conditions. At the same time, the existing control does not fully consider the changes in vehicle status information and driver needs, which can easily cause creep control to fail to meet the needs of complex working conditions in actual driving. Therefore, how to provide an effective information interaction method that can quickly and reliably transmit key information between multiple modules to ensure the real-time, stability and safety of the autonomous driving system has become an important research direction in the current technical field. Summary of the invention

[0003] The present invention provides a driving anti-skid control method for an electric vehicle, which solves the problems of large torque fluctuation and poor stability in complex working conditions when the existing electric vehicle performs creep control, can improve the driving stability and driver participation of the electric vehicle in the creep mode, and enhance the adaptability to complex working conditions.

[0004] To achieve the above objectives, the present invention provides the following technical solutions:

[0005] A driving anti-skid control method for an electric vehicle, comprising:

[0006] Get the vehicle status signal and determine whether the creep function flag is activated. If yes, enter the creep control mode. If not, output the final torque TqOut = 0.

[0007] According to the vehicle's brake pedal, steering wheel steering angle and the road slope on which the vehicle is traveling, the basic torque TqBase, the crawling auxiliary torque TqClimb and the steering wheel angle correction coefficient XSteer required for crawling are obtained;

[0008] According to the formula TqOut=XSteer×(TqBase + TqClimb), the final torque TqOut is calculated and given to the torque actuator for creep control.

[0009] Preferably, obtaining the base torque TqBase includes:

[0010] A corresponding table of gear position, vehicle speed and torque is set according to empirical data and driving experience, and the output torque T1 is obtained by looking up the table;

[0011] Calculate the brake correction factor Xbrk according to the brake pedal depth;

[0012] According to the formula: TqBase=T1×Xbrk, the basic torque TqBase is calculated.

[0013] Preferably, the calculation of the brake correction coefficient Xbrk according to the brake pedal depth includes:

[0014] Determine whether the brake pedal depth exceeds the set threshold and the duration reaches the first time threshold a. If yes, Xbrk=0;

[0015] If not, it is determined whether the brake pedal depth exceeds a set threshold and the duration reaches a second time threshold b. If yes, Xbrk is set to a constant value to limit the basic torque, wherein the second time threshold b is less than the first time threshold a.

[0016] If not, Xbrk places no limit on the base torque.

[0017] Preferably, obtaining the creep assist torque TqClimb includes:

[0018] Determine whether the slope assist flag is activated. If so, calculate the crawl assist torque TqClimb according to the formula: TqClimb = T2×Ybrk, where T2 is the compensation torque required for the vehicle to go uphill and Ybrk is the brake attenuation coefficient.

[0019] Preferably, the step of determining whether the slope assist flag is activated includes:

[0020] If the vehicle is traveling on a slope greater than a first slope threshold and less than a second slope threshold, causing the gear position to be in the opposite direction to the motor speed, the slope assist flag is activated;

[0021] If the slope is greater than the second slope threshold, the slope assist flag is deactivated.

[0022] Preferably, it also includes:

[0023] The relationship table between the gear position, motor speed and compensation torque of the vehicle is set according to the vehicle crawling uphill without exceeding the target vehicle speed, and the compensation torque T2 is obtained by looking up the table through the gear position and the filtered motor speed.

[0024] Preferably, it also includes:

[0025] According to the driver controlling the creeping speed through the brake pedal when going downhill, a corresponding table of brake pedal depth and attenuation coefficient is set, and the attenuation coefficient Ybrk is obtained by looking up the brake pedal depth in the table.

[0026] Preferably, obtaining the steering wheel angle correction coefficient XSteer includes:

[0027] Determine whether the steering angle correction function is allowed to be turned on. If the correction function is turned on, the correction coefficient XSteer is obtained by looking up the table according to the steering wheel steering angle. If the correction function is not turned on, the correction coefficient XSteer is a set constant value.

[0028] Preferably, the activation condition of the steering angle correction function is: the setting is performed when the vehicle speed is greater than the allowed steering speed, and the setting is cancelled when the vehicle speed is less than the prohibited steering speed.

[0029] Preferably, the step of obtaining the vehicle status signal and determining whether to activate the creep function flag includes:

[0030] The current vehicle speed, actual motor speed, vehicle steering angle, actual throttle and brake pedal opening are collected in real time through the CANFD bus to determine whether the current working condition enters crawling. If so, the crawling function flag is activated.

[0031] The present invention provides a driving anti-skid control method for an electric vehicle. The method determines whether a creeping function flag is activated based on a vehicle status signal. If so, the function validity flag is output and the torque is calculated. Then, a torque output function is performed according to the output torque signal. The method solves the problems of large torque fluctuation and poor stability in complex working conditions when the existing electric vehicle performs creep control. The method can improve the driving stability of the electric vehicle in the creeping mode and the driver's participation, and enhance the adaptability to complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below.

[0033] Figure 1 It is a schematic diagram of a driving anti-skid control method for an electric vehicle provided by the present invention.

[0034] Figure 2 It is a logic flow chart of creep control provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to enable persons skilled in the art to better understand the solutions of the embodiments of the present invention, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and implementation modes.

[0036] In view of the problems existing in the creep control of current electric vehicles, the present invention provides a drive anti-skid control method for electric vehicles, which solves the problems of large torque fluctuation and poor stability in complex working conditions when the existing electric vehicles perform creep control. It can improve the driving stability of the electric vehicle in the creep mode and the driver's participation, and enhance the adaptability to complex working conditions.

[0037] like Figure 1 and Figure 2 As shown, a driving anti-skid control method for an electric vehicle comprises:

[0038] S1: Get the vehicle status signal and determine whether the creep function flag is activated. If yes, enter the creep control mode. If not, output the final torque TqOut = 0.

[0039] S2: According to the vehicle's brake pedal, steering wheel steering angle and the slope of the road on which the vehicle is traveling, the base torque TqBase, the crawling auxiliary torque TqClimb and the steering wheel angle correction coefficient XSteer required for crawling are obtained.

[0040] S3: According to the formula TqOut=XSteer×(TqBase + TqClimb), the final torque TqOut is calculated and given to the torque actuator for creep control.

[0041] Specifically, the vehicle status signal includes: current vehicle speed, actual motor speed, vehicle steering angle, actual throttle and brake pedal opening, etc. The vehicle status signal is used to determine whether the vehicle is in creeping mode. If so, the creeping function flag is activated and the torque is calculated. The calculated torque is output to the torque actuator to control the vehicle creeping. The flag can be calculated by the following formula: automatic parking enabled &&EPB status &&AVH status &&cruise status &&vehicle working mode. The creeping torque calculation can be divided into three parts: basic creeping torque TqBase, slope assist torque TqClimb, and steering wheel angle correction coefficient XSteer. The final torque TqOut is calculated as: TqOut=XSteer×(TqBase + TqClimb). This method improves the driving stability and driver participation of electric vehicles in creeping mode, while enhancing the adaptability to complex working conditions.

[0042] Further, the basic torque TqBase is obtained, including: setting a corresponding table of gear position, vehicle speed and torque according to empirical data and driving experience, and obtaining the output torque T1 by looking up the table; calculating the braking correction coefficient Xbrk according to the brake pedal depth; and calculating the basic torque TqBase according to the formula: TqBase=T1×Xbrk.

[0043] Further, the calculation of the brake correction coefficient Xbrk according to the brake pedal depth includes:

[0044] Determine whether the brake pedal depth exceeds the set threshold and the duration reaches the first time threshold a. If yes, Xbrk=0;

[0045] If not, it is determined whether the brake pedal depth exceeds a set threshold and the duration reaches a second time threshold b. If yes, Xbrk is set to a constant value to limit the basic torque, wherein the second time threshold b is less than the first time threshold a.

[0046] If not, Xbrk places no limit on the base torque.

[0047] In actual application, the basic creep torque TqBase is used to look up the table output torque T1 according to the gear position and vehicle speed. The table selects the best data based on empirical data and driving experience to achieve better stability and drivability. In addition, the driver controls the creeping speed according to demand to obtain the brake pedal depth, and obtains the brake correction coefficient Xbrk based on the brake pedal depth.

[0048] Further, the crawl assist torque TqClimb is obtained, including:

[0049] Determine whether the slope assist flag is activated. If so, calculate the crawl assist torque TqClimb according to the formula: TqClimb = T2×Ybrk, where T2 is the compensation torque required for the vehicle to go uphill and Ybrk is the brake attenuation coefficient.

[0050] Further, the determining whether the slope assist flag is activated includes:

[0051] If the vehicle is traveling on a slope greater than a first slope threshold and less than a second slope threshold, causing the gear position to be in the opposite direction to the motor speed, the slope assist flag is activated;

[0052] If the slope is greater than the second slope threshold, the slope assist flag is deactivated.

[0053] The method also includes: setting a relationship table of vehicle gear, motor speed and compensation torque according to the vehicle crawling uphill without exceeding the target vehicle speed, and obtaining the compensation torque T2 by looking up the table through the gear and filtered motor speed.

[0054] The method also includes: setting a corresponding table of brake pedal depth and attenuation coefficient according to the driver controlling the creeping speed through the brake pedal when going downhill, and obtaining the attenuation coefficient Ybrk by looking up the brake pedal depth table.

[0055] In practical applications, the slope assist torque TqClimb is first determined by the slope assist flag. When the slope is greater than the threshold c and less than the threshold d, the flag is activated when the gear position and the motor speed are in the opposite direction. When the slope is greater than the threshold d, the flag is deactivated. After the flag is activated, the compensation torque T2 is output according to the gear position and the motor speed after filtering, and the attenuation coefficient Ybrk is output according to the brake pedal depth. The two are multiplied to obtain the slope assist torque; the flag is not activated TqClimb=0.

[0056] Further, the steering wheel angle correction coefficient XSteer is obtained, including:

[0057] Determine whether the steering angle correction function is allowed to be turned on. If the correction function is turned on, the correction coefficient XSteer is obtained by looking up the table according to the steering wheel steering angle. If the correction function is not turned on, the correction coefficient XSteer is a set constant value.

[0058] Furthermore, the activation condition of the steering angle correction function is: the setting is performed when the vehicle speed is greater than the steering-allowed speed, and the setting is canceled when the vehicle speed is less than the steering-prohibited speed.

[0059] Further, the obtaining of the vehicle status signal and determining whether to activate the creep function flag includes:

[0060] The current vehicle speed, actual motor speed, vehicle steering angle, actual throttle and brake pedal opening are collected in real time through the CANFD bus to determine whether the current working condition enters crawling. If so, the crawling function flag is activated.

[0061] It can be seen that the present invention provides a driving anti-skid control method for an electric vehicle, which determines whether to activate the creep function flag based on the vehicle status signal, and if so, outputs its function validity flag and calculates the torque, and then executes the torque output function according to the output torque signal, thereby solving the problems of large torque fluctuations and poor stability in complex working conditions when performing creep control in existing electric vehicles, and can improve the driving stability of the electric vehicle in the creep mode and the driver's participation, and enhance the adaptability to complex working conditions.

[0062] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. A driving anti-skid control method for an electric vehicle, characterized in that: include: Get the vehicle status signal and determine whether the creep function flag is activated. If yes, enter the creep control mode. If not, output the final torque TqOut = 0. According to the vehicle's brake pedal, steering wheel steering angle and the road slope on which the vehicle is traveling, the basic torque TqBase, the crawling auxiliary torque TqClimb and the steering wheel angle correction coefficient XSteer required for crawling are obtained; According to the formula TqOut=XSteer×(TqBase + TqClimb), the final torque TqOut is calculated and given to the torque actuator for creep control.

2. The driving anti-skid control method of an electric vehicle according to claim 1, characterized in that: Get the base torque TqBase, including: A corresponding table of gear position, vehicle speed and torque is set according to empirical data and driving experience, and the output torque T1 is obtained by looking up the table; Calculate the brake correction factor Xbrk according to the brake pedal depth; According to the formula: TqBase=T1×Xbrk, the basic torque TqBase is calculated.

3. The driving anti-skid control method of an electric vehicle according to claim 2, characterized in that: The step of calculating the brake correction coefficient Xbrk according to the brake pedal depth includes: Determine whether the brake pedal depth exceeds the set threshold and the duration reaches the first time threshold a. If yes, Xbrk=0; If not, it is determined whether the brake pedal depth exceeds a set threshold and the duration reaches a second time threshold b. If yes, Xbrk is set to a constant value to limit the basic torque, wherein the second time threshold b is less than the first time threshold a. If not, Xbrk places no limit on the base torque.

4. The driving anti-skid control method of an electric vehicle according to claim 3, characterized in that: Get the creep assist torque TqClimb, including: Determine whether the slope assist flag is activated. If so, calculate the crawl assist torque TqClimb according to the formula: TqClimb = T2×Ybrk, where T2 is the compensation torque required for the vehicle to go uphill and Ybrk is the brake attenuation coefficient.

5. The driving anti-skid control method of an electric vehicle according to claim 4, characterized in that: The step of determining whether the slope assist flag is activated includes: If the vehicle is traveling on a slope greater than a first slope threshold and less than a second slope threshold, causing the gear position to be in the opposite direction to the motor speed, the slope assist flag is activated; If the slope is greater than the second slope threshold, the slope assist flag is deactivated.

6. The driving anti-skid control method of an electric vehicle according to claim 5, characterized in that: Also includes: The relationship table between the gear position, motor speed and compensation torque of the vehicle is set according to the vehicle crawling uphill without exceeding the target vehicle speed, and the compensation torque T2 is obtained by looking up the table through the gear position and the filtered motor speed.

7. The driving anti-skid control method of an electric vehicle according to claim 6, characterized in that: Also includes: According to the driver controlling the creeping speed through the brake pedal when going downhill, a corresponding table between the brake pedal depth and the attenuation coefficient is set, and the attenuation coefficient Ybrk is obtained by looking up the brake pedal depth in the table.

8. The driving anti-skid control method of an electric vehicle according to claim 7, characterized in that: Get the steering wheel angle correction coefficient XSteer, including: Determine whether the steering angle correction function is allowed to be turned on. If the correction function is turned on, the correction coefficient XSteer is obtained by looking up the table according to the steering wheel steering angle. If the correction function is not turned on, the correction coefficient XSteer is a set constant value.

9. The driving anti-skid control method of an electric vehicle according to claim 8, characterized in that: The activation condition of the steering angle correction function is: the setting is performed when the vehicle speed is greater than the allowed steering speed, and the setting is canceled when the vehicle speed is less than the prohibited steering speed.

10. The driving anti-skid control method of an electric vehicle according to claim 9, characterized in that: The obtaining of the vehicle status signal and determining whether to activate the creeping function flag bit includes: The current vehicle speed, actual motor speed, vehicle steering angle, actual throttle and brake pedal opening are collected in real time through the CANFD bus to determine whether the current working condition enters crawling. If so, the crawling function flag is activated.

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