A drive slip control method for an electric vehicle

Abstract

The application discloses a kind of electric vehicle's drive anti-skid control method, comprising: obtaining vehicle state signal and judging whether to activate crawl function flag bit, if yes, enter crawl control mode, if no, output final torque TqOut=0;According to the brake pedal of vehicle, steering wheel steering angle and the road slope of vehicle travel, obtain the corresponding base torque TqBase required for crawling, crawl auxiliary torque TqClimb and steering wheel angle correction coefficient XSteer;According to formula TqOut=XSteer×(TqBase+TqClimb), final torque TqOut is calculated, and the final torque TqOut calculated is given torque actuator, to carry out crawl control.The application can improve the driving stability of electric vehicle in crawl mode and the participation of driver, and enhance the adaptability to complex working conditions.

Description

Technical Field

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

[0002] With increasing global emphasis on energy conservation and environmental protection policies, electric vehicles (EVs), with their zero emissions, low noise, and high efficiency, are gradually becoming an important direction for future transportation development. EVs achieve stable driving under various operating conditions by precisely controlling the torque and speed of their motors. However, the driving state of EVs is affected by various factors, such as slope and road conditions. Crawl control, as one of the basic driving control modes, has a wide range of applications, such as vehicle start-up and slow following. Existing crawl control systems mostly use PID control, which, if the parameters are not set properly, can lead to large torque fluctuations and poor stability under conditions such as starting on slopes or complex road surfaces. Furthermore, existing control systems do not fully consider changes in vehicle status information and driver needs, making crawl control unable to meet the demands of complex driving conditions in real-world scenarios. Therefore, providing an effective information exchange method that can quickly and reliably transmit key information between multiple modules to ensure the real-time performance, stability, and safety of autonomous driving systems has become an important research direction in the current technological field. Summary of the Invention

[0003] This invention provides a driving anti-slip control method for electric vehicles, which solves the problems of large torque fluctuations and poor stability in complex working conditions when existing electric vehicles perform creep control. It can improve the driving stability of electric vehicles in creep mode and the driver's participation, and enhance their adaptability to complex working conditions.

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

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

[0006] Acquire vehicle status signals and determine whether the crawl function flag is activated. If yes, enter crawl control mode; otherwise, output the final torque TqOut = 0.

[0007] Based on the vehicle's brake pedal, steering wheel angle, and road surface gradient, obtain the base torque TqBase, crawl assist torque TqClimb, and steering wheel angle correction coefficient XSteer required for crawling.

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

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

[0010] Based on experience data and driving experience, a table showing the correspondence between gear, vehicle speed, and torque is set up, and the output torque T1 is obtained by looking up the table.

[0011] Calculate the braking correction factor Xbrk based on the brake pedal depth;

[0012] The basic torque TqBase is calculated using the formula: TqBase=T1×Xbrk.

[0013] Preferably, the step of calculating the braking correction coefficient Xbrk based on 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 so, Xbrk=0.

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

[0016] If not, Xbrk does not impose a limit on the base torque.

[0017] Preferably, obtaining the crawling 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 climb the slope and Ybrk is the braking attenuation coefficient.

[0019] Preferably, determining whether the slope auxiliary flag is activated includes:

[0020] If the gradient of the vehicle is greater than the first gradient threshold but less than the second gradient threshold, causing the gear position and motor speed to be opposite, then the gradient assist flag will be activated.

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

[0022] Preferred options also include:

[0023] Based on the relationship table of vehicle speed, motor speed and compensation torque for uphill crawling without exceeding the target speed, the compensation torque T2 is obtained by looking up the table using the gear and the filtered motor speed.

[0024] Preferred options also include:

[0025] Based on the driver's control of the crawling speed by using the brake pedal when going downhill, a table corresponding to the brake pedal depth and the attenuation coefficient is set up, and the attenuation coefficient Ybrk is obtained by looking up the table by the brake pedal depth.

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

[0027] Determine whether the steering angle correction function is allowed. If the correction function is enabled, obtain the correction coefficient XSteer from the table based on the steering wheel angle. If the correction function is not enabled, the correction coefficient XSteer is a set constant value.

[0028] Preferably, the steering angle correction function is activated when the vehicle speed is greater than the permissible steering speed and deactivated when the vehicle speed is less than the prohibited steering speed.

[0029] Preferably, the step of acquiring the vehicle status signal and determining whether the crawl function flag is activated includes:

[0030] The current vehicle speed, actual motor speed, vehicle steering angle, and actual throttle and brake pedal openings are collected in real time via the CANFD bus to determine whether the current operating condition has entered the crawling state. If so, the crawling function flag is activated.

[0031] This invention provides a drive anti-slip control method for electric vehicles. Based on the vehicle status signal, it determines whether the crawl function flag is activated. If activated, it outputs the function validity flag and calculates the torque. Then, it executes the torque output function according to the output torque signal. This solves the problem of large torque fluctuation and poor stability in complex conditions when existing electric vehicles perform crawl control. It can improve the driving stability of electric vehicles in crawl mode and the driver's participation, and enhance the adaptability to complex conditions. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below.

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

[0034] Figure 2 This is a logic flowchart of crawling control provided in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the embodiments of the present invention, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and implementation methods.

[0036] To address the problems existing in current electric vehicles' crawl control, this invention provides a drive anti-slip control method for electric vehicles. This method solves the problems of large torque fluctuations and poor stability in complex operating conditions when existing electric vehicles perform crawl control. It can improve the driving stability and driver participation of electric vehicles in crawl mode and enhance their adaptability to complex operating conditions.

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

[0038] S1: Obtain the vehicle status signal and determine whether the crawl function flag is activated. If yes, enter the crawl control mode; otherwise, output the final torque TqOut = 0.

[0039] S2: Based on the vehicle's brake pedal, steering wheel angle, and road surface slope, obtain the base torque TqBase, crawl assist torque TqClimb, and steering wheel angle correction coefficient XSteer required for crawling.

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

[0041] Specifically, vehicle status signals include: current vehicle speed, actual motor speed, vehicle steering angle, and actual throttle and brake pedal openings. Based on these signals, it is determined whether the vehicle is currently in a crawling state. If so, the crawling function flag is activated, and torque is calculated. The calculated torque is then output to the torque actuator for vehicle crawling control. The flag can be calculated using the following formula: Automatic Parking Enable && EPB Status && AVH Status && Cruise Status && Vehicle Operating Mode. The crawling torque calculation consists of three parts: basic crawling 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 engagement of electric vehicles in crawl mode, while also enhancing adaptability to complex operating conditions.

[0042] Furthermore, the basic torque TqBase is obtained, including: setting a correspondence table between gear, vehicle speed and torque based on experience data and driving experience, and looking up the table to obtain the output torque T1; calculating the braking correction coefficient Xbrk based on the brake pedal depth; and calculating the basic torque TqBase according to the formula: TqBase=T1×Xbrk.

[0043] Furthermore, the calculation of the braking correction coefficient Xbrk based on 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 so, Xbrk=0.

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

[0046] If not, Xbrk does not impose a limit on the base torque.

[0047] In practical applications, the base creep torque TqBase is used, and the torque T1 is output from a table based on the gear and vehicle speed. The table selects the best data based on experience and driving experience to achieve optimal stability and drivability. Furthermore, the driver controls the creep speed according to needs to obtain the brake pedal depth, and derives the braking correction coefficient Xbrk based on the brake pedal depth.

[0048] Furthermore, the crawling 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 climb the slope and Ybrk is the braking attenuation coefficient.

[0050] Furthermore, determining whether the slope auxiliary flag is activated includes:

[0051] If the gradient of the vehicle is greater than the first gradient threshold but less than the second gradient threshold, causing the gear position and motor speed to be opposite, then the gradient assist flag will be activated.

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

[0053] The method also includes: setting a relationship table between the vehicle's gear, motor speed, and compensation torque based on the vehicle's uphill crawling speed not exceeding the target speed, and obtaining the compensation torque T2 by looking up the table using the gear and the filtered motor speed.

[0054] The method also includes: setting a correspondence table between brake pedal depth and attenuation coefficient based on the driver controlling the crawling speed through the brake pedal when going downhill, and obtaining the attenuation coefficient Ybrk by looking up the table through the brake pedal depth.

[0055] In practical applications, the slope assist torque TqClimb is determined by first checking the slope assist flag. The flag is activated when the slope is greater than threshold c but less than threshold d, causing the gear position and motor speed to be in opposite directions. The flag is deactivated when the slope is greater than threshold d. After activation, the compensation torque T2 is output from a table based on the gear position and the filtered motor speed, and the attenuation coefficient Ybrk is output from a table based on the brake pedal depth. Multiplying these two values ​​yields the slope assist torque. If the flag is not activated, TqClimb = 0.

[0056] Furthermore, obtain the steering wheel angle correction coefficient XSteer, including:

[0057] Determine whether the steering angle correction function is allowed. If the correction function is enabled, obtain the correction coefficient XSteer from the table based on the steering wheel angle. If the correction function is not enabled, the correction coefficient XSteer is a set constant value.

[0058] Furthermore, the activation condition for the steering angle correction function is: it is activated when the vehicle speed is greater than the permissible steering speed, and deactivated when the vehicle speed is less than the prohibited steering speed.

[0059] Furthermore, the step of acquiring the vehicle status signal and determining whether the crawling function flag is activated includes:

[0060] The current vehicle speed, actual motor speed, vehicle steering angle, and actual throttle and brake pedal openings are collected in real time via the CANFD bus to determine whether the current operating condition has entered the crawling state. If so, the crawling function flag is activated.

[0061] As can be seen, the present invention provides a driving anti-slip control method for electric vehicles. Based on the vehicle status signal, it determines whether the crawl function flag is activated. If so, it outputs the function validity flag and calculates the torque. Then, it executes the torque output function according to the output torque signal. This solves the problem of large torque fluctuation and poor stability in complex working conditions when existing electric vehicles perform crawl control. It can improve the driving stability of electric vehicles in crawl mode and the driver's participation, and enhance the adaptability to complex working conditions.

[0062] The structure, features, and effects of the present invention have been described in detail above with reference to the embodiments shown in the figures. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall be within the protection scope of the present invention as long as they do not exceed the spirit covered by the specification and figures.

Claims

1. A method for driving anti-skid control of an electric vehicle, characterized in that, include: Acquire vehicle status signals and determine whether the crawl function flag is activated. If yes, enter crawl control mode; otherwise, output the final torque TqOut = 0. Based on the vehicle's brake pedal, steering wheel angle, and road surface gradient, obtain the base torque TqBase, crawl assist torque TqClimb, and steering wheel angle correction coefficient XSteer required for crawling. The final torque TqOut is calculated according to the formula TqOut=XSteer×(TqBase + TqClimb), and the calculated final torque TqOut is given to the torque actuator for creep control. To obtain the base torque TqBase, the following is included: Based on experience data and driving experience, a table showing the correspondence between gear, vehicle speed, and torque is set up, and the output torque T1 is obtained by looking up the table. Calculate the braking correction factor Xbrk based on the brake pedal depth; The base torque TqBase is calculated using the formula: TqBase=T1×Xbrk. The calculation of the braking correction coefficient Xbrk based on 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 so, Xbrk=0. If not, determine whether the brake pedal depth exceeds the set threshold and the duration reaches the second time threshold b. If yes, Xbrk is a set constant value to limit the base torque, wherein the second time threshold b is less than the first time threshold a. If not, Xbrk does not impose a limit on the base torque.

2. The drive anti-skid control method for electric vehicles according to claim 1, characterized in that, To obtain the crawling assist torque TqClimb, the following is included: 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 climb the slope and Ybrk is the braking attenuation coefficient.

3. The method for driving anti-slip control of an electric vehicle according to claim 2, characterized in that, The determination of whether the slope auxiliary flag is activated includes: If the gradient of the vehicle is greater than the first gradient threshold but less than the second gradient threshold, causing the gear position and motor speed to be opposite, then the gradient assist flag will be activated. If the slope is greater than the second slope threshold, the slope auxiliary flag is deactivated.

4. The drive anti-slip control method for electric vehicles according to claim 3, characterized in that, Also includes: Based on the relationship table of vehicle speed, motor speed and compensation torque for uphill crawling without exceeding the target speed, the compensation torque T2 is obtained by looking up the table using the gear and the filtered motor speed.

5. The drive anti-slip control method for electric vehicles according to claim 4, characterized in that, Also includes: Based on the driver's control of the crawling speed by using the brake pedal when going downhill, a table corresponding to the brake pedal depth and the attenuation coefficient is set up, and the attenuation coefficient Ybrk is obtained by looking up the table by the brake pedal depth.

6. The method for driving anti-slip control of an electric vehicle according to claim 5, characterized in that, To obtain the steering wheel angle correction factor XSteer, the following is included: Determine whether the steering angle correction function is allowed. If the correction function is enabled, obtain the correction coefficient XSteer from the table based on the steering wheel angle. If the correction function is not enabled, the correction coefficient XSteer is a set constant value.

7. The drive anti-slip control method for electric vehicles according to claim 6, characterized in that, The steering angle correction function is activated when the vehicle speed is greater than the permissible steering speed and deactivated when the vehicle speed is less than the prohibited steering speed.

8. The method for driving anti-slip control of an electric vehicle according to claim 7, characterized in that, The step of acquiring the vehicle status signal and determining whether the crawl function flag is activated includes: The current vehicle speed, actual motor speed, vehicle steering angle, and actual throttle and brake pedal openings are collected in real time via the CANFD bus to determine whether the current operating condition has entered the crawling state. If so, the crawling function flag is activated.

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