Slip control method, device and electronic equipment for pure electric vehicle

Abstract

This invention discloses a slip control method, apparatus, and electronic device for pure electric vehicles, comprising the following steps: an acquisition step, acquiring wheel speed signals of each wheel of the vehicle; a calculation step, determining a reference vehicle speed based on the wheel speed signals of each wheel, and calculating the actual slip amount of each drive wheel of the vehicle; a braking torque control step, adjusting the braking torque applied to the drive wheels based on the difference between the slip threshold of each drive wheel and the actual slip amount; and a target speed control step, acquiring a target motor speed of the vehicle based on the reference vehicle speed and the average slip threshold, and controlling the motor according to the target speed. This slip control method can fully utilize ground adhesion, reduce drive wheel slippage, and maintain the directional stability of the vehicle.

Description

Technical Field

[0001] This invention relates to the automotive field, and more particularly to a slip control method, apparatus, and electronic device for pure electric vehicles. Background Technology

[0002] Currently, when drivers press the accelerator pedal to start or accelerate a vehicle, the drive wheels often slip, leading to safety accidents and posing a significant threat to vehicle safety. Therefore, there is a need for a method that fully utilizes ground adhesion to reduce drive wheel slippage and maintain the vehicle's directional stability. Summary of the Invention

[0003] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a slip control method, device and electronic device for pure electric vehicles. The slip control method can make full use of the ground adhesion, reduce the slippage of the drive wheels and maintain the directional stability of the vehicle.

[0004] According to one aspect of the present invention, a slip control method for a pure electric vehicle is provided, characterized by comprising the following steps: an acquisition step, acquiring wheel speed signals of each wheel of the vehicle; a calculation step, determining a reference vehicle speed based on the wheel speed signals of each wheel, and calculating the actual slip amount of each drive wheel of the vehicle; a braking torque control step, adjusting the braking torque applied to the drive wheel based on the difference between the slip threshold of each drive wheel and the actual slip amount; and a target speed control step, acquiring a target motor speed of the vehicle based on the reference vehicle speed and the average slip threshold, and controlling the motor according to the target speed.

[0005] Preferably, in the braking torque control step, the difference between the slip threshold of at least one pair of drive wheels and the actual slip amount is respectively input to at least one pair of PID controllers, and the absolute value of the difference between the outputs of at least one pair of PID controllers is applied to the drive wheel with the larger actual slip amount among at least one pair of drive wheels.

[0006] Preferably, the actual slip of each of the drive wheels is obtained by subtracting the vehicle speed of each drive wheel from the reference vehicle speed.

[0007] Preferably, the reference vehicle speed is obtained based on the wheel speed signals of the non-driving wheels of the vehicle.

[0008] Preferably, the difference between the slip threshold of each drive wheel and the actual slip amount is based on feedback control.

[0009] Preferably, the slip threshold of each drive wheel is pre-calibrated in a table corresponding to the reference vehicle speed, and the table is stored in the vehicle.

[0010] Preferably, the target rotational speed is the sum of the reference vehicle speed and the average slip threshold.

[0011] According to another aspect of the present invention, a slip control device for a pure electric vehicle is provided, characterized in that it comprises: an acquisition module for acquiring wheel speed signals of each wheel of the vehicle; a calculation module for determining a reference vehicle speed based on the wheel speed signals of each wheel and calculating the actual slip amount of each drive wheel of the vehicle; a braking torque control module for adjusting the braking torque applied to the drive wheels based on the difference between the slip threshold of each drive wheel and the actual slip amount; and a target speed control module for acquiring a target motor speed of the vehicle based on the reference vehicle speed and the average slip threshold, and controlling the motor according to the target speed.

[0012] Preferably, in the braking torque control module, the difference between the slip threshold of at least one pair of drive wheels and the actual slip amount is respectively input to at least one pair of PID controllers, and the absolute value of the difference between the outputs of at least one pair of PID controllers is applied to the drive wheel with the larger actual slip amount among at least one pair of drive wheels.

[0013] According to another aspect of the present invention, an electronic device is provided, characterized in that it comprises: at least one processor and a memory, the memory storing computer execution instructions, the at least one processor executing the computer execution instructions stored in the memory, causing the at least one processor to perform the method described above.

[0014] According to another aspect of the present invention, a computer-readable storage medium is provided, characterized in that the computer-readable storage medium stores at least one instruction or at least one program, wherein the at least one instruction or at least one program is loaded and executed by a processor to implement the above-described method.

[0015] According to the present invention, ground adhesion can be fully utilized to reduce slippage of the drive wheels and maintain the directional stability of the vehicle. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of a skid control method for pure electric vehicles provided in an embodiment of the present invention.

[0017] Figure 2 This is a control block diagram of the braking torque control step in the slip control method for pure electric vehicles provided in the embodiments of the present invention.

[0018] Figure 3 A schematic diagram of the slip control device for pure electric vehicles provided in this embodiment of the invention.

[0019] Figure 4 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the invention. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0021] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the said feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded.

[0022] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0023] Figure 1 This is a flowchart illustrating a skid control method for pure electric vehicles provided in an embodiment of the present invention. This specification provides the method operation steps as shown in the embodiments or flowcharts, but based on conventional or non-inventive labor, more or fewer operation steps may be included. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only possible execution order. In actual system or server product execution, the method can be executed sequentially according to the embodiments or drawings, or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0024] like Figure 1 As shown, the slip control method for pure electric vehicles provided in this embodiment includes the following steps.

[0025] Step S101: Obtain the wheel speed signals of each wheel of vehicle 1.

[0026] Vehicle 1 can be a two-wheel drive vehicle or a four-wheel drive vehicle; in this embodiment, a front-wheel drive vehicle will be used as an example. That is, the drive wheels of vehicle 1 are the left front wheel (FL) and the right front wheel (FR), and the non-drive wheels are the left rear wheel (RL) and the right rear wheel (RR). The wheel speed signals of each wheel can be obtained by sensor devices such as wheel speed sensors installed on vehicle 1.

[0027] Step S102: Determine the reference vehicle speed based on the wheel speed signals of each wheel, and calculate the actual slip of each drive wheel of the vehicle.

[0028] By obtaining the wheel speed signals of each wheel in step S101, the vehicle speed of each wheel can be obtained. The speed of the left front wheel is denoted as V_FL, the speed of the right front wheel as V_FR, the speed of the left rear wheel as V_RL, and the speed of the right rear wheel as V_RR.

[0029] The reference speed of vehicle 1 can be calculated using the following formula (1) based on the speeds of the non-driving wheels, namely the left rear wheel RL and the right rear wheel RR.

[0030] V_REF=(V_RL+V_RR) / 2 (1)

[0031] Where V_REF represents the reference speed of vehicle 1.

[0032] The actual slip of the drive wheels (left front wheel FL and right front wheel FR) can be obtained by subtracting the speed of the left front wheel FL and the right front wheel FR from the reference speed, respectively. That is, it can be calculated according to the following formulas (2) and (3).

[0033] SLIP_FL=V_FL–V_REF (2)

[0034] SLIP_FR=V_FR–V_REF (3)

[0035] Wherein, SLIP_FL represents the actual slip of the left front wheel FL, and SLIP_FR represents the actual slip of the right front wheel FR.

[0036] Step S103: Adjust the braking torque applied to the drive wheels based on the difference between the slip threshold of each drive wheel and the actual slip amount.

[0037] The slip threshold of the drive wheels is the target slip value of the drive wheels. Furthermore, the slip threshold also serves as the activation and deactivation condition for the braking control of the entire traction controller. When the actual slip amount is lower than the slip threshold, the braking control is not activated; when the actual slip amount exceeds the slip threshold, the braking control is activated. If the actual slip amount is lower than the slip threshold for a preset time after the braking control is activated, the braking control deactivates. The slip thresholds of each drive wheel are pre-calibrated in a table corresponding to the reference vehicle speed, and this table is stored in vehicle 1. Therefore, the corresponding calibrated slip threshold value can be found and determined in the table based on the reference vehicle speed of vehicle 1. In this embodiment, the slip threshold of the left front wheel FL is set to Command_FL, and the slip threshold of the right front wheel FR is set to Command_FR.

[0038] Figure 2 This is a control block diagram of the braking torque control step in the slip control method for pure electric vehicles provided in an embodiment of the present invention. The following is based on... Figure 2 The specific control methods in the braking torque control steps are explained.

[0039] In this embodiment, the difference between the slip thresholds Command_FL and Command_FR of a pair of drive wheels (left front wheel FL and right front wheel FR) and the actual slip amounts SLIP_FL and SLIP_FR are respectively input to the PID controllers 110 and 120.

[0040] A PID controller is a control loop feedback mechanism that attempts to minimize errors by adjusting the process control input. A PID controller typically uses three control tuning parameters: proportional, integral, and derivative. The PID controller is a general architecture for implementing closed-loop speed control. The following equation (4) provides the general form for a PID control scheme.

[0041]

[0042] Where u is the controller output, K p For proportional gain, K i For integral gain, K d Let e ​​be the differential gain, e be the error, and t be the time.

[0043] In this embodiment, the inputs of PID controllers 110 and 120, namely the error terms e1(t) and e2(t), are respectively given by equations (5) and (6).

[0044] e1(t)=SLIP_FL(t)–Command_FL(t) (5)

[0045] e2(t)=SLIP_FR(t)–Command_FR(t) (6)

[0046] We can see that e1(t) and e2(t) are the differences between the current left front wheel slip threshold Command_FL and the current left front wheel slip amount SLIP_FL, and the current right front wheel slip threshold Command_FR and the current right front wheel slip amount SLIP_FR, respectively.

[0047] In this embodiment, the outputs of PID controllers 110 and 120 can be written as equations (7) and (8) respectively.

[0048]

[0049]

[0050] Proportional Gain K p1 K p2 Integral gain K i1 K i2 Differential gain K i1 K i2 The calibration values ​​are pre-calibrated in a table corresponding to the reference vehicle speed, and this table is stored in vehicle 1. Therefore, the calibration value of the corresponding coefficient can be found and determined in the table based on the reference vehicle speed of vehicle 1.

[0051] The final output is the absolute value of the difference between the outputs of PID controllers 110 and 120. That is, u(t) = abs[u1(t) – u2(t)]. The braking torque u(t) of this final output is input to the brake actuator and applied to the drive wheel with the larger actual slippage in a pair of drive wheels (left front wheel FL, right front wheel FR).

[0052] Step S104: Obtain the target motor speed of the vehicle based on the reference vehicle speed and the average slip threshold, and control the motor according to the target speed.

[0053] The target speed of the motor can be obtained by adding the reference vehicle speed to the average slip threshold. The average slip threshold is obtained by averaging the slip thresholds of each drive wheel. In this embodiment, the average slip threshold = (Command_FL + Command_FR) / 2.

[0054] The calculation of the target speed of the motor involves unit conversion, because the unit of the reference vehicle speed is kilometers per hour (kph), while the unit of the target speed of the motor is revolutions per minute (rpm).

[0055] Specifically, in some embodiments, the conversion can be performed according to the following formula (9).

[0056]

[0057] Where r is the rolling radius of the wheel, and pi is pi (circumference of a circle).

[0058] Therefore, in the slip control method for pure electric vehicles involved in this invention, during the driving process after the vehicle starts, the braking torque calculated by this method is applied to the drive wheels, and the target speed of the motor is always calculated and sent to the motor so that the motor controls the actual speed near the target speed, thereby reducing the slippage of the drive wheels.

[0059] In actual working conditions, there are roughly three situations:

[0060] 1) Both the left and right front wheels are on low-friction surfaces. At this time, the slippage of the two wheels is large, but the difference should not be significant. The outputs of the two PID controllers are not significantly different, and the final difference (i.e., braking torque) is not large. Therefore, the braking effect is very small, and the motor needs to respond to the target speed.

[0061] 2) Both the left and right front wheels are on the high-friction surface. At this time, the slippage of the two wheels is very small, but it should not be much different. The output results of the two PID controllers are also not much different, and the final difference (i.e., braking torque) is not large. Therefore, the braking effect is very small, and the motor needs to respond to the target speed.

[0062] 3) The left front wheel and the right front wheel are on the low-friction and high-friction road surfaces respectively. At this time, the wheel on the low-friction side has a large slippage, while the wheel on the high-friction side has a small slippage (or almost no slippage). The calculated braking torque will then be applied to the wheel with the large slippage, allowing the vehicle to start using the high-friction side.

[0063] Therefore, it can be seen that the slip control method for pure electric vehicles according to the present invention can make full use of ground adhesion and reduce the slippage of the drive wheels in almost all actual working conditions, thereby improving the stability of vehicle driving.

[0064] This embodiment uses a front-wheel drive vehicle as an example, but it can also be applied to rear-wheel drive vehicles, and even four-wheel drive vehicles. In the case of a four-wheel drive vehicle... Figure 2 The control block diagram of the braking torque control step shown requires the addition of another pair of PID controllers. The input of the controllers is the difference between the slip threshold of the other pair of drive wheels and the actual slip amount. Then, the absolute value of the difference between the outputs of the other pair of PID controllers is applied to the drive wheel with the larger actual slip amount in the other pair of drive wheels.

[0065] Figure 3 A schematic diagram of the slip control device for pure electric vehicles provided in this embodiment of the invention.

[0066] like Figure 3 As shown, the skid control device 200 for pure electric vehicles includes: an acquisition module 201, a calculation module 202, a braking torque control module 203, and a target speed control module 203.

[0067] The acquisition module 201 acquires the wheel speed signals of each wheel of vehicle 1. The calculation module 202 determines the reference vehicle speed of vehicle 1 based on the wheel speed signals of each wheel and calculates the actual slip of each drive wheel of vehicle 1. The braking torque control module 203 adjusts the braking torque applied to the drive wheels based on the difference between the slip threshold and the actual slip of each drive wheel. Specifically, the difference between the slip threshold and the actual slip of at least one pair of drive wheels is input to at least one pair of PID controllers, and the absolute value of the difference between the outputs of at least one pair of PID controllers is applied to the drive wheel with the larger actual slip of the at least one pair of drive wheels. The target speed control module 203 acquires the target motor speed of vehicle 1 based on the reference vehicle speed and the average slip threshold, and controls the motor according to the target speed.

[0068] The apparatus and method embodiments in this invention are based on the same application concept.

[0069] This application provides an electronic device 300, characterized in that it includes: at least one processor 301 and a memory 302, wherein the memory 302 stores computer execution instructions, and the at least one processor 301 executes the computer execution instructions stored in the memory 302, causing the at least one processor to execute the above-described method for calculating the peak road adhesion coefficient.

[0070] This invention also provides a computer storage medium, characterized in that the storage medium stores at least one instruction or at least one program, wherein the at least one instruction or at least one program is loaded and executed by a processor to implement the above-described method for calculating the peak adhesion coefficient of the road surface.

[0071] Optionally, in this embodiment, the storage medium may be located at at least one of the multiple network servers in a computer network. Optionally, in this embodiment, the storage medium may include, but is not limited to, various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0072] Those skilled in the art will recognize that the modules, units, and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of electronic hardware and software, the components and steps of the examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can implement the described functions using different methods for each specific application, but such implementations should not be considered beyond the scope of the invention.

[0073] Although the present invention has been described with reference to specific embodiments, those skilled in the art should recognize that the scope of the invention is not limited to the specific combinations of the above-described technical features, but also includes other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the present invention.

Claims

1. A slip control method for pure electric vehicles, characterized in that, Includes the following steps: The acquisition step involves acquiring the wheel speed signals of each wheel of the vehicle. The calculation steps involve determining the reference vehicle speed based on the wheel speed signals of each wheel, and calculating the actual slippage of each drive wheel of the vehicle. The braking torque control step adjusts the braking torque applied to the drive wheels based on the difference between the slip threshold of each drive wheel and the actual slip amount, wherein the slip threshold of the drive wheel is a target value for the slip of the drive wheel; and The target speed control step involves obtaining the target motor speed of the vehicle based on the reference vehicle speed and the average slip threshold, and controlling the motor according to the target speed. The average slip threshold is the average value of the slip thresholds of the drive wheels. In the braking torque control step, the difference between the slip threshold of at least one pair of drive wheels and the actual slip amount is respectively input to at least one pair of PID controllers, and the absolute value of the difference output by at least one pair of PID controllers is applied to the drive wheel with the larger actual slip amount among at least one pair of drive wheels.

2. The slip control method for pure electric vehicles as described in claim 1, characterized in that, The actual slip of each of the drive wheels is obtained by subtracting the vehicle speed of each drive wheel from the reference vehicle speed.

3. The slip control method for pure electric vehicles as described in claim 1 or 2, characterized in that, The reference vehicle speed is obtained based on the wheel speed signals of the non-driving wheels of the vehicle.

4. The slip control method for pure electric vehicles as described in claim 1 or 2, characterized in that, The difference between the slip threshold of each drive wheel and the actual slip amount is based on feedback control.

5. The slip control method for pure electric vehicles as described in claim 1 or 2, characterized in that, The slip threshold of each drive wheel is pre-calibrated in a table corresponding to the reference vehicle speed, and the table is stored in the vehicle.

6. The slip control method for pure electric vehicles as described in claim 1 or 2, characterized in that, The target rotational speed is the sum of the reference vehicle speed and the average slip threshold.

7. A skid control device for a pure electric vehicle, characterized in that, include: The acquisition module acquires the wheel speed signals of each wheel of the vehicle; The calculation module determines the reference speed of the vehicle based on the wheel speed signals of each wheel, and calculates the actual slippage of each drive wheel of the vehicle. A braking torque control module adjusts the braking torque applied to each drive wheel based on the difference between the slip threshold of each drive wheel and the actual slip amount, wherein the slip threshold of each drive wheel is a target slip value of the drive wheel; and The target speed control module obtains the target motor speed of the vehicle based on the reference vehicle speed and the average slip threshold, and controls the motor according to the target speed. The average slip threshold is the average value of the slip thresholds of the drive wheels. In the braking torque control module, the difference between the slip threshold of at least one pair of drive wheels and the actual slip amount is respectively input to at least one pair of PID controllers, and the absolute value of the difference output by at least one pair of PID controllers is applied to the drive wheel with the larger actual slip amount among at least one pair of drive wheels.

8. An electronic device, characterized in that, include: At least one processor and memory, The memory stores computer-executed instructions. The at least one processor executes computer execution instructions stored in the memory, causing the at least one processor to perform the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores at least one instruction or at least one program, which is loaded and executed by a processor to implement the method as described in any one of claims 1 to 6.

Images