Friction compensation method for automobile electric power steering system

Abstract

The invention relates to the technical field of automobile auxiliary driving, and provides a friction compensation method for an automobile electric power steering system, which comprises the following steps of: obtaining a torque demand degree according to a change condition of an input torque; obtaining a compensation starting moment according to the input torque and the vehicle speed; according to the torque demand degree from the compensation starting moment to the target moment, the torque process amount is obtained; according to the cumulative change relation of the torque process quantity from the compensation starting moment to the target moment, the steering scene efficiency is obtained; obtaining a dynamic vehicle speed weight; obtaining a mapping torque according to the input torque at the target moment, the dynamic vehicle speed weight and the steering scene efficiency; obtaining a torque compensation amount according to the torque demand degree and the mapping torque; the compensated torque is obtained according to the torque compensation amount, and driving adjustment is conducted on the steering motor according to the compensated torque; in the driving and adjusting process of the steering motor, more accurate friction compensation is carried out on automobile running according to the expected rotating angle and the input angle, and the stability of automobile running is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive auxiliary drive, and particularly to a friction compensation method for an automotive electric power steering system. Background Art

[0002] An automotive electric power steering system is a steering technology that provides auxiliary torque through an electric motor, replacing the traditional hydraulic power steering system. Its core consists of a torque sensor, an electronic control unit (ECU), and an assist motor. When the driver turns the steering wheel, the sensor real-time detects signals such as steering torque and vehicle speed. The ECU calculates the required assist force and controls the motor to output the corresponding auxiliary force, making the steering more lightweight and precise. This system has advantages such as low energy consumption, compact structure, and the ability to dynamically adjust the assist force according to the vehicle speed. At the same time, it avoids the problem of hydraulic oil leakage, significantly improving energy efficiency and driving safety, and is widely used in modern intelligent vehicles.

[0003] In order to eliminate the non-ideal interference caused by the frictional resistance of mechanical components in the steering mechanism and ensure precise and controllable steering assistance, an automotive electric power steering system needs to perform friction compensation. During the steering process, friction will cause a deviation between the actual steering torque and the sensor signal, affecting the ECU's judgment of the driver's intention and resulting in problems such as a rigid steering feel, dead zone, or hysteresis. Through the friction compensation algorithm, the ECU can dynamically identify and offset the influence of friction, making the assist force output by the motor more matched with the driver's operation, improving the steering smoothness, linearity, and authenticity of the feedback. At the same time, it enhances the lightness of low-speed steering and the stability of high-speed driving, ensuring driving safety and a comfortable experience.

[0004] The existing technology combines the frictional interferences from different sources such as viscous friction, Coulomb friction, and tire-road friction in an electric power steering system into a comprehensive friction torque model, and uses a linear superposition formula or a static look-up table method for unified compensation. This method has low accuracy in judging the dominant factors of the friction influence at each moment during vehicle travel, resulting in frequent changes in the direction of the output compensation amount. Moreover, the compensation amount changes faster at high speeds, leading to frequent changes in the direction of the friction torque and affecting the vehicle driving stability. Summary of the Invention

[0005] The present invention provides a friction compensation method for an automotive electric power steering system to solve the problem that the frequent change of the direction of the existing friction torque affects the vehicle driving stability. The specific technical solutions adopted are as follows: The present invention proposes a friction compensation method for an automotive electric power steering system, which includes the following steps: Obtain the input torque, input angle, and vehicle speed at each moment during vehicle travel; According to the change of the input torque, obtain the torque demand degree at each moment; obtain the start compensation moment according to the input torque and the vehicle speed; record any moment during the compensation process after the start compensation moment as the target moment; obtain the torque process quantity at the target moment according to the torque demand degree from the start compensation moment to the target moment; obtain the steering scenario efficiency at the target moment according to the cumulative change relationship of the torque process quantity from the start compensation moment to the target moment. Obtain the dynamic vehicle speed weight at the target moment according to the vehicle speed at the target moment; obtain the mapped torque at the target moment according to the input torque, the dynamic vehicle speed weight and the steering scenario efficiency at the target moment; obtain the torque compensation quantity at the target moment according to the change of the torque demand degree and the mapped torque at the target moment. Obtain the compensated torque at the target moment according to the torque compensation quantity at the target moment, and drive and adjust the steering motor according to the compensated torque at the target moment; obtain the expected rotation angle at the target moment according to the compensated torque at the target moment, and during the process of driving and adjusting the steering motor, according to the similarity relationship between the expected rotation angle and the input angle, use the electric power steering system of the vehicle to perform friction compensation on the vehicle driving.

[0006] Further, the specific method for obtaining the torque demand degree at each moment according to the change of the input torque includes: For any moment, the ratio of the difference obtained by subtracting the input torque at the previous moment from the input torque at this moment to the preset acquisition interval is recorded as the torque demand degree at this moment.

[0007] Further, the specific method for obtaining the start compensation moment according to the input torque and the vehicle speed includes: Take the vehicle speed being greater than the preset vehicle speed threshold and the input torque being greater than the preset torque threshold as the compensation condition; During the vehicle driving process, if the current moment satisfies the compensation condition while the previous moment does not, then take the current moment as the start compensation moment.

[0008] Further, the specific method for obtaining the torque process quantity at the target moment according to the torque demand degree from the start compensation moment to the target moment includes: Obtain the mean value and the standard deviation of the torque demand degrees at all moments from the start compensation moment to the target moment, and the ratio of the difference obtained by subtracting the mean value from the torque demand degree at the target moment to the standard deviation is recorded as the torque process quantity at the target moment.

[0009] Further, the specific method for obtaining the steering scenario efficiency at the target moment according to the cumulative change relationship of the torque process quantity from the start compensation moment to the target moment includes: The cube of the torque process quantity at any moment from the start compensation moment to the target moment is denoted as the torque degree at that moment. The sum of the torque degrees at all moments from the start compensation moment to the target moment is denoted as the steering scenario efficiency at the target moment.

[0010] Further, the specific method for obtaining the dynamic vehicle speed weight at the target moment according to the vehicle speed at the target moment includes: The inverse proportional normalization result of the ratio of the preset acquisition interval to the vehicle speed at the target moment is denoted as the dynamic vehicle speed weight at the target moment.

[0011] Further, the specific method for obtaining the mapped torque at the target moment according to the input torque, dynamic vehicle speed weight, and steering scenario efficiency at the target moment includes: The calculation method of the mapped torque at the target moment is: In the formula, is the mapped torque at the target moment; is the dynamic vehicle speed weight at the target moment; is the input torque at the target moment; is the steering scenario efficiency at the target moment; is the steering scenario efficiency at the previous moment of the target moment; is a hyperparameter.

[0012] Further, the specific method for obtaining the torque compensation amount at the target moment according to the change of the torque demand degree at the target moment and the mapped torque includes: The calculation method of the torque compensation amount at the target moment is: In the formula, is the torque compensation amount at the target moment; is the torque demand degree at the target moment; is the torque demand degree at the previous moment of the target moment; is the preset friction coefficient; is the mapped torque at the target moment; is the absolute value function; is a hyperparameter.

[0013] Further, the specific method for obtaining the compensated torque at the target moment according to the torque compensation amount at the target moment and driving and adjusting the steering motor according to the compensated torque at the target moment includes: The sum of the torque compensation amount at the target moment and the input torque at the target moment is denoted as the compensated torque at the target moment; The ratio of the compensated torque at the target moment to the motor torque constant is denoted as the steering motor drive current at the target moment, and at the target moment, the steering motor is driven and adjusted using the steering motor drive current at the target moment, thereby controlling vehicle steering.

[0014] Further, during the process of driving and adjusting the steering motor, according to the similarity relationship between the expected angle and the input angle, the automotive electric power steering system is used to perform friction compensation for vehicle driving. The specific method includes: Using the compensated torque at the target moment, according to the response curve of the steering wheel angle and torque of the vehicle during driving, the expected angle at the target moment is obtained; At each moment after the start compensation moment, the steering control motor is controlled to steer using the steering motor drive current corresponding to each moment. Until the current input angle is equal to the expected angle, if the vehicle meets the compensation condition, the current moment is used as the new start compensation moment, and the friction of the automotive electric power steering system is compensated according to the above method. If the vehicle does not meet the compensation condition, no friction compensation is performed.

[0015] The beneficial effects of the present invention are as follows: When performing friction compensation using the automotive electric power steering system, it is necessary to clarify whether the driver needs the vehicle to steer. The present invention obtains the steering scenario efficiency through the torque process quantity at the target moment to determine whether the driving scenario where the driver is currently located requires steering; when performing friction compensation on the vehicle, the faster the vehicle speed, the greater the deviation will be formed by a small steering of the vehicle. The present invention obtains the dynamic vehicle speed weight and uses the dynamic vehicle speed weight to adjust the input torque, improving the stability of the input torque in the case of a higher vehicle speed; when the driver controls the vehicle to steer, the present invention obtains the torque compensation amount at the target moment through the change situation of the torque demand degree at the target moment and the mapped torque, and then obtains the compensated torque, and drives and adjusts the steering motor. Thus, the present invention performs friction compensation using the automotive electric power steering system through the torque compensation amount, improving the stability of vehicle driving. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a schematic flow chart of a friction compensation method for an automotive electric power steering system provided by an embodiment of the present invention. Detailed Embodiments

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] Please refer to Figure 1 , which shows a flowchart of a friction compensation method for an automotive electric power steering system provided by an embodiment of the present invention. The method includes the following steps: Step S001: Obtain the input torque, input angle, and vehicle speed at each moment during the vehicle driving process.

[0020] It should be noted that when performing friction compensation on the automotive electric power steering system, it is first necessary to collect the driving data of the vehicle. Since the automotive electric power steering system mainly provides electric assistance for the driver's steering process of turning the steering wheel during driving, it is necessary to collect the driver's operation on the steering wheel and the vehicle speed during driving.

[0021] Specifically, a torque sensor is installed on the steering shaft between the steering wheel and the steering gear, close to the steering wheel end, for obtaining the input torque of the driver on the steering wheel during the vehicle driving process; A vehicle speed sensor is installed inside the transmission housing for obtaining the vehicle speed of the vehicle; A resolver is installed on the steering knuckle for obtaining the steering angle of the vehicle wheels; Using the vehicle speed sensor, torque sensor, and resolver, the vehicle speed, the input torque of the driver on the steering wheel, and the input angle are collected once every seconds as a moment. The input torque and the input angle are based on the calibrated position where the steering wheel is centered and not deflected as 0, with the clockwise direction being positive and the counterclockwise direction being negative; where is a preset collection interval, and this embodiment is described by taking as an example; Step S002: Obtain the torque demand degree at each moment according to the change of the input torque; obtain the start compensation moment according to the input torque and the vehicle speed; record any moment during the compensation process after the start compensation moment as the target moment; obtain the torque process quantity at the target moment according to the torque demand degree from the start compensation moment to the target moment; obtain the steering scenario efficiency at the target moment according to the cumulative change relationship of the torque process quantity from the start compensation moment to the target moment.

[0022] It should be noted that during the vehicle driving process, the driver has the highest priority in controlling the vehicle behavior. Therefore, it is necessary to determine the moment when the electric power steering system starts friction compensation according to the input torque of the driver on the steering wheel and the vehicle speed of the car. When the car is driving at a high speed, in order to offset the friction resistance of the mechanical components in the steering system and avoid incomplete steering wheel return or control delay caused by friction interference, the friction compensation of the electric power steering system is particularly important.

[0023] Specifically, for any moment, the ratio of the difference obtained by subtracting the input torque at the previous moment from the input torque at this moment to the preset acquisition interval is denoted as the torque demand degree at this moment.

[0024] Taking the vehicle speed being greater than the preset vehicle speed threshold and the input torque being greater than the preset torque threshold as the compensation conditions; where the preset vehicle speed threshold is 60 km / h and the preset torque threshold is 15 N·m, this embodiment is described by taking this as an example. During the driving process of the car, if the current moment meets the compensation conditions while the previous moment does not, then the current moment is taken as the start compensation moment.

[0025] It should be noted that after the start compensation moment, it is necessary to use the electric power steering system to start friction compensation. When compensating, it is necessary to clarify that the driver needs the vehicle to turn. During the process of vehicle torque change, if the torque changes continuously in a certain direction, it means that the greater the degree of vehicle turning required at present, the more friction compensation is needed.

[0026] Specifically, any moment during the compensation process after the start compensation moment is denoted as the target moment. The mean value and standard deviation of the torque demand degrees of all moments from the start compensation moment to the target moment are obtained. The ratio of the difference obtained by subtracting the mean value from the torque demand degree at the target moment to the standard deviation is denoted as the torque process quantity at the target moment.

[0027] It should be further noted that when the torque process quantity at the target moment is continuously large, it means that the greater the degree of vehicle turning required at present, the more the electric power steering system needs to perform friction compensation. And if due to the uneven road surface, the driver continuously adjusts the steering wheel to keep the vehicle stable. At this time, the driver will adjust the steering wheel left and right. In this scenario, the degree of vehicle turning required is not large. Therefore, it is necessary to judge the steering scenario efficiency in the current vehicle driving scenario according to the change of the torque process quantity after the start compensation moment.

[0028] Specifically, the cube of the torque process quantity at any moment from the start compensation moment to the target moment is denoted as the torque degree at this moment. The sum value of the torque degrees of all moments from the start compensation moment to the target moment is denoted as the steering scenario efficiency at the target moment.

[0029] It should be noted that when the steering scenario efficiency at the target moment is greater, it indicates that the vehicle at the target moment needs to make a large - amplitude turn and compensation is required; when the steering scenario efficiency at the target moment is smaller, it shows that although the driver continuously adjusts the vehicle, the direction of adjustment is constantly changing, indicating that the driver is aiming to keep the vehicle stable during this adjustment process, but there is no substantial vehicle steering requirement.

[0030] Step S003: Obtain the dynamic vehicle - speed weight at the target moment according to the vehicle speed at the target moment; obtain the mapped torque at the target moment according to the input torque at the target moment, the dynamic vehicle - speed weight, and the steering scenario efficiency; obtain the torque compensation amount at the target moment according to the change of the torque demand degree at the target moment and the mapped torque.

[0031] It should be noted that during the friction compensation process, the driver actively inputs torque, and there is a situation of supplementary steering during road driving, that is, if the wheel steering angle is insufficient, the driver controls the vehicle to adjust the wheel steering angle. Therefore, the usage of the steering scenario efficiency is further judged, and the input - torque jitter change caused by road unevenness is analyzed through the steering scenario efficiency. After filtering the road jitter, the driver's compensation action is identified and the torque compensation amount is supplemented for the compensation action output, so as to ensure that the actual output compensation result more conforms to the driver's actual steering - demand result.

[0032] It should be further noted that when the vehicle speed is faster, even a small turn of the vehicle will result in a large deviation. Therefore, the control weight of the driver's input torque to the steering wheel should be increased more, so as to complete the evaluation of the vehicle - speed environment during the actual driving process of the vehicle, which is convenient for the subsequent gain of the compensation amount to fit the actual driving speed.

[0033] Specifically, the inverse - normalization result of the ratio of the preset acquisition interval to the vehicle speed at the target moment is denoted as the dynamic vehicle - speed weight at the target moment; The calculation method of the mapped torque at the target moment is as follows: In the formula, is the mapped torque at the target moment; is the dynamic vehicle - speed weight at the target moment; is the input torque at the target moment; is the steering scenario efficiency at the target moment; is the steering scenario efficiency at the previous moment of the target moment; is a hyper - parameter to prevent the denominator from being 0. In this embodiment, is taken as an example for description.

[0034] What is described above is The larger it is, the greater the change in the steering scenario efficiency at the target moment compared to the previous moment. In a scenario with a relatively low vehicle speed, the mapped torque of the target is larger, and the steering torque provided when the driver controls the steering wheel is larger.

[0035] The calculation method of the torque compensation amount at the target moment is as follows: In the formula, is the torque compensation amount at the target moment; is the torque demand degree at the target moment; is the torque demand degree at the previous moment of the target moment; is the preset friction coefficient. In this embodiment, is used as an example for description; is the mapped torque at the target moment; is the absolute value function; is a hyperparameter to prevent the denominator from being zero. In this embodiment, is used as an example for description.

[0036] It should be noted that the smaller it is, the smaller the torque input controlled by the driver at the target moment, and the larger the torque compensation amount required at the target moment. When the difference between the torque demand degree at the target moment and the torque demand degree at the previous moment is greater, it means that the driver may need a greater degree of steering, and a larger torque compensation amount is required at the target moment.

[0037] Step S004: Obtain the compensated torque at the target moment according to the torque compensation amount at the target moment, and drive and adjust the steering motor according to the compensated torque at the target moment; obtain the expected rotation angle at the target moment according to the compensated torque at the target moment. During the process of driving and adjusting the steering motor, according to the similarity relationship between the expected rotation angle and the input angle, use the electric power steering system of the vehicle to perform friction compensation on the vehicle driving.

[0038] It should be noted that after obtaining the torque compensation amount at the target moment, it is necessary to combine the input torque to obtain the compensated torque, and then adjust the drive current of the steering motor to control the steering.

[0039] Specifically, the sum of the torque compensation amount at the target moment and the input torque at the target moment is denoted as the compensated torque at the target moment; The ratio of the compensated torque at the target moment to the motor torque constant is denoted as the drive current of the steering motor at the target moment, and at the target moment, use the drive current of the steering motor at the target moment to drive and adjust the steering motor, so as to control the vehicle steering; among them, the motor torque constant is 0.1. In this embodiment, this is used as an example for description.

[0040] It should be noted that there is a corresponding relationship between the steering angle of the steering wheel and the torque provided at that steering angle. During the process of electric power steering of a vehicle, if the steering angle of the steering wheel is sufficient to provide the torque required for the current steering, then friction compensation needs to be stopped to prevent overcompensation from causing unstable vehicle driving.

[0041] Specifically, according to the response curve of the steering wheel angle and torque of the vehicle during driving, the expected angle at the target moment is obtained by using the compensated torque at the target moment. The response curve of the steering wheel angle and torque is the functional correspondence between the steering wheel angle and the steering wheel torque, and the response curve of the steering wheel angle and torque is a prior attribute of the vehicle. At each moment after the start compensation moment, the steering control motor is controlled to steer by using the steering motor drive current corresponding to each moment. Until the current input angle is equal to the expected angle, if the vehicle meets the compensation condition, the current moment is used as the new start compensation moment, and the friction of the vehicle electric power steering system is compensated according to the above method. If the vehicle does not meet the compensation condition, no friction compensation is performed.

[0042] It should be noted that if the vehicle speed is less than the preset stop compensation threshold during the compensation process, the friction compensation is stopped. The purpose is to prevent false triggering caused by the driver frequently fine-tuning the steering wheel, such as the jitter suppression during frequent steering in a parking lot. Among them, the preset stop compensation threshold is 10 km / h, and this embodiment is described by taking this as an example.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A friction compensation method for an automotive electric power steering system, characterized in that, The method includes the following steps: Obtain the input torque, input rotation angle, and vehicle speed at each moment during the vehicle driving process; According to the change of the input torque, obtain the torque demand degree at each moment; obtain the start compensation moment according to the input torque and vehicle speed; record any moment during the compensation process after the start compensation moment as the target moment; obtain the torque process quantity at the target moment according to the torque demand degree from the start compensation moment to the target moment; obtain the steering scenario efficiency at the target moment according to the cumulative change relationship of the torque process quantity from the start compensation moment to the target moment; Obtain the dynamic vehicle speed weight at the target moment according to the vehicle speed at the target moment; obtain the mapped torque at the target moment according to the input torque, dynamic vehicle speed weight, and steering scenario efficiency at the target moment; obtain the torque compensation quantity at the target moment according to the change of the torque demand degree and the mapped torque at the target moment; Obtain the post-compensation torque at the target moment according to the torque compensation quantity at the target moment, and drive and adjust the steering motor according to the post-compensation torque at the target moment; obtain the expected rotation angle at the target moment according to the post-compensation torque at the target moment, and during the process of driving and adjusting the steering motor, perform friction compensation on the vehicle driving according to the similarity relationship between the expected rotation angle and the input angle by using the vehicle electric power steering system.

2. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, The specific method for obtaining the torque demand degree at each moment according to the change of the input torque includes: For any moment, the ratio of the difference obtained by subtracting the input torque at the previous moment from the input torque at this moment to the preset acquisition interval is denoted as the torque demand degree at this moment.

3. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, The specific method for obtaining the start compensation moment according to the input torque and vehicle speed includes: Taking the vehicle speed being greater than the preset vehicle speed threshold and the input torque being greater than the preset torque threshold as the compensation condition; During the vehicle driving process, if the current moment meets the compensation condition while the previous moment does not, then the current moment is taken as the start compensation moment.

4. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, The specific method for obtaining the torque process quantity at the target moment according to the torque demand degree from the start compensation moment to the target moment includes: Obtain the mean and standard deviation of the torque demand degrees at all moments from the start compensation moment to the target moment, and the ratio of the difference obtained by subtracting the mean from the torque demand degree at the target moment to the standard deviation is denoted as the torque process quantity at the target moment.

5. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, The specific method for obtaining the steering scenario efficiency at the target moment according to the cumulative change relationship of the torque process quantity from the start compensation moment to the target moment includes: Cubing the torque process quantity at any moment from the start compensation moment to the target moment is denoted as the torque degree at this moment; The sum value of the torque degrees at all moments from the start compensation moment to the target moment is denoted as the steering scenario efficiency at the target moment.

6. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, The specific method for obtaining the dynamic vehicle speed weight at the target moment according to the vehicle speed at the target moment includes: The inverse proportional normalization result of the ratio of the preset acquisition interval to the vehicle speed at the target moment is denoted as the dynamic vehicle speed weight at the target moment.

7. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, The specific method for obtaining the mapped torque at the target moment according to the input torque, dynamic vehicle speed weight, and steering scenario efficiency at the target moment includes: The mapping torque at the target moment is calculated as follows: In the formula, is the mapping torque at the target moment; is the dynamic vehicle speed weight at the target moment; is the input torque at the target moment; is the steering scenario efficiency at the target moment; is the steering scenario efficiency at the previous moment of the target moment; is a hyperparameter.

8. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, Obtaining the torque compensation amount at the target moment according to the change situation of the torque demand degree at the target moment and the mapped torque, the specific method included is as follows: The calculation method of the torque compensation amount at the target moment is as follows: In the formula, is the torque compensation amount at the target moment; is the torque demand degree at the target moment; is the torque demand degree at the moment immediately preceding the target moment; is the preset friction coefficient; is the mapped torque at the target moment; is the absolute value function; is the hyperparameter.

9. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that, Obtaining the compensated torque at the target moment according to the torque compensation amount at the target moment, and driving and adjusting the steering motor according to the compensated torque at the target moment, the specific method included is as follows: Denote the sum value of the torque compensation amount at the target moment and the input torque at the target moment as the compensated torque at the target moment; Denote the ratio of the compensated torque at the target moment to the motor torque constant as the steering motor drive current at the target moment, and drive and adjust the steering motor at the target moment by using the steering motor drive current at the target moment, so as to control the vehicle steering.

10. The friction compensation method for an automotive electric power steering system according to claim 1, characterized in that,During the process of driving and adjusting the steering motor, according to the similarity relationship between the expected angle and the input angle, using the electric power steering system of the vehicle to perform friction compensation on the vehicle driving, the specific method included is as follows: Obtain the expected angle at the target moment according to the compensated torque at the target moment and the response curve of the steering wheel angle and torque of the vehicle during driving; At each moment after the start compensation moment, control the steering control motor to steer by using the steering motor drive current corresponding to each moment until the current input angle is equal to the expected angle. If the vehicle meets the compensation condition, take the current moment as the new start compensation moment, and compensate the friction of the electric power steering system of the vehicle according to the above method. If the vehicle does not meet the compensation condition, no friction compensation is performed.

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