Automobile steering zero position automatic calibration method

Abstract

The invention discloses an automatic calibration method for an automobile steering zero position, which comprises the following steps of: performing zero position calibration in the running process of an automobile, monitoring the running state of the automobile in real time when the zero position calibration is performed, judging whether the automobile is in a zero position meeting state or not based on the running state of the automobile, and if so, executing the step 2; if yes, the steering position at the moment serves as the zero position to be stored in the EPS controller; and if not, continuously monitoring the vehicle driving state. The method has the advantages that the calibration operation of the steering zero position is achieved in an automatic identification and automatic calibration mode, and the user experience is improved; according to the scheme, the current running state is automatically recognized, the current straight running state of the vehicle is obtained, whether zero position calibration is carried out or not is judged based on the straight running state, and the zero position is recorded, so that zero position calibration is accurate and reliable and can be carried out automatically, and meanwhile the hardware cost is low.

Description

Technical Field

[0001] The present invention relates to the field of automotive automatic control, and particularly to an automatic calibration method for the zero position of vehicle steering. Background Art

[0002] During the off-line detection process of a vehicle, the electric power steering system (EPS) of the vehicle performs zero position calibration to ensure that a vehicle with an active return-to-zero function can return to the zero position of the vehicle after steering, has the ability to maintain straight-line driving, and enables a vehicle equipped with assisted driving to maintain lane centering. The electric power steering system (EPS) of a vehicle usually finds the zero position of the whole vehicle through four-wheel alignment equipment during the initial vehicle manufacturing off-line detection and calibrates the steering zero position. After the vehicle has traveled a certain mileage, the stress release and wear of the vehicle chassis components will cause the zero position of the whole vehicle to change, resulting in a deviation between the steering zero position calibrated at the factory off-line and the actual zero position of the whole vehicle. The direction of actively returning to the zero position through EPS at low speed will cause the vehicle to deviate, and a vehicle with L2 or above assisted driving function will not be able to keep the vehicle in the middle of the lane. To solve this problem, it is usually necessary to go to the after-sales service network for four-wheel alignment. However, four-wheel alignment needs to consider the accuracy of the four-wheel alignment equipment and the professionalism of the operator. Otherwise, the zero position cannot be accurately recalibrated, and redoing the four-wheel alignment will incur certain maintenance costs, resulting in an increase in vehicle use costs. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an automatic calibration method and system for the zero position of vehicle steering, which realizes the calibration operation of the steering zero position through automatic recognition and automatic calibration, thereby improving the user experience.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is: an automatic calibration method for the zero position of vehicle steering, which includes performing zero position calibration during the vehicle driving process, and during the zero position calibration, the driving state of the vehicle is monitored in real time and it is determined whether the current state meets the zero position state based on the driving state of the vehicle. If so, the steering position at this time is stored as the zero position in the EPS controller; if not, the driving state of the vehicle is continuously monitored.

[0005] Based on the loss state of the vehicle chassis, it is determined whether to perform zero position calibration.

[0006] The loss state of the chassis is judged by collecting the driving mileage of the vehicle, and it is determined whether to perform zero position calibration based on the loss state.

[0007] A mileage threshold is set in advance, and the real-time cumulative mileage of the vehicle is compared with the mileage threshold. When the real-time cumulative mileage of the vehicle is greater than the mileage threshold, it is determined to enter zero position calibration.

[0008] When entering zero-position calibration, if it is determined that the current vehicle meets the zero-position state, the steering position at this time is stored as the zero position in the EPS controller, and the original zero position of the EPS controller is saved as an alternative position.

[0009] The EPS controller is equipped with a zero-position recovery button. After the EPS controller detects the zero-position recovery button, it restores and stores the original zero position as the new zero position in the EPS controller.

[0010] Judging whether the current state meets the zero-position state based on the driving state of the vehicle includes: collecting vehicle speed signals, EPS corner fluctuation signals, lateral acceleration signals, and yaw rate signals, and judging whether the current vehicle meets the zero-position state based on the vehicle speed signals, EPS corner fluctuation signals, lateral acceleration signals, and yaw rate signals.

[0011] When the vehicle speed is greater than the vehicle speed threshold, the EPS corner fluctuation is less than the angle threshold, the lateral acceleration is less than the acceleration threshold, the yaw rate is less than the set angular velocity threshold, and the duration is greater than the set time threshold, it is determined that the current vehicle meets the zero-position state.

[0012] When the real-time cumulative mileage of the vehicle is less than or equal to the mileage threshold, if it is monitored that the user manually triggers the calibration button, zero-position calibration is entered. At this time, when the vehicle meets the zero-position state, the steering position at this time is compared with the zero position in the EPS controller, and the zero-position information stored in the EPS controller is adjusted according to the comparison result.

[0013] Adjusting the zero-position information stored in the EPS controller according to the comparison result includes: if the steering position when the zero-position state is met is compared with the zero position in the EPS controller, if the difference between the two is less than the set threshold, the EPS controller does not adjust the zero position; otherwise, the average of the steering position when the zero-position state is met and the zero position in the EPS controller is taken as the final zero position and stored in the EPS controller.

[0014] The advantages of the present invention are as follows: The calibration operation of the steering zero position is realized through the method of automatic recognition and automatic calibration, improving the user experience; by automatically identifying the current operating state, obtaining the current straight-ahead state of the vehicle and judging whether the zero-position calibration is in progress and recording the zero position based on the straight-ahead state. This solution has accurate and reliable zero-position calibration, can be carried out automatically, and has low hardware costs. Brief Description of the Drawings

[0015] The following briefly describes the content expressed in each drawing of the present invention specification and the marks in the drawings:

[0016] Figure 1 It is a schematic flow chart of the method for automatically calibrating the steering zero position of the present invention. Detailed Embodiment

[0017] The following will further describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings through the description of the optimal embodiments.

[0018] The steering zero position is generally stored in the EPS controller of the vehicle's electric power steering system. Zero position calibration is to write the accurate steering position into the EPS controller as the zero position. This solution solves the defect of inaccurate zero position that may occur due to wear and tear when the driving mileage is greater than a certain mileage through the method of automatic recognition for calibration. It can be considered that the chassis needs to be automatically calibrated after wear when the mileage is greater than the set mileage, and the user can also manually start the calibration when the mileage has not been reached.

[0019] The stress release and wear of the vehicle chassis components will cause the change of the steering zero position. By automatically learning and calibrating the steering zero position during the vehicle driving process and storing it in the EPS controller, the steering zero position is corrected according to the real-time state of the vehicle so as to more accurately control the vehicle's active return position and keep the vehicle driving straight. At the same time, it provides a precise control reference for assisted driving to ensure the vehicle's ability to actively maintain lane centering and improve driving safety. After the steering zero position changes, it is automatically learned and corrected through the vehicle's dynamic driving, avoiding the need to use four-wheel alignment equipment for calibration after sales and reducing the vehicle use cost.

[0020] An automatic calibration method for the steering zero position of a vehicle provided by this solution includes performing zero position calibration during the vehicle driving process. When performing zero position calibration, the driving state of the vehicle is monitored in real time and it is judged based on the driving state of the vehicle whether the current state meets the zero position state. If so, the steering position at this time is stored as the zero position in the EPS controller; if not, the driving state of the vehicle is continuously monitored.

[0021] Since the vehicle zero position calibration must be due to the wear and stress release of the chassis resulting in the inaccuracy of the originally calibrated zero position, the condition for starting zero position calibration is to judge whether to perform zero position calibration based on the loss state of the vehicle chassis.

[0022] Since the wear of the chassis cannot be quantitatively characterized, in this solution, the loss state of the chassis is judged by collecting the driving mileage of the vehicle and whether to perform zero position calibration is judged based on the loss state. Because the greater the driving mileage, the greater the chassis wear, and the smaller the driving mileage, the smaller the wear, so the chassis state can be qualitatively evaluated by the amount of mileage. Specifically:

[0023] A mileage threshold is set in advance, and the real-time cumulative mileage of the vehicle is compared with the mileage threshold. When the real-time cumulative mileage of the vehicle is greater than the mileage threshold, it is judged to enter zero position calibration; if it is less than the mileage threshold, it does not enter zero position calibration.

[0024] When entering zero calibration, if it is determined that the current vehicle meets the zero position state, the steering position at this time is stored as the zero position in the EPS controller, and the original zero position of the EPS controller is saved as an alternative position. Since the zero position is stored in the EPS controller, to write a new zero position, the original zero position cannot be deleted but still saved. The purpose of this is that if the updated zero position still does not meet the requirements after the zero position is updated, it can still be restored to the original zero position, thus providing an option for the user.

[0025] If the requirements are met after zero calibration, the user can do nothing. However, if the user is not satisfied after zero calibration, they can backtrack to the previous zero position. Through the zero position recovery button available on the EPS controller, after the EPS controller detects that the zero position recovery button is triggered, it restores and stores the original zero position as the new zero position in the EPS controller, thus achieving the purpose of allowing the user to backtrack the zero position and providing the user with more options.

[0026] In this embodiment, determining whether the current state meets the zero position state based on the driving state of the vehicle includes: collecting vehicle speed signals, EPS corner fluctuation signals, lateral acceleration signals, and yaw rate signals, and determining whether the current vehicle meets the zero position state based on the vehicle speed signals, EPS corner fluctuation signals, lateral acceleration signals, and yaw rate signals. The vehicle determines the steering zero position through vehicle speed, corner value, lateral acceleration value, and yaw rate and writes it into the controller to calibrate the vehicle's steering zero position.

[0027] Preferably, when the vehicle speed is greater than the vehicle speed threshold, the EPS corner fluctuation is less than the angle threshold, the lateral acceleration is less than the acceleration threshold, the yaw rate is less than the set angular velocity threshold, and the duration is greater than the set time threshold, it is determined that the current vehicle meets the zero position state.

[0028] As Figure 1 shown, the conditions for meeting the zero position state in this solution include: when the driving vehicle speed ≥ 60 km / h, the EPS corner fluctuation is within 0.5°, the lateral acceleration value is within ±0.1 m / s 2 , the yaw rate ≤ 0.1° / s, then the EPS automatically enters the steering zero position learning, and the duration ≥ 3 s.

[0029] In this embodiment, when the real-time cumulative mileage of the vehicle is less than or equal to the mileage threshold, if it is monitored that the user manually triggers the calibration button, zero-position calibration is entered. At this time, when the vehicle meets the zero-position state, the steering position at this time is compared with the zero-position in the EPS controller, and the zero-position information stored in the EPS controller is adjusted according to the comparison result. The manually triggered calibration button is connected to the EPS controller, which can reuse the in-vehicle button or be implemented through a soft button to meet the purpose of the user's manual trigger calibration. The user can manually start the zero-position calibration according to their own needs. After manually starting the zero-position calibration, it is judged whether the zero-position state is met through vehicle data, the steering position corresponding to the zero-position state is obtained, and the steering position is compared with the zero-position to judge and adjust the zero-position in the EPS. Because it is manually turned on, the wear and tear of the chassis are not serious at this time. Therefore, it is necessary to compare the two to judge whether it is necessary to adjust the zero-position state in the EPS, so as to achieve more accurate calibration.

[0030] Adjusting the zero-position information stored in the EPS controller according to the comparison result includes: when the steering position when the zero-position state is met is compared with the zero-position in the EPS controller, if the difference between the two is less than the set threshold, the EPS controller does not adjust the zero-position, otherwise, the steering position when the zero-position state is met and the zero-position in the EPS controller are averaged as the final zero-position and stored in the EPS controller. If the difference between the two is large, it means that the wear also meets the requirements at this time, then the steering position of the vehicle when the zero-position state is met is used as the new zero-position and stored in the EPS. After being written into the EPS controller, the EPS uses the newly written zero-position for vehicle control in subsequent controls. If the difference between the two is small, the zero-position adjustment can be not done. In order to meet the adjustment needs of the user, the two can also be averaged or the middle value of the two positions can be used as the new zero-position and written into the EPS controller, so as to realize the update of the zero-position.

[0031] This method finds the zero-position of the whole vehicle during the straight-line driving of the vehicle and corrects the steering zero-position stored in the EPS. During the driving of the vehicle, the vehicle speed, EPS corner, lateral acceleration, and yaw rate are monitored and calculated. When the driving speed ≥ 60 km / h, the EPS corner fluctuation is within 0.5°, the lateral acceleration value is within ±0.1 m / s 2 , and the yaw rate ≤ 0.1° / s, the EPS automatically enters the steering zero-position learning. If the duration is ≥ 3 s, the steering position at this time is counted as the zero-position and stored in the EPS controller as the steering zero-position for active return and assisted driving control.

[0032] Based on the fact that stress release and wear of vehicle chassis components can cause changes in the steering zero position, this solution automatically learns and calibrates the steering zero position during vehicle driving and stores it in the EPS controller, so that the steering zero position can be corrected according to the real-time state of the vehicle to more precisely control the active return position of the vehicle, enabling the vehicle to maintain a straight driving state. At the same time, it provides an accurate control reference for assisted driving to ensure the vehicle's ability to actively maintain lane centering and improve driving safety. After the steering zero position changes, it is automatically learned and corrected through dynamic vehicle driving, avoiding the need to use four-wheel alignment equipment for calibration after sales and reducing the vehicle use cost.

[0033] Obviously, the specific implementation of the present invention is not limited by the above methods. As long as various non-substantive improvements are made using the method concept and technical solution of the present invention, they are all within the protection scope of the present invention.

Claims

1. A method for automatically calibrating a vehicle's steering zero position, characterized in that: Including performing zero-position calibration during vehicle driving, monitoring the driving state of the vehicle in real time during the zero-position calibration and judging whether the vehicle is currently in a zero-position state based on the driving state of the vehicle, and if so, storing the steering position at this time as the zero position in the EPS controller; Otherwise, the vehicle's driving status is continuously monitored.

2. The method for automatically calibrating the zero position of a vehicle steering according to claim 1, characterized in that: Determine whether to perform zero calibration based on the wear status of the vehicle's chassis.

3. The method for automatically calibrating the zero position of a vehicle steering according to claim 2, characterized in that: The wear status of the chassis is determined by the collected vehicle mileage, and whether to perform zero-position calibration is determined based on the wear status.

4. A method for automatically calibrating a vehicle steering zero position as claimed in claim 3, characterized in that: A mileage threshold is set in advance, and the vehicle's cumulative mileage is compared with the mileage threshold. When the vehicle's real-time cumulative mileage is greater than the mileage threshold, it is determined to enter zero-position calibration.

5. A method for automatically calibrating a vehicle steering zero position according to any one of claims 1 to 4, characterized in that: When entering the zero position calibration, if it is determined that the current vehicle meets the zero position state, the steering position at this time is stored in the EPS controller as the zero position, and the original zero position of the EPS controller is saved as an alternative position.

6. A method for automatically calibrating a vehicle steering zero position as claimed in claim 5, characterized in that: The EPS controller is equipped with a zero position recovery button. After detecting the zero position recovery button, the EPS controller recovers the original zero position and stores it in the EPS controller as a new zero position.

7. A method for automatically calibrating a vehicle steering zero position according to any one of claims 1 to 5, characterized in that: Judging whether the vehicle is currently in a zero-position state based on the vehicle's driving state includes: collecting vehicle speed signals, EPS steering angle fluctuation signals, lateral acceleration signals, and yaw angular velocity signals; judging whether the vehicle is currently in a zero-position state based on the vehicle speed signals, EPS steering angle fluctuation signals, lateral acceleration signals, and yaw angular velocity signals.

8. The method for automatically calibrating the zero position of a vehicle steering according to claim 7, characterized in that: When the vehicle speed is greater than the vehicle speed threshold, the EPS steering angle fluctuation is less than the angle threshold, the lateral acceleration is less than the acceleration threshold, the yaw angular velocity is less than the set angular velocity threshold and the duration is greater than the set time threshold, it is determined that the current vehicle meets the zero position state.

9. The method for automatically calibrating the zero position of a vehicle steering according to claim 4, characterized in that: When the vehicle's real-time accumulated mileage is less than or equal to the mileage threshold, if the user manually triggers the calibration button, it enters zero-position calibration. When the vehicle meets the zero-position state, the steering position at this time is compared with the zero-position in the EPS controller, and the zero-position information stored in the EPS controller is adjusted according to the comparison result.

10. The method for automatically calibrating the zero position of a vehicle steering according to claim 9, characterized in that: Adjusting the zero position information stored in the EPS controller according to the comparison result includes: if the steering position when the zero position state is met is compared with the zero position in the EPS controller, if the difference between the two is less than the set threshold, the EPS controller will not make a zero position adjustment; if not, the steering position when the zero position state is met and the zero position in the EPS controller are averaged as the final zero position and stored in the EPS controller.

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