Control method for zero calibration of steering wheel in middle of lane

Abstract

The invention discloses a lane centering steering wheel zero calibration control method, which comprises the following steps of: after a lane centering function is activated, judging whether a current vehicle runs on a straight road and is in a stable running state, and if so, recording a distance y from an original point of a vehicle coordinate system to a lane center line; calculating a corresponding compensation angle component according to the distance y; the EPS controls steering of the steering wheel according to the compensation angle component. After the lane centering keeping function is started, stepping compensation is carried out on the zero deviation of the steering wheel, and therefore the problem that the vehicle is not centered or draws a dragon is solved.

Description

Technical Field

[0001] The invention relates to the field of automobile assisted driving control, and in particular to a control method for lane centering steering wheel zero position calibration. Background Art

[0002] The current automotive industry generally has the problem of vehicle steering wheel zero-position drift. In particular, the longer the time after the vehicle's four-wheel alignment, the greater the steering wheel zero-position drift. Because of the existence of zero-position drift, the centering control in assisted driving cannot be achieved directly through the steering wheel zero-position control, and compensation control is required to achieve the centering control of assisted driving.

[0003] In the prior art, the driving assistance system handles the steering wheel zero-position drift by generally directly compensating the deviation value at one time after finding out the actual deviation. The one-time compensation means that after obtaining the actual zero-position angle deviation, the deviation angle is directly compensated by automatic control, and the direction of the vehicle is controlled by this angle to achieve centering control.

[0004] Although one-time compensation can quickly reach the center position, due to the existence of zero-position error, this method easily causes the vehicle to swing back and forth between lane lines, resulting in a dragon-drawing phenomenon; in addition, because the deviation value is a one-time compensation, when the deviation value is too large, the vehicle turning angle will fluctuate too much at the moment of compensation, causing discomfort to the vehicle user, causing user disgust, and resulting in a poor user experience. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a control method for lane centering steering wheel zero position calibration. After the lane centering function is turned on, the steering wheel zero position deviation is compensated in a step-by-step manner, thereby solving problems such as vehicle non-centering or dragon drawing.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a control method for lane centering steering wheel zero position calibration, after the lane centering function is activated, it is determined whether the current vehicle is driving on a straight road and whether it is in a stable driving state. If so, the distance y from the origin of the vehicle coordinate system to the center line of the lane is recorded; the corresponding compensation angle component is calculated according to the distance y; EPS controls the steering of the steering wheel according to the compensation angle component.

[0007] After the vehicle is started, vehicle status data is collected and based on the vehicle status data, it is determined whether the lane centering function is activated.

[0008] The collected vehicle status data include: vehicle four doors and two hood status data, vehicle speed data, gear data, lateral and longitudinal acceleration data, yaw angle data, lane line recognition data, vehicle fault data and activation button trigger status data. Based on the collected vehicle status data, it is determined whether the lane centering keeping function is activated.

[0009] Determining whether the vehicle is traveling on a straight road includes: obtaining the radius of the lane in front of the vehicle through image recognition, and when the radius of the lane in front is ≥ a set threshold R, determining that the vehicle is traveling on a straight road.

[0010] Determining whether the vehicle is in a stable driving state includes: when the vehicle is driving on a straight road and the driving duration is ≥ a set time threshold T, then determining that the vehicle is in a stable driving state.

[0011] When the vehicle is traveling on a straight road and in a stable driving state, the distance y from the origin of the vehicle's own coordinate system to the center line of the lane is collected in real time, and the angle compensation value that matches it is calculated in real time based on the distance y. The compensation value is sent to EPS, and EPS controls the direction of the vehicle based on the compensation value.

[0012] A comparison table between the distance y and the angle compensation value is pre-calibrated, and the angle compensation value matching the distance y is obtained according to the comparison table, and then the steering wheel is steered.

[0013] According to the value range of distance y, the corresponding angle compensation value is obtained, and the comparison information is as follows:

[0014] When the distance y is greater than the threshold D1, the angle compensation value is φ1;

[0015] When the distance threshold D2<y≤threshold D1, the angle compensation value is φ2;

[0016] When threshold D0<y≤threshold D2, the angle compensation value is φ3;

[0017] When y<threshold D0, the angle compensation value is 0.

[0018] When the vehicle is traveling on a straight road and in a stable driving state, the distance y is updated according to the time period threshold and the compensation angle value is obtained in real time according to the updated distance y to control the direction of the vehicle.

[0019] The advantages of the present invention are: 1. In the steering wheel self-calibration mode, the lateral distance from the origin of the vehicle coordinate system to the center line of the lane is calculated and used as the initial input for angle compensation, thereby avoiding the problem of stable side-by-side driving of the vehicle.

[0020] 2. In view of the zero-position deviation of the steering wheel, the present invention adopts a method of compensating the angle step component to avoid problems such as vehicle stuttering and physical discomfort caused by excessive single compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following is a brief description of the contents expressed in the drawings of the present invention and the symbols in the drawings:

[0022] Figure 1 The invention discloses an in-vehicle hardware system framework involved in the lane centering steering wheel zero position self-calibration method of the present invention.

[0023] Figure 2 The present invention is a flowchart of the lane centering steering wheel zero position self-calibration method. DETAILED DESCRIPTION

[0024] The specific implementation of the present invention will be further explained in detail below by describing the optimal embodiment with reference to the accompanying drawings.

[0025] This solution proposes a method for lane centering steering wheel zero position self-calibration, which can automatically compensate for the steering wheel zero position deviation value after the lane centering function is activated, so as to improve the accuracy of the system's control of the vehicle angle, thereby ensuring the stability of the vehicle centering, which has certain promotion significance. The existing technology solution recognizes the centering deviation and calculates an angle directly adjusted to the center line to control the centering. This adjustment method is too drastic, resulting in insufficient user experience, and it is easy to cause the vehicle to snake left and right along the center line of the lane, affecting the experience and the safety of assisted driving.

[0026] In this embodiment, a control method for lane centering steering wheel zero position calibration is used. After the lane centering function is activated, it is determined whether the current vehicle is driving on a straight road and whether it is in a stable driving state. If so, the distance y from the origin of the vehicle coordinate system to the center line of the lane is recorded; the corresponding compensation angle component is calculated based on the distance y; EPS controls the steering of the steering wheel based on the compensation angle component. With this solution, since the distance y is constantly changing, the angle is also gradually changing, so it is possible to achieve a step-by-step and gradual control approach to the center line of the lane while maintaining control while driving toward the center line, thereby improving the user experience.

[0027] The judgment condition of whether the centering function is activated is as follows: after the vehicle is started, the vehicle status data is collected and based on the vehicle status data, whether the lane centering function is activated is judged. The collected vehicle status data includes: vehicle four doors and two lids status data, vehicle speed data, gear data, lateral and longitudinal acceleration data, yaw angle data, lane line recognition data, vehicle fault data and activation button trigger status data, and based on the collected vehicle status data, it is judged whether the lane centering function is activated. The activation condition of the lane centering function is met when the vehicle's four doors and two lids are in a closed state, the vehicle speed data, gear data, lateral and longitudinal acceleration data, and yaw angle data meet the preset range, and the lane line data is identified, the vehicle has no faults, and the centering function activation button is triggered and pressed. At this time, the lane centering function is activated. Otherwise, if any of the conditions is not met, it is judged that the lane centering function is not activated.

[0028] After the function is activated, it is first determined whether the vehicle is driving on a straight road. The determination of whether the vehicle is driving on a straight road includes: obtaining the radius of the lane in front of the vehicle through image recognition. If the radius of the lane in front is ≥ the set threshold R, the vehicle is determined to be driving on a straight road. The image of the lane in front is collected by the vehicle camera, and the lane line data is obtained based on image recognition. Then, the arc of the lane line is calculated based on the lane line and converted to obtain the radius of the corresponding lane. When the calculated lane radius is greater than the set threshold R, it is determined to be a straight road.

[0029] When it is determined that the current vehicle is driving on a straight road, it is further determined whether the vehicle is in a stable driving state, wherein the determination of whether the vehicle is in a stable driving state includes: when the vehicle is driving on a straight road and the driving duration is ≥ the set time threshold T, the vehicle is determined to be in a stable driving state. When the vehicle is driving on a straight road and in a stable driving state, the vehicle should be controlled to drive in the center, so the direction of the vehicle needs to be automatically controlled at this time, and the specific control includes:

[0030] When the vehicle is driving on a straight road and in a stable driving state, the distance y from the origin of the vehicle's own coordinate system to the center line of the lane is collected in real time, and the angle compensation value that matches it is calculated in real time based on the distance y. The compensation value is sent to the EPS, and the EPS controls the direction of the vehicle based on the compensation value. The origin position of the vehicle's own coordinate system is pre-calibrated, usually the center of the vehicle's rear axle, and then the position of the center line of the lane is analyzed through the image collected by the camera, and then the distance y from the origin of the vehicle coordinate system to the center line is calculated. This distance y is the reason why the vehicle is not driving in the center, so the angle compensation value that matches it is calculated based on the distance y, and then the angle compensation value is sent to the EPS, and the EPS controller controls the direction of the vehicle based on the angle compensation value.

[0031] Calculating the angle compensation value based on distance y can be achieved through a pre-calibrated comparison table between distance y and angle compensation value. The comparison table is a comparison relationship between distance y and angle compensation value. After calculating the distance y, the angle compensation value matching the distance y is obtained according to the comparison table, and then the steering wheel is steered. The comparison relationship can be achieved in a variety of ways such as a map table, a mathematical relationship or a one-to-one correspondence.

[0032] In a preferred embodiment, the present solution adopts a method of calculating and obtaining the distance y value range in correspondence with the angle compensation value, and obtains the corresponding angle compensation value according to the distance y value range, and the comparison information is as follows:

[0033] When the distance y is greater than the threshold D1, the angle compensation value is φ1;

[0034] When the distance threshold D2<y≤threshold D1, the angle compensation value is φ2;

[0035] When threshold D0<y≤threshold D2, the angle compensation value is φ3;

[0036] When y<threshold D0, the angle compensation value is 0.

[0037] After the distance y is calculated, the corresponding angle compensation value is obtained according to the comparison information to control the direction of the vehicle, thereby controlling the vehicle to achieve the purpose of driving in the center of the lane.

[0038] When the vehicle is in a straight road and in a stable driving state, the distance y is updated according to the time cycle threshold and the compensation angle value is obtained in real time according to the updated distance y to control the direction of the vehicle. The time cycle threshold can be set according to different calibration times, so as to adjust the angle compensation value in a dynamic and gradual manner, thereby achieving control of the direction, meeting the purpose of stable control and thus achieving the purpose of lane centering control. After calculating the distance y each time, the compensation angle value is used to compensate the direction, and the time when the vehicle is in a straight road and in a stable driving state is monitored. When the time is continuously greater than the time cycle threshold, the y value is recalculated and updated, and then the next round of compensation control is entered.

[0039] The technical problem to be solved by the solution provided in this embodiment is to solve the problems of vehicle misalignment or dragon drawing by performing step-by-step compensation for the zero position deviation of the steering wheel after the lane centering function is turned on. The steps of the technical solution can be summarized as follows:

[0040] (1) After the lane centering function is activated, the vehicle searches for a straight road with a lane radius ≥ threshold R for driving;

[0041] (2) When the vehicle's stable driving time is greater than or equal to the time threshold T, the distance y from the origin of the vehicle coordinate system to the center line of the lane is recorded;

[0042] (3) According to the size of y, select the angle step component according to the table below, add the component value to the original steering wheel angle request signal and send it to EPS to request EPS to execute.

[0043] Distance y>threshold D1 Threshold D2<y≤Threshold D1 Threshold D0<y≤Threshold D2 Compensation value φ1 φ2 φ3

[0044] Table 1

[0045] During angle calibration, since D1>D2>D0, φ1>φ2>φ3, the larger y is, the larger the corresponding compensation value is, so that y can be reduced as quickly as possible; the upper limit of φ will be different for each vehicle model because of its different status. It is determined according to the actual calibration situation of the vehicle model, but in general, it is not recommended to set φ too large, as it will cause the vehicle to be distorted;

[0046] The calibrated angles φ1, 2, and 3 are defined by each car manufacturer, with positive on the left and negative on the right. The angles can be controlled in a positive or negative manner on the left or right.

[0047] (4) After receiving the steering wheel angle request, EPS controls the steering wheel to steer according to the principle of left positive and right negative.

[0048] (5) After the first compensation, the vehicle continues to drive. When the stable driving time exceeds the set time threshold T, the MCU recalculates the lateral distance y from the origin of the vehicle coordinate system to the center line of the current lane, and selects the corresponding step component according to the above table to perform angle compensation until the lateral distance y ≤ the set threshold D0.

[0049] like Figure 1 As shown, the vehicle control components involved in the control method of the present invention include: ESP controller, EPS controller, VCU controller, BCM controller, and front camera module.

[0050] The ESP controller, EPS controller, and VCU controller provide vehicle body information and execute front camera module requests. The BCM controller provides the status of the four doors and two covers of the vehicle body, as well as the status of the driver's switch buttons, etc.

[0051] The front camera module adopts the form of a front-view all-in-one machine, which has a camera module, SOC and MCU inside. It is installed on the inside of the front windshield to enable the lane centering function and detect the lane line ahead.

[0052] When the vehicle turns on the lane centering function, the road video collected by the camera module is input into the SOC, and the SOC inputs the identified lane radius and lane line position information into the MCU for logic processing.

[0053] When the lane radius ≥ threshold R, if the stable driving time ≥ the set time threshold T, it means that the vehicle has reached steady-state control. At this time, the MCU calculates the lane centerline position through the left and right lane line positions input by the SOC, and calculates the lateral distance y from the origin of the vehicle coordinate system (usually the center of the vehicle's rear axle) to the lane centerline. The compensation strategy is executed according to the following strategy:

[0054] ① If y>threshold D1, the system compensates the angle step component φ1 based on the original steering wheel angle request (the original steering wheel angle is the angle at which the steering wheel needs to be turned for normal centering, such as an absolute straight road at this time, which requires a steering wheel angle of 0°; or an approximately straight road at this time, but the steering wheel needs to be turned 0.1°);

[0055] ② If the threshold D2<y≤threshold D1, the system compensates the angle step component φ2;

[0056] ③ If the threshold value D0<y≤threshold value D2, the system compensates the angle step component φ3;

[0057] After the above compensation is completed, the vehicle needs to continue driving for a certain period of time until it reaches a stable state. At this time, the distance y from the origin of the current vehicle coordinate system to the center line of the lane is re-recorded, and the above compensation operation is performed again until y ≤ threshold D0. At this time, the distance between the origin of the vehicle coordinate system and the center line of the lane is relatively close, and the vehicle can maintain normal centering without the need for compensation again.

[0058] The working principle of lane centering steering wheel zero position self-calibration in this embodiment is: during the lane centering process, the steering wheel angle is compensated for the step component by calculating the lateral distance y from the origin of the vehicle coordinate system to the center line of the lane in the steady state. After the first compensation, when the vehicle reaches a steady state again, the steering wheel angle is compensated for the second time according to the current distance y, and so on, until the lateral distance ≤ the set threshold D0. Each compensation value is not the actual deviation value of the steering wheel, but the angle step component after calibration according to the actual vehicle effect, to ensure that the body feels comfortable, the steering is not abrupt, and the vehicle is not a dragon during the real vehicle self-calibration process.

[0059] The above scheme is used to control the zero position compensation of the vehicle's lane centering steering wheel. After entering the steering wheel zero position self-calibration mode, different angle compensation values ​​can be set by calculating the lateral distance from the origin of the vehicle coordinate system to the center line of the lane; for angle compensation, the steering wheel zero position deviation is compensated by using the compensation angle step component. In this way, the vehicle steering compensation control is performed to avoid the problem of stable side-by-side driving of the vehicle.

[0060] Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial 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 control method for lane centering steering wheel zero position calibration, characterized in that: After the lane centering function is activated, determine whether the current vehicle is driving on a straight road and whether it is in a stable driving state. If so, record the distance y from the origin of the vehicle coordinate system to the center line of the lane; The corresponding compensation angle component is calculated according to the distance y; EPS controls the steering of the steering wheel according to the compensation angle component.

2. A lane centering steering wheel zero position control method as claimed in claim 1, characterized in that: After the vehicle is started, vehicle status data is collected and based on the vehicle status data, it is determined whether the lane centering function is activated.

3. A lane centering steering wheel zero position control method as claimed in claim 2, characterized in that: The collected vehicle status data include: vehicle four doors and two hood status data, vehicle speed data, gear data, lateral and longitudinal acceleration data, yaw angle data, lane line recognition data, vehicle fault data and activation button trigger status data. Based on the collected vehicle status data, it is determined whether the lane centering keeping function is activated.

4. A lane centering steering wheel zero position control method as claimed in claim 1, characterized in that: Determining whether the vehicle is traveling on a straight road includes: obtaining the radius of the lane in front of the vehicle through image recognition, and when the radius of the lane in front is ≥ a set threshold R, determining that the vehicle is traveling on a straight road.

5. The lane centering steering wheel zero position control method according to claim 1, characterized in that: Determining whether the vehicle is in a stable driving state includes: when the vehicle is driving on a straight road and the driving duration is ≥ a set time threshold T, then determining that the vehicle is in a stable driving state.

6. A lane centering steering wheel zero position control method according to any one of claims 1 to 5, characterized in that: When the vehicle is traveling on a straight road and in a stable driving state, the distance y from the origin of the vehicle's own coordinate system to the center line of the lane is collected in real time, and the angle compensation value that matches it is calculated in real time based on the distance y. The compensation value is sent to EPS, and EPS controls the direction of the vehicle based on the compensation value.

7. A lane centering steering wheel zero position control method as claimed in claim 6, characterized in that: The comparison relationship between the distance y and the angle compensation value is pre-calibrated, and the angle compensation value matching the distance y is obtained according to the comparison relationship, and then the steering wheel is steered.

8. A lane centering steering wheel zero position control method as claimed in claim 7, characterized in that: According to the value range of distance y, the corresponding angle compensation value is obtained, and the comparison information is as follows: When the distance y is greater than the threshold D1, the angle compensation value is φ1; When the distance threshold D2<y≤threshold D1, the angle compensation value is φ2; When threshold D0<y≤threshold D2, the angle compensation value is φ3; When y<threshold D0, the angle compensation value is 0.

9. A lane centering steering wheel zero position control method according to any one of claims 1 to 8, characterized in that: When the vehicle is traveling on a straight road and in a stable driving state, the distance y is updated according to the time period threshold and the compensation angle value is obtained in real time according to the updated distance y to control the direction of the vehicle.

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