A control method for lane centering steering wheel zero calibration

Abstract

The application discloses a control method for lane centering steering wheel zero position calibration, after the lane centering function is activated, whether the current vehicle is driving on a straight road and whether the vehicle is in a stable driving state are judged, if yes, the distance y from the vehicle coordinate system origin to the lane center line is recorded; the corresponding compensation angle component is calculated according to the distance y; the steering of the steering wheel is controlled by the EPS according to the compensation angle component. After the lane centering keeping function is opened, the step-by-step compensation for the steering wheel zero position deviation is carried out, so that the problems of vehicle non-centering or drawing a dragon are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile auxiliary driving control, in particular to a lane centering steering wheel zero position calibration control method. BACKGROUND

[0002] The current automobile industry generally has the problem of vehicle steering wheel zero position drift, especially the longer the time after vehicle four-wheel positioning, the greater the steering wheel zero position drift. Because of the existence of zero position drift, it cannot be directly controlled to achieve centering through the steering wheel zero position in the centering control in the auxiliary driving, and compensation control is needed to achieve the centering control of the auxiliary driving.

[0003] In the prior art, the driving assistance system generally directly compensates the deviation value once through the actual deviation to handle the steering wheel zero position drift. One-time compensation refers to directly compensating the deviation angle through automatic control after obtaining the actual zero position angle deviation, and controlling the direction of the vehicle through the angle to achieve centering control.

[0004] Although one-time compensation can quickly reach the centering position, due to the existence of zero position error, this method is prone to cause the vehicle to swing back and forth between the lane lines, causing the phenomenon of drawing a dragon. In addition, because the deviation value is compensated once, when the deviation value is too large, the vehicle turning angle will fluctuate too much at the compensation moment, which will bring discomfort to the user of the vehicle and cause the user to be disgusted, resulting in poor user experience. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a lane centering steering wheel zero position calibration control method. After the lane centering function is activated, the steering wheel zero position deviation is compensated step by step, thereby solving the problem of vehicle not centering or drawing a dragon.

[0006] In order to achieve the above purpose, the technical solution adopted by the present application is as follows: a lane centering steering wheel zero position calibration control method, after the lane centering function is activated, it is judged 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; the EPS controls the steering of the steering wheel according to the compensation angle component.

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

[0008] The state data of the vehicle includes: vehicle four-door two-cover state data, vehicle speed data, gear data, transverse and longitudinal acceleration data, yaw angle data, lane line recognition data, vehicle fault data and active button trigger state data, and whether the lane centering function is activated is determined based on the collected state data of the vehicle.

[0009] The vehicle is determined to be in straight driving by image recognition to obtain the radius of the lane in front of the vehicle, and when the radius of the front lane is greater than or equal to a set threshold R, the vehicle is determined to be in straight driving.

[0010] The vehicle is determined to be in a stable driving state when the vehicle is in straight driving and the driving duration is greater than or equal to a set time threshold T.

[0011] When the vehicle is in straight driving and in a stable driving state, the distance y from the origin of the vehicle coordinate system to the center line of the lane is collected in real time, the angle compensation value matched with the distance y is calculated in real time, and the compensation value is sent to the EPS, and the EPS controls the direction of the vehicle according to the compensation value.

[0012] A comparison table between the distance y and the angle compensation value is calibrated in advance, the angle compensation value matched with the distance y is obtained according to the comparison table, and then the steering control of the steering wheel is performed.

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

[0014] When the distance y is greater than a threshold D1, the angle compensation value is phi1;

[0015] When the distance threshold D2 is less than y and less than or equal to the threshold D1, the angle compensation value is phi2;

[0016] When the threshold D0 is less than y and less than or equal to the threshold D2, the angle compensation value is phi3;

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

[0018] When the vehicle is in straight driving and in a stable driving state, the distance y is updated according to a 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 application 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 as the initial input for angle compensation, so as to avoid the problem of stable side driving of the vehicle.

[0020] 2. For the zero deviation of the steering wheel, the present application adopts the step component of the compensation angle, which avoids the problem of overcompensation of the vehicle and the discomfort of the driver. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0025] This solution proposes a method for lane centering steering wheel zero position self-calibration. This method automatically compensates for steering wheel zero position deviation after lane centering is activated, improving the system's accuracy in vehicle angle control and ensuring vehicle centering stability. This approach has considerable potential for widespread adoption. Existing solutions identify centering deviations and calculate an angle directly adjusted to the centerline for centering control. This drastic adjustment method results in an inadequate user experience and can easily cause the vehicle to snaking left and right along the lane centerline, impacting both the user experience and the safety of assisted driving.

[0026] In this embodiment, a control method for lane centering steering wheel zero calibration is described. After the lane centering function is activated, the method determines whether the vehicle is currently traveling on a straight road and in a stable driving state. If so, the distance y from the origin of the vehicle coordinate system to the lane centerline is recorded. A corresponding compensation angle component is calculated based on the distance y. The EPS controls steering based on the compensation angle component. Because the distance y is constantly changing, the angle also changes gradually. This method allows for a gradual, controlled approach to the lane centerline, maintaining control while gradually approaching the lane centerline, thereby improving the user experience.

[0027] The judgment condition of whether the centering function is activated is that the vehicle state data is collected after the vehicle is started and whether the lane centering function is activated is judged based on the vehicle state data. The vehicle state data includes four-door two-cover state data, speed data, gear data, transverse and longitudinal acceleration data, yaw angle data, lane line recognition data, vehicle fault data, and activation button trigger state data. Based on the collected vehicle state data, it is determined whether the lane centering function is activated. When the four-door two-cover of the vehicle is in the closed state, the speed data, the gear data, the transverse and longitudinal acceleration data, the yaw angle data meet the preset range, and the lane line data is recognized, the vehicle has no fault, and the centering function activation button is triggered and pressed, the lane centering function activation condition is met, at this time the lane centering function is activated, otherwise any condition is not met, then 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 whether the vehicle is driving on a straight road includes: obtaining the radius of the front lane of the vehicle through image recognition, and when the radius of the front lane is greater than or equal to a set threshold R, it is determined that the vehicle is driving on a straight road. The front lane image is collected by the vehicle camera, the lane line data is obtained based on image recognition, and then the radius of the lane is calculated and converted based on the curvature of the lane line to obtain the corresponding radius of the lane. When the calculated radius of the lane 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. The determination whether the vehicle is in a stable driving state includes: when the vehicle is driving on a straight road and the driving duration is greater than or equal to a set time threshold T, it is determined that the vehicle is in a stable driving state. When the vehicle is driving on a straight road and is in a stable driving state, the vehicle should be controlled to drive in the center at this time, so the direction of the vehicle needs to be automatically controlled at this time, and the specific control includes:

[0030] In the state that the vehicle is driving on a straight road and is in a stable driving state, the distance y from the origin of the vehicle coordinate system to the center line of the lane is collected in real time, the angle compensation value matched with the distance y is calculated in real time according to the distance y, and the compensation value is sent to the EPS. The position of the origin of the vehicle coordinate system is pre-calibrated, which is usually the center of the rear axle of the vehicle. 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. Therefore, the angle compensation value matched with the distance y is calculated based on the distance y, and then the angle compensation value is sent to the EPS. The controller of the EPS controls the direction of the vehicle according to the angle compensation value.

[0031] The calculation of the angle compensation value based on the distance y can be realized by a pre-calibrated correspondence table between the distance y and the angle compensation value, the correspondence table being a correspondence relationship between the distance y and the angle compensation value, after the distance y is calculated, the angle compensation value matched with the distance y is obtained according to the correspondence table, and then the steering control is performed on the steering wheel, and the correspondence relationship can be realized in various ways such as a map table, a mathematical relationship or a one-to-one correspondence.

[0032] In a preferred embodiment, the scheme is calculated and obtained in a way that the value range of the distance y corresponds to the angle compensation value, the corresponding angle compensation value is obtained according to the value range of the distance y, and the correspondence 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 the 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 correspondence information to control the direction of the vehicle, so as to control the vehicle to realize the purpose of lane center driving.

[0038] When the vehicle is in straight driving and in a stable driving state, the distance y is updated according to a 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, the time period threshold can be set according to different calibration times, so as to realize dynamic and gradual adjustment of the angle compensation value, thereby realizing control of the direction and meeting the purpose of stable control to realize the purpose of lane center control. After calculating the distance y each time, the compensation angle value is used to compensate and control the direction, and the time when the vehicle is in straight driving and in a stable driving state is monitored, when the time lasts for more than the time period 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 scheme provided in the embodiment is to solve the problems of vehicle non-centering or drawing a dragon by step-by-step compensation of the steering wheel zero deviation after the lane centering function is turned on. The steps of the technical scheme can be summarized as:

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

[0041] (2) When the vehicle 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 at this time;

[0042] (3) According to the size of y, the angle step component is selected according to the following table, and the component value is added to the original steering wheel angle request signal and sent to the EPS to request the EPS to execute.

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

[0044] Table 1

[0045] In the angle calibration, because D1>D2>D0, φ1>φ2>φ3, the larger y is, the larger the corresponding compensation value is, so that y can be reduced as soon as possible; the upper limit of φ is different for each vehicle state, and the actual calibration of each vehicle model is determined, but generally, it is not recommended that φ is too large, which will cause the vehicle to draw a dragon;

[0046] The calibrated angles φ1, 2, and 3 are positive on the left and negative on the right, which is defined by each vehicle factory itself, and the left and right positive and negative modes can be used to control the angle.

[0047] (4) After receiving the steering wheel angle request, the 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, and when the stable driving time exceeds the set time threshold T, the MCU re-calculates the lateral distance y from the origin of the vehicle coordinate system to the current lane center line, and selects the corresponding step component according to the table to compensate the angle, until the lateral distance y is less than or equal to the set threshold D0.

[0049] As shown in Figure 1 The control method of the present application involves whole vehicle control components, including: ESP controller, EPS controller, VCU controller, BCM controller, front camera module.

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

[0051] The front camera module adopts a front-view integrated machine form, which has a camera module, a SOC and an MCU inside, and is installed inside the front windshield glass, used to start the lane centering function and detect the front lane line.

[0052] When the vehicle starts 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 logical processing.

[0053] When the lane radius is greater than or equal to the threshold value R, if the stable driving time is greater than or equal to the set time threshold value T, it is indicated that the vehicle reaches the steady state control, at this time, the MCU calculates the lane center line position through the left and right lane line positions input by the SOC, and calculates the lateral distance y from the original point of the vehicle coordinate system (usually the center of the rear axle of the vehicle) to the lane center line, and executes the compensation strategy according to the following strategy:

[0054] ①If y is greater than the threshold value 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 of the steering wheel required for normal centering, for example, at this time, the absolute straight line, the steering wheel angle is 0°; or at this time, the approximate straight line, but the steering wheel needs to be turned by 0.1°);

[0055] ②If the threshold value D2 is less than y and y is less than or equal to the threshold value D1, the system compensates the angle step component φ2;

[0056] ③If the threshold value D0 is less than y and y is less than or equal to the 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 time to reach the stable state, at this time, the distance y from the original point of the vehicle coordinate system to the lane center line is recorded again, and the above compensation operation is performed again until y is less than or equal to the threshold value D0. At this time, the distance from the original point of the vehicle coordinate system to the lane center line is close, and the vehicle can normally maintain the centering driving without further compensation.

[0058] The working principle of the lane centering steering wheel zero position self-calibration in the embodiment is as follows: in the lane centering maintaining process, the lateral distance y from the original point of the vehicle coordinate system to the lane center line in the steady state is calculated to compensate the steering wheel angle by the step component. After the first compensation, when the vehicle reaches the 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 is less than or equal to the set threshold value D0. Each compensation value is not the actual deviation value of the steering wheel, but the angle step component calibrated according to the actual vehicle effect, to ensure that the self-calibration process of the actual vehicle is comfortable, the steering is not abrupt, and the vehicle does not draw a dragon.

[0059] The lane centering steering wheel zero position compensation control of the vehicle by using the above scheme can set different angle compensation values by calculating the lateral distance from the original point of the vehicle coordinate system to the lane center line after entering the steering wheel zero position self-calibration mode; 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 driving of the vehicle.

[0060] Obviously, the specific implementation of the present application is not limited by the above method, as long as various non-essential improvements are made by using the method concept and technical scheme of the present application, which are within the protection scope of the present application.

Claims

1. A control method for lane centering steering wheel zero position calibration, characterized by: After the lane centering function is activated, the system determines whether the vehicle is currently traveling on a straight road and in a stable driving state. If so, the system records the distance y from the origin of the vehicle coordinate system to the lane centerline. The corresponding compensation angle component is calculated based on the distance y. The EPS controls the steering wheel according to the compensation angle component. Obtain the corresponding angle compensation value based on the value range of distance y. 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.

2. The lane centering steering wheel zero position control method according to 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. The lane centering steering wheel zero position control method according to claim 2, characterized in that: The collected vehicle status data includes: vehicle four-door 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 function is activated.

4. The lane centering steering wheel zero position control method according to claim 1, characterized in that: Determining whether the vehicle is traveling on a straight road includes: obtaining the radius of a lane in front of the vehicle through image recognition; if the radius of the lane in front is greater than or equal to 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 greater than or equal to a set time threshold T, 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. The angle compensation value that matches it is calculated in real time based on the distance y, and the compensation value is sent to the EPS, which controls the vehicle direction based on the compensation value.

7. The lane centering steering wheel zero position control method according to 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 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 is updated according to the time period threshold and a compensation angle value is obtained in real time based on the updated distance y to control the direction of the vehicle.

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