KR101962890B1 - System and method for compensating vehicle sensor's offset - Google Patents

Abstract

A vehicle sensor offset correction system and method are disclosed. The system and method determine the straight running of the vehicle by using four wheel speed sensors, a yaw rate sensor, and heading angle information from a video camera of the vehicle. The steering angle offset obtained from the steering angle sensor in the straight- do. Also, the heading angle and the steering angle information are used to determine that the vehicle is traveling on a curved road, and a heading angle corresponding thereto is estimated to compensate for the heading angle offset. Accordingly, it is possible to compensate the offset of the vehicle sensor for the LKAS (Lane Keeping Assist System) when the wheel is broken or when the vehicle is traveling on a curve road.

Description

Technical Field [0001] The present invention relates to a system and method for compensating vehicle sensor offset,

The present invention relates to a Lane Keeping Assist System (LKAS), and more particularly to a technique for compensating for the offset of a vehicle sensor for LKAS.

The LKAS is a preventive safety system that recognizes the lane through the video device of the vehicle and assists the vehicle in leaving the lane by generating an auxiliary steering torque when the lane departure of the vehicle is expected for the recognized lane. The LKAS generally includes an image sensor for recognizing the front lane, a steering angle sensor (SAS) for sensing the driver's steering state, a system ECU (ECU) for determining the driving state of the vehicle, And a steering actuator for generating an auxiliary steering torque. In order to use the measurement value of the steering angle sensor, a reference corresponding to an absolute zero point is required. This reference setting must be used for offset correction of the steering angle sensor. Even if the offset of the steering angle sensor is initially corrected, the steering angle may be distorted due to a long-term operation or other external influences. In such a case, if the offset can not be compensated, it will affect precise steering control, resulting in deterioration of LKAS performance.

In this regard, an invention relating to a steering angle sensor initial fault detection method and apparatus is known from Korean Patent Laid-Open Publication No. 10-2011-0041034. SUMMARY OF THE INVENTION It is an object of the present invention to provide a steering angle sensor that detects an offset angle occurring at the time of initialization of a steering angle sensor and detects a failure of initialization of the steering angle sensor based on the detected offset angle. According to an aspect of the present invention, there is provided a steering angle sensor comprising: a steering angle sensor initialization sensing unit for sensing that initialization of a steering angle sensor of a vehicle has been performed; a steering angle sensor for sensing a steering angle, The steering angle and the offset angle are obtained from the steering angle sensor when the determination unit and the vehicle are determined to be in the straight state, the difference value between the obtained straight line steering angle and the offset angle is calculated, and when the calculated difference value exceeds the threshold value And a failure detection unit for detecting a failure of the steering angle sensor upon initialization.

However, according to the present invention, when a straight line is determined to be a straight line in the straight line determination unit, a difference value between the straight line steering angle and the offset angle is calculated. When the calculated difference value exceeds the threshold value, The steering angle sensor is always judged as a failure. That is, there is no mention of a problem with the setting of a threshold value at which a situation in which a calculated difference value exceeds a threshold value even though the vehicle is running straight. Also, when a failure of the wheel speed sensor or a failure of the steering torque sensor occurs, not a failure of the steering angle sensor, a problem of declaring the failure of the steering angle sensor occurs.

An object of the present invention is to provide a technical solution that can compensate for an offset of a vehicle sensor even when the vehicle speed is different on both sides of the vehicle due to a large external shock or various factors.

Another object of the present invention is to provide a technical solution which can compensate for the offset of the vehicle sensor even when the vehicle is traveling on a curved road.

According to an aspect of the present invention, there is provided a vehicle sensor offset correction system including wheel speed sensors for sensing a wheel speed, a yaw rate sensor for sensing a yaw rate of a vehicle, a steering angle sensor for sensing a steering angle of the vehicle, Sensor, an image camera for photographing a running road of the vehicle, a storage unit for storing an initial yaw rate offset, an initial steering angle offset and an initial heading angle offset information, and a storage unit for storing the sensed yaw rate and the sensed steering angle, Estimates a heading angle through the image received from the image camera, and updates the initial heading angle offset information stored in the storage unit with the estimated heading angle offset.

Wherein the control unit determines that the difference between the wheel speeds of both sides of the vehicle is constant over a predetermined period of time based on the wheel speed data sensed by the wheel speed sensors and that the sensed rate is zero, And updates the initial steering angle offset information stored in the storage unit with the detected steering angle offset when it is determined that the vehicle is traveling straight ahead.

Wherein the control unit stores the detected yaw rate offset, the detected steering angle offset, and heading angle information estimated from the image as initial offset information in the storage unit when the vehicle starts, Is the offset in the middle. Here, the controller determines whether the difference between the wheel speeds detected by the wheel speed sensors is constant, and determines that the vehicle is running straight.

According to another aspect of the present invention, there is provided a method of correcting a vehicle sensor offset, the method comprising: storing a rate offset, a steering angle offset, and a vehicle heading offset information in an offset memory block, And updating the offset memory block with the current steering angle offset when the difference between the wheel speeds of both sides of the vehicle is constant, the rate is zero, and it is determined that the vehicle runs straight through the vehicle heading angle.

Further, the method further includes determining that the vehicle is traveling on a curved road through a vehicle rate and a steering angle, estimating a corresponding heading angle, and updating the offset memory block with the estimated heading angle offset.

The system and method according to the present invention can compensate for the offset of the LKAS vehicle sensor even when the wheel speeds of both sides of the vehicle are different, such as when the wheel is broken. It is also possible to compensate for the offset of the LKAS vehicle sensor even when the vehicle is traveling on a curved road.

1 is a block diagram of a vehicle sensor offset correction system according to an embodiment of the present invention;
2 is a flowchart illustrating initial offset information storage when a vehicle engine is started according to an embodiment of the present invention;
3 is a flowchart of offset correction at the time of vehicle straight ahead according to an embodiment of the present invention.
FIG. 4 is a flowchart illustrating offset correction when traveling on a curved road of a vehicle according to an embodiment of the present invention; FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and further aspects of the present invention will become more apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a vehicle sensor offset correction system according to an embodiment of the present invention.

The vehicle sensor offset correction system is a system for correcting an offset of a vehicle sensor for an LKAS. The system includes wheel speed sensors 100, 200, 300 and 400, a yaw rate sensor 500, a steering angle sensor 600, An offset storage unit 800, and a control unit 900. The wheel speed sensors include an FL wheel speed sensor 100 for sensing the speed of the left front tire wheel, an RL wheel speed sensor 200 for sensing the speed of the left rear tire wheel, and an FR wheel speed sensor 200 for sensing the speed of the right front tire wheel. Sensor 300 and an RR wheel speed sensor 400 for sensing the speed of the right rear tire wheel. The yaw rate sensor 500 senses a yaw rate in the vertical axis direction of the vehicle, that is, a rotational angular velocity. The steering angle sensor 600 senses a steering angle by a driver's operation. The video camera 700 is a camera for photographing a running road of a vehicle, for example, photographing a front running road of the vehicle. The offset storage 800 is a memory for storing offset information, and includes an offset memory block for storing offset information of vehicle sensors for the LKAS. The offset memory block stores the rate offset, the heading angle offset of the vehicle, and the steering angle offset information. The control unit 900 is a control unit that performs a vehicle sensor offset correction process.

FIG. 2 is a flowchart of initial offset information storage when the vehicle engine is started according to an embodiment of the present invention.

When the vehicle start key is turned on, the control unit 900 estimates and primarily compensates the rate offset detected by the rate sensor 500 (S210) (S220). Next, the control unit 900 determines whether the specified condition is satisfied (S230). Specifically, the controller 900 determines whether the vehicle is traveling on a straight road for a predetermined time set as a threshold value. If the vehicle runs on a straight road and the rate is 0 (zero), the controller 900 estimates the steering angle offset, It is judged whether it is. At this time, the controller 900 uses four wheel speed data to determine whether the vehicle is traveling on a straight road. If it is determined that the vehicle is traveling on the straight road through the four wheel speed data, the initial steering angle offset is estimated and compensated (S240). The control unit 900 estimates a heading angle offset of the vehicle obtained from the image of the image camera 700 to determine whether it has a bias and compensates the heading angle offset when the bias is present (S250) (S260). The control unit 900 stores the initial offset information including the rate offset, the steering angle offset, and the steering angle offset in the offset memory block of the offset storage unit 800 (S270).

3 is a flowchart of offset correction at the time of vehicle straight ahead according to an embodiment of the present invention.

In order to correct the offset when the vehicle is straight ahead, the controller 900 first determines whether the specified condition is satisfied (S310). More specifically, the control unit 900 controls the head speed of the vehicle at both sides of the vehicle for a predetermined time using the heading angle information obtained from the wheel speed sensors 100, 200, 300, 400, the yaw rate sensor 500, It is determined whether or not the difference is constantly output with no change, the rate is zero, and straight through the heading angle. Here, the difference between the wheel speeds of both sides of the vehicle is obtained by averaging the sum of the wheel speed of the FL wheel speed sensor 100 and the wheel speed of the RL wheel speed sensor 200, the wheel speed of the FR wheel speed sensor 300, Means a difference between a value obtained by averaging the sum of the wheel speeds of the speed sensors 400. If the difference between the wheel speeds of both sides of the vehicle is constantly output without change, the rate is 0, and it is confirmed that the steering wheel is straight through the heading angle, the control unit 900 determines whether the current steering angle offset sensed by the steering angle sensor 600 If the steering angle offset stored in the offset memory block of the offset storage unit 800 matches the steering angle offset stored in the offset memory block of the offset storage unit 800, the steering angle offset information stored in the offset memory block 800 is updated to the current steering angle offset (S320) S330). Therefore, even if the wheel is broken, the offset can be estimated by compensating for the error.

4 is a flowchart illustrating an offset correction process when the vehicle is traveling on a curved road according to an embodiment of the present invention.

When the yaw rate and the steering angle are compensated, the controller 900 determines whether the vehicle is traveling on the curved road using the compensated yaw rate and the steering angle information (S410). If it is determined that the vehicle is traveling on a curved road, the controller 900 estimates the current heading angle corresponding thereto. The control unit 900 determines whether the estimated current heading angle matches the heading angle stored in the offset memory block of the offset storage unit 800. If the heading angle does not match, The offset information is updated (S420) (S430). Therefore, offset compensation of the LKAS vehicle sensor is possible even when the vehicle travels on a curved road.

For reference, the offset estimation equation is as shown in Equation (1).

The offset estimation equation can increase or decrease the number of data according to the signal characteristics, and can reduce the influence of instantaneous bouncing noise by using the remaining data excluding the maximum value and the minimum value of the data.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

100: FL wheel speed sensor 200: RL wheel speed sensor
300: FR wheel speed sensor 400: RR wheel speed sensor
500: Rate sensor 600: Steering angle sensor
700: image camera 800: offset storage unit
900:

Claims (6)

Wheel speed sensors for sensing the wheel speed;
A rate sensor for sensing a rate of a vehicle;
A steering angle sensor for sensing a steering angle of the vehicle;
A video camera for photographing a running road of the vehicle;
An initial rate offset, an initial steering angle offset, and an initial heading angle offset information; And
When the vehicle start key is turned on, a rate offset detected by the rate sensor is estimated and compensated first, then the vehicle travels on a straight road, and when the rate is 0 (zero), the steering angle offset is estimated, Compensates the stored initial steering angle offset information, estimates a heading angle offset of the vehicle obtained from the image of the image camera, compensates and updates the initial heading angle offset information stored in the storage unit, Estimating a heading angle through an image received from the image camera when it is determined that the vehicle is traveling on a curved road through a steering angle, and updating initial heading angle offset information stored in the storage unit with the estimated heading angle offset A control unit;
The vehicle sensor offset correction system comprising: delete The method according to claim 1,
Wherein the control unit stores the detected yaw rate offset, the detected steering angle offset, and heading angle information estimated from the image as initial offset information in the storage unit when the vehicle starts, Wherein the offset of the vehicle sensor offset correction system is an offset when the vehicle is in the middle of the vehicle. The method of claim 3,
Wherein the control unit determines whether the difference between the wheel speeds detected by the wheel speed sensors is constant, and determines that the vehicle is running straight when constant. Storing a rate offset, a steering angle offset, and a vehicle heading angle offset information at a vehicle start in an offset memory block;
The offset memory block is updated at the current steering angle offset when the difference between the wheel speeds of both sides of the vehicle is constant for a predetermined time, the rate is zero, and it is determined that the vehicle runs straight through the vehicle heading angle, Estimating a heading angle offset of the vehicle and updating the offset memory block with a current heading angle offset; And
Determining that the vehicle is traveling on a curved road through a compensated yaw rate of the vehicle and a compensated steering angle, estimating a corresponding heading angle, and updating the offset memory block with the estimated heading angle offset Wherein the vehicle sensor offset correction method comprises the steps of: delete

Images