KR102287312B1 - Apparatus for controlling lane keeping assist system in vehicle and method thereof - Google Patents

Abstract

The present invention relates to an LKAS control apparatus and method for a vehicle, and when a vehicle traveling on one road enters another road at a Junction Cross (JC) of the road, by assisting the lane maintenance of the vehicle based on the road's guard rail. , to provide a vehicle LKAS control device and method for preventing errors caused by not recognizing the lanes of other roads.
To this end, the present invention provides an LKAS control device for a vehicle, comprising: a stereo camera for acquiring a stereo image of the front of the vehicle; a guardrail recognition unit for recognizing a guardrail from a stereo image; and a controller for controlling a Lane Keeping Assist System (LKAS) to assist in lane keeping based on the calculation of the distance to the guard rail recognized by the guard rail recognition unit when the vehicle diverges from the road junction.

Description

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an LKAS control device for a vehicle and a method therefor, and more particularly, when a vehicle traveling on one road enters another road at a Junction Cross (JC) of the road, the lane of the vehicle is based on the guard rail of the road It relates to technology that assists in maintenance.

In general, a Lane Keeping Assist System (LKAS) is driven in the following order.

First, an image of the road ahead is acquired using a camera system mounted in the space between the vehicle's windshield and the rearview mirror.

Thereafter, through image processing, the lateral offset of the vehicle from the center of the own lane or the line or edge of the lane being driven, the curvature of the road, the lane Lane information such as a heading angle formed by the vehicle center line is extracted.

Thereafter, in order to estimate the current driving state of the vehicle, lane departure is monitored based on signal information of various sensors mounted on the vehicle.

Thereafter, when the driver's unintentional lane departure occurs, the vehicle is pushed into the currently driving lane to assist the driver in driving. At this time, the steering system, MDPS (Motor Driven Power System), acts as an actuator that generates actual steering using the steering torque signal received from the LKAS.

Such a conventional lane keeping assist system, when a vehicle traveling on one road enters another road at a junction, cannot recognize the lane of another road until it completely enters the other road. There was a problem of giving a sense of heterogeneity and discomfort to the driver.

Republic of Korea Patent Publication No. 2011-0126820

In order to solve the problems of the prior art as described above, the present invention assists in maintaining the lane of the vehicle based on the guard rail of the road when a vehicle traveling on one road enters another road at a Junction Cross (JC) of the road. An object of the present invention is to provide an LKAS control device and method for a vehicle that prevents errors caused by not recognizing the lane of another road.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned can be understood by the following description, and will be more clearly understood by the examples of the present invention. Moreover, it will be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The apparatus of the present invention for achieving the above object, in the LKAS control apparatus of a vehicle, a stereo camera for acquiring a stereo image of the front of the vehicle; a guardrail recognition unit for recognizing a guardrail from a stereo image; and a controller configured to control a Lane Keeping Assist System (LKAS) to assist in lane keeping based on the calculation of the distance to the guard rail recognized by the guard rail recognition unit when the vehicle diverges from the road junction.

The method of the present invention for achieving the above object, in the LKAS control method of the vehicle, the stereo camera acquiring a stereo image of the front of the vehicle; recognizing, by a guardrail recognition unit, a guardrail from a stereo image; and controlling a Lane Keeping Assist System (LKAS) to assist lane keeping based on the calculated distance from the recognized guard rail when the vehicle diverges from the road junction.

In the present invention as described above, when a vehicle traveling on one road enters another road at a Junction Cross (JC) of the road, the lane of the other road is not recognized by assisting the vehicle's lane maintenance based on the road guard rail. This has the effect of preventing errors caused by not doing so.

1 is a conceptual diagram of a lane keeping assist system according to an embodiment of the present invention;
2 is a configuration diagram of an embodiment of an LKAS control apparatus for a vehicle according to the present invention;
3 is an explanatory diagram of an embodiment of the LKAS control method according to the present invention;
4 is a flowchart illustrating an LKAS control method of a vehicle according to an embodiment of the present invention.

The above-described objects, features, and advantages will become more clear through the detailed description described below in detail with reference to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains can understand the technical spirit of the present invention. can be easily implemented. In addition, in the description of the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a lane keeping assist system to which the present invention is applied.

The Lane Keeping Assist System (LKAS) 100 uses the relative information between the vehicle and the lane obtained through the front camera sensor and the vehicle state information obtained through the vehicle CAN communication to prevent the vehicle from deviating from the lane while driving. A system that assists in the steering operation of

The lane keeping assisting system 100 should be controlled in a direction that does not give the driver a sense of steering difference when the vehicle deviates from the lane while driving or when the driver's will to steer is sensed.

To this end, the lane keeping assisting system 100 includes a driving information detector 110 , a control start determiner 120 , a lane keeping controller 130 , and a control release determiner 140 .

First, each configuration of FIG. 1 will be briefly described as follows.

The driving information detector 110 performs a function of acquiring information between a vehicle and a lane through a camera sensor and a vehicle sensor.

The driving information detector 110 acquires relative information between the vehicle and the lane (offset between the vehicle center and left and right lanes, road curvature, heading angle, etc.) through a camera sensor, and vehicle state information (steering angle, yaw rate, driver's steering torque, vehicle speed, etc.).

Since the accuracy of the measured information directly affects the performance of the lane keeping assisting system 100 , the lane compensation logic is used to improve the reliability of the system 100 . make it

The control start determiner 120 performs a function of determining a timing for controlling the vehicle to prevent lane departure by using information detected through the driving information detector 110 .

The control start determiner 120 is a block that determines a control start time for preventing the vehicle from leaving a lane using the information measured by the driving information detector 110. The control start time is determined by using a lateral offset between the vehicle and the lane. decide

The lane keeping controller 130 calculates a control amount necessary for lane departure prevention by using information detected through the driving information detector 110 .

The lane keeping controller 130 is a block that generates an auxiliary steering torque value for preventing lane departure by using the vehicle speed, yaw rate, steering angle, relative distance to the lane, and curvature measured by the driving information detector 110 .

The control release determiner 140 performs a function of determining when to end the vehicle departure prevention control by using the information detected through the driving information detector 110 .

The control release determiner 140 determines a control end time by using the information measured by the driving information detector 110 .

First, the control release determiner 140 releases the control when it is determined that the vehicle has not departed based on the measured value of the lane during the lane maintenance control.

Second, when the lane keeping control is operating but the vehicle deviates from the lane, a large control input is required to maintain the lane, and this operation causes the driver's steering sense of discomfort or anxiety. In order to prevent this, the control release determiner 140 releases the control when the vehicle deviates from the lane by more than a specific value.

Third, a certain physical parameter of the vehicle for lane keeping control is calculated using vehicle state information and lane information. If the reliability of this value is not guaranteed, an incorrect control amount is calculated and the reliability of the controller is not guaranteed. does not In order to prevent this, the control release determiner 140 releases the control when the reliability of the lane information does not satisfy a predetermined criterion.

Fourth, the control release determiner 140 releases the control when it is measured that the driver issues a signal for determining that the driver has intention to change lanes or performs a driving operation for determining that the driver has intention to change lanes.

Each configuration of FIG. 1 will be described in detail.

(1) Driving information detector 110

The driving information detector 110 obtains lane information (offset between the center of the vehicle and the left and right lanes, road curvature, heading angle, etc.) and vehicle state information (steering angle, yaw rate, driver steering torque, vehicle speed, etc.) through a sensor.

The information obtained through the sensor is greatly influenced by the surrounding environment. Snow, rain, backlight, and surrounding environments such as road guardrails, tunnels, and junctions/merging points affect the unrecognized/misrecognized lane, and this information directly affects the calculation of the control amount, so it is possible to improve the reliability of the lane. For this purpose, compensation for lane information should be made.

The driving information detector 110 determines whether a lane is misrecognized/unrecognized using the measured lane offset, lane curvature, change rate of heading angle, left/right comparison, and lane reliability value, etc. Through compensation, the reliability of the next best line can be improved.

On the other hand, the driving information detector 110 may compensate for the lane misrecognition section by comparing the change rate and left/right values of information such as lane quality, offset, curvature, heading value, etc., in the case of not recognizing a short section It is possible to prevent frequent loss of control by compensating using the changing tendency of the previous lane.

The magnitude of the change rate of the lane offset cannot be greater than the predetermined value (A), and compensation is performed when the rate of change of the left or right lane offset is greater than or equal to the predetermined value (A). When the offset change rate on either the left or right side is equal to or greater than a certain value (A), offset compensation is performed using the other offset. For example, if the rate of change of the offset on the left is equal to or greater than the predetermined value (A), compensation is performed using the offset on the right.

Left offset (t) = Left offset (t-1) + Right offset rate of change

When both the left and right change rates are equal to or greater than a predetermined value (A), the lane offset is compensated for a predetermined time by using the average rate of change (B).

Left/Right Offset (t) = Left/Right Offset (t-1) + Average Offset Change Rate (B)

If the left/right values are different from the curvature value and the heading value, it is judged as a misrecognition, and the rate of change of the left/right values is compensated with a value equal to or less than a certain value (Cc, Ch).

If the left/right values are different, the opposite lane value is compensated with a value whose rate of change is less than or equal to a certain value (Cc, Ch). For example, when the rate of change on the left is less than or equal to a certain value, the value on the left is replaced with the value on the right. If both left and right are below a certain value (Cc, Ch), the average value of the rate of change is used to compensate. If both left and right are above a certain value (Cc, Ch), the average value of the change rate is used to compensate for a certain period of time.

The above is based on the fact that the lane, curvature, heading value, etc. do not change discontinuously. The constant values (A, Cc, Ch) are values set based on the lane information obtained through the test, and the lane quality is high. It is a value calculated using data from , and has a different value depending on the speed. The rate of change indicates a difference between the current value and the previous sampling value, and the average rate of change indicates a value obtained by averaging the rate of change for a certain period of time.

(2) control start determiner 120

The control start determiner 120 determines a control start condition for preventing the vehicle from leaving a lane by using the lane information and the vehicle state information output from the driving information detector 110 .

The control start determiner 120 determines a control start condition by using the offset and the lane width between the vehicle center and the left and right lanes.

The control start determiner 120 starts control when the distance between the left wheel and the lane or the distance between the right wheel and the lane becomes less than or equal to the limit value E. In this case, the limit value E may vary according to the lane width.

(3) lane keeping controller 130

The lane keeping controller 130 includes lane information (offset between the vehicle center and left and right lanes, road curvature, heading angle, etc.) output from the driving information detector 110 and vehicle state information (steering angle, yaw rate, driver steering torque, vehicle speed, etc.) etc.) to calculate the control amount for lane keeping control.

The lane keeping controller 130 may include a target trajectory calculator, a target yaw rate calculator, a target steering angle calculator, and a target steering torque calculator.

The target trajectory calculator generates a target trajectory for following the generated virtual line for estimating an arbitrary offset specified from the center of the vehicle by using a target distance that can be varied according to the vehicle speed. In this case, the target trajectory calculator 131 may generate the target trajectory as coordinates (x, y).

The target yaw rate calculator generates a target yaw rate YRdes for following the target trajectory.

The target steering angle calculator calculates the target steering angle δdes based on the target yaw rate.

The target steering torque calculator generates the target steering torque Tdes from the target steering angle through FeedForward control or FeedBack control.

(4) control release determiner (140)

The control release determiner 140 determines the end time of the lane keeping control (lane departure prevention control) by using the information measured by the driving information detector 110 .

First, the control release determiner 140 releases the control when it is determined that the vehicle does not depart based on the measured value for the lane during the lane maintenance control.

The control release determiner 140 releases the control when the distances Dl and Dr between the left/right wheels and the lane are equal to or greater than the limit value F. The limit value F may vary according to the lane width. The limit value F is set larger than the limit value E. This is to prevent the control from starting immediately after the control is released by the limit value F.

Second, when the lane keeping control is in operation but the vehicle deviates from the lane, a large control input is required to maintain the lane, and this operation causes the driver's steering sense of discomfort or anxiety. In order to prevent this, the control release determiner 140 releases the control when the vehicle deviates from the lane by more than a specific value.

Third, a certain physical parameter of the vehicle for lane maintenance control is calculated using vehicle state information and lane information. not guaranteed In order to prevent this, the control release determiner 140 releases the control when the reliability value of the lane information does not satisfy a predetermined criterion.

The control release determiner 140 determines when the lane quality is less than a predetermined value in both lanes, when the rate of change of the lane offset in both lanes is equal to or greater than a predetermined value, when the rate of change in the curvature of the lane or the heading angle is equal to or greater than a predetermined value, the curvature or heading angle of the left and right lanes It is determined that the reliability of the lane information is not guaranteed when the difference in the rate of change is greater than or equal to a certain value.

Fourth, the control release determiner 140 releases the control when it is measured that the driver issues a signal for determining that the driver has the intention to change the lane or performs a driving operation for determining that the driver has the intention to change the lane. The control release determiner 140 releases the control when it is determined that the driver intends to change the lane.

When the vehicle turn signal (lane change signal) input is received, the control release determiner 140 may determine that the driver has expressed the intention to change the lane and release the control. Also, when the driver's steering torque value is equal to or greater than the limit value G, the control release determiner 140 may determine that the driver's intention to change the lane is detected and release the control. The limit value G may vary according to the size and direction of the curvature radius of the road.

2 is a configuration diagram of an LKAS control apparatus for a vehicle according to an embodiment of the present invention.

As shown in FIG. 2 , the LKAS control device for a vehicle according to the present invention is a device for controlling the LKAS when a vehicle traveling on one road enters another road at a Junction Cross (JC) of the road, and a stereo camera 20 ), a guard rail recognition unit 21 , and a control unit 22 .

Looking at each of the components, first, the stereo camera 20 acquires a stereo image of the front of the vehicle.

Next, the guardrail recognition unit 21 recognizes the guardrail from the stereo image.

Next, the control unit 22 performs overall control so that each of the components can perform their functions normally.

In particular, when the vehicle diverges at a road junction, that is, when a vehicle traveling on one road enters another road at a Junction Cross (JC) of the road, the control unit 22 recognizes the guard rail recognized by the guard rail recognition unit 21 . After calculating the distance to and based on this, the LKAS 100 is controlled to assist lane keeping. In this case, the LKAS 100 performs the functions described with reference to FIG. 1 , but assists in lane maintenance based on the guard rail rather than the lane.

In this case, whether the vehicle is branched is recognized as branching when a turn signal (lane change signal) of the vehicle is input, when the driver's steering torque value is equal to or greater than the limit value (G). In this case, the limit value G may vary according to the size and direction of the radius of curvature of the road. In addition, it is possible to determine whether to branch through the route information of the navigation system.

Hereinafter, a process in which the controller 22 calculates the distance to the guard rail will be described with reference to FIG. 3 .

3 is an explanatory diagram of one embodiment of the LKAS control method according to the present invention.

In FIG. 3 , d1 _L is the distance between the vehicle and the left lane, d1 _L ' is the distance between the vehicle and the left lane after t seconds, d1 _R is the distance between the vehicle and the right lane, and d1 _R ' is the vehicle and the vehicle after t seconds Distance from the right lane, d2 _R is the distance between the _{vehicle and the junction, d2 R} ' is the distance between the _{vehicle and the junction after t seconds, d3 R} is the distance between the vehicle and the guard rail on a straight road, d3 _R ' is It represents the distance between the vehicle and the guard rail at the junction, respectively.

The controller 22 calculates _{the distance d3 R} ′ from the junction to the guard rail based on the following [Equation 1].

[Equation 1]

d3 _R ' = d3 _R + Gd _R

Here, Gd _R satisfies the following [Equation 2].

[Equation 2]

Here, v denotes vehicle speed, t denotes time, and 'Curvature' denotes the curvature of the guard rail.

Meanwhile, the LKAS 100 assists in lane keeping of the vehicle based on Equation 3 below.

[Equation 3]

d3 _R '< Δy

이다. 이때, v_x는 차량의 종방향 속도, Ψ는 헤딩각(heading angle), t는 시간을 각각 의미한다.here,

am. In this case, v _x denotes the longitudinal speed of the vehicle, Ψ denotes a heading angle, and t denotes time.

4 is a flowchart illustrating an LKAS control method of a vehicle according to an embodiment of the present invention.

First, the stereo camera 20 acquires a stereo image of the front of the vehicle ( 401 ).

Thereafter, the guardrail recognition unit 21 recognizes the guardrail from the stereo image acquired by the stereo camera 20 ( 402 ).

Thereafter, when the vehicle diverges from the road junction, the controller 22 calculates the recognized distance to the guard rail and controls the Lane Keeping Assist System (LKAS) to assist in lane keeping based on the calculated distance ( 403 ).

On the other hand, the method of the present invention as described above can be written in a computer program. And codes and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), read and executed by the computer to implement the method of the present invention. And the recording medium includes all types of computer-readable recording media.

The present invention described above, for those of ordinary skill in the art to which the present invention pertains, various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention. It is not limited by the drawings.

20: stereo camera
21: guard rail recognition unit
22: control unit

Claims (6)

a stereo camera for acquiring a stereo image of the front of the vehicle;
a guardrail recognition unit for recognizing a guardrail from a stereo image; and
When the vehicle diverges from the road junction, the distance to the guard rail recognized by the guard rail recognition unit is calculated, and based on this, the LKAS (Lane Including; a control unit for controlling the Keeping Assist System);
The control unit is
An LKAS control device for a vehicle, characterized in that the distance between the vehicle and the guard rail is calculated when entering the junction, and the lateral movement distance of the vehicle after a predetermined time is maintained to be smaller than the calculated distance.
The method of claim 1,
The control unit is
An LKAS control device for a vehicle, characterized in that it is determined whether the vehicle is diverged at a road junction through a vehicle turn signal.
The method of claim 1,
The control unit is
LKAS control device for a vehicle, characterized in that it is determined whether the vehicle is diverged at a road junction through the route information of the navigation system.
acquiring, by a stereo camera, a stereo image of the front of the vehicle;
recognizing, by a guardrail recognition unit, a guardrail from a stereo image; and
When the vehicle diverges from the road junction, the controller calculates the distance to the recognized guard rail, and based on this, LKAS (Lane Keeping Assist System) assists lane keeping through lane compensation in the unrecognized or misrecognized section of the lane. including; controlling
The step of controlling the LKAS to assist the lane keeping comprises:
A method for controlling an LKAS of a vehicle, characterized in that the distance between the vehicle and the guard rail is calculated at the time of entering the junction, and the lateral movement distance of the vehicle after a predetermined period of time is controlled to be maintained smaller than the calculated distance.
5. The method of claim 4,
The control step is
LKAS control method of a vehicle, characterized in that it is determined whether the vehicle is branched at a road junction through a turn signal of the vehicle.
5. The method of claim 4,
The control step is
LKAS control method of a vehicle, characterized in that it is determined whether the vehicle is diverged at a road junction through route information of a navigation system.

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