KR100766594B1 - Early lane departure warning method for vehicle - Google Patents

Abstract

According to the present invention, a vehicle lane early warning method capable of early warning of lane departure according to whether a horizontal coordinate value of a center point on a driving road of the vehicle coincides with a horizontal coordinate value of a target point on a road coordinate assuming an ideal driving state on the road of the vehicle It is about.

  According to the lane departure early warning method of the preferred embodiment, the front road information image of the driving vehicle is captured to extract the left and right lanes of the vehicle, and the image coordinates of the extracted left and right lane information are converted into road coordinates. Obtains the circumference of the left / right lane of the vehicle and the radius of curvature of the circumference of the vehicle, obtains a road coordinate value of a target point that satisfies the condition that the vehicle travels ideally along the circumference, and then stores the road coordinate value Invert the display to be displayed on the screen, obtain a center point for a plurality of points that pass through the target point on the screen and are parallel to the horizontal axis, and compare the horizontal coordinate value of the center point with the horizontal coordinate value of the target point. A lane of the vehicle according to a comparison result between the horizontal coordinate value of the center point and the horizontal coordinate value of the target point It is controlling the ride of an alarm.

Further, according to the present invention, the lane departure early warning process may be performed by a mobile phone with a camera, or by a vehicle-mounted navigation with a camera.

Description

Early warning of lane departure of vehicles {EARLY LANE DEPARTURE WARNING METHOD FOR VEHICLE}

1A and 1B are block diagrams of an apparatus for implementing a lane departure early warning method for a vehicle according to a preferred embodiment of the present invention;

2 is a flowchart for explaining a lane departure early warning method for a vehicle according to the present invention;

3A and 3B are views for explaining a lane departure early warning method of a vehicle according to the present invention;

4A and 4B are exemplary views illustrating a process of preventing lane departure by adjusting a steering wheel in a target point direction by a lane departure early warning method according to the present invention.

* Description of the symbols for the main parts of the drawings *

10: imaging unit, 12: image processing unit,

14: lane departure detection unit, 16: display unit,

18: Alarm generating unit.

The present invention relates to a method for early warning of lane departure of a vehicle. More particularly, the present invention relates to a driver by determining in advance the possibility of lane departure with respect to the center of the left and right lanes of the vehicle based on the geometrical characteristics of the road in the driving state of the vehicle. The present invention relates to a method for early warning of lane departure of a vehicle for warning.

In general, when the vehicle is traveling, the road is repeatedly faced with straight roads and curved roads. When the vehicle is running on roads, steering control is appropriately adapted to the geometrical state of the road (ie, straight road or curved road). Although the possibility of lane departure is reduced only when the driver's driving condition is poor, the driver is likely to leave the lane considerably on a curved road as well as on a straight road in a state in which the driver's immature driving or poor visibility is likely to cause a safety accident.

Therefore, in recent years, various technologies have been proposed to detect the departure from the left lane or the right lane of the vehicle to alert the driver to alert the driver to prevent safety accidents.

An example of such a lane departure warning of a vehicle is a method of generating alarm information depending on how close to which lane the left lane and the right lane of the driving vehicle approaches the center vertical axis of the image or its deformation.

Another example of a lane departure warning of a vehicle is the calculation of a target steering angle for driving along the centerline of the left and right lanes, which define the driving route that the vehicle travels on when the vehicle travels on the road, and the rotation of the current steering shaft. This method detects an angle and generates a boundary alarm when the difference exceeds a certain limit.

Here, according to the former method, it is possible to operate relatively well on a straight road, whereas malfunction is likely to occur on a curved road. When the sensitivity is reduced to minimize the malfunction on a curved road, the malfunction on the curved road is reduced. Is reduced, but the sensitivity is significantly degraded on the straight road.

For example, on a curved road that curves to the right, the left lane looks closer to the vehicle (body), which is more likely to cause a malfunction that warns of a departure to the left lane. The closer you look to the vehicle, the greater the likelihood that a malfunction will occur that alerts you of a departure to the right lane.

In addition, the latter method is advantageous in that an early warning for generating an alarm before the vehicle leaves the lane is possible, but the assumption and guidance formula of the driving model for calculating the target steering angle should be applied. Since there is no way to verify the accuracy or validity of the target steering angle, it is disadvantageous in that it is difficult to set an alarm reference.

Moreover, in the latter method, the inconvenience of attaching the encoder for detecting the steering angle of the steering shaft corresponding to the rotation of the steering wheel (ie, the handle) is followed.

Accordingly, the present invention has been made in view of the above-described circumstances of the prior art, and it is possible to make early warning of lane departure without inducing any mathematical model for steering angle calculation or assumption of any model such as two-wheeled vehicle model, and curvature even in a straight road. The object of the present invention is to provide an early warning method for lane departure of a vehicle in which a false error rate is remarkably improved even on this large curved road.

In order to achieve the above object, according to a preferred embodiment of the present invention, the first step of extracting the road information image of the front of the driving vehicle and extracting the left and right lanes of the vehicle; Converting the image coordinates of the extracted left / right lane information into road coordinates to obtain a circumference of the left / right lane in which the vehicle is running and a radius of curvature of the circumference; Constant distance from the camera mounted on the vehicle under conditions for the vehicle to travel ideally along the circumference of the curvature, i.e. under the condition that the center of the vehicle is on the circumference and the direction in which the vehicle lies must match the tangential direction of the circumference. A third step of obtaining a circumferential point (called a target point) spaced apart by a gaze distance of the target point, obtaining a road coordinate value of the target point, and inverting the road coordinate value into an image coordinate value to be displayed on a screen; A fourth step of obtaining two points where a line segment parallel to the horizontal axis passing through the target point on the screen intersects the left and right lane images, and then obtaining a center point between the two points and comparing the horizontal coordinate value of the center point with the horizontal coordinate value of the target point; There is provided a lane departure early warning method comprising a fifth process of controlling a lane departure alarm occurrence of the vehicle when the difference between the horizontal coordinate value of the center point and the horizontal coordinate value of the target point is greater than a predetermined threshold. do.

According to the present invention, the second process draws three or more horizontal lines on the extracted left and right lanes, obtains two points intersecting the left / right lanes for each horizontal line, and calculates a center point between two points for each horizontal line. Obtaining three or more image coordinate values, and converting the image coordinates of the three or more center points into road coordinates to obtain a circumference passing through the center point and a radius of curvature of the circumference.

The third process is a position away from the center point of the vehicle by a predetermined distance from the center point of the vehicle, assuming that the vehicle is located on the circumference of the radius of curvature and placed in the tangential direction of the circumference. Assume the forward perspective distance at, the line segment perpendicular to the Yw-axis intersecting the circumference while passing through the forward peripheral distance point as the target point, obtain the road coordinate value of this target point, and calculate the road coordinate value of the target point. And converting the coordinates into coordinates to display the screen.

In addition, the fourth process draws a horizontal horizontal line parallel to the horizontal axis of the screen while passing through the target point displayed on the screen, obtains two points where the horizontal line intersects the left / right lanes, and the horizontal of the center points between the two points. The method may include determining a coordinate value and determining whether the horizontal coordinate value of the target point on the image coordinate coincides with the horizontal coordinate value of the center point.

If the horizontal coordinate value of the center point and the horizontal coordinate value of the target point do not coincide with each other, the fifth process determines whether an instantaneous difference value or an integral value of the difference value exceeds a predetermined threshold value for a predetermined time, and when the threshold value is exceeded, the lane departure warning Generating a signal to early warning of a lane departure possibility.

According to the present invention having the above-described configuration, in order to obtain an ideal driving state on any road faced by the vehicle, the center of the vehicle must lie on the center line of the road and the direction of the vehicle (ie, vehicle attitude) is tangent to the center line at the point where the vehicle is located. It must satisfy the condition that it must match the direction. After assuming that such an abnormal condition is satisfied, the target point is set to the point where the line segment parallel to the Xw axis located at a constant forward viewing distance from the vehicle meets the circumference of the radius of curvature, and the road coordinate system of the target point is calculated. The target point is then inversely transformed and displayed on the screen. A horizontal line parallel to the horizontal axis of the screen is drawn while passing through the target point displayed on the screen, and the horizontal coordinate value of the center point between the two points is obtained by obtaining two points where the horizontal line intersects the left / right lane. If there is a difference in the horizontal coordinate values of these two points, this indicates that the vehicle's position and attitude are out of the normal (ideal) position and attitude. If the difference or the temporal integral of the difference exceeds the set threshold, Early warning of lane departure Therefore, the risk of lane departure can be detected early on any curvature road or driving condition, so the risk can be detected early.

Furthermore, according to the present invention, unlike the conventional method, it is not necessary to detect the current steering angle of the steering shaft, so that the mounting of the steering angle sensing encoder or the steering angle output signal is unnecessary on the steering shaft of the steering wheel.

In addition, according to the present invention, the above-described first to fifth processes can be executed by a mobile phone with a camera, or by vehicle-mounted navigation with a camera.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

1A and 1B are block diagrams of an apparatus for implementing a lane departure early warning method of a vehicle according to an exemplary embodiment of the present invention.

In FIG. 1A, 10 denotes an image capturing unit which is installed at the upper front of a vehicle to obtain a road information image in front of the vehicle while the image capturing unit 10 may be a CCD camera, a CMOS camera, or another suitable image capturing device. have.

12 shows the front road information image of the vehicle captured by the imaging unit 10, and the left lane (see '40' in FIG. 3A) and the right lane ('in FIG. 3A) by a known image processing technique. 42 ').

In FIG. 14, the lane departure alarm control signal is generated based on the left lane and the right lane of the vehicle extracted by the image processor 12, and if the vehicle is not in a normal driving state. It is a lane departure detection unit.

16 is a display unit for visually displaying the result of the lane departure information by the lane departure detection unit and the result of the calculation of the inadequacy of the traveling direction.

18 is an alarm generator that outputs a lane departure alarm in response to the lane departure alarm generation signal applied by the lane departure detection unit 14 to alert the driver not to leave the lane.

Here, according to the present invention, the device shown in FIG. 1A is configured separately for early departure of the vehicle, but FIG. 1B is a case where the device shown in FIG. 1A is applied to a mobile phone or a navigation device 60 having a camera. It is assumed that the configuration.

That is, the camera equipped in the mobile phone or the navigation 60 performs the function of the imaging unit 10 and the control means (CPU or microcomputer) is the image processing unit 12 and the lane departure detection unit 14. The display unit 16 allows the display device of the mobile phone or the navigation 60 to perform the corresponding function, and the alarm generating unit 18 has the same microphone or speaker of the mobile phone or the navigation 60. Can perform a function.

The above-described lane departure early warning method for a vehicle according to the present invention will be described in detail with reference to the flowchart shown in FIG. 2.

First, when the imaging unit 10 acquires a road information image in front of the vehicle and applies it to the image processing unit 12 while the vehicle is driving in step 20, the image processing unit 12 is configured to display the vehicle information in the road information image. The lane information is extracted to the lane departure detection unit 14 by extracting the left lane and the right lane.

In step 22, the lane departure detection unit 14 includes a plurality of horizontal lines (that is, at least three horizontal lines in the present invention) on the extracted left lane 40 and the right lane 42 (43 in the left figure of FIG. 3A). 44,46 are drawn, and for each horizontal line 43, 44, 46, two intersection points intersecting the left lane 40 and the right lane 42 are obtained, and two on each horizontal line 43, 44, 46 are obtained. The center point between the intersection points (43a, 44a, 46a in the left figure of FIG. 3a) is obtained.

Then, in step 24, the lane departure detection unit 14 sets the forward peripheral direction to the Yw-axis at the current position of the vehicle, and Xw the axis passing through the center point of the vehicle perpendicular to the Yw-axis. In the case of defining by the -axis and defining the road coordinates, the coordinates of the image coordinates of the three center points (43a, 44a, 46a in the left figure of FIG. 3A) captured by the imaging unit 10 are coordinated with the road coordinate values. Transform (ie, see 43b, 44b, 46b in the right figure of FIG. 3a).

In step 26, the lane departure detection unit 14 has a circumference of curvature passing through the three points 43b, 44b, and 46b located on the road coordinates to detect the curvature of the curved road on which the vehicle travels. The radius of curvature R (48 in Fig. 3a) is obtained.

Here, in the case of a straight road, the radius of curvature is calculated as a value approaching infinity.

In addition, in order for the corresponding vehicle to travel ideally along the circumference of the curvature described above, the center of the vehicle body must be located on the circumference thereof, and the attitude direction of the vehicle must match the tangential direction of the circumference of the circle. The lane departure detection unit 14 assumes that the curvature ideally travels on the circumference of the curvature (see the dotted line in the right figure of FIG. 3A or the right figure of FIG. 3B), that is, the center of the vehicle is on the circumference. Assuming that the vehicle attitude direction coincides with the tangential direction of the circumference, a point away from the vehicle's camera by a certain forward peripheral distance (Xw'-Yw 'axis in the right figure of FIG. 3A or 50 in the right figure of FIG. 3B). While passing through, obtain a point where the line segment perpendicular to the forward circumferential direction (that is, 50 in the right figure of FIG. 3B) intersects the circumference (target point) (52 in the right figure of FIG. 3B) and the road coordinate value of the target point 52. Saved All.

Then, in step 30, the lane departure detection unit 14 coordinate-converts the road coordinate value (right picture of FIG. 3B) of the target point 52 to an image coordinate value (left picture of FIG. 3B), and converts the target point 52 a to the reverse point. The position of is to be displayed on the display unit 16. In FIG. 3B, the line segment 50a corresponds to the inverse coordinate transformation value on the horizontal line segment (50 in FIG. 3A) on the road coordinate separated by the viewing distance.
Target Point The position value on the road coordinate system at 52 in FIG. 3B and the lane center point at 54 in FIG. 3A coincide in normal driving conditions, but the difference is issued as the vehicle leaves the center line of the lane. Deviation alarms are generated depending on the size of or the time integration value.

Further, in step 32, the lane departure detection unit 14 draws a horizontal line parallel to the horizontal axis of the screen of the display unit 16 while passing through the target point 52a displayed on the display unit 16, and the horizontal line is the left lane. Two points intersecting the 40 and the right lane 42 are obtained, and a center point between the two points (see 54a in the left figure of FIG. 3B) is obtained. This center point 54a corresponds to the inverse coordinate transformation point of point 54 in FIG. 3A.

Then, the lane departure detection unit 14 compares the horizontal coordinate value of the target point 52a on the image coordinate with the horizontal coordinate value of the center point 54 to determine whether there is a match.

If it is determined in step 32 that the horizontal coordinate value of the target point 52a on the image coordinate and the horizontal coordinate value of the center point 54 do not coincide, in step 34, the lane departure detecting unit 14 makes an instantaneous difference. It is determined whether the integral value of the value or the difference value for a predetermined time exceeds the set threshold.

If it is determined in step 34 that the threshold value is exceeded, the lane departure detection unit 14 applies the lane departure alarm generation signal to the alarm generation unit 18 in step 36 so that the lane departure alarm is output, thereby premature lane departure. Will alert you.

4A shows an example in which the center point 54 on the road does not coincide with the target point 54a and is shown on the right side of the target point 54a, in which case the vehicle is separated in the left direction, in this case clockwise. The steering wheel must be rotated to prevent lane departure.

In contrast, FIG. 4B shows a state in which a lane departure alarm is generated so that the driver rotates the steering wheel clockwise so that the center point 54 of the lane coincides with the target point 54a to normally drive a given road.

When the vehicle travels on a linear straight road, the target point always appears on the Ys' axis regardless of the size of the viewing distance.

On the other hand, in the above description has been described a case where the present invention is configured as a separate device to be installed in the vehicle, the present invention described above is applied to the mobile phone with a built-in camera or attached to the navigation of the road guidance function May be executed.

That is, when applied to a mobile phone, the camera of the corresponding mobile phone performs the function of the imaging unit 10 and the control means (CPU or microcomputer) of the mobile phone is the image processing unit 12 and the lane departure detection unit 14 The display unit 16 is replaced by the display unit of the mobile phone and the alarm generating unit 18 functions by the sound output device (ie, the microphone) of the mobile phone, thereby leaving the lane of the vehicle by the mobile phone. Early warning may be configured to be executed.

In addition, even when applied to a navigation camera attached to the camera, the road information image captured by the camera is subjected to a process for the lane departure warning of the above-described process by the control means (CPU or microcomputer) of the navigation device and the display device of the navigation device. May perform the function of the display unit 16 and the speaker for voice guidance of the road information may perform the function of the alarm generator 18.

As described above, according to the early lane departure warning method of the vehicle according to the present invention, even if the center of the vehicle is deviated from the center line or not at present, there is a possibility that the current vehicle attitude may be linked to the lane departure early. By detecting lane departure warning, it is possible to guarantee high accuracy and sensitivity of lane departure warning in any road conditions or driving conditions such as straight road or curved road as compared with the prior art, and also has an effect of early warning.

In addition, the present invention can be implemented by applying to a mobile phone or navigation camera is attached.

Claims (7)

A first step of capturing a front road information image of a traveling vehicle and extracting lanes on the left and right sides of the vehicle; Converting the image coordinates of the extracted left / right lane information into road coordinates to obtain a circumference of the left / right lane in which the vehicle is running and a radius of curvature of the circumference; A circumferential image spaced by a predetermined forward distance of a certain size in a state in which the center point of the vehicle is located on the circumference and the attitude direction of the vehicle satisfies the condition that the vehicle's posture direction coincides with the tangential direction of the circumference. A third step of obtaining a point as a target value and then obtaining a road coordinate value of the target point and inverting the road coordinate value into an image coordinate value to be displayed on the screen; A fourth step of obtaining a center point between two points where a line segment parallel to the horizontal axis passing through the displayed target point on the screen intersects the left and right lane images, and comparing the horizontal coordinate value of the center point with the horizontal coordinate value of the target point; And comparing a horizontal coordinate value of the center point with the horizontal coordinate value of the target point, and controlling a lane departure alarm occurrence of the vehicle according to the magnitude of the difference. The method of claim 1, wherein the second process draws three or more horizontal lines on the extracted left and right lanes, Find two points crossing each horizontal line on the left and right lanes, Obtain three or more image coordinates of the center point between two horizontal points for each horizontal line, And converting the image coordinates of the three or more center points into road coordinates to obtain the circumference passing through the three points indicated in the road coordinates and the radius of curvature of the circumference. The method of claim 1, wherein the third process assumes that the vehicle ideally travels on the curvature circumference, that is, the center point of the vehicle is located on the circumference of the curvature and the posture direction of the vehicle coincides with the tangential direction of the circumference. Assume that the forward looking distance is located a certain distance away from the center point of the vehicle in the direction of view (Yw-axis direction), Set the point where the horizontal line that is separated by the forward circumference distance meets the circumference as a target point and calculates the road coordinate value thereof, And displaying the screen by inverting the road coordinate value of the target point to the image coordinate value. The method of claim 1, wherein the fourth process draws a line segment parallel to the horizontal axis of the screen while passing through a target point displayed on the screen. Obtaining two points at which the line segments intersect the left / right lanes, and obtaining a horizontal coordinate value of the center point between the two points; And determining whether or not the horizontal coordinate value of the target point on the image coordinate and the horizontal coordinate value of the center point coincide with each other. The method of claim 1, wherein the fifth process determines whether the instantaneous difference value or the integral value of the difference value exceeds a predetermined threshold value when the horizontal coordinate value of the center point and the horizontal coordinate value of the target point do not coincide. And generating a lane departure warning signal when the threshold value is exceeded, thereby early warning of a lane departure possibility. The early warning method for preventing lane departure of a vehicle according to any one of claims 1 to 5, wherein the first to fifth processes are executed by a mobile phone equipped with a camera. The method of claim 1, wherein the first to fifth processes are performed by a vehicle-mounted navigation device equipped with a camera.

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