Method for predicting lane line and lane departure warning system using the same

• US 8,687,063 B2
• Filed: 01/25/2008
• Issued: 04/01/2014
• Est. Priority Date: 08/30/2007
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Liao, Yung-Sheng, Lin, Che-Chung, Lin, Chi-Wei, Huang, Dau-Chen, Hsieh, Hsi-Wen
• Primary Examiner(s): Dharia, Rupal
• Assistant Examiner(s): MCKENZIE, MARCUS A
• Application Number:
  US12/019,936
• Publication Number:
  US 20090058622A1
• Time in Patent Office: 2,258 Days
• Field of Search: 348/148
• US Class Current: 348/148
• CPC Class Codes: B60Q 9/008 for anti-collision purposes
• CPC Class Codes: G06V 20/588 Recognition of the road, e.g. of lane markings; Recognition of the vehicle driving pattern in relation to the road
• CPC Class Codes: G08G 1/167 Driving aids for lane monitoring, lane changing, e.g. blind spot detection

Abstract

A method for predicting lane line is provided in the present invention, in which the method is capable of predicting and reconstructing the unidentified lane line according to a predetermined geometry relationship based on the recognized lane line data previously while one side of lane line is unable to be identified. In one embodiment, a lane predicting relationship formula is formed by describing the geometry relationship between the two identified lines defined the lane. When the one side of line of the lane is unable to be identified, a new predicted line can be reconstructed for representing the unidentified line of lane according to the lane predicting relationship curve. In another embodiment, a lane departure warning system utilizing the foregoing method is provided for monitoring vehicle moving status and alerting the driver so as to enhance the vehicle safety.

Claims

1. A method for reconstructing an unidentified boundary of a traffic lane including a left boundary and right boundary, comprising the steps of:

capturing a plurality of traffic lane images by a front imaging unit;

providing a top boundary predicting relationship curve and a bottom boundary predicting relationship curve by a control unit, wherein the top boundary predicting relationship curve defines a top geometric relationship between the left boundary and the right boundary at top of a region of interest (ROI) in a traffic lane image, and the bottom boundary predicting relationship curve defines a bottom geometric relationship between the left boundary and the right boundary at bottom of the ROI in the traffic lane image, and the top boundary predicting relationship curve and the bottom boundary predicting relationship curve are determined by a determining process comprising the steps of;

identifying the left boundary and the right boundary of the traffic lane in the plurality of traffic lane images, and setting a virtual center line for the traffic lane;

forming the ROI in each traffic lane image, wherein each ROI in each traffic lane image comprises;

a top left point, wherein the top left point is where the left boundary intercepts top of the ROI;

a top right point, wherein the top right point is where the right boundary intercepts top of the ROI;

a bottom left point, wherein the bottom left point is where the left boundary intercepts bottom of the ROI; and

a bottom right point, wherein the bottom right point is where the right boundary intercepts bottom of the ROI;

acquiring a plurality of distance information sets by acquiring each distance information set from each of the traffic lane images, wherein each distance information set comprises;

a top left distance measured between the top left point and the virtual center line;

a top right distance measured between the top right point and the virtual center line;

a bottom left distance measured between the bottom left point and the virtual center line of the lane; and

a bottom right distance measured between the bottom right point and the virtual center line; and

performing a numerical analysis upon the plurality of distance information sets as a first set of characteristic values and a second set of characteristic values to obtain the top boundary predicting relationship curve and the bottom boundary predicting relationship curve;

reconstructing the unidentifiable boundary in any traffic lane image by applying the measured first and second set of characteristic values into the top boundary predicting relationship curve and the bottom boundary predicting relationship curve, by the control unit;

dynamically updating the top boundary predicting relationship curve and the bottom boundary predicting relationship curve when width of the lane is changed by repeating the determining process to update the top boundary predicting relationship curve and the bottom boundary predicting relationship curve;

detecting a vehicle status by a vehicle status detecting unit, and forwarding the vehicle status to control unit;

issuing an alarm signal by the control unit as the control unit evaluates the vehicle status and determine a precaution is needed; and

generating an alarm by an alerting unit, wherein the alerting unit is coupled to the control unit for receiving the alarm signal to generate the alarm.

2. The method of claim 1, wherein the first set of characteristic values includes the top left distance and the top right distance.

3. The method of claim 1, wherein the obtaining the top boundary predicting relationship curve and the bottom boundary predicting relationship curve further comprises:

determining types of the top boundary predicting relationship curve and the bottom boundary predicting relationship curve;

imaging at least two traffic lane images each with an identifiable left boundary and an identifiable right boundary; and

acquiring two consecutive distance information sets.

4. The method of claim 1, further comprises displaying the reconstructed unidentifiable boundary.

5. The method of claim 1, wherein the dynamically updating the top boundary predicting relationship curve and the bottom boundary predicting relationship curve further comprises

updating the distance information sets from a plurality of newly fetched traffic lane images.

6. A traffic lane departure warning system, comprising:

a front imaging unit, for capturing a plurality of traffic lane images of a traffic lane on which a vehicle travels on the traffic lane, wherein the traffic lane has a left boundary and a right boundary;

a vehicle status detecting unit, for detecting a status of the vehicle and thus generating a status signal;

an image processing/controlling module, reconstructing an identifiable boundary of the traffic lane and evaluating the status signal so as to generate an alarm signal;

a displaying unit, coupled to the image processing/controlling module for displaying an image of lane line according; and

an alerting unit, coupled to the image processing/controlling module for receiving the alarm signal and thus generating an alarm;

wherein the image processing/controlling module reconstructs the identifiable boundary by;

identifying the left boundary and the right boundary of the traffic lane in the plurality of traffic lane images, and setting a virtual center line for the traffic lane;

forming the ROI in each traffic lane image, wherein each ROI in each traffic lane image comprises;

a top left point, wherein the top left point is where the left boundary intercepts top of the ROI;

a top right point, wherein the top right point is where the right boundary intercepts top of the ROI;

a bottom left point, wherein the bottom left point is where the left boundary intercepts bottom of the ROI; and

a bottom right point, wherein the bottom right point is where the right boundary intercepts bottom of the ROI;

acquiring a plurality of distance information sets by acquiring each distance information set from each of the traffic lane images, wherein each distance information set comprises;

a top left distance measured between the top left point and the virtual center line;

a top right distance measured between the top right point and the virtual center line;

a bottom left distance measured between the bottom left point and the virtual center line of the lane; and

a bottom right distance measured between the bottom right point and the virtual center line; and

performing a numerical analysis upon the plurality of distance information sets as a first set of characteristic values and a second set of characteristic values to obtain the top boundary predicting relationship curve and the bottom boundary predicting relationship curve.

7. The system of claim 6, wherein the front imaging unit is a camcorder.

8. The system of claim 7, wherein the camcorder is a device selected from the group consisting of a charge-coupled device (CCD), and a complementary metal-oxide semiconductor (CMOS).

9. The system of claim 6, wherein the front imaging unit is an infrared imaging unit.

10. The system of claim 6, wherein the alarm generated by the alerting unit is selected from the group consisting of a sound, a light, a vibration.

11. The system of claim 6, further comprising a control unit, provided to be used by a user as a control interface for disarming the alarm and adjusting system parameters.

12. The system of claim 6, wherein the image processing/controlling module further comprises:

an image fetching/decoding unit, coupled to the front imaging unit for converting the traffic lane image into a digital image data;

a digital signal processing/controlling unit, for analyzing the digital image data received from the image fetching/decoding unit; and

an image encoding/outputting unit, coupled to the digital signal processing/controlling unit and the displaying unit for receiving a control signal from the digital signal processing/controlling unit and using the control signal for image encoding and thus outputting an output image data to the displaying unit.

13. The system of claim 12, wherein the image processing/controlling module further comprises:

an image random access memory, for storing the digital image data and a processed image data, wherein the processed image data is outputted from the digital signal processing/controlling unit for providing the digital image data to the digital signal processing/controlling unit for providing the processed image data to the image encoding/outputting unit; and

a non-volatile programmable memory, for registering an analysis result of traffic lane information received from the digital signal processing/controlling unit.

14. The system of claim 12, wherein the digital signal processing/controlling unit is configured to transmit a traffic lane boundary recognition data and an abnormal driving data to the displaying unit.

15. The system of claim 14, wherein the traffic lane boundary recognition data includes data of vehicle departure, turning orientation, and lane curvature.

16. The system of claim 6, wherein the image processing/controlling module dynamically updates the top boundary predicting relationship curve and the bottom boundary predicting relationship curve.

17. The system of claim 6, wherein the vehicle status is a measurement selected from a group consisting speed, brake signal, turning signal, and the combination thereof.