System and method for automatically steering a vehicle within a lane in a road

• US 5,245,422 A
• Filed: 06/28/1991
• Issued: 09/14/1993
• Est. Priority Date: 06/28/1991
• Status: Expired due to Fees

• Current Assignee: Zexel Corporation (Robert Bosch GmbH)
• Original Assignee: Zexel Corporation (Robert Bosch GmbH)
• Inventors: Liou, Shih-Ping, Jurzak, Jacek L., Borcherts, Robert H., Yeh, Tse-Liang A.
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US07/722,661
• Time in Patent Office: 809 Days
• Field of Search: 358/103, 358/105, 364/424.01, 364/424.02, 364/426.01, 364/426.04, 180/179
• US Class Current: 348/119
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/081 using distance control
• CPC Class Codes: B60T 2201/087 using active steering actuation
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means

Abstract

An automatic vehicle steering system is provided for automatically steering a vehicle along a lane in a road. A video sensor is included for generating a plurality of frames of video images of the road. A computer processor analyzes the frames to determine the lane boundaries of the road and the position of the vehicle. The system advantageously utilizes engagement of a cruise control switch and a steering control switch to initiate processing of the image data and automatic steering of the vehicle. In such manner, the reliability and efficiency of the system is increased while at the same time minimizing complexity and cost.

Claims

1. A system for automatically steering a vehicle along a lane in a road, said system comprising:

sensor means mounted to the vehicle for generating position information about the road in front of the vehicle;

cruise control means for controlling the speed of the vehicle, the cruise control means including a switch for initiating automatic speed control;

processor means, coupled to the sensor means and also to the cruise control switch, for analyzing the information from the sensor means;

the processor beginning the analysis of the information when the cruise control switch is engaged; and

steering control means for automatically controlling the steering of the vehicle to maintain the vehicle within the lane in the road as a function of the analysis by the processor.

2. The system of claim 1 wherein said steering control means includes a manually actuable switch, and wherein said system initiates automatic steering of the vehicle when the driver has actuated both the cruise control switch and the steering control switch.

3. The system of claim 2 wherein manual actuation of said steering control switch further actuates said cruise control switch, thereby allowing the system to initiate automatic steering of the vehicle.

4. The system of claim 3 which further comprises:

steering angle sensor means for detecting the angle of the wheels of the vehicle;

said processor being coupled to the steering angle sensor means and using output signals therefrom to determine when to initiate the processing of the position information; and

said processor further providing initialization of said processing means and the steering control means when the processing is initiated and when the driver maintains the vehicle within a lane in the road prior to actual engagement of said steering control means.

5. The system of claim 4 wherein said steering control means comprises;

steering actuator means for controlling the steering angle of the wheels of the vehicle; and

steering actuator control means for controlling the steering control actuator means.

6. The system of claim 5 wherein said steering actuator control means receives signals from said processor means and steering angle sensor means and determines the necessary direction for maintaining the vehicle in a desired position within the lane boundaries of a road.

7. The system of claim 6 which further comprises:

driver steering sensor means for detecting manual steering effort by the driver of the vehicle, said steering sensor means being adapted to provide a signal to said steering actuator control means to disengage the system when manual steering effort is detected and re-engage the system once the manual steering effort is no longer detected.

8. The system of claim 7 wherein said processor means comprises;

digitization means for receiving each of the plurality of frames of video images and converting said video images from analog signals to digital signals; and

digital image processing means for processing the digital signals.

9. The system of claim 8 wherein said digital image processing means further comprises:

lane identification means for providing image processing for detecting a left and a right boundary of the lane in the road in front of the vehicle; and

lane centering means for determining the desired vehicle position.

10. The system of claim 9 wherein said digital image processing means further provides for analyzing the digital signals of each frame, said analysis including detection of strong line response and consistent line orientation, said boundaries of the lane being determined as a function of said line response and line orientation.

11. The system of claim 10 wherein said processor means further comprises predictor means for determining the necessary area to be searched.

12. The system of claim 10 wherein said lane detection means determines a projected tangent line for each of said left and right boundaries within a chosen search area specified by said predictor means, said lane centering means analyzing the location of said tangent lines to determine the desired vehicle direction.

13. The system of claim 10 wherein said predictor means further provides for adjusting said search area to include the location of the intersection of said tangent lines therein.

14. The system of claim 1 wherein:

said sensor means comprises detector means for generating the position information including distance and orientation of the vehicle relative to the lane on the road;

said processor means comprising position information processing means for determining vehicle trajectory and contour of the lane in the vicinity of the vehicle; and

wherein the cruise control switch is engaged manually by the driver.

15. The system of claim 1 wherein the sensor means is a video sensor which generates a plurality of frames of video images of the road in front of the vehicle.

16. An automatic vehicle steering system for automatically steering a vehicle along a lane in a road, said system comprising:

video sensor means mounted to the vehicle for generating a plurality of frames of video images of the road in front of the vehicle;

cruise control means for controlling the speed of the vehicle, the cruise control means including a manually actuable switch for initiating speed control;

processor means coupled to the video sensor means and also to the cruise control switch, for analyzing frames of the video images;

steering control means for automatically controlling the steering of the vehicle to maintain the vehicle within the lane in the road as a function of the analysis of the processor;

steering control switch means including a manually actuable switch means for engaging the system to begin processing of the video images and provide automatic vehicle steering; and

said system initiating automatic steering of the vehicle when the driver has actuated both the cruise control switch and the steering control switch.

17. The system of claim 16 further comprising:

steering angle sensor means for detecting driver effort to steer the vehicle; and

said steering control means allowing the steering control function to be overridden while such driver effort is detected.

18. The system of claim 17 wherein said processor means comprises;

digitization means for receiving each of the plurality of frames of video images and converting said video images from analog signals to digital signals; and

digital image processing means for providing digital image processing of the digital signals.

19. The system of claim 18 wherein:

said digital image processing provides image processing for detecting a left and a right boundary of the lane in the road in front of the vehicle; and

said processor further providing initialization of said video image processing and steering control means when the processing is initiated and when the driver maintains the vehicle within a lane in the road prior to actual engagement of said steering control means.

20. The system of claim 19 wherein said digital image processing further provides for analyzing the digital signals of each frame, said analysis including detection of strong line response and consistent line orientation, said boundaries of the lane being determined as a function of said strong line response and with consistent orientation.

21. The system of claim 20 wherein said computer processor means further comprises a predictor means for improving image processing speed, said predictor means providing:

an automatically adjustable search area for determining the intersection and the location of said tangent lines therein, said search area being automatically adjusted to provide for a minimal search area.

22. A method for providing automatic steering of a vehicle along a lane in a road, said method comprising:

generating a plurality of frames of video images of the road in front of the vehicle;

controlling the speed of the vehicle with cruise control means having a manually actuable switch for initiating speed control;

processing the plurality of frames of video images to analyze and detect the lane boundaries of the road in front of the vehicle based on predicted possible lane boundary locations in the image and determine the direction of the lane and provide a control response that will maintain the vehicle at a desired position within the lane;

controlling the steering of the vehicle to maintain it within the lane in the road as a function of the analysis of the processor; and

initiating processing of said video images and providing automatic steering control when a manually actuable steering control switch is engaged while the cruise control system is operating.

23. The method of claim 22 further comprising the step of:

disengaging the automatic steering control when a driver steering effort is detected; and

re-engaging the automatic steering control when the driver steering effort is no longer detected.

24. The method of claim 23 wherein said processing step further comprises digitizing the analog signals of said video images to provide a plurality of digital signals.

25. The method of claim 24 wherein said processing step further includes digital processing which comprises:

detecting strong line response and consistent line orientation to determine a left and a right boundary of the lane;

determining the direction necessary to maintain the vehicle in the desired position within the lane, said processing step including locating a projected tangent line extending from each of said boundaries, determining the location of each tangent line within a chosen search area and adjusting the search area to provide for the possible intersection area of the tangent lines therein, said intersection of the tangent lines being the desired vehicle direction.

26. The method of claim 22 further comprising the step of:

initializing said processing of frames and said steering controlling when said processing is initiated and the vehicle is maintained along a lane in the road prior to actual steering controlling.

27. A system for automatically steering a vehicle along a lane in a road, said system comprising:

video sensor means mounted to the vehicle for generating a plurality of frames of video images of the road in front of the vehicle;

processor means, coupled to the video sensor means for analyzing frames of the video images;

steering control means for automatically controlling the steering of the vehicle to maintain it within the lane as a function of the analysis by the processor means;

said processor means including digitization means for converting said video images from analog signals to digital signals and having digital image processing means for processing the digital signals;

said digital image processing means further including lane identification means for detecting a left and a right boundary of the lane by analyzing the digital signals and determining the lane boundaries as a function of a strong line response and a consistent line orientation, and further including lane centering means for determining the desired vehicle position;

said processor means further including a predictor means for determining an area to be searched; and

lane identification means being adapted to determine a projected tangent line from each of said left and right boundaries within a chosen search area specified by said predictor means, said lane centering means analyzing the location of said tangent lines to determine the desired vehicle direction, with said predictor means being adapted to adjust the search area to include the location of the intersection of said tangent lines therein.