Lateral control of vehicle for lane following

• US 6,473,678 B1
• Filed: 07/28/2000
• Issued: 10/29/2002
• Est. Priority Date: 08/02/1999
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Uenuma, Kenya, Mouri, Hiroshi, Shimakage, Masayasu, Satoh, Shigeki, Furusho, Hiroyuki
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/628,686
• Time in Patent Office: 823 Days
• Field of Search: 701/41, 701/23, 180/168, 180/167, 180/169, 180/141, 180/142, 340/439, 340/438, 340/435, 340/425.5, 348/119, 348/118, 342/113
• US Class Current: 701/41
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/087 using active steering actuation
• CPC Class Codes: B62D 1/28 non-mechanical , e.g. following a line or other known markers
• CPC Class Codes: B62D 15/025 Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation B62D1/28 takes precedence
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means

Abstract

An apparatus for vehicle lane following in which a look ahead sensor including a CCD camera and an image processor detects a lane marking on the surface of a roadway. The image processor estimates a lateral displacement of a point at a preview distance in front of a vehicle from a target line. The target line is a line between lane markings defining a lane. An electric motor coupled to the steering mechanism is used to provide a bias (a torque input) to the steering, which may either assist or oppose to the steering torque from the driver. A steering controller is designed to assist the driver to maintain the vehicle'"'"'s lane position by holding the vehicle at the target line using a biasing torque if the lane following is selected by the driver. In order to reflect the driver preference in the lane following, the controller collects a sufficient number of measures of the vehicle lateral displacement when the lane following is not selected. Based on the collected data, the controller updates the target line position. In the subsequent lane following, the driver is assisted to maintain the vehicle at this updated target line.

Claims

1. A lane-following system of facilitating steering of a vehicle by tracking a lane of a roadway, the vehicle having a steering system including a steering mechanism, said lane-following system comprising:

sensor means for detecting a position of lane marking on the surface of a roadway in relation to the vehicle, said lane marking defining a lane of a roadway;

means operatively coupled to said sensor means to estimate a lateral displacement of a point at a preview distance in front of the vehicle from the detected lane marking;

an actuator coupled to the steering mechanism to provide a steering bias to the steering system, which may either assist or oppose a steer torque from a vehicle driver, in response to a steering control signal;

steering controller means for producing said steering control signal based on said estimated lateral displacement to assist the driver of the vehicle to maintain the vehicle at a target line within the lane using the steering bias,

said steering controller means being operable, when the vehicle travels without lateral control for lane following, to collect said estimated lateral displacement to produce lateral displacement data,

said steering controller means being operable to update a position of the target line using said lateral displacement data.

2. A method of facilitating steering of a vehicle by tracking a lane of a roadway, the vehicle having a steering system including a steering mechanism, said method comprising:

detecting a position of lane marking on the surface of a roadway in relation to the vehicle, said lane marking defining a lane of a roadway;

estimating a lateral displacement of a point at a preview distance in front of the vehicle from the detected lane marking;

producing a steering control signal based on said estimated lateral displacement to assist a driver of the vehicle to maintain the vehicle at a target line within the lane using a steering bias;

collecting, when the vehicle travels without lateral control for lane following, said estimated lateral displacement to produce lateral displacement data; and

updating a position of the target line using said lateral displacement data.

3. A lane-following system of facilitating steering of a vehicle by tracking a lane of a roadway, the vehicle having a steering system including a steering mechanism, said lane-following system comprising:

a sensor detecting a position of lane marking on the surface of a roadway in relation to the vehicle, said lane marking defining a lane of a roadway;

a signal processor operatively coupled to said sensor to estimate a lateral displacement of a point at a preview distance in front of the vehicle from the detected lane marking;

an actuator coupled to the steering mechanism to provide a steering bias to the steering system, which may either assist or oppose the steer torque from a vehicle driver, in response to a steering control signal;

a steering controller producing said steering control signal based on said estimated lateral displacement to assist the driver of the vehicle to maintain the vehicle at a target line within the lane using the steering bias,

said steering controller being operable, when the vehicle travels without lateral control for lane following, to collect said estimated lateral displacement to produce lateral displacement data,

said steering controller being operable to update a position of the target line using said lateral displacement data.

4. The lane-following system as claimed in claim 3, wherein, when the vehicle travels without lateral control for lane following, said steering controller is operable to determine whether or not a current traveling condition of the vehicle is appropriate for collecting said estimated lateral displacement for production of said lateral displacement data, and wherein said steering controller is operable, when it is determined that the current traveling condition of the vehicle is appropriate for collecting said estimated lateral displacement for production of said lateral displacement data under condition where the vehicle travels without lateral control for lane following, to collect said estimated lateral displacement data within a historical reference time to provide said lateral displacement data, and wherein said steering controller is operable to calculate an average of said lateral displacement data based on said estimated lateral displacement collected within said historical reference time.

5. The lane-following system as claimed in claim 4, wherein said steering controller is operable to determine whether or not a deviation of a roadway from straightness is less than a predetermined magnitude.

6. The lane-following system as claimed in claim 3, wherein said steering controller is operable to limit a difference between the position of the target line and the position of the lane centerline within a predetermined window set around the lane centerline.

7. The lane-following system as claimed in claim 3, further comprising a torque sensor detecting steer torque from a driver of the vehicle,

wherein, during lateral control for lane following, said steering controller is operable to update a target deviation from said target line upon elapse of a historical reference time in such a manner as to reduce the average of steer torque data collected within said historical reference time toward zero.

8. The lane-following system as claimed in claim 3, wherein, during lateral control for lane following, said steering controller is operable to update a target deviation from said target line upon elapse of a historical reference time in such a manner as to reduce the average of the steering control signal data collected within said historical reference time toward zero.