On-board object detector and on-board object detection method

• US 20060250516A1
• Filed: 05/05/2006
• Published: 11/09/2006
• Est. Priority Date: 05/06/2005
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Nishiuchi, Hidekazu
• Granted Patent: US 7,777,807 B2
• Time in Patent Office: Days
• US Class Current: 348/370
• CPC Class Codes: B60R 21/01538 for image processing, e.g. cameras or sensor arrays
• CPC Class Codes: B60R 21/01552 detecting position of specific human body parts, e.g. face, eyes or hands
• CPC Class Codes: G06V 10/145 Illumination specially adapted for pattern recognition, e.g. using gratings
• CPC Class Codes: G06V 20/58 Recognition of moving objects or obstacles, e.g. vehicles or pedestrians; Recognition of traffic objects, e.g. traffic signs, traffic lights or roads
• CPC Class Codes: G08G 1/16 Anti-collision systems road vehicle drive control systems for predicting or avoiding probable or impending collision otherwise than by control of a particular sub-unit B60W30/08

Abstract

An on-board object detector and on-board object detection method for detecting an object present in a pickup image at a high level of precision. A controller controls a projector to irradiate a line of light while shifting the irradiation angle, and images in the coverage area of the line of light are captured for multiple frames using a camera. Then, shifts in the moving speed of the line of light in the images across the frames are computed based on the images captured, and shifting points in the moving speed of the line of light are detected based on the computed shifts in the moving speed of the line of light in the images across the frames. The position and size of an object that is present in the images are specified based on said detected shifting points in the moving speed of the line of light.

Claims

1. An on-board object detector, comprising:

a projector operable to irradiate a horizontally-extending line of light in a direction of an object to be detected while shifting an irradiation angle of the line of light in a vertical direction;

a pickup device operable to capture images within a coverage area where the line of light is irradiated;

a controller operable to compute shifts in a moving speed of the line of light within the images and to detect the object based on the shifts in the moving speed of the line of light.

2. The on-board object detector according to claim 1 wherein the controller is further operable to detect positions of shifting points in the moving speed of the line of light, the shifting points being boundaries of the object in the vertical direction.

3. The on-board object detector according to claim 1 wherein the controller is further operable to compute at least one of a height of the object and a distance from the pickup device to the object based on detected boundaries of the object in the vertical direction.

4. The on-board object detector according to claim 3 wherein the controller is operable to compute the height using the formula

(hc·

tan θ

1−

hl−

tan θ

cy)/(tan θ

cy−

tan θ

1);

wherein hc is an installation height of the pickup device from a road surface, hl is an installation height of the projector from the road surface, θ

1 is a current irradiation angle of the line of light in the vertical direction, and θ

cy is an angle in the vertical direction at which an observation point on the object is visible from the pickup device.

5. The on-board object detector according to claim 3 wherein the controller is operable to compute the distance using the formula

(hc−

hl)/(tan θ

cy−

tan θ

1);

wherein hc is an installation height of the pickup device from a road surface, hl is an installation height of the projector from the road surface, θ

1 is a current irradiation angle of the line of light in the vertical direction, and θ

cy is an angle in the vertical direction at which an observation point on the object is visible from the pickup device.

6. The on-board object detector according to claim 5 wherein the controller is further operable to compute at least one of a position of the object in a horizontal direction and a width of the object based on the distance.

7. The on-board object detector according to claim 6 wherein the controller is operable to compute the position of the object in a horizontal direction using the formula

tan θ

cx=x/d;

wherein

x is a lateral position of the observation point on the object, d is the distance and θ

cx is an angle in a horizontal direction at which the object is visible from the pickup device.

8. The on-board object detector according to claim 7 wherein the controller is further operable to calculate lateral positions x for multiple observation points within multiple observation lines placed on the image, the lateral positions x indicating the width of the object.

9. The on-board object detector according to claim 3 wherein the controller is further operable to compute at least one of a position of the object in a horizontal direction and a width of the object based on the distance.

10. The on-board object detector according to claim 1 wherein the controller is further operable to compute at least one of a position of the object in a horizontal direction and a width of the object based on a computed distance to the object from the pickup device.

11. The on-board object detector according to claim 1 wherein the pickup device is further operable to capture images sequentially over prescribed time intervals.

12. The on-board object detector according to claim 1 wherein the projector is operable to shift the irradiation angle of the line of light from a bottom up.

13. An on-board object detector, comprising:

projection means for irradiating a horizontally-extending line of light in a direction of an object to be detected while shifting an irradiation angle in the vertical direction;

pickup means for capturing images within a coverage area where the line of light is irradiated by the projection means;

velocity computation means for computing shifts in a moving speed of the line of light within the images based on the images captured by the pickup means; and

object detection means for detecting the object based on the shifts in the moving speed of the line of light within the images as computed by the velocity computation means.

14. An on-board object detection method, comprising:

irradiating a horizontally-extending line of light in a direction of an object to be detected while shifting an irradiation angle in a vertical direction;

capturing images within a coverage area where the line of light is irradiated;

computing shifts in a moving speed of the line of light within the images; and

detecting the object based on the shifts in the moving speed of the line of light.

15. The on-board object detection method according to claim 14, further comprising:

calculating the moving speed of the line of light within the images.

16. The on-board object detection method according to claim 15, further comprising:

dividing the images by multiple observation lines with a prescribed width; and

wherein calculating the moving speed of the line of light within the images further includes computing the moving speed of the line of light within adjacent observation lines by dividing position shifts of the line of light across successive images by a frame rate.

17. The on-board object detection method according to claim 14 wherein detecting the object based on the shifts in the moving speed of the line of light further comprises detecting positions of shifting points in the moving speed, the positions of the shifting points indicating boundaries of the object in the vertical direction.

18. The on-board object detection method according to claim 17, further comprising:

computing at least one of a height of the object and a distance from a camera capturing the images based on the boundaries of the object in the vertical direction.

19. The on-board object detection method according to claim 14, further comprising:

computing at least one of a position of the object in a horizontal direction and a width of the object based on a computed distance to the object from a camera capturing the images.

20. The on-board object detection method according to claim 14 wherein shifting the irradiation angle in the vertical direction further comprises shifting the irradiation angle of the line of light from a bottom up.