Method for evaluation, by motor vehicle, of the characteristics of a front element

• US 20070198189A1
• Filed: 11/07/2006
• Published: 08/23/2007
• Est. Priority Date: 11/10/2005
• Status: Active Grant

• Current Assignee: Valeo Vision (Valeo SE)
• Original Assignee: Valeo Vision (Valeo SE)
• Inventors: Herbin, Anne, Leleve, Joel
• Granted Patent: US 7,987,052 B2
• Time in Patent Office: Days
• US Class Current: 701/300
• CPC Class Codes: B60Q 1/0023 the element being a sensor, e.g. distance sensor, camera
• CPC Class Codes: B60Q 9/008 for anti-collision purposes
• CPC Class Codes: G06T 7/593 from stereo images
• 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 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes

Abstract

A method that utilizes at least a first camera and a second camera, which have optical axes that are parallel to a first axis of an orthogonal reference frame, the first and the second camera being positioned so as to have a first offset along a second axis and a second offset along a third axis of the orthogonal reference frame. The first offset is used to carry out a first stereoscopic calculation, and the second offset is used to carry out a second stereoscopic calculation, the distance sought finally being established by taking into consideration these two stereoscopic calculations.

Claims

1. A method for evaluation, within a motor vehicle, of the characteristics of a front element, said motor vehicle being equipped at least with a first camera and a second camera, wherein the method comprises the steps of:

placing the first camera in a first position and the second camera in a second position, the first position and the second position being characterized in particular by the fact that, considering an orthogonal three-dimensional reference frame having an abscissa axis oriented parallel to a direction of displacement of the vehicle, a horizontal applicate axis and a vertical ordinate axis;

the first camera and the second camera respectively have a first optical axis and a second optical axis, respectively, that are generally parallel to the abscissa axis;

the first camera and the second camera have a first offset along the applicate axis;

the first camera and the second camera have a second offset along the vertical ordinate axis;

establishing a first evaluation of a distance separating the vehicle from the front element by using the first offset to carry out a first stereoscopic calculation;

establishing a second evaluation of the distance separating the vehicle from the front element by using the second offset to carry out a second stereoscopic calculation; and

determining the distance separating the vehicle from the front element by combining the first distance evaluation and the second distance evaluation.

2. The method according to claim 1, comprising the additional step of:

prior to the steps of establishing the first distance evaluation and the second distance evaluation, carrying out a calibration operation on the first and second cameras to determine the relative positions of said first and second cameras.

3. The method according to claim 2, comprising the additional step of storing the relative positions of the cameras for each calibration operation carried out.

4. The method according to claim 3, comprising the various additional steps of:

for each new calibration operation, comparing the obtained relative positions with the last stored relative positions;

if a difference greater than a predetermined threshold results from the comparison operation, indicating a probable error in the determination of the distance separating the vehicle from the front element.

5. The method according to claim 2, wherein the calibration operation is carried out only when the vehicle is stationary.

6. The method according to claim 5, wherein the calibration operation is carried out each time the ignition of the vehicle is started.

7. The method according to claim 5, wherein the calibration operation is carried out when the vehicle, with the engine running, reaches a zero speed.

8. The method according to claim 1, wherein the operation consisting in combining the first distance evaluation and the second distance evaluation, in order to determine the distance separating the vehicle from the front element, is carried out by forming a weighted mean of the first distance evaluation and of the second distance evaluation, the first distance evaluation being associated with a first weighting coefficient and the second distance evaluation being associated with a second weighting coefficient, the first weighting coefficient and the second weighting coefficient respectively depending on a risk factor concerning a risk of variation in the first offset and second offset, respectively.

9. The method according to claim 1, wherein the first camera is arranged at a rear view mirror of the vehicle, and in that the second camera is arranged at a front headlamp of the vehicle.

10. The method according to claim 9, wherein the first camera is also used for an operation of detecting lines and/or curbs, and in that the second camera is used for a functionality directly connected with a lighting functionality.

11. The method according to claim 1, wherein the second offset is used to determine a height of the front element.

12. A motor vehicle equipped at least with a first camera and a second camera for determining, using a stereoscopic calculation, characteristics of a front element, wherein the first camera is placed in a first position and the second camera is placed in a second position, the first position and the second position being characterized in particular by the fact that, considering an orthogonal three-dimensional reference frame having an abscissa axis oriented parallel to a direction of displacement of the vehicle, a horizontal applicate axis and a vertical ordinate;

wherein

the first camera and the second camera respectively have a first optical axis and a second optical axis that are generally parallel to the abscissa axis;

the first camera and the second camera have a first offset along the horizontal applicate axis;

the first camera and the second camera have a second offset along the vertical ordinate axis.

13. A method for determining a distance between a front element and a vehicle, said method comprising the steps of:

situating a first camera at a first position on the vehicle;

situating a second camera at a second position on the vehicle;

determining a first offset for said first and second cameras along a first axis;

determining a second offset for said first and second cameras along a second axis;

using said first offset to determine a first distance and said second offset to determine a second distance; and

using said first and second distances to perform at least one stereoscopic calculation in order to determine the distance between the front element and the vehicle.

14. The method as recited in claim 13 wherein said first axis is a horizontal axis and said second axis is a vertical axis.

15. The method as recited in claim 13 wherein an optical axis of each of said first and second cameras is generally parallel to an axis of travel of the vehicle.

16. The method as recited in claim 13 wherein said first camera is arranged on a mirror of the vehicle.

17. The method as recited in claim 13 wherein said second camera is arrange at a front headlamp of the vehicle.

18. The method as recited in claim 16 wherein said second camera is arranged at a front headlamp of the vehicle.

19. The method as recited in claim 13 wherein said second offset is used to determine a height of the front element.