Method for estimating the roll angle in a travelling vehicle

• US 8,824,741 B2
• Filed: 11/16/2010
• Issued: 09/02/2014
• Est. Priority Date: 11/25/2009
• Status: Active Grant

• Current Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Original Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Inventors: Walter, Michael
• Primary Examiner(s): Tabatabai, Abolfazl
• Application Number:
  US13/511,733
• Publication Number:
  US 20120281881A1
• Time in Patent Office: 1,386 Days
• Field of Search: 382/104, 382/106, 348/118, 348/119, 348/120, 348/211.9, 348/837, 340/425.5, 340/441, 340/901, 340/903, 340/933, 340/935, 340/988, 340/991, 340/992, 340/994, 701/32.5, 701/45, 701/527
• US Class Current: 382/104
• CPC Class Codes: B60G 2400/0511 Roll angle
• CPC Class Codes: B60T 2230/03 Overturn, rollover
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60W 2420/403 Image sensing, e.g. optical camera
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 40/11 Pitch movement
• CPC Class Codes: B60W 40/112 Roll movement
• CPC Class Codes: B60W 40/114 Yaw movement

Abstract

The invention relates to a method for estimating the roll angle in a travelling vehicle (7), comprising the following steps. In step a), a camera (8) is used to record a sequence of images of the vehicle'"'"'s surroundings, in particular of the road (1) ahead. In step b), at least one signature (S1-S6) on the road surface is extracted from the camera images, i.e. said signature is determined and tracked. The changed position of the at least one signature (S1-S6) in one or more subsequent camera image(s) is used in step c) to determine in which direction the camera (8) is turned with regard to the roll angle.

The value of the roll angle is estimated in step d).

For this purpose, the roll angle is either directly estimated in step d1), taking into account the vehicle speed (v) and an imaging model of the camera (8), or the roll angle is iteratively increased or decreased by a defined correction angle in step d2) until the roll angle sufficiently compensates for the turning of the camera (8). On this basis, the estimated roll angle is obtained as an overall correction value.

Claims

1. A method for estimating the roll angle of a camera in a vehicle traveling on a road surface, by using the camera, comprising the following steps:

a) the camera is used to record a sequence of camera images of the vehicle'"'"'s surroundings,

b) from the camera images, at least one signature on the road surface is determined and tracked,

c) from a changed position of the at least one signature in at least one subsequent camera image it is determined in which roll angle direction the camera is turned,

d) a value of the roll angle is

d1) directly estimated, taking into account the vehicle'"'"'s speed and an imaging model of the camera or

d2) estimated and iteratively corrected by a correction angle until a resulting estimated roll angle sufficiently compensates for the turning of the camera.

2. The method according to claim 1, wherein the distance of at least one signature from the camera in the vehicle'"'"'s longitudinal direction is determined in the step d1), taking into account an imaging model of the camera.

3. The method according to claim 2, wherein the distance of the signature that has been determined and the vehicle'"'"'s speed are used to predict a predicted distance of the signature after a time interval.

4. The method according to claim 3, wherein a subsequent camera image that has been recorded at the time interval after the first camera image is used to measure a measured distance of the same signature from the camera in the vehicle'"'"'s longitudinal direction by back-projection.

5. A method according to claim 4, wherein a deviation of the measured distance from the predicted distance is used to estimate the roll angle, taking into account the imaging model of the camera.

6. The method according to claim 1, wherein

in the step b), at least one first signature (is determined and tracked in a left image half and, in the same or a subsequent camera image, a second signature is determined and tracked in a right image half, and additionally the vehicle'"'"'s speed at the time each camera image is recorded is stored,

in the step c), a separate prediction of the signature distance is made for each signature, taking into account the respective vehicle speed and the imaging model of the camera, and the signature distance is measured in a subsequent camera image, and the turning direction of the camera is determined by comparing the deviation of the predicted signature distance from the signature distance that has been measured taking into account the currently estimated roll angle in both image halves, and

the roll angle is iteratively corrected according to the step d2).

7. The method according to claim 1, wherein

in the step b), at least one first signature is determined and tracked in a left lower image quadrant and, in the same or a subsequent camera image, a second signature is determined and tracked in the right lower image quadrant, and additionally the vehicle'"'"'s speed at the time each camera image is recorded is stored,

in the step c), for each one of the signatures the change of a signature position thereof in the camera image is related as a ratio to the respective vehicle speed and the ratio is compared for both image halves, and it is deduced that the camera is turned in the direction of the image half where this ratio is larger, and

the roll angle is iteratively corrected according to the step d2).

8. A device for estimating the roll angle of a camera in a travelling vehicle, comprising a camera and an evaluation unit including means for estimating the roll angle according to the method of claim 1.

9. The method according to claim 1, wherein the step d) comprises the step d2).

10. The method according to claim 1, wherein the step d) does not comprise the step d1).

11. The method according to claim 1, wherein the step d2) comprises initially estimating the roll angle as zero at a start of the method.

12. The method according to claim 1, wherein, in the step d2), the estimated roll angle sufficiently compensates for the turning of the camera when the correction angle no longer deviates from zero by more than the angular resolution of the camera.

13. The method according to claim 12, wherein the angular resolution of the camera is less than 0.5E.

14. The method according to claim 12, wherein the angular resolution of the camera is less than 0.1E.

15. The method according to claim 1, wherein the correction angle has a prescribed constant value.

16. The method according to claim 1, wherein in the step b), at least one first signature is determined and tracked in a left image half and, in the same or a subsequent camera image, a second signature is determined and tracked in a right image half, and additionally the vehicle'"'"'s speed at the time each camera image is recorded is stored,

in the step c), a separate prediction of the signature distance is made for each signature, taking into account the respective vehicle speed and an imaging model of the camera, and the signature distance is measured in a subsequent camera image, and

in the step d2), the correction angle assumes a value that is proportional to a result of a first ratio minus a second ratio, wherein the first ratio is an averaged ratio of the measured signature distances relative to the predicted signature distances for the left image half, and the second ratio is an averaged ratio of the measured signature distances relative to the predicted signature distances for the right image half.