Vision system and a method for scanning a traveling surface to detect surface defects thereof

• US 20060274930A1
• Filed: 06/02/2005
• Published: 12/07/2006
• Est. Priority Date: 06/02/2005
• Status: Active Grant

• Current Assignee: Institut national d'optique
• Original Assignee: Institut national d'optique
• Inventors: Laurent, John, Doucet, Michel
• Granted Patent: US 7,801,333 B2
• Time in Patent Office: Days
• US Class Current: 382/141
• CPC Class Codes: G01C 7/04 involving a vehicle which moves along the profile to be traced
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/8901 Optical details; Scanning details per se G02B

Abstract

There is provided a vision system and a method for scanning a traveling surface such a road to detect surface defects thereof such as cracks. The vision system, which is mountable on a vehicle, is provided with a linear imaging system for imaging successive adjacent transversal linear portions of the traveling surface as the vehicle advances. The vision system is also provided with laser line projecting means angularly projecting a laser line onto the transversal linear portion of the traveling surface to be imaged in a substantially coplanar relationship with the linear imaging system. The present vision system is particularly devised to be immune to surrounding light conditions variations to provide optimum cracks image contrast for both transverse and longitudinal cracks.

Claims

1. A vision system mountable on a vehicle traveling onto a traveling surface for scanning said traveling surface to detect surface defects thereof, said vision system comprising:

a linear imaging system having a linear sensor directed towards said traveling surface substantially transversally thereto along an optical axis substantially perpendicular to said traveling surface for successively imaging adjacent transversal linear portions of said traveling surface as said vehicle advances, thereby providing corresponding adjacent transversal linear images of said traveling surface;

laser line projecting means extending distal from said imaging system and having a laser beam axis angularly directed towards said traveling surface in a substantially coplanar relationship with the optical axis and the linear sensor of said imaging system for angularly projecting a laser line along said laser beam axis across said traveling surface on the corresponding transversal portion thereof to generate a transverse profile thereof in the corresponding image; and

processing means operatively connected to said imaging system for processing said adjacent transversal linear images, thereby allowing to detect surface defects on said traveling surface.

2. The vision system according to claim 1, wherein said laser line extends substantially transversally on said traveling surface at a slant scanning angle comprised between 0 and 45 degrees.

3. The vision system according to claim 2, wherein said slant scanning angle is 5 degrees.

4. The vision system according to claim 1, wherein said linear imaging system is provided with an optical filter extending in front of the linear sensor.

5. The vision system according to claim 1, wherein said vision system comprises an additional linear imaging system mountable on said vehicle distal from said imaging system, said additional linear imaging system having a linear sensor directed towards said traveling surface substantially transversally thereto along an optical axis substantially perpendicular to said traveling surface for successively imaging additional adjacent transversal linear portions of said traveling surface, each being transversally adjoined to a corresponding one of said transversal linear portions, thereby providing corresponding additional adjacent transversal linear images of said traveling surface, said vision system further comprising additional laser line projecting means mountable on said vehicle distal from said additional linear imaging system and having a laser beam axis angularly directed towards said traveling surface in a substantially coplanar relationship with the optical axis and the linear sensor of said additional imaging system for angularly projecting an additional laser line along said laser beam axis across said traveling surface on the corresponding additional transversal linear portion thereof to generate a transverse profile thereof in the corresponding additional image.

6. The vision system according to claim 5, wherein each of said laser line and additional laser line extends on said traveling surface in a parallel relationship with each other.

7. The vision system according to claim 5, wherein each of said laser line and additional laser line extends on said traveling surface in a non-collinear relationship with each other.

8. The vision system according to claim 5, wherein each of said laser line and additional laser line extends on said traveling surface in a non-overlapping relationship.

9. The vision system according to claim 5, wherein each of said laser lines extends substantially transversally on said traveling surface in a substantially parallel relationship with each other at a slant scanning angle comprised between 0 and 45 degrees.

10. The vision system according to claim 9, wherein said slant scanning angle is 5 degrees.

11. The vision system according to claim 5, wherein said laser line projecting means extend proximal to said additional imaging system and said additional laser line projecting means extend proximal to said imaging system for projecting the corresponding laser lines on said traveling surface in a non-overlapping cross configuration.

12. The vision system according to claim 11, wherein each of said laser line projecting means extends outwards to the corresponding one of said imaging systems.

13. The vision system according to claim 11 wherein each of said laser line projecting means projects the corresponding laser line on said traveling surface in a parallel and non-collinear relationship to each other.

14. The vision system according to claim 11, wherein said vision system further comprises a first and a second casing, each being mountable on said vehicle, said first casing receiving said imaging system and said additional laser projecting means while said second casing receives said additional imaging system and said laser projecting means therein.

15. The vision system according to claim 14, wherein each of said laser line and additional laser line extends substantially transversally on said traveling surface in a parallel and non-collinear relationship to each other at a slant scanning angle of 5 degrees.

16. A vision method for scanning a surface to detect surface defects thereof, said vision method comprising the steps of:

a) providing a vehicle traveling on said surface, said vehicle being provided with a vision system comprising laser line projecting means for projecting a laser line on said surface and linear imaging means distal from said laser projecting means for imaging said laser line;

b) angularly projecting said laser line across said surface within a laser projection plane extending in a substantially transversal and perpendicular relationship with said surface;

c) successively imaging said laser line substantially perpendicularly to said surface in a substantially coplanar relationship with said laser projection plane for providing successive adjacent transversal linear images of said surface as said vehicle advances; and

d) processing said adjacent transversal linear images for detecting surface defects on said surface.

17. The vision method according to claim 16, wherein said step b) further comprises the sub-step of angularly projecting an additional laser line across said surface within a distinct additional laser projection plane adjoining said laser projection plane and extending in a substantially transversal and perpendicular relationship with said surface, and wherein said step c) further comprises the sub-step of successively imaging said additional laser line substantially perpendicularly to said surface in a substantially coplanar relationship with said additional laser projection plane.