LASER PROJECTION SYSTEM AND METHOD

• US 20130250094A1
• Filed: 10/16/2012
• Published: 09/26/2013
• Est. Priority Date: 03/22/2012
• Status: Active Grant

• Current Assignee: AGV Technology Canada, ULC
• Original Assignee: Virtek Vision International Inc. (Lectra SA)
• Inventors: Rueb, Kurt D.
• Granted Patent: US 9,200,899 B2
• Time in Patent Office: Days
• US Class Current: 348/94
• CPC Class Codes: B23Q 17/2423 by projecting crossing light beams
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/005 coordinate measuring machines
• CPC Class Codes: G01B 11/2545 with one projection direction and several detection directions, e.g. stereo
• CPC Class Codes: G01C 11/00 Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
• CPC Class Codes: G01C 11/02 Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
• CPC Class Codes: G01C 11/025 by scanning the object
• CPC Class Codes: G01C 11/08 the pictures not being supported in the same relative position as when they were taken
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 2207/10028 Range image; Depth image; 3D point clouds
• CPC Class Codes: G06T 2207/20224 Image subtraction
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 2207/30204 Marker
• CPC Class Codes: G06T 7/0006 using a design-rule based approach
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/194 involving foreground-background segmentation
• CPC Class Codes: G06T 7/74 involving reference images or patches
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/254 : in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 23/00 : Cameras or camera modules comprising electronic image sensors; Control thereof
• CPC Class Codes: H04N 9/3129 : scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161

Abstract

A laser projection system for projecting an image on a workpiece includes a photogrammetry assembly and a laser projector, each communicating with a computer. The photogrammetry assembly includes a first camera for scanning the workpiece, and the laser projector projects a laser image to arbitrary locations. Light is conveyed from the direction of the workpiece to the photogrammetry assembly. The photogrammetry assembly signals the coordinates light conveyed toward the photogrammetry assembly to the computer with the computer being programmable for determining a geometric location of the laser image. The computer establishes a geometric correlation between the photogrammetry assembly, the laser projector, and the workpiece for realigning the laser image to a corrected geometric location relative to the workpiece.

Claims

1. A laser projection system for projecting an image on a workpiece, comprising:

a photogrammetry assembly and a laser projector, each communicating with a computer;

said photogrammetry assembly including a first camera for scanning the workpiece, and said laser projector projecting a laser image to arbitrary locations with said laser image being readable by said camera;

said photogrammetry assembly signaling the coordinates of the work piece to the computer by scanning light conveyed from the direction of the workpiece with said computer being programmable for determining a geometric location of the workpiece from the light conveyed from the direction of the workpiece; and

said computer establishing geometric correlation between said photogrammetry assembly, said laser projector, and the workpiece and signaling said laser projector to project a template onto a geometric desirable location of the workpiece.

2. The system set forth in claim 1, wherein said photogrammetry assembly includes a light source for transmitting light being readable by said photogrammetry assembly distinguishable from the laser image.

3. The system set forth in claim 2, wherein said light source transmits light having a light wavelength and said laser transmits a laser image having a laser wavelength that is close in value to a value of said light wavelength.

4. The system set forth in claim 2, further including a scale bar having reflective targets spaced by a known distance for reflecting light transmitted from said light source to said camera.

5. The system set forth in claim 4, wherein said scale bar comprises unidirectional carbon fiber for providing temperature resistant distance between said reflective targets.

6. The system set forth in claim 1, wherein said photogrammetry assembly includes a second camera spaced from said first camera by a known distance.

7. The system set forth in claim 6, wherein said first and second cameras are spaced apart by a scale bar comprising unidirectional carbon fiber.

8. The system set forth in claim 2, further including retroreflective targets affixed to the workpiece for reflecting light from said light source thereby conveying the light to said camera, said camera signaling said computer a location of said retroreflective targets and said computer determining a location of the workpiece.

9. The system set forth in claim 8, wherein said retroreflective targets include encoding enabling said computer to identify said retroreflective targets from light conveyed by said retroflective targets.

10. The system set forth in claim 2, further including a probe having reflective targets disposed thereon for manually identifying features of the workpiece with light transmitted from said a light source and conveyed by said reflective targets to said photogrammetry assembly.

11. The system set forth in claim 1, wherein said laser projector is programmed to project an image onto the workpiece enabling said photogrammetry assembly to determine a location of the workpiece within a three dimensional coordinate system.

12. The system set forth in claim 1, wherein the image projected by said laser projector is a manufacturing template providing a location for performing work on the workpiece.

13. A method of projecting patterns on a workpiece, comprising the steps of:

providing a photogrammetry assembly and a laser projector;

conveying light from the direction of the workpiece to said photogrammetry assembly;

determining a location in a three dimensional coordinate system of the laser projector relative to the photogrammetry assembly by scanning arbitrary laser images projected by the laser projector;

determining a location of the workpiece in the three dimensional coordinate system relative to said photogrammetry assembly and to said laser projector from light conveyed from the direction of the workpiece to said photogrammetry assembly; and

transmitting a template onto a geometric desirable location of the workpiece from said laser projector upon determining a location of the workpiece in the three dimensional coordinate system.

14. The method set forth in claim 13, wherein said step of conveying light from the direction of the workpiece is further defined by reflecting light from at least one of a light source or a pattern generated by said laser projector to said photogrammetry assembly.

15. The method set forth in claim 14, further including the step of said photogrammetry assembly scanning a space comprising the workpiece for establishing a background image and subtracting the background image from the light conveyed from the direction of the workpiece.

16. The method set forth in claim 14, further including the step of transmitting a pattern toward the workpiece having at least four laser spots from said laser projector with some of said laser spots being transmitted onto the workpiece.

17. The method set forth in claim 13, further including the step of transmitting light from a light source to reflective targets disposed on the workpiece for conveying light toward said photogrammetry assembly and determining a spacial relationship of the workpiece to said photogrammetry assembly.

18. The method set forth in claim 13, wherein said step of conveying light from the direction of the workpiece is further defined by locating features on the workpiece by contacting the features with a reflective probe and reflecting light toward the photogrammetry assembly for determining a geometric location of the features.

19. The method set forth in claim 13, wherein said step of providing a photogrammetry assembly is further defined by providing a photogrammetry assembly with two cameras separated by a known length.

20. The method set forth in claim 13, further including the step of determining a spacial relationship of the workpiece to said photogrammetry assembly by scanning light reflected back to said photogrammetry assembly.

21. The method set forth in claim 13, wherein said step of providing a laser projector is further defined my providing a plurality of laser projectors.

22. The method set forth in claim 18, further including the step of detecting variation of the laser pattern and making an adjustment to the laser pattern to correct the spacial relationship between the laser pattern and the light reflected back to said photogrammetry assembly.

23. The method set forth in claim 18, wherein said steps of transmitting light from said light source and transmitting a laser pattern from said laser projector is further defined by transmitting light and transmitting a laser pattern having similar wavelengths.

24. The method set forth in claim 18, further including the step of periodically measuring the spacial relationship between the reflected light and the laser pattern to verify the location of the laser pattern and making corrections to the transmission of the laser pattern by said laser projector.

25. The method set forth in claim 18, further including the step of affixing reflective targets to the workpiece for conveying light to the photogrammetry assembly generated from a light source for determining a location of the workpiece in the three dimensional coordinate system.