Three-dimensional (3D) measuring with multiple reference frames

• US 7,307,737 B1
• Filed: 10/08/2004
• Issued: 12/11/2007
• Est. Priority Date: 10/08/2004
• Status: Active Grant

• Current Assignee: Snap-On Incorporated
• Original Assignee: Snap-On Incorporated
• Inventors: Rogers, Steven W., Brown, Adam C., Mashburn, James F., Kling, Michael J. III
• Primary Examiner(s): Punnoose; Roy M.
• Application Number:
  US10/960,293
• Time in Patent Office: 1,159 Days
• Field of Search: 356/614, 356/620, 356/623
• US Class Current: 356/614
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge

Abstract

A measurement system processes data representing an images of an optical target, e.g. on a contact probe, to determine position of each of a number of points on a vehicle or other object. The system uses two reference frames and processes an image of the two frames, to define a three-dimensional (3D) coordinate system, for example, in relation to a designated first frame. The image processing determines the position of the other frame in that coordinate system. For any measurement in which the first reference frame is visible in an image with the probe, processing directly determines position of the point in the 3D coordinate system. For any measurement in which that reference frame is not sufficiently visible, but the second reference frame is sufficiently visible, the image processing determines position relative to the second reference frame and transforms that position into a measurement in the defined three-dimensional coordinate system.

Claims

1. A method of optically measuring locations of a plurality of points on an object, comprising:

mounting a first reference frame supporting at least three optical targets so as to define a first reference plane, at a first location and with a first orientation on the object;

mounting a second reference frame supporting at least three optical targets so as to define a second reference plane independent of the first reference plane, at a second location and with a second orientation on the object, wherein the second location and the second orientation of the second reference frame are substantially independent of the location and the orientation of the first reference frame and the second reference plane is at an angle with respect to the first reference plane;

obtaining at least one image of optical targets on both the first reference frame and the second reference frame;

processing the at least one image to define a three-dimensional coordinate system and to determine a position of the second reference frame in the defined three-dimensional coordinate system;

placing an optical probe target in predetermined relationship to each of the points on the object;

obtaining at least one respective image of the optical probe target when placed in the predetermined relationship to each of the points on the object;

processing the at least one respective image of the optical probe target when placed in the predetermined relationship to each of the points on the object to determine a position of each of the points on the object in the defined three-dimensional coordinate system, wherein;

for a measurement of position of a first one of the points, in which the optical targets of the first reference frame are visible in a first respective image, the processing of the first respective image comprises determining position of the first point in the defined three-dimensional coordinate system;

for a measurement of position of a second one of the points, in which less than three of the optical targets of the first reference frame are visible in a second respective image but the optical targets of the second reference frame are visible in the second respective image, the processing of the second respective image comprises determining position of the second point relative to the second reference frame and transforming the position of the second point relative to the second reference frame into position of the second point in the defined three-dimensional coordinate system based on the determined position of the second frame in the defined three-dimensional coordinate system; and

providing at least one output based on the determined positions of the first and second points in the defined three-dimensional coordinate system.

2. The method of claim 1, wherein the object is a vehicle.

3. The method of claim 2, wherein the vehicle is a truck or automobile.

4. The method of claim 1, wherein:

the at least one image of the optical targets on the first reference frame and the second reference frame provides three-dimensional image information; and

each at least one respective image of the optical probe target when placed in the predetermined relationship to each of the points on the object provides three-dimensional image information.

5. The method of claim 4, wherein:

the at least one image of the optical targets on the first reference frame and the second reference frame comprises a horizontal image and a vertical image; and

each at least one respective image of the optical probe target when placed in the predetermined relationship to each of the points on the object comprises a horizontal image and a vertical image.

6. The method of claim 1, wherein:

the optical targets on the first reference frame and the second reference frame comprise emitters for emitting detectable radiant energy; and

the optical probe target comprises a plurality of emitters for emitting detectable radiant energy.

7. The method of claim 6, wherein each of the emitters comprises a light emitting diode (LED).

8. The method of claim 1, wherein at least one point on the object is a reference point for the object, and the method further comprises:

determining a positional relationship of the reference point in the defined three-dimensional coordinate system; and

transforming each determined position of one of the plurality of points on the object in the defined three-dimensional coordinate system into a position in a three-dimensional coordinate system for the object.

9. The method of claim 8, further comprising comparing reference data regarding locations of the plurality of points on the object to the transformed positions of the plurality of points in the three-dimensional coordinate system for the object.

10. The method of claim 1, further comprising:

mounting a third reference frame supporting at least three optical targets so as to define a third reference plane independent of the first and second reference planes, at a third location and with a third orientation on the object, wherein the third location and the third orientation of the third reference frame are substantially independent of the locations and the orientations of the first and second reference frames;

obtaining at least one image of optical targets on the third reference frame and on one of the first and second reference frames; and

processing the at least one image of optical targets on the third reference frame and on one of the first and second reference frames, to determine a position of the third reference frame with respect to the one of the first and second reference frames;

wherein for a measurement of position of a third one of the points, in which less than three of the optical targets of the first reference frame and less than three of the optical targets of the second reference frame are visible in a third respective image but the optical targets of the third reference frame are visible in the third respective image, the processing of the third respective image comprises determining position of the third point relative to the third reference frame and transforming the position of the third point relative to the third reference frame into position of the third point in the defined three-dimensional coordinate system based on the determined position of the third frame with respect to the one of the first and second reference frames.

11. A method of measuring positions of points on an object, comprising;

receiving a signal representing at least one image of optical targets on two separate reference frames mounted at independent locations on the object;

processing the signal representing at least one image to determine a three-dimensional coordinate system with respect to a first one of the reference frames and to determine a position of the second one of the reference frames in the three-dimensional coordinate system defined with respect to the first reference frame;

receiving a signal representing at least one first image of an optical probe target positioned with regard to a first point on the object and of the optical targets on the first reference frame;

processing the signal representing at least one first image of the optical probe target to determine position of the first point on the object in the three-dimensional coordinate system defined with respect to the first reference frame;

receiving a signal representing at least one second image of the optical probe target positioned with regard to a second point on the object and of the optical targets on the second reference frame, the at least one second image of the optical probe target not including all of the optical targets on the first reference frame;

processing the signal representing at least one second image of the optical probe target to determine position of the second point relative to the second reference frame;

transforming the position of the second point relative to the second reference frame into position of the second point in the three-dimensional coordinate system, based on the position of the second reference frame in the three-dimensional coordinate system; and

providing at least one output based on the positions of the first point and the second point in the three-dimensional coordinate system.

12. A product comprising executable code for implementation of the method of claim 11 and a machine readable medium bearing the executable code.

13. A computer system programmed for implementation of the method of claim 11.

14. The method of claim 11, further comprising:

receiving a signal representing at least one image of optical targets on one of the two reference frames and optical targets on a separate third reference frame mounted at an independent location on the object;

processing the signal representing at least one image of the one reference frame and the third reference frame, to determine a position of the third reference frame with respect to the one reference frame;

receiving a signal representing at least one third image of the optical probe target positioned with regard to a third point on the object and of the optical targets on the third reference frame, the at least one third image of the optical probe target not including all of the optical targets on either the first reference frame or the second reference frame;

processing the signal representing at least one third image of the optical probe target to determine position of the third point relative to the third reference frame; and

transforming the position of the third point relative to the third reference frame into position of the third point in the three-dimensional coordinate system, based on the position of the third reference frame with respect to the one reference frame.

15. A product comprising executable code for implementation of the method of claim 14 and a machine readable medium bearing the executable code.

16. A computer system programmed for implementation of the method of claim 14.

17. The method of claim 11, further comprising:

determining a positional relationship of reference points on the object in the three-dimensional coordinate system;

transforming the positions of the first and second points in the determined three-dimensional coordinate system into positions of the first and second points in a three-dimensional coordinate system for the object determined in relation to the reference points.

18. The method of claim 17, wherein the object is a vehicle, and the method further comprises comparing reference data regarding locations of the first and second points on the vehicle to the transformed positions of the first and second points in the three-dimensional coordinate system for the object.

19. A system for analyzing damage at points on a vehicle, comprising:

a probe for contact with the points on the vehicle to be tested for displacement due to damage of the vehicle, the probe comprising an optically detectable target;

a first reference frame comprising three optically detectable targets defining a first reference plane, and a mount for removably attaching the first reference frame to a first location on the vehicle;

a second reference frame comprising three optically detectable targets defining a second reference plane, and a mount for removably attaching the second reference frame to a second location on the vehicle separate from the first location on the vehicle and independent from mounting of the first reference frame;

a three dimensional imaging system, for generating signals representative of images; and

a programmed computer responsive to image signals representing images of targets on the reference frames and image signals representing images of the target on the probe when the probe contacts points on the vehicle, for determining positions of the points on the vehicle in a three-dimensional coordinate system defined with respect to at least one of the reference frames as mounted on the vehicle.

20. The system of claim 19, wherein the three-dimensional coordinate system is defined with respect to the first reference frame as mounted at the first location on the vehicle.

21. The system of claim 20, wherein the computer is programmed to process an imaging signal representing an image of the probe in which less than three targets on the first reference frame are visible but three targets on the second reference frame are visible, to determine position of a point contacted by the probe relative to the second reference frame and transform the position relative to the second reference frame into a position in the three-dimensional coordinate system defined with respect to the first reference frame based on the position of the second reference frame in the three-dimensional coordinate system.

22. The system of claim 19, wherein the computer is further programmed to determine a three-dimensional coordinate system for the vehicle, and transform the positions of the points on the vehicle in the three-dimensional coordinate system defined with respect to at least one of the reference frames as mounted on the vehicle into positions of the points on the vehicle in the three-dimensional coordinate system for the vehicle.

23. The system of claim 22, wherein the computer is further programmed to compare reference data regarding locations of the points on the vehicle to the transformed positions of the points on the vehicle in the three-dimensional coordinate system for the vehicle.

24. A system for analyzing damage at points on a object, comprising:

a probe for contact with the points on the object to be tested for displacement due to damage of the object, the probe comprising an optically detectable target;

a first reference frame comprising three optically detectable targets defining a first reference plane, and a mount for removably attaching the first reference frame to a first location on the object;

a second reference frame comprising three optically detectable targets defining a second reference plane, and a mount for removably attaching the second reference frame to a second location on the object separate from the first location on the object and independent from mounting of the first reference frame;

a three dimensional imaging system, for generating signals representative of images; and

means, responsive to image signals from the three dimensional imaging system, for processing a signal representing an image containing the reference frames to define a three-dimensional coordinate system with respect to at least one of the reference frames when both reference frames are mounted on the object, and for processing image signals representing images containing the probe and at least one of the reference frames to determine positions of the points in the defined three-dimensional coordinate system.

25. The system of claim 24, wherein the reference frames are configured for mounting on a vehicle type object.

26. The system of claim 25, wherein the means are further for converting positions of the points in the defined three-dimensional coordinate system into positions in a three-dimensional coordinate system defined with respect to the vehicle.

27. The system of claim 26, wherein the means are configured to facilitate comparison of the positions of the points in the three-dimensional coordinate system defined with respect to the vehicle to reference data for the positions of the points on the vehicle.

28. The system of claim 24, further comprising a third reference frame comprising three optically detectable targets defining a third reference plane, and a mount for removably attaching the third reference frame to a third location on the object separate from the first and second locations on the object and independent from mounting of the first and second reference frames.

29. The system of claim 28, further comprising a fourth reference frame comprising three optically detectable targets defining a fourth reference plane, and a mount for removably attaching the fourth reference frame to a fourth location on the object separate from the first, second and third locations on the object and independent from mounting of the first, second and third reference frames.

30. A method of optically measuring a location of a point on an object, comprising:

mounting a first reference frame supporting at least three optical targets so as to define a first reference plane, at a first location and with a first orientation on the object;

mounting a second reference frame supporting at least three optical targets so as to define a second reference plane independent of the first reference plane, at a second location and with a second orientation on the object, wherein the second location and the second orientation of the second reference frame are substantially independent of the location and the orientation of the first reference frame and the second reference plane is at an angle with respect to the first reference plane;

obtaining at least one image of optical targets on both the first reference frame and the second reference frame;

processing the at least one image to define a three-dimensional coordinate system in relation to the first reference frame and to determine a position of the second reference frame in the defined three-dimensional coordinate system;

placing an optical probe target in predetermined relationship to the point on the object;

obtaining at least one image of the optical probe target when placed in the predetermined relationship to the point on the object, wherein one or more of the optical targets of the first reference frame are not visible in the at least one image of the optical probe target but the optical targets of the second reference frame are visible in the at least one image of the optical probe target;

processing the at least one image of the optical probe target to determine position of the point on the object relative to the second reference frame;

transforming the position of the point on the object relative to the second reference frame into position of the point on the object in the defined three-dimensional coordinate system, based on the determined position of the second frame in the defined three-dimensional coordinate system; and

providing at least one output based on the position of the point on the object in the defined three-dimensional coordinate system.

31. A method of measuring position of a point on an object, comprising;

receiving a signal representing at least one image of optical targets on two separate reference frames mounted at independent locations on the object;

processing the signal representing at least one image to determine a three-dimensional coordinate system with respect to a first one of the reference frames and to determine a position of the second one of the reference frames in the three-dimensional coordinate system defined with respect to the first reference frame;

receiving a signal representing at least one image of an optical probe target positioned with regard to the point on the object and of the optical targets on the second reference frame, the at least one image of the optical probe target not including all of the optical targets on the first reference frame;

processing the signal representing at least one image of the optical probe target to determine position of the point relative to the second reference frame;

transforming the position of the point relative to the second reference frame into position of the point in the three-dimensional coordinate system, based on the position of the second reference frame in the three-dimensional coordinate system; and

providing at least one output based on position of the point in the three-dimensional coordinate system.

32. A product comprising executable code for implementation of the method of claim 31 and a machine readable medium bearing the executable code.

33. A computer system programmed for implementation of the method of claim 31.

34. A method of measuring a location of a point on an object, comprising:

mounting a first reference frame supporting at least three targets so as to define a first reference plane, at a first location and with a first orientation on the object;

mounting a second reference frame supporting at least three targets so as to define a second reference plane independent of the first reference plane, at a second location and with a second orientation on the object, wherein the second location and the second orientation of the second reference frame are substantially independent of the location and the orientation of the first reference frame and the second reference plane is at an angle with respect to the first reference plane;

obtaining a sensing signal relating to targets on both the first reference frame and the second reference frame;

processing the sensing signal to define a three-dimensional coordinate system in relation to the first reference frame and to determine a position of the second reference frame in the defined three-dimensional coordinate system;

placing a probe target in predetermined relationship to the point on the object;

obtaining a sensing signal relating to the probe target when placed in the predetermined relationship to the point on the object, wherein one or more of the targets of the first reference frame are not identifiable in the sensing signal relating to the probe target but the targets of the second reference frame are identifiable in the sensing signal relating to the probe target;

processing the sensing signal relating to the probe target to determine position of the point on the object relative to the second reference frame;

transforming the position of the point on the object relative to the second reference frame into position of the point on the object in the defined three-dimensional coordinate system, based on the determined position of the second frame in the defined three-dimensional coordinate system; and

producing at least one output based on the position of the point on the object in the defined three-dimensional coordinate system.

35. A method of measuring position of a point on an object, comprising;

receiving a sensing signal regarding targets on two separate reference frames mounted at independent locations on the object;

processing the signal to determine a three-dimensional coordinate system with respect to a first one of the reference frames and to determine a position of the second one of the reference frames in the three-dimensional coordinate system defined with respect to the first reference frame;

receiving a sensing signal regarding a probe target positioned with regard to the point on the object and of the targets on the second reference frame, the sensing signal regarding the probe target not including a representation of all of the targets on the first reference frame;

processing the sensing signal regarding the probe target to determine position of the point relative to the second reference frame;

transforming the position of the point relative to the second reference frame into position of the point in the three-dimensional coordinate system, based on the position of the second reference frame in the three-dimensional coordinate system; and

providing at least one output based on the position of the point in the three-dimensional coordinate system.

36. A product comprising executable code for implementation of the method of claim 35 and a machine readable medium bearing the executable code.

37. A computer system programmed for implementation of the method of claim 35.