Method and system for geometry measurements

• US 5,805,287 A
• Filed: 12/17/1996
• Issued: 09/08/1998
• Est. Priority Date: 05/24/1993
• Status: Expired due to Term

• Current Assignee: Metronor AS
• Original Assignee: Metronor AS
• Inventors: Pettersen, Alf, R.o slashed.tvold, .O slashed.yvind
• Primary Examiner(s): HANTIS, KAREN
• Application Number:
  US08/769,800
• Time in Patent Office: 630 Days
• Field of Search: 306/375, 306/141.1, 306/152.1-152.3, 306/3.01-5.15, 306/376, 33/502, 33/503, 33/504, 33/554, 33/555, 33/556
• US Class Current: 356/614
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G01C 11/06 by comparison of two or more pictures of the same area
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

A method and system for determining the position and/or orientation of a number of objects relative to each other. At least two cameras having electro-optical sensors are provided. A network of help reference points is established. The positions of some points in the network relative to each other can be known or they are determined using at least one of the cameras positioned in multiple arbitrary locations. The positions of some of the objects relative to each other, are determined based on the determined positions of some of the points in the network. The position of at least one of the objects is determined by holding a probing tool in contact with a point on the object, and obtaining measurement data from the probing tool using at least two of the cameras.

Claims

1. A method of determining the position and/or orientation of a number of objects relative to each other, the method comprising the steps of:

(A) providing at least two cameras;

(B) establishing a network of help reference points;

(C) determining the spatial positions of some points in the network relative to each other using at least one of the cameras positioned in multiple arbitrary locations, said at least one camera determining projections of the positions of said some network points;

(D) positioning some of the cameras;

(E) determining the positions and orientations of the some of the cameras using the spatial positions of network points determined in step (C); and

(F) determining the position of some of the objects relative to each other, based on the determined positions and orientations of some of the cameras, whereby the position of at least one of the objects is determined by;

(i) holding a probing tool in contact with at least one point on the object, and

(ii) obtaining measurement data from the probing tool using at least two of the cameras whose positions were determined in step (D).

2. The method as in claims 1, wherein the probing tool has a touch point and wherein step (F)(i) comprises the step of holding the touch point of the probing tool in contact with the point on the object.

3. The method as in claim 1, further comprising the steps of:

positioning at least one reference bar within a measurement volume containing the objects; and

obtaining scale information from the reference bar.

4. The method of claim 1, wherein some of the network points are light sources, and wherein the step C of determining the positions comprises determined the positions of some of the light sources.

5. The method of claim 4 wherein the light sources are selected from a group consisting of active light sources and passive light sources.

6. The method of claims 5 wherein the active light sources are selected from a group consisting of permanently mounted light sources, projected light spots, and illuminated reflectors.

7. The method of claim 1, wherein the position of at least one of the points in the network is determined using the probing tool.

8. The method of claim 1 wherein the probing tool has light sources attached thereto.

9. The method of claim 8 wherein the light sources are selected from a group consisting of active light sources and passive light sources.

10. The method of claim 1, wherein the network includes at least two points having a known mutual separation distance, the method further comprising the step of using the two points to determine a correct length scale.

11. The method of claim 1 further comprising the step of:

determining optical lens distortions of at least one of the cameras based on observed projections of the network points.

12. The method of claim 1 wherein the positions of some of the points in the network define a coordinate system, and wherein step (F) determines the position of each object relative to the coordinate system.

13. The method of claim 1, wherein the network is established within a volume, the method further comprising the step of:

bringing objects within the volume prior to the step of determining their positions.

14. The method of claim 1 wherein the objects are used to locate and/or hold parts in a station in a manufacturing production line.

15. The method of claim 14, wherein the network is established on a moveable device, the method further comprising the steps of:

moving the movable device into the station before performing steps (E) and (F).

16. The method of claim 1, wherein the network is established on a moveable device, the method further comprising the steps of:

moving the movable device into each of a plurality of stations in a production line and then performing steps (E) and (F) in each of the stations.

17. A method according to claim 1, wherein the method operates relative to a defined coordinate system and wherein a minimum of three of the network points have at least one of their coordinate values known relative to the defined coordinate system such that a minimum of six coordinate values are known and distributed such that three values are defined relative to one coordinate axis of the defined coordinate system, two values are defined relative to a second coordinate axis of the defined coordinate system, and one value is defined relative to a third axis of the defined coordinate system, the method further comprising the step of:

calculating the positions and orientations of other points and geometrical objects relative to this defined coordinate system using the known coordinate values.

18. A method as in claim 1, further comprising the step of, prior to the step of determining the positions and orientations of some of the cameras:

locating at least two of the cameras such that their field of view includes at least three network points of known positions and an object whose position and/or orientation are to be determined.

41. A method as in any of claims 1, 19, 21, 36, 38 or 40, wherein step (B) comprises the step of establishing the network of help reference points at locations spaced apart from the probing tool and any of the objects.

42. A method as in claim 41, wherein said objects include:

(a) geometric objects selected from a group consisting of planes, lines, holes, cylinders, spheres, and

(b) combined objects selected from a group consisting of robot arms and industrial production equipment.

43. A method as in any of claims 1, 19, 21, 36, 38 or 40 wherein step (B) comprises the step of establishing at least one the help reference points at a location apart from the probing tool and any of the objects.

44. A method as in claim 43, wherein said objects include:

(a) geometric objects selected from a group consisting of planes, lines, holes, cylinders, spheres, and

(b) combined objects selected from a group consisting of robot arms and industrial production equipment.

45. A method as in any of claims 1 or 19 wherein the cameras used in step (C) are the same as the cameras used in step (D).

46. A method as in claim 45, wherein said objects include:

(a) geometric objects selected from a group consisting of planes, lines, holes, cylinders, spheres, and

(b) combined objects selected from a group consisting of robot arms and industrial production equipment.

49. A method as in one of claims 1-40, wherein said objects include:

(a) geometric objects selected from a group consisting of planes, lines, holes, cylinders, spheres; and

(b) combined objects selected from a group consisting of robot arms and industrial production equipment.

19. A method of determining the position and/or orientation of a number of objects relative to each other, the method comprising the steps of:

(A) providing at least two cameras;

(B) establishing a network of help reference points, some of the reference points being light sources;

(C) determining the spatial positions of some points in the network relative to each other using at least one of the cameras positioned in multiple arbitrary locations, said at least one camera determining projections of the positions of said some network points, said determine being by;

(i) when the reference points are light sources, determining the projections of the light sources; and

(ii) determining the projections of at least one of the points in the network using a probing tool having light sources attached thereto;

(D) positioning some of the cameras;

(E) determining the positions and orientations of the some of the cameras using the spatial positions of network points determined in step (C); and

(F) determining the spatial position of each of the objects relative to each other, based on the determined positions and orientations of some of the cameras, whereby the position of at least one of the objects is determined by;

(i) holding a touch point of the probing tool in contact with at least one point on the object, and

(ii) obtaining measurement data from the probing tool using at least two of the cameras whose positions were determined.

20. The method of claim 19, wherein the light sources are selected from a group consisting of active light sources and passive light sources.

21. A method of determining the position and/or orientation of a number of objects relative to each other, the method comprising the steps of:

(A) providing at least two cameras;

(B) providing a network of help reference points having known positions relative to each other;

(C) positioning some of the cameras;

(D) individually determining the positions and orientations of some of the cameras relative to each other and to the network points using the known positions of network points; and

(E) determining the spatial positions of the objects relative to each other based on the known positions and orientations of some of the cameras, whereby the position of at least one of the objects is determined by;

(i) holding the probing tool in contact with at least one point on the object, and

(ii) obtaining measurement data from the probing tool using at least two of the cameras whose positions were determined in step (D).

22. The method as in claim 21, wherein the probing tool has a touch point and wherein step (E)(i) comprises the step of holding the touch point of the probing tool in contact with the point on the object.

23. The method as in claim 21, further comprising the steps of:

positioning at least one reference bar within a measurement volume containing the objects; and

obtaining scale information from the reference bar.

24. The method of claim 21, wherein some of the network points are light sources.

25. The method of claim 24, wherein the light sources are selected from a group consisting of active light sources and passive light sources.

26. The method of claims 25, wherein the active light sources are selected from a group consisting of permanently mounted light sources, projected light spots, and illuminated reflectors.

27. The method of claim 21, wherein the probing tool has light sources attached thereto.

28. The method of claim 27 wherein the light sources are selected from a group consisting of active light sources and passive light sources.

29. The method of claim 21, wherein the network includes at least two points having a known mutual separation distance, the method further comprising the step of using the two points to determine a correct length scale.

30. The method of claim 21, further comprising the step of:

determining optical lens distortions of one of the cameras based on observed positions of the network points.

31. The method of claim 21, wherein the positions of some of the points in the network define a coordinate system, and wherein step (E) determines the position of each object relative to the coordinate system.

32. The method of claim 21, wherein the network is established within a volume, the method further comprising the step of:

bringing objects within the volume prior to the step of determining their positions.

33. The method of claim 21, wherein the objects are used to locate and/or hold parts in a station in a manufacturing production line.

34. The method of claim 33, wherein the network is established on a moveable device, the method further comprising the step of:

moving the movable device into the station before performing steps (D) and (E).

35. The method of claim 21, wherein the network is established on a moveable device, the method further comprising the steps of:

moving the movable device into each of a plurality of stations in a production line and then performing steps (D) and (E) in each of the stations.

36. A method of determining the position and/or orientation of a number of objects relative to each other, the objects being used to locate and/or hold parts in a station in a manufacturing production line, the method comprising the steps of:

(A) providing at least two cameras;

(B) providing a network of help reference points on a moveable device;

(C) determining the spatial positions of some points in the network relative to each other using at least one of the cameras positioned in multiple arbitrary locations, said at least one camera determining projections of the positions of said some network points;

(D) moving the movable device into the station;

(E) positioning some of the cameras;

(F) determining the positions and orientations of some of the cameras using the spatial positions of network points determined in step (C); and

(G) determining the spatial position of some of the objects relative to each other, based on the determined positions and orientations of some of the cameras, whereby the position of at least one of the objects is determined by;

(i) holding a probing tool in contact with at least one point on the object, and

(ii) obtaining measurement data from the probing tool using at least two of the cameras.

37. The method as in claim 36, wherein the probing tool has a touch point and wherein step (G)(i) comprises the step of holding the touch point of the probing tool in contact with the point on the object.

47. A method as in any of claims 36 or 40, wherein the cameras used in step (C) are the same as the cameras used in step (E).

48. A method as in claim 47, wherein said objects include:

(a) geometric objects selected from a group consisting of planes, lines, holes, cylinders, spheres, and

(b) combined objects selected from a group consisting of robot arms and industrial production equipment.

38. A method of determining the position and/or orientation of a number of objects relative to each other, the objects being used to locate and/or hold parts in a station in a manufacturing production line, the method comprising the steps of:

(A) providing at least two cameras;

(B) providing a network of help reference points having known spatial positions relative to each other on a moveable device;

(C) moving the movable device into the station;

(D) positioning some of the cameras;

(E) determining the positions and orientations of the some of the cameras using the known spatial positions of network points; and

(F) determining the spatial position of some of the objects relative to each other, based on the determined positions and orientations of some of the cameras, whereby the position of at least one of the objects is determined by;

(i) holding the probing tool in contact with at least one point on the object, and

(ii) obtaining measurement data from the probing tool using at least two of the cameras whose positions were determined in step (D).

39. The method as in claim 38, wherein the probing tool has a touch point and wherein step (F)(i) comprises the step of holding the touch point of the probing tool in contact with the point on the object.

40. A method of determining the position and/or orientation of a number of objects relative to each other, said objects being used to locate and/or hold parts in a plurality of stations in an automobile manufacturing production line, the method comprising the steps of:

(A) providing at least two cameras;

(B) establishing a network of help reference points on a movable device;

(C) determining the spatial positions of some points in the network relative to each other based on projections of said some points obtained by using at least one of the cameras positioned in multiple arbitrary locations;

(D) moving the movable device into each of the plurality of stations and, in each of the stations,

(E) positioning some of the cameras;

(F) determining the positions and orientations of the some of the cameras using the spatial positions of network points determined in step (C); and

(G) determining the spatial position of some of the objects relative to each other, based on the determined positions and orientations of some of the cameras, whereby the position of at least one of the objects is determined by;

(i) holding a probing tool in contact with at least one point on the object, and

(ii) obtaining measurement data from the probing tool using at least two of the cameras whose positions were determined in step (E).