Method and apparatus for electro-optically determining the dimension, location and attitude of objects

• US 6,211,506 B1
• Filed: 06/05/1995
• Issued: 04/03/2001
• Est. Priority Date: 04/30/1979
• Status: Expired due to Term

• Current Assignee: LMI Technologies Inc.
• Original Assignee: Diffracto, Ltd. (LMI Technologies Inc.)
• Inventors: Liptay-Wagner, Nick, Hageniers, Omer L., Pastorius, W. J., Pryor, Timothy R., Hockley, Bernard
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): Lee, John R
• Application Number:
  US08/462,248
• Time in Patent Office: 2,129 Days
• Field of Search: 250/559.07, 250/559.08, 250/559.29, 250/559.3, 250/559.31, 250/559.33, 250/559.36, 250/559.37, 250/559.4, 250/208.1, 356/3.01, 356/3.02, 356/3.03, 356/3.06, 356/3.07, 356/3.1, 356/3.12, 356/4.01, 356/375, 901/9, 901/46, 901/47, 348/86, 348/94, 348/95, 348/135, 348/142
• US Class Current: 250/208.1
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01B 11/2416 of gears optical projection profile comparators G01B9/08
• 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: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/491 Details of non-pulse systems

Abstract

A method and apparatus for optically determining the dimension of part surfaces. Particular embodiments describe optical triangulation based coordinate measurement machines capable of accurate measurement of complex surfaces, such as gear teeth and turbine blades. Other embodiments provide highly useful sensors for robot guidance and related purposes. Up to 5 axis sensing capability is provided on surfaces of widely varying form.

Claims

1. Apparatus for measuring an object having a surface, said apparatus comprising:

a sensor comprising a solid state TV camera having an output, said sensor being capable of determining the location of a point on said object surface;

means for moving said sensor relative to said object in at least three axes; and

processing means for receiving said output from said sensor and data related to movement of said sensor by said means for moving said sensor and for determining a measurement of said object based on a location of a first point on said object surface which is determined by said sensor, a location of a second point on said object surface which is determined by said sensor after said sensor is moved, and said data related to said movement of said sensor.

2. Apparatus according to claim 1 wherein said processing occurs substantially at the frame rate of said tv camera.

3. Apparatus according to claim 1 further incorporating a microcomputer to control light gathering of said tv camera.

4. Apparatus according to claim 3, wherein said TV camera is scanned to provide said output and-said microcomputer is adapted to control the scan rate of said TV camera.

5. Apparatus according to claim 3, wherein said TV camera is scanned to provide said output and said microcomputer is adapted to control the scan rate within a scan of said TV camera.

6. Apparatus according to claim 1, wherein said processing means determines a measurement of said object based on a first set of points for which locations are determined before a movement of said sensor and a second set of points for which locations are determined after said movement of said sensor.

7. Apparatus according to claim 1, wherein said means for moving said sensor comprises a robot capable of six axes of positional movement.

8. Apparatus according to claim 1 further comprising means for providing a video display of said output of said TV camera.

9. Apparatus according to claim 1 further comprising range sensing means to determine the range of said sensor to said object.

10. Apparatus according to claim 9 wherein said range sensing means does not comprise said TV camera of said sensor means.

11. Apparatus according to claim 9 wherein said range sensing means comprises a laser.

12. Apparatus according to claim 9, further comprising laser means for projecting light on to said object.

13. Apparatus according to claim 1, wherein said TV camera has an optical axis, said apparatus further comprising means for determining the location of at least one edge of said object relative to said optical axis of said TV camera.

14. Apparatus according to claim 1 further comprising means for positioning said sensor based upon design data of said object.

15. Apparatus for measuring an object, comprising:

solid state TV camera means to view at least a portion of said object, said TV camera means having an output,

means for determining at least one edge location of said object using said output of said TV camera means,

means for storing data concerning said object,

machine means for moving said TV camera means to a plurality of locations relative to said object,

means responsive to said at least one edge location for controlling movements of said machine means, and

means for combining said at least one edge location of said object with said data concerning said object to determine a measurement of said object.

16. Apparatus according to claim 15, further comprising a microcomputer for controlling the light gathered by said TV camera.

17. Apparatus according to claim 16, wherein said TV camera is scanned to provide said output and said microcomputer is adapted to control the scan rate of said TV camera.

18. Apparatus according to claim 16, wherein said TV camera is scanned to provide said output and said microcomputer is adapted to control the scan rate within a scan of said TV camera.

19. Apparatus according to claim 15, wherein said means for storing data concerning said object stores data concerning said object provided by said TV camera.

20. Apparatus according to claim 15, wherein said means for storing data concerning said object stores data concerning said object provided by a predetermined data base of said object.

21. Apparatus according to claim 15, wherein said means for determining at least one edge location of said object utilizes optical triangulation for determining said at least one edge location.

22. A method for control of a machine for inspection of an object, comprising the steps of:

providing a non-contact sensor on said machine,

sensing range data with respect to said object with a range sensor,

using said range data, positioning said non-contact sensor at a desired range relative to said object or a feature thereof, and

forming an image of a portion of the surface of said object with said non-contact sensor and providing an output of said sensor, and

using said output of said non-contact sensor, inspecting said object.

23. A method according to claim 22, wherein said range sensor is separate from said non-contact sensor.

24. A method according to claim 23, further comprising, using said range data, positioning said non-contact sensor at a desired attitude relative to said object or a feature thereof.

25. A method according to claim 22, wherein said non-contact sensor comprises a photodetector matrix array.

26. A method according to claim 25, wherein said step of forming an image of a portion of the surface of said object comprises forming an image comprising at least three points on said surface of said object using said photodetector matrix array.

27. A method according to claim 22, further comprising comparing said output of said non-contact sensor to predetermined data.

28. A method for control of a machine used to position a non-contact inspection device relative to an object, comprising the steps of:

providing a sensor on said machine in a predetermined position relative to said inspection device,

with said sensor, sensing the attitude of said inspection device with respect to said object,

positioning said inspection device at a desired attitude relative to the object or a feature thereof, and

performing an inspection of said object with said inspection device.

29. A method according to claim 28, wherein said inspection device has an optical axis and said inspection device is positioned such that the optical axis of said inspection device is perpendicular to a portion of the surface of said object.

30. A method according to claim 28, wherein said attitude is sensed in two planes.

31. A method according to claim 30, wherein said inspection device has an optical axis and said inspection device is positioned such that the optical axis of said inspection device is perpendicular to a portion of the surface of said object in two planes.

32. A method according to claim 28, wherein said inspection device comprises a photodetector matrix array and wherein the scan rate of said photodetector array is controlled during said inspection.

33. A method according to claim 28, further comprising flashing light onto said object in performing said inspection of said object.

34. A method for measuring an object comprising:

providing a measuring device for measuring a portion of said object,

providing a sensor means attached to said measuring device,

moving said sensor means and said measuring device relative to said object along a predetermined path,

determining from the output of said sensor means, the location of an edge of said object, and

modifying said predetermined path of said sensor and said measuring device as a function of said edge location.

35. A method according to claim 34, wherein said measuring device comprises a scanning photodetector array.

36. A method according to claim 35, further comprising controlling the scan rate of said scanning photodetector array.

37. A method according to claim 34, wherein said sensor means comprises a photodetector array, said method further comprising scanning said photodetector array to provide said output of said sensor means.

38. A method according to claim 37, wherein said sensor means further comprises a laser, said method further comprising using triangulation in determining the location of an edge of said object.

39. A method according to claim 37, further comprising determining said predetermined path based on design data related to said object.

40. A method according to claim 37, further comprising performing optical triangulation with said measuring machine for measuring said portion of said object.

41. A method according to claim 34, wherein determining said location of an edge comprises determining a location of an edge of a hole in said object.