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

• US 5,866,915 A
• Filed: 06/05/1995
• Issued: 02/02/1999
• Est. Priority Date: 04/30/1979
• Status: Expired due to Term

• Current Assignee: Diffracto, Ltd. (LMI Technologies Inc.)
• Original Assignee: Sensor Adaptive Machines, Inc.
• Inventors: Pryor, Timothy R., Hockley, Bernard, Liptay-Wagner, Nick, Hageniers, Omer L., Pastorius, W. J.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): Lee, John R.
• Application Number:
  US08/465,260
• Time in Patent Office: 1,338 Days
• Field of Search: 250/559.07, 250/559.08, 250/559.29, 250/559.3, 250/559.33, 250/559.35, 250/559.37, 250/559.4, 250/208.1, 250/208.2, 250/559.2 , 250/559.23, 250/559.31, 250/559.38, 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, 356/376, 901/9, 901/46, 901/47, 348/94, 348/95, 348/142
• US Class Current: 250/559.2
• 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. A machine for determining dimensional characteristics of an object, comprising:

electro-optical sensor means for determining range to said object, said sensor means including a laser to project light onto said object,

machine means for moving said sensor means in at least 2 Cartesian axes relative to said object,

rotation means for rotating at least one of said object and said sensor means, and

computer means for combining range data from said sensor means with data related to the position of said sensor means and data related to rotation of said rotation means to determine dimensional characteristics of said object.

2. Apparatus according to claim 1 further comprising means for providing a video display of said light projected by said laser on said object.

3. Apparatus according to claim 1 further comprising means for controlling the light gathered by said sensor means.

4. Apparatus according to claim 3, wherein said means for controlling the light gathered by said sensor means varies the intensity of said laser.

5. Apparatus according to claim 3, wherein said means for controlling the light gathered by said sensor means varies the amount of time said laser projects light onto said object.

6. Apparatus according to claim 3, wherein said sensor means comprises a scanning photodetector array and said means for controlling the light gathered by said sensor means changes the scan rate of said photodetector array.

7. Apparatus according to claim 1 wherein said machine means for moving said sensor means moves said sensor means in accordance with design data concerning said object.

8. Apparatus according to claim 1, wherein said sensor means operates by triangulation.

9. Apparatus according to claim 1, wherein said laser is a laser diode.

10. Apparatus according to claim 1, wherein said sensor means has an optical axis, said apparatus further including means to determine if said axis of said sensor means is normal to said object.

11. Apparatus according to claim 1, wherein said electro-optical sensor means further comprises a photodetector array and wherein light reflected from said object impinges on less than all the elements of said photodetector array simultaneously.

12. Apparatus according to claim 1, wherein said rotation means rotates said object.

13. A method for determining dimensional characteristics of an object comprising the steps of:

providing at least one electro-optical sensor means for determining range to said object, said sensor means including a laser to project light onto said object,

moving, with a machine, said sensor means in 2 cartesian axes relative to said object,

rotating at least one of said object and said sensor means, and

using a computer means, combining range data from said sensor means with data related to the position of said sensor means and data related to said rotation to determine dimensional characteristics of said object.

14. A method according to claim 13, further comprising providing a video display of said light projected by said laser onto said object.

15. A method according to claim 13, further comprising controlling the light gathered by said electro-optical sensor means.

16. A method according to claim 15, further comprising controlling said light gathered by said sensor means by varying the intensity of said laser.

17. A method according to claim 15, further comprising controlling said light gathered by said sensor means by varying the amount of time said laser beam projects light onto said object.

18. A method according to claim 15, wherein said sensor means comprises a scanning photodetector array, said method further comprising controlling and said light gathered by said sensor means by changing the scan rate of said photodetector array.

19. A method according to claim 13, further comprising moving said sensor means in accordance with design data concerning said object.

20. A method according to claim 13, wherein said range data to said object is determined using triangulation.

21. A method according to claim 13, wherein said sensor means has an optical axis, said method further comprising determining if said optical axis of said sensor means is normal to said object.

22. A method according to claim 13, wherein said electro-optical sensor means further comprises a photodetector array, said method further comprising focusing said light reflected from said object so that it impinges on less than all the elements of said photodetector array simultaneously.

23. A method according to claim 13, wherein said rotation means rotates said object.

24. Apparatus for determining dimensional characteristics of an object comprising:

a sensor means having an output,

machine means for moving said sensor means relative to said object along a predetermined path,

means to determine from the output of said sensor means the location of a feature of said object,

means to modify said path as a function of said location of said feature, and

means to determine dimensional characteristics of said object based upon said output of said sensor means and data related to said movement of said sensor means.

25. Apparatus according to claim 24 wherein said sensor means is electro-optical.

26. Apparatus according to claim 25, wherein said sensor means comprises a scanning photodetector array, said apparatus further comprising means for controlling the light gathered by said photodetector array.

27. Apparatus according to claim 26, wherein said means for controlling the light gathered by said photodetector array controls the intensity of a light source providing light which is gathered by said photodetector array.

28. Apparatus according to claim 26, wherein said means for controlling the light gathered by said photodetector array controls the scan rate of said photodetector array.

29. Apparatus according to claim 24 wherein said sensor means includes means for determining distance to said object.

30. Apparatus according to claim 29, wherein said sensor means uses triangulation for determining said distance.

31. Apparatus according to claim 24 wherein said sensor means has an optical axis, and further including means to determine if said optical axis is normal to said object.

32. Apparatus according to claim 24, wherein said means to determine from the output of said sensor means the location of a feature of said object determines the location of an edge of said object.

33. A method for determining dimensional characteristics of an object comprising the steps of:

providing a sensor means having an output,

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

determining from the output of said sensor means, the location of a feature of said object,

modifying said path as a function of said location of said feature, and determining dimensional characteristics of said object based upon said output of said sensor means and data related to said movement of said sensor means.

34. A method according to claim 33 wherein said sensor means is electro-optical.

35. A method according to claim 34, wherein said sensor means comprises a scanning photodetector array, said method further comprising controlling the light gathered by said photodetector array.

36. A method according to claim 35, wherein the light gathered by said photodetector array is controlled by controlling the intensity of a light source providing light which is gathered by said photodetector array.

37. A method according to claim 35, wherein the light gathered by said photodetector array is controlled by controlling the scan rate of said photodetector array.

38. A method according to claim 33, further comprising determining distance to said object with said sensor means.

39. A method according to claim 38, further comprising using triangulation for determining said distance.

40. A method according to claim 33, wherein said step of determining the location of a feature of said object determines the location of an edge of said object.