Method and system for optoelectronic detection and location of objects

• US 8,237,099 B2
• Filed: 06/15/2007
• Issued: 08/07/2012
• Est. Priority Date: 06/15/2007
• Status: Active Grant

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Silver, William M.
• Primary Examiner(s): LEE, JOHN R
• Application Number:
  US11/763,752
• Publication Number:
  US 20080309920A1
• Time in Patent Office: 1,880 Days
• Field of Search: 250/208.1, 348/135, 382/124, 382/312
• US Class Current: 250/208.1
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G06T 2207/30108 Industrial image inspection
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51
• CPC Class Codes: G06T 7/70 Determining position or orientation of objects or cameras camera calibration G06T7/80

Abstract

Disclosed are methods and systems for optoelectronic detection and location of moving objects. The disclosed methods and systems capture one-dimensional images of a field of view through which objects may be moving, make measurements in those images, select from among those measurements those that are likely to correspond to objects in the field of view, make decisions responsive to various characteristics of the objects, and produce signals that indicate those decisions. The disclosed methods and systems provide excellent object discrimination, electronic setting of a reference point, no latency, high repeatability, and other advantages that will be apparent to one of ordinary skill in the art.

Claims

1. An optoelectronic system for providing information describing an object, comprising:

an optical sensor that makes light measurements in a field of view;

means for performing a motion process that provides relative motion between the object and the field of view in a direction of motion, such that the object passes through the field of view;

means for performing a capture process that captures a plurality of one-dimensional images of the field of view, wherein

each of the plurality of images are responsive to the respective light measurements;

the images are oriented approximately parallel to the direction of motion; and

at least a portion of the images correspond to a plurality of positions of the object relative to the field of view; and

means for performing a process that analyzes at least a portion of the images so as to provide the information describing the object.

2. The system of claim 1, wherein the information describing the object comprises knowledge responsive to object presence in the field of view.

3. The system of claim 1, wherein

the motion process is such that the object crosses a reference point at a reference time;

and

the information describing the object comprises an estimate of the reference time.

4. The system of claim 3, further comprising an electronic human-machine interface, and wherein the reference point is adjusted in response to the human-machine interface.

5. The system of claim 3, further comprising a signaling process that produces a signal that indicates the estimate of the reference time by occurring at a signal time that is responsive to the estimate of the reference time.

6. The system of claim 5, further comprising an electronic human-machine interface, and wherein the signal time is adjusted in response to the human-machine interface.

7. The system of claim 5, wherein there is no latency between the reference time and the signal time.

8. The system of claim 3, wherein the estimate of the reference time is determined by predicting the reference time.

9. The system of claim 3, further comprising

an example object;

and

a setup signal that indicates that the example object is placed in the field of view at a setup position; and

wherein the reference point is set responsive to the example object, the setup signal, and the setup position.

10. The system of claim 9, further comprising a signaling process that produces a signal responsive to the information describing the object, and wherein the signal occurs at a time when the object crosses the setup position.

11. The system of claim 9, further comprising a signaling process that produces a signal responsive to the information describing the object, and wherein the signal occurs at a time when the object is upstream from the setup position.

12. The system of claim 3, further comprising

a test object;

and

a human-machine interface comprising an indicator that indicates a detection state chosen from among

the test object is detected upstream from the reference point;

the test object is detected downstream from the reference point; and

the test object is not detected.

13. The system as in any one of claims 1-3, wherein the optical sensor comprises a linear optical sensor comprising a one-dimensional array of photoreceptors.

14. An optoelectronic system for providing information describing an object, comprising:

an optical sensor that makes light measurements in a field of view;

a motion element that provides relative motion between the object and the field of view in a direction of motion, such that the object passes through the field of view;

a capture element that captures a plurality of one-dimensional images of the field of view, wherein

each of the plurality of images are responsive to the respective light measurements;

the images are oriented approximately parallel to the direction of motion; and

at least a portion of the images correspond to a plurality of positions of the object relative to the field of view;

a measurement element that analyzes at least a portion of the images so as to produce image measurements;

a selection element that selects object measurements from among the image measurements, the object measurements comprising image measurements that are judged responsive to the object; and

a decision element that analyzes the object measurements so as to produce the information describing the object.

15. The system of claim 14, wherein

at least a portion of the image measurements are responsive to object presence in the field of view;

the selection element is responsive to at least a portion of the image measurements that are responsive to object presence in the field of view; and

the information describing the object comprises knowledge responsive to object presence in the field of view.

16. The system of claim 14, wherein

the motion element is such that the object crosses a reference point at a reference time;

at least a portion of the image measurements are responsive to object position in the field of view;

at least a portion of the object measurements are selected from among the image measurements that are responsive to object position in the field of view;

the decision element is responsive to at least a portion of the object measurements that are selected from among the image measurements that are responsive to object position in the field of view; and

the information describing the object comprises an estimate of the reference time.

17. The system of claim 16, wherein

the capture element process produces a plurality of capture times, each capture time being responsive to a time at which a corresponding image was captured;

and

the decision element is responsive to at least one of the capture times.

18. The system of claim 17, wherein the decision element comprises fitting a curve to points comprising at least a portion of the capture times and corresponding object measurements that are selected from among the image measurements that are responsive to object position in the field of view.

19. The system of claim 16, further comprising an electronic human-machine interface, and wherein the reference point is adjusted in response to the human-machine interface.

20. The system of claim 16, further comprising a signaling element that produces a signal responsive to the information describing the object, and wherein the signal indicates the information describing the object by occurring at a signal time that is responsive to the estimate of the reference time.

21. The system of claim 20, further comprising an electronic human-machine interface, and wherein the signal time is adjusted in response to the human-machine interface.

22. The system of claim 20, wherein there is no latency between the reference time and the signal time.

23. The system of claim 16, wherein the decision element determines the estimate of the reference time by predicting the reference time.

24. The system of claim 16, further comprising

an example object;

and

a setup signal that indicates that the example object is placed in the field of view at a setup position; and

wherein the reference point is set responsive to the example object, the setup signal, and the setup position.

25. The system of claim 24, further comprising a signaling element that produces a signal responsive to the information describing the object, and wherein the signal occurs at a time when the object crosses the setup position.

26. The system of claim 24, further comprising a signaling element that produces a signal responsive to the information describing the object, and wherein the signal occurs at a time when the object is upstream from the setup position.

27. The system of claim 16, further comprising

a test object;

and

a human-machine interface comprising an indicator that indicates a detection state chosen from among

the test object is detected upstream from the reference point;

the test object is detected downstream from the reference point; and

the test object is not detected.

28. The system as in any one of claims 14-16, wherein the measurement element comprises a pattern detection element.

29. The system of claim 28, further comprising

an example object;

and

a training element that obtains a model pattern responsive to the example object; and

wherein the pattern detection element is responsive to the model pattern.

30. The system of claim 28, wherein the pattern detection element comprises a normalized correlation element.

31. The system as in any one of claims 14-16, wherein the optical sensor comprises a linear optical sensor comprising a one-dimensional array of photo receptors.

32. An optoelectronic system for detecting and locating an object, comprising:

a linear optical sensor comprising a linear array of photoreceptors that makes light measurements in a field of view;

means for performing a motion process that provides relative motion between the object and the field of view in a direction of motion, such that the object passes through the field of view and crosses a reference point at a reference time;

means for performing a capture process that captures a plurality of one-dimensional images of the field of view, and produces a plurality of capture times, each capture time being responsive to a time at which a corresponding image was captured, and wherein

each of the plurality of images are responsive to the respective light measurements;

the images are oriented approximately parallel to the direction of motion; and

at least a portion of the images correspond to a plurality of positions of the object relative to the field of view;

means for performing a measurement process that analyzes at least a portion of the images so as to produce position measurements and score measurements;

means for performing a decision process that uses the capture times, the position measurements, and the score measurements to produce an estimate of the reference time; and

means for performing a signaling process that produces a signal that indicates the reference time by occurring at a signal time that is responsive to the estimate of the reference time.

33. The system of claim 32, wherein the decision process estimates the reference time by predicting the reference time.

34. The system of claim 32, wherein there is no latency between the reference time and the signal time.

35. An optoelectronic method for providing information describing an object, comprising:

using an optical sensor to make light measurements in a field of view;

providing relative motion between the object and the optical sensor in a direction of motion, such that the object passes through the field of view;

capturing a plurality of one-dimensional images of the field of view, wherein

each of the plurality of images are responsive to the respective light measurements;

the images are oriented approximately parallel to the direction of motion; and

at least a portion of the images correspond to a plurality of positions of the object relative to the field of view; and

analyzing at least a portion of the images so as to provide the information describing the object.

36. The method of claim 35, wherein the information describing the object comprises knowledge responsive to object presence in the field of view.

37. The method of claim 35, wherein

the relative motion is such that the object crosses a reference point at a reference time;

and

the information describing the object comprises an estimate of the reference time.

38. The method of claim 37, further comprising using an electronic human-machine interface to adjust the reference point.

39. The method of claim 37, further comprising producing a signal that indicates the estimate of the reference time by occurring at a signal time that is responsive to the estimate of the reference time.

40. The method of claim 39, further comprising using an electronic human-machine interface to adjust the signal time.

41. The method of claim 39, wherein there is no latency between the reference time and the signal time.

42. The method of claim 37, wherein the analyzing step comprises predicting the reference time.

43. The method of claim 37, further comprising

providing an example object;

providing a setup signal that indicates that the example object is placed in the field of view at a setup position; and

setting the reference point in response to the example object, the setup signal, and the setup position.

44. The method of claim 43, further comprising producing a signal responsive to the information describing the object, wherein the signal occurs at a time when the object crosses the setup position.

45. The method of claim 43, further comprising producing a signal responsive to the information describing the object, and wherein the signal occurs at a time when the object is upstream from the setup position.

46. The method of claim 37, further comprising

providing a test object;

and

using a human-machine interface to indicate a detection state chosen from among

the test object is detected upstream from the reference point;

the test object is detected downstream from the reference point; and

the test object is not detected.

47. The system as in any one of claims 35-37, wherein the optical sensor comprises a linear optical sensor comprising a one-dimensional array of photoreceptors.

48. An optoelectronic method for providing information describing an object, comprising:

using an optical sensor to make light measurements in a field of view;

providing relative motion between the object and the optical sensor in a direction of motion, such that the object passes through the field of view;

capturing a plurality of one-dimensional images of the field of view, wherein

each of the plurality of images are responsive to the respective light measurements;

the images are oriented approximately parallel to the direction of motion; and

at least a portion of the images correspond to a plurality of positions of the object relative to the field of view;

analyzing at least a portion of the images so as to produce image measurements;

selecting object measurements from among the image measurements, the object measurements comprising image measurements that are judged responsive to the object; and

analyzing the object measurements so as to produce the information describing the object.

49. The method of claim 48, wherein

at least a portion of the image measurements are responsive to object presence in the field of view;

the selecting step is responsive to at least a portion of the image measurements that are responsive to object presence in the field of view; and

the information describing the object comprises knowledge responsive to object presence in the field of view.

50. The method of claim 48, wherein

the relative motion is such that the object crosses a reference point at a reference time;

at least a portion of the image measurements are responsive to object position in the field of view;

at least a portion of the object measurements are selected from among the image measurements that are responsive to object position in the field of view;

the step of analyzing the object measurements is responsive to at least a portion of the object measurements that are selected from among the image measurements that are responsive to object position in the field of view; and

the information describing the object comprises an estimate of the reference time.

51. The method of claim 50,

further comprising producing a plurality of capture times, each capture time being responsive to a time at which a corresponding image was captured;

and

wherein the step of analyzing the object measurements is further responsive to at least one of the capture times.

52. The method of claim 51, wherein the step of analyzing the object measurements comprises fitting a curve to points comprising at least a portion of the capture times and corresponding object measurements that are selected from among the image measurements that are responsive to object position in the field of view.

53. The method of claim 50, further comprising using an electronic human-machine interface to adjust the reference point.

54. The method of claim 50, further comprising producing a signal that indicates the estimate of the reference time by occurring at a signal time that is responsive to the estimate of the reference time.

55. The method of claim 54, further comprising using an electronic human-machine interface to adjust the signal time relative to the estimate of the reference time.

56. The method of claim 54, wherein there is no latency between the reference time and the signal time.

57. The method of claim 50, wherein the estimate of the reference time is determined by predicting the reference time.

58. The method of claim 50, further comprising

providing an example object;

providing a setup signal that indicates that the example object is placed in the field of view at a setup position; and

setting the reference point in response to the example object, the setup signal, and the setup position.

59. The method of claim 58, further comprising producing a signal responsive to the estimate of the reference time, wherein the signal occurs at a time when the object crosses the setup position.

60. The method of claim 58, further comprising producing a signal responsive to the estimate of the reference time, and wherein the signal occurs at a time when the object is upstream from the setup position.

61. The method of claim 50, further comprising

providing a test object;

and

using a human-machine interface to indicate a detection state chosen from among

the test object is detected upstream from the reference point;

the test object is detected downstream from the reference point; and

the test object is not detected.

62. The method as in any one of claims 48-50, wherein the step of analyzing at least a portion of the plurality of images comprises performing pattern detection.

63. The method of claim 62, further comprising

providing an example object;

and

obtaining a model pattern responsive to the example object; and

wherein the pattern detection is responsive to the model pattern.

64. The method of claim 62, wherein the pattern detection step comprises performing normalized correlation.

65. The method as in any one of claims 48-50, wherein the optical sensor comprises a linear optical sensor comprising a one-dimensional array of photoreceptors.

66. An optoelectronic method for detecting and locating an object, comprising:

using a linear optical sensor to make light measurements in a field of view;

providing relative motion between the object and the optical sensor in a direction of motion, such that the object passes through the field of view and crosses a reference point at a reference time;

capturing a plurality of one-dimensional images of the field of view, wherein

each of the plurality of images are responsive to the respective light measurements;

the images are oriented approximately parallel to the direction of motion; and

at least a portion of the images correspond to a plurality of positions of the object relative to the field of view;

producing a plurality of capture times, each capture time being responsive to a time at which a corresponding image was captured;

analyzing at least a portion of the plurality of images so as to produce position measurements and score measurements;

using the capture times, the position measurements, and the score measurements to produce an estimate of the reference time; and

producing a signal that indicates the reference time by occurring at a signal time that is responsive to the estimate of the reference time.

67. The method of claim 66, wherein the step of using the capture times, the position measurements, and the score measurements to produce an estimate of the reference time comprises predicting the reference time.

68. The method of claim 66, wherein there is no latency between the reference time and the signal time.