Method of and apparatus for distinguishing one workpiece from another workpiece and detecting workpiece position

• US 5,835,623 A
• Filed: 09/17/1997
• Issued: 11/10/1998
• Est. Priority Date: 08/23/1993
• Status: Expired due to Fees

• Current Assignee: Mazda Motor Corporation
• Original Assignee: Mazda Motor Corporation
• Inventors: Shinohara, Kazuhiro, Nishijima, Takayoshi, Yonezawa, Yasuaki, Nozaki, Tomoyuki, Arataki, Hiroo
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Tadayon, Bijan
• Application Number:
  US08/931,937
• Time in Patent Office: 419 Days
• Field of Search: 382/156, 382/203, 382/141, 382/172, 382/226, 382/291, 382/110, 382/168, 382/100, 382/101, 382/102, 382/142, 382/143, 382/144, 382/149, 382/152, 382/181, 382/190, 382/209, 382/312, 348/94, 348/89, 348/91, 348/142, 348/349, 348/125, 348/92, 395/94, 395/97, 209/556, 209/586, 209/587, 209/939, 358/448, 358/458
• US Class Current: 382/152
• CPC Class Codes: G06V 10/44 Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components

Abstract

A method is used for discerning a specific type of a work, including a plurality of specified contoured portions forming parts of the work, from an image including the subject work. Each specified contoured portion, which may be defined by geometric characteristics, such as an area, a peripheral length of a specified contoured portion and a ratio between the area and peripheral length, is recognized in the image based on two-valued image data into which many-valued image data representative of the subject work is transformed with a threshold value. A position of the subject work is discerned based on a relative position of each two specified contoured portions defined by geometric characteristics, such as a distance between centers of each two specified contoured portions and an angle of a center line of each two specified contoured portions relative to a center line of another two specified contoured portions.

Claims

1. A method of discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, which are separated from one another and specified by a predetermined quantitative distinction independent from said specified distinctive geometric patterns and form part of the whole surface thereof and being placed on a pallet, and handling said specific subject work so as to transport said specific subject work from said pallet to a predetermined position remote from said pallet, said method comprising the steps of:

positioning a camera so as to pick up an image of a predetermined area including at least one of said subject works;

processing said image to retrieve a quantitative distinction of each of said geometric patterns included in said image;

comparing said quantitative distinction retrieved from the geometric pattern included in said image with said predetermined quantitative distinction to recognize each geometric pattern in said image as one of said specified distinctive geometric patterns when said quantitative distinction retrieved from said image is within predetermined limits of said predetermined quantitative distinction;

detecting a relative position of at least two geometric patterns included in said image which are recognized as said specified distinctive geometric patterns;

comparing said relative position with a predetermined reference position and identifying a subject work which includes at least two distinctive geometric patterns having a relative position coincident with said predetermined reference position as said specific subject work, thereby discerning said specific subject work from the other subject works;

recognizing a position of said specific subject work based on said relative positions of said specified distinctive geometric patterns belonging to said specific subject work; and

shifting a handling device having a pick-up head engageable with said specific subject work to said position of said specific subject work and causing said handling device to pick up said specific subject work from said pallet by engaging said specific subject work at said two geometric patterns and transport said specific subject work from said pallet to said predetermined position.

2. A method as defined in claim 1, wherein each of said specified distinctive geometric patterns is defined as a specified point on a simple geometric figure.

10. A method as defined in claim 1, wherein said at least two of said specified distinctive geometric patterns are adjacent to each other.

11. A method as defined in claim 1, wherein said specified distinctive geometric pattern is isolated inside from a contour of said whole surface of said specific subject work.

12. A method as defined in claim 1, wherein said specified distinctive geometric pattern is defined as a specified point on a simple geometric figure.

13. A method as defined in claim 1, wherein said specified distinctive geometric pattern is isolated inside from a contour of said whole surface of said subject work and defined as a specified point on a simple geometric figure.

14. A method as defined in claim 1, wherein each of said specified distinctive geometric patterns is defined as a specified point on a simple geometric figure, said relative position being defined by a distance between specified points of each of two simple geometric figures and compared with a predetermined distance.

15. A method as defined in claim 1, wherein each of said specified distinctive geometric patterns is defined as a specified point on a simple geometric figure, said relative position being defined by an angle between a straight line connecting specified points of each of two simple geometric figures and a straight line connecting specified points of another two simple geometric figures and compared with a predetermined angle.

16. A method as defined in claim 1, wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by a distance between specified points of each of two simple geometric figures and compared with a predetermined distance.

17. A method as defined in claim 1, wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by an angle between a straight line connecting specified points of each of two simple geometric figures and a straight line connecting specified points of another two simple geometric figures and compared with a predetermined angle.

18. A method as defined in claim 16, wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work.

19. A method as defined in claim 17, wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work.

38. A method as defined in claim 1, wherein said at least two of said specified distinctive geometric patterns are defined by holes.

39. A method as defined in claim 38, wherein said processing of said image is made by transforming many-valued data representative of said image into two-valued data with a threshold value.

40. A method as defined in claim 39, wherein said threshold value is changed from an initially established threshold value when said relative position is not comparable with said reference position.

41. A method as defined in claim 40, wherein said initially established threshold value is changed after a predetermined number of changes of said threshold value.

42. A method as defined in claim 38, wherein said specific subject work is a cylinder head formed with a bore, for receiving a spark plug, having a circular contour.

43. A method as defined in claim 38, wherein said specific subject work is a cylinder block formed with a cylinder bore having a circular contour.

3. An apparatus for discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, which are separated from one another and specified by a predetermined quantitative distinction independent from said specified distinctive geometric patterns and form part of the whole surface thereof and placed on a pallet, and for transporting said specific subject work with a handling device having a pick-up head engageable with said specific subject work which includes two of said specified distinctive geometric patterns from said pallet to a predetermined position remote from said pallet, said apparatus comprising:

image forming means for forming an image of a predetermined area including at least one of said subject works;

image processing means for processing said image to retrieve a quantitative distinction of each of said geometric patterns included in said image; and

controlling means for comparing said quantitative distinction retrieved from the geometric pattern included in said image with said predetermined quantitative distinction to recognize each said geometric pattern in said image as one of said specified distinctive geometric patterns when said quantitative distinction retrieved from said image is within predetermined limits of said predetermined quantitative distinction, detecting a relative position of at least two of said specified distinctive geometric patterns included in said image which are recognized as said specified distinctive geometric patterns, comparing said relative position with a predetermined reference position and identifying a subject work which includes at least two distinctive geometric patterns having a relative position coincident with said predetermined reference position as said specific subject work, thereby discerning said specific subject work from the other subject works, recognizing a position of said specific subject work based on said relative positions of said specified distinctive geometric patterns belonging to said specified subject work, shifting a handling device having a pick-up head engageable with said specific subject work to said position of said specific subject work, and causing said handling device to pick up said specific subject work from said pallet by engaging said specific subject work at said two specified distinctive geometric patterns and transport said specific subject work from said pallet to said predetermined position.

4. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is defined as a specified point on a simple geometric figure.

5. An apparatus as defined in claim 3, wherein image processing is made by transforming many-valued data representative of said image into two-valued data with a threshold value.

6. An apparatus as defined in claim 5, wherein said threshold value is changed from an initially established threshold value when said relative position is not comparable with said reference position.

7. An apparatus as defined in claim 5, wherein said image forming means is changeable in focal length.

8. An apparatus as defined in claim 7, wherein said image forming means zooms in said image after a predetermined number of said changes of threshold value.

9. An apparatus as defined in claim 8, wherein said initially established threshold value is changed after said predetermined number of said changes of threshold value.

26. An apparatus as defined in claim 3, wherein said at least two of said specified distinctive geometric patterns are adjacent to each other.

27. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is isolated inside from a contour of the whole surface of said specific subject work.

28. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is defined as a specified point on a simple geometric figure.

29. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is isolated inside from a contour of the whole surface of said specific subject work and defined as a specified point on a simple geometric figure.

30. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is defined as a specified point on a simple geometric figure, said relative position being defined by a distance between specified points of each of two simple geometric figures and compared with a predetermined distance.

31. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is defined as a specified point on a simple geometric figure, said relative position being defined by an angle between a straight line connecting specified points of each of two simple geometric figures and a straight line connecting specified points of another two simple geometric figures and compared with a predetermined angle.

32. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by a distance between specified points of each of two simple geometric figures and compared with a predetermined distance.

33. An apparatus as defined in claim 3, wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by an angle between a straight line connecting specified points of each of two simple geometric figures and a straight line connecting specified points of another two simple geometric figures and compared with a predetermined angle.

34. An apparatus as defined in claim 32, wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work.

35. An apparatus as defined in claim 33, wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work.

20. A method of discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, separated from one another, forming parts of the whole surface thereof and being placed on a pallet, and handling said specific subject work so as to transport said specific subject work from said pallet to a predetermined position remote from said pallet, said method comprising the steps of:

positioning a camera so as to pick up an image of a predetermined area including at least one of said subject works;

processing said image to recognize each of said specified distinctive geometric patterns;

detecting a relative position of at least two of said specified distinctive geometric patterns;

comparing said relative position of said at least two of said specified distinctive geometric patterns with a predetermined reference position and identifying a subject work which includes at least two distinctive geometric patterns having a relative position coincident with said predetermined reference position as said specific subject work, thereby discerning said specific subject work from the other subject works;

recognizing a position of said specific subject work based on said relative positions of said specified distinctive geometric patterns belonging to said specific subject work; and

shifting a handling device to said position of said specific subject work and causing said handling device to pick up and transport said specific subject work from said pallet to said predetermined position;

wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by a distance between specified points of each of two simple geometric figures and compared with a predetermined distance;

wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work; and

wherein said specific subject work has at least four bores, at least two of said bores being engaged by positioning means of said handling device for positioning said handling device and at least two other bores, symmetrical in position with respect to a geometric center of said subject work, being engaged by pick-up means of said handling device.

22. A method as defined in claim 20, wherein said specific subject work is a cylinder head formed with more than four bores, for receiving spark plugs, respectively, two inner bores of said more than four bores being engaged by said positioning means and two outer bores of said more than four bores being engaged by said pick-up means.

23. A method as defined in claim 20, wherein said specific subject work is a cylinder block formed with more than four cylinder bores, two inner cylinder bores of said more than four cylinder bores being engaged by said positioning means and two outer cylinder bores of said more than four cylinder bores being engaged by said pick-up means.

44. A method as defined in claim 20, wherein said processing of said image is made by transforming many-valued data representative of said image into two-valued data with a threshold value.

45. A method as defined in claim 44, wherein said threshold value is changed from an initially established threshold value when said relative position is not comparable with said reference position.

46. A method as defined in claim 45, wherein said initially established threshold value is changed after a predetermined number of changes of said threshold value.

47. A method as defined in claim 20, wherein said specific subject work is a cylinder head formed with a bore, for receiving a spark plug, having a circular contour.

48. A method as defined in claim 20, wherein said specific subject work is a cylinder block formed with a cylinder bore having a circular contour.

21. A method of discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, separated from one another, forming parts of the whole surface thereof and being placed on a pallet, and handling said specific subject work so as to transport said specific subject work from said pallet to a predetermined position remote from said pallet, said method comprising the steps of:

positioning a camera so as to pick up an image of a predetermined area including at least one of said subject works;

processing said image to recognize each of said specified distinctive geometric patterns;

detecting a relative position of at least two of said specified distinctive geometric patterns;

comparing said relative position of said at least two of said specified distinctive geometric patterns with a predetermined reference position and identifying a subject work which includes at least two distinctive geometric patterns having a relative position coincident with said predetermined reference position as said specific subject work, thereby discerning said specific subject work from the other subject works;

recognizing a position of said specific subject work based on said relative positions of said specified distinctive geometric patterns belonging to said specific subject work; and

shifting a handling device to said position of said specific subject work and causing said handling device to pick up and transport said specific subject work from said pallet to said predetermined position;

wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by an angle between a straight line connecting specified points of each of two simple geometric figures and a straight line connecting specified points of another two simple geometric figures and compared with a predetermined angle;

wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work; and

wherein said specified subject work has at least four bores, at least two of said bores being engaged by positioning means of said handling device for positioning said handling device and at least two other bores, symmetrical in position with respect to a geometric center of said subject work, being engaged by pick-up means of said handling device.

24. A method as defined in claim 21, wherein said specific subject work is a cylinder head formed with more than four bores, for receiving spark plugs, respectively, two inner bores of said more than four bores being engaged by said positioning means and two outer bores of said more than four bores being engaged by said pick-up means.

25. A method as defined in claim 21, wherein said specific subject work is a cylinder block formed with more than four cylinder bores, two inner cylinder bores of said more than four cylinder bores being engaged by said positioning means and two outer cylinder bores of said more than four cylinder bores being engaged by said pick-up means.

49. A method as defined in claim 21, wherein said processing of said image is made by transforming many-valued data representative of said image into two-valued data with a threshold value.

50. A method as defined in claim 49, wherein said threshold value is changed from an initially established threshold value when said relative position is not comparable with said reference position.

51. A method as defined in claim 50, wherein said initially established threshold value is changed after a predetermined number of changes of said threshold value.

52. A method as defined in claim 21, wherein said specific subject work is a cylinder head formed with a bore, for receiving a spark plug, having a circular contour.

53. A method as defined in claim 21, wherein said specific subject work is a cylinder block formed with a cylinder bore having a circular contour.

36. An apparatus for discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, separated from one another, forming parts of the whole surface thereof and placed on a pallet, and transporting said specific subject work with a handling device from said pallet to a predetermined position remote from said pallet, said apparatus comprising:

image forming means for forming an image of a predetermined area including at least one of said subject works;

image processing means for recognizing each of said specified distinctive geometric patterns; and

controlling means for detecting a relative position of two of said specified distinctive geometric patterns, comparing said relative position of said two of said specified distinctive geometric patterns with a predetermined reference position and identifying a subject work which includes said two of said specified distinctive geometric patterns having a relative position coincident with said predetermined reference position as said specific subject work, thereby discerning and recognizing a position of said specific subject work based on said relative positions of said specified distinctive geometric patterns belonging to said specified subject work, causing said handling device to pick up and transport said specific subject work to said predetermined position;

wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by a distance between specified points of each of two simple geometric figures and compared with a predetermined distance;

wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work; and

wherein said specific subject work has at least four bores, said handling means having positioning means engageable with at least two of said at least four bores for positioning said handling device and pick-up means engageable with at least two others of said at least four bores symmetrical in position with respect to a geometric center of said specific subject work for picking up said specific subject work.

54. An apparatus as defined in claim 36, wherein said image processing means transforms many-valued data representative of said image into two-valued data with a threshold value.

55. An apparatus as defined in claim 54, wherein said threshold value is changed from an initially established threshold value when said relative position is not comparable with said reference position.

56. An apparatus as defined in claim 55, wherein said initially established threshold value is changed after a predetermined number of changes of said threshold value.

57. An apparatus as defined in claim 36, wherein said specific subject work is a cylinder head formed with a bore, for receiving a spark plug, having a circular contour.

58. An apparatus as defined in claim 36, wherein said specific subject work is a cylinder block formed with a cylinder bore having a circular contour.

59. An apparatus as defined in claim 57, wherein said image processing means transforms many-valued data representative of said image into two-valued data with a threshold value.

60. An apparatus as defined in claim 59, wherein said threshold value is changed from an initially established threshold value when said relative position is not comparable with said reference position.

61. An apparatus as defined in claim 60, wherein said initially established threshold value is changed after a predetermined number of changes of said threshold value.

37. An apparatus for discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, separated from one another, forming parts of the whole surface thereof and placed on a pallet, and transporting said specific subject work with a handling device from said pallet to a predetermined position remote from said pallet, said apparatus comprising:

image forming means for forming an image of a predetermined area including at least one of said subject works;

image processing means for recognizing each of said specified distinctive geometric patterns; and

controlling means for detecting a relative position of two of said specified distinctive geometric patterns, comparing said relative position of said two of said specified distinctive geometric patterns with a predetermined reference position and identifying a subject work which includes said two of said specified distinctive geometric patterns having a relative position coincident with said predetermined reference position as said specific subject work, thereby discerning and recognizing a position of said specific subject work based on said relative positions of said specified distinctive geometric patterns belonging to said specified subject work, causing said handling device to pick up and transport said specific subject work to said predetermined position;

wherein each of said specified distinctive geometric patterns is isolated inside from a contour of said whole surface of said specific subject work and defined as a specified point on a simple geometric figure, said relative position being defined by an angle between a straight line connecting specified points of each of two simple geometric figures and a straight line connecting specified points of another two simple geometric figures and compared with a predetermined angle;

wherein said simple geometric figure is defined as a contour of a bore formed in said specific subject work; and

wherein said specific subject work has at least four bores, said handling means having positioning means engageable with at least two of said at least four bores for positioning said handling device and pick-up means engageable with at least two others of said at least four bores symmetrical in position with respect to a geometric center of said specific subject work for picking up said specific subject work.

62. An apparatus as defined in claim 37, wherein said specific subject work is a cylinder head formed with a bore, for receiving a spark plug, having a circular contour.

63. An apparatus as defined in claim 37, wherein said specific subject work is a cylinder block formed with a cylinder bore having a circular contour.

64. A method of discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, which are separated from one another and specified by a predetermined quantitative distinction independent from said specified distinctive geometric patterns, and form part of the whole surface thereof and being placed on a pallet, and handling said specified subject work to transport said specific subject work from said pallet to a predetermined position remote from said pallet, said method comprising the steps of:

positioning a camera so as to pick up an image of a predetermined area including at least one of said subject works;

processing said image to retrieve a quantitative distinction of each said geometric pattern included in said image;

comparing said quantitative distinction retrieved from said geometric pattern included in said image with said predetermined quantitative distinction to recognize each said geometric pattern in said image as said specified distinctive geometric pattern when said quantitative distinction retrieved from said image is within predetermined limits of said predetermined quantitative distinction;

detecting a relative position between at least two said geometric patterns included in said image which are recognized as said specified distinctive geometric pattern;

comparing said relative position with a predetermined reference position and identifying a subject work which includes at least two distinctive geometric patterns having a relative position coincident with said predetermined reference position as a specified subject work, thereby discerning said specific subject work from the other subject works; and

recognizing a position of said specific subject work based on said relative position of said specified distinctive geometric patterns belonging to said specific subject work.

65. An apparatus for discerning a specific subject work from a plurality of subject works of the same type, each of said subject works including a plurality of specified distinctive geometric patterns, which are separated from one another and specified by a predetermined quantitative distinction independent from said specified distinctive geometric pattern and form part of the whole surface thereof, and being placed on a pallet, and for transporting a specified subject work with a handling device having a pick-up head engageable with said specific subject work which includes two said specified distinctive geometric patterns from said pallet to a predetermined position remote from said pallet, said apparatus comprising:

image forming means for forming an image of a predetermined area including at least one of said subject works;

image processing means for processing said image to retrieve a quantitative distinction of each said geometric pattern included in said image; and

identifying means for comparing said quantitative distinction retrieved from said geometric pattern included in said image with said predetermined quantitative distinction to recognize each said geometric pattern in said image as said specified distinctive geometric pattern when said quantitative distinction retrieved from said image is within predetermined limits of said predetermined quantitative distinction, detecting a relative position between at least two said geometric patterns included in said image which are recognized as said specified distinctive geometric pattern, comparing said relative position with a predetermined reference position and identifying a subject work which includes at least two distinctive geometric patterns having a relative position coincident with said predetermined reference position as a specified subject work so as thereby to discern said specific subject work from the other subject works, and recognizing a position of said specific subject work based on said relative position of said specified distinctive geometric patterns belonging to said specific subject work.