Conveyor induction system

• US 6,629,593 B2
• Filed: 05/08/2001
• Issued: 10/07/2003
• Est. Priority Date: 05/11/2000
• Status: Expired due to Fees

• Current Assignee: Dematic Corporation (KION GROUP AG)
• Original Assignee: Rapistan Systems Advertising Corporation (OSI Systems Incorporated)
• Inventors: Zeitler, David W.
• Primary Examiner(s): Valenza, Joseph E.
• Application Number:
  US09/851,021
• Publication Number:
  US 20010035332A1
• Time in Patent Office: 882 Days
• Field of Search: 198/460.1, 198/460.3
• US Class Current: 198/460.1
• CPC Class Codes: B65G 43/08 Control devices operated by article or material being fed, conveyed or discharged and controlling the discharging devices B65G47/42
• CPC Class Codes: B65G 43/10 Sequence control of conveyors operating in combination
• CPC Class Codes: B65G 47/31 by varying the relative speeds of the conveyors forming the series

Abstract

A conveyor induct system includes a control point subsystem for measuring the point at which control of an article transitions from one conveyor to another. The induct system also includes a subsystem for accurately creating or controlling the gaps between articles on the conveyor system. The control point subsystem monitors the location, and changes in the speed, of an article as it passes between two conveyors operating at different speeds. The gap control subsystem provides real time monitoring and measuring of the package gaps. The measured package gaps are fed into a feedback control system which alters the speed of a conveyor in order to change the gapping as desired.

Claims

1. A method for determining a control point of an article traveling on a conveyor system comprising:

providing a first conveyor having a downstream end, said first conveyor having a first article conveying surface;

providing a second conveyor having an upstream end aligned with said downstream end of said first conveyor, said second conveyor having a second article conveying surface operating at least occasionally at a different speed than said first article conveying surface;

defining a reference point at a known location with respect to said first conveyor;

detecting a change in the speed of an article due to said article having moved sufficiently from said first conveying surface to said second conveying surface such that the speed of said article is controlled by said second conveying surface rather than said first conveying surface; and

determining a position of the article with respect to the reference point when said change in speed is detected and defining a control point for the article based on the position determination.

2. The method of claim 1 wherein said detecting of said change in speed of said article comprises detecting a change in spacing between said article and an upstream article adjacent to said article.

3. The method of claim 1 wherein said fixed reference point is located halfway between said first and said second conveyors.

4. The method of claim 1 further comprising:

providing a horizontal array of photo-detectors positioned alongside said first conveyor; and

monitoring said photo-detectors to determine when said change in speed of said article occurs.

5. The method of claim 4 further comprising detecting a change in spacing between said article and an upstream article adjacent to said article.

6. The method of claim 1 further including adjusting the relative speed of said first conveying surface with respect to said second conveying surface after said control point has been determined.

7. The method of claim 6 wherein the adjusting of the relative speed of said first conveying surface with respect to said second conveying surface includes setting the speeds of said first and second conveying surfaces equal to each other.

8. The method of claim 1 further including detecting a front edge of said article, determining the position of said front edge of said article on said second conveying surface when said change in speed occurs, and computing the distance of said front edge to said control point of said article.

9. A method of controlling a gap between articles traveling on a conveyer system comprising:

providing a first, a second, and a third conveyor, said second conveyor operable at a different speed than said first conveyor, at least one of said second and third conveyors being an adjustable speed conveyor;

determining a control point of a first article as said first article passes from said first conveyor to said second conveyor, said control point being reliable for determining when the first article is controllable by the adjustable speed conveyor;

selecting a gap between said first article and a second article;

measuring the selected gap while said first article is traveling at least partially on said adjustable speed conveyor;

comparing said measured gap to a desired gap; and

adjusting the speed of said adjustable speed conveyor when the first article is controllable by said adjustable speed conveyor in order to reduce any difference between said measured gap and said desired gap.

10. The method of claim 9 wherein said adjustable speed conveyor is said second conveyor.

11. The method of claim 9 wherein said measuring of said gap comprises:

measuring the location of a leading edge of said first article at a particular time;

measuring the location of a trailing edge of said second article at substantially the same time as said leading edge of said first article is measured; and

determining the distance between said leading edge of said first article and said trailing edge of said second article.

12. The method of claim 9, further comprising:

re-measuring said selected gap between said first article and said second article while said first article is at least partially still on said adjustable speed conveyor, and

readjusting said speed of said adjustable speed conveyor based upon any difference between said re-measured gap and said desired gap.

13. The method of claim 12 wherein said re-measuring of said selected gap and said readjusting of said speed are repeated multiple times per second.

14. The method of claim 9 wherein determining the control point of said first article as said first article passes from said first conveyor to said second conveyor comprises:

detecting when a change occurs in the speed of said first article due to said first article having reached said second conveyor; and

determining said control point of said first article to be the paint on said first article which is aligned with a fixed reference point when said change in speed occurs.

15. The method of claim 14 wherein said detecting of said change in speed of said first article comprises detecting a change in spacing between said first article and a third article adjacent to and upstream of said first article.

16. The method of claim 9 wherein said first article is positioned upstream from said second article.

17. The method of claim 9 wherein said measuring of the selected gap further comprises providing a horizontal array of photo detectors positioned at least partially along said adjustable speed conveyor.

18. The method of claim 17 wherein said array of photo detectors includes an array of photo emitters positioned along a first side of said adjustable speed conveyor and an array of photo receptors positioned along a second side of said adjustable speed conveyor, said array of photo emitters periodically emitting electromagnetic signals which are detected by said array of photo receptors unless one or more articles are positioned on said adjustable speed conveyor between said array of photo emitters and said array of photo receptors.

19. The method of claim 9 further including measuring a length of said first article.

20. The method of claim 9 further including limiting the acceleration of said adjustable speed conveyor.

21. The method of claim 20 further including changing the limit of the acceleration of said adjustable speed conveyor based at least partially upon the determination of the control point of said first article.

22. A device for determining a control point of an article traveling on a conveyor system comprising:

a first conveyor,

a second conveyor aligned with said first conveyor and downstream of said first conveyor, said second conveyor operating at least occasionally at a different speed than said first conveyor;

a sensor adapted to detect when a change in speed occurs in said article due to said article having moved sufficiently onto said second conveyor such that second conveyor controls the speed of said article

a controller adapted to determine a position of the article with respect to a reference point when said change in speed is detected and to define a control point for the article based on the position determination.

23. The device of claim 22 wherein said sensor comprises a horizontal array of photo-detectors positioned alongside said first conveyor.

24. The device of claim 22 wherein said sensor comprises a horizontal array of photo-detectors positioned alongside said first conveyor.

25. The device of claim 24 wherein said horizontal array of photo-detectors extends for a horizontal distance at least equal to the distance of the greatest expected length of said article.

26. The device of claim 25 wherein said horizontal array of photo-detectors has an upstream end and a downstream end, said downstream end being placed midway between said first and said second conveyors, and said upstream end being placed upstream of said downstream end.

27. A conveyor induct system comprising:

a first conveyor;

a second conveyor aligned with said first conveyor, said second conveyor operable at a different speed than said first conveyor;

a first controller which, in conjunction with a first sensor, determines a control point of a first article as said first article passes from said first conveyor to said second conveyor, said control point being reliable for determining when control of the first article will transition onto, or off of, an adjustable speed conveyor;

a second sensor which selects and measures any gap between said first article and a second article while said first article is traveling at least partially on the adjustable speed conveyor, and

a second controller which compares said measured gap to a desired gap and adjusts the speed of said adjustable speed conveyor while the control point of the first article has a particular positional relationship to a defined reference location in order to reduce any difference between said measured gap and said desired gap.

28. The system of claim 27 wherein said adjustable speed conveyor is the same as said second conveyor.

29. The system of claim 27 wherein said first sensor comprises a horizontal array of photo-detectors.

30. The system of claim 29 wherein said second sensor comprises a horizontal array of photo-detectors.

31. The system of claim 30 wherein said second sensor measures the location of a leading edge of said first article and a trailing edge of said second article at substantially the same time.

32. The system of claim 27 wherein said second sensor measures any gap between said first and said second article at least ten times per second.

33. A method of controlling a gap between articles traveling on a conveyor system, comprising:

defining a first interface having first adjacent conveying surfaces that are capable of traveling at substantially different speeds and a second interface having second adjacent conveying surfaces that are capable of traveling at substantially different speeds;

providing a first sensor and detecting wit said first sensor a change in spacing between a first article and a second article while said first and second articles are adjacent to said first interface, said second article being downstream of said first article;

determining a control point for said second article based on the detected change in spacing between said first and second articles, said control point indicating when control of the second article will transition from one of the second adjacent conveying surfaces to the other of the second adjacent conveying surfaces;

providing a gap selector and selecting with said gap selector a controllable gap between said second article and a third article, said third article being downstream of said second article;

providing a second sensor and detecting with said second sensor a size of said gap; and

controlling said second adjacent conveying surfaces to adjust the size of said gap while the control point of the second article has a particular positional relationship to a defined reference location.

34. The method of claim 33 wherein said first sensor comprises a horizontal sensor array.

35. The method of claim 33 wherein said first sensor comprises a video capture system.

36. The method of claim 33 wherein said second sensor comprises a horizontal sensor array.

37. The method of claim 33 said second sensor comprises a video capture system.

38. The method of claim 33 wherein said controlling includes comparing said gap with a desired gap and controlling said second conveying surfaces such that any difference between said gap and said desired gap is reduced.

39. The method of claim 38 said particular positional relationship is defined by said control point being upstream of the defined reference location.

40. The method of claim 39 wherein said conveying surfaces of said first and second interfaces are defined by belts.

41. The method of claim 33 wherein said second adjacent conveying surfaces are controlled to adjust said gap by adjusting the speed of a downstream one of said second adjacent conveying surfaces.

42. The method of claim 33 wherein said second adjacent conveying surfaces are controlled to adjust said gap by adjusting the speed of an upstream one of said second adjacent conveying surfaces.

43. A conveyor induct system, comprising:

a first interface defined by first adjacent conveying surfaces that are capable of traveling at substantially different speeds and a second interface defined by second adjacent conveying surfaces that are capable of traveling at substantially different speeds;

a first sensor adapted to detect a change in spacing between a first article and a second article while said first and second articles are adjacent said first interface, said second article being downstream of said first article;

a calculator that calculates a control point for said second article based on the detected change in spacing between said first and second articles, said control point indicating when control of the second article will transition from one of the second adjacent conveying surfaces to the other of the second adjacent conveying surfaces;

a gap selector adapted to select a gap between said second article and a third article positioned downstream of said second article;

a second sensor adapted to detect a size of sad gap; and

a controller adapted to control said second adjacent conveying surfaces to adjust the size of said gap while the control point of the second article has a particular positional relationship to a defined reference location.

44. The induct system of claim 43 wherein said conveying surfaces of said first and second interfaces are defined by belts.

45. The induct system of claim 43, wherein said first sensor comprises a horizontal sensor array.

46. The induct system of claim 43 herein said first sensor comprises a video capture system.

47. The induct system of claim 43 wherein said second sensor comprises a horizontal sensor array.

48. The induct system of claim 43 wherein said second sensor comprises a video capture system.

49. The induct system of claim 43 wherein said controller compares said gap with a desired gap and controls said second conveying surfaces such that any difference between said gap and said desired gap is reduced.

50. The induct system of claim 43 wherein said particular positional relationship is defined by said control point being upstream of the defined reference location.

51. The system of claim 43 wherein said controller controls said second adjacent conveying surfaces to adjust said gap by adjusting the speed of a downstream one of said second adjacent conveying surfaces.

52. The system of herein said controller controls said second adjacent conveying surfaces to adjust said gap by adjusting the speed of an upstream one of said second adjacent conveying surfaces.