System and method for sensing torque on a rotating shaft

• US 6,948,381 B1
• Filed: 04/09/2003
• Issued: 09/27/2005
• Est. Priority Date: 04/09/2002
• Status: Expired due to Fees

• Current Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Discenzo, Frederick M.
• Primary Examiner(s): Noori, Max
• Assistant Examiner(s): MILLER, TAKISHA S
• Application Number:
  US10/409,894
• Time in Patent Office: 902 Days
• Field of Search: 738/623.24, 738/626.24, 738/00
• US Class Current: 73/862.324
• CPC Class Codes: G01L 3/12 involving photoelectric means

Abstract

A system and method relating to the measuring of torque in a rotating shaft is provided. An optical torque sensing system comprises a rotating shaft, wherein a sleeve of photo-elastic material overlays a portion of the shaft. A light emitting component delivers light into the photo-elastic material, wherein the light delivered by the light emitting component is directed through the photo-elastic material along an axis of the rotating shaft. A capturing component captures the light that exits the photo-elastic material. The exiting light comprises fringe pattern data, and a computing system computes torsion strain of the shaft based at least in part on the fringe pattern information.

Claims

1. An optical torque sensing system comprising:

a sleeve of photo-elastic material that overlays a portion of a shaft;

a light emitting component that delivers light to the sleeve at an angle to the axis of the shaft;

a notch that is coated with a reflective substance, wherein the edges of the notch are at an angle to the light delivered by the light emitting component such that light is redirected by the notch along a longitudinal axis of the shaft through the photo-elastic material;

a capturing component that captures light exiting the photo-elastic material, the exiting light manifesting characteristics relating to the shaft; and

a computing system that receives data from the capturing component relating to the shaft.

2. The system of claim 1, the received data comprising fringe pattern information corresponding to strain of the shaft.

3. The system of claim 2, the strain being torsional strain.

4. The system of claim 1, the computing system further comprising an artificial intelligence (AI) system.

5. The system of claim 4, the AI system comprising at least one of:

a neural network, an expert system, a support vector machine (SVM), a Bayesian belief network, a data fusion system.

6. The system of claim 1 further comprising an implicitly trained classifier.

7. The system of claim 1, the computing system is configured to compute at least one of the following shaft parameters from fringe pattern images:

rotational speed, rotational acceleration, shaft displacement, shaft vibration, shaft temperature, and longitudinal strain.

8. The system of claim 7, wherein the computing system uses a classifier to determine which parameters of the shaft to compute.

9. The system of claim 1, the computing system utilizing fringe pattern images to monitor a surface of the shaft.

10. The system of claim 1, further comprising a control component that controls operation of rotating shaft, the control being based at least in part upon information relayed from the computing system.

11. The system of claim 10, the control component comprises an open-loop control system.

12. The system of claim 10, the control component comprises a closed-loop control system.

13. The system of claim 1, further comprising a display component that displays data provided by the computing system.

14. The system of claim 13, wherein the display component displays the data graphically.

15. The system of claim 13, wherein the display component displays the data numerically.

16. The system of claim 1, wherein at least one collar of the photo-elastic material is coated with a reflective substance.

17. The system of claim 16, the light passing along a longitudinal axis of the shaft twice, initially transmitted and then reflected.

18. The system of claim 1, the capturing component is a digital camera.

19. The system of claim 1, the capturing component relays a grayscale image to the computing system.

20. The system of claim 1, the capturing component relays a color image to the computing component.

21. The system of claim 20, wherein the computing system converts the color image to a grayscale image.

22. The system of claim 1, the capturing component relays digital data to the computing system.

23. The system of claim 1, the capturing component relays analog data to the computing system.

24. The system of claim 23, wherein the computing system converts the analog data to digital data.

25. The system of claim 1, the computing system is employed to utilize diagnostic techniques to inform an operator that replacement/repair of the rotating shaft is necessary.

26. The system of claim 1, the computing system prognoses future state of the shaft.

27. An optical torque sensing system, comprising:

an emission component that transmits light; and

a photo-elastic collar with a notch coated with a reflective substance that circumferentially conforms to a portion of a shaft, wherein the edges of the notch are at an angle to the light delivered by the emission component such that the photo-elastic collar receives light from the emission component at an angle to an axis of the shaft and redirects the light via the notch along a longitudinal axial direction of the shaft.

28. The system of claim 27, the photo-elastic collar comprising at least one of;

a polycarbonate-based compound, a polyester-based compound, a polysulfone-based compound, a polyether sulfone-based compound, a polystyrene-based compound, a polyolefin-based compound, a polyvinyl alcohol-based compound, a cellulose acetate-based compound, a polyvinyl chloride-based compound, a polymethyl methacrylate-based compound, a polyacrylate-based compound, a polyamide-based compound and/or a combination thereof.

29. The system of claim 27, the photo-elastic collar deforming as a function of stress of the shaft.

30. The system of claim 27, the collar comprising a beam-splitter.

31. The system of claim 27, the photo-elastic material comprising gratings.

32. The system of claim 27, the photo-elastic material comprising dopants.

33. The system of claim 27, the photo-elastic material comprising photosensitive materials.

34. The system of claim 27, the collar comprising a reflective coating.

35. The system of claim 27, the light traveling in two orthogonal directions within the collar.

36. The system of claim 27, the light traveling in two parallel paths within the collar.

37. A method that facilitates the determination of torsion strain in a rotating shaft comprising:

delivering light to a photo-elastic material at an angle orthogonal to an axis of the shaft, the photo-elastic material encircling at least a portion of a rotating shaft;

receiving light at one end of the photo-elastic material;

redirecting the light from the end of the material along a longitudinal axis of the shaft via a notch coated with a reflective substance, the edges of the notch are at an angle to the light received;

capturing a fringe pattern created by the light as the light exits the photo-elastic material;

relaying the captured fringe pattern to a computing system; and

determining the torsion strain in the rotating shaft by analyzing the fringe pattern.

38. The method of claim 37, further comprising employing a classifier to facilitate determining the torsion strain in the rotating shaft.

39. The method of claim 37, further comprising employing a digital camera to capture the fringe pattern.

40. The method of claim 37, further comprising relaying the torsion strain computed by the computing system to a control component, wherein the control component controls operation of the rotating shaft.

41. The method of claim 37, further comprising relaying the torsion strain computed by the computing system to a storage component, wherein the storage component stores the torsion strain computed by the computing component.

42. The method of claim 37, further comprising relaying the torsion strain computed by the computing system to a display component, wherein the display component displays the torsion strain computed by the computing component.

43. A system that facilitates monitoring a rotating shaft comprising:

means for receiving light from an external source emitted at an angle to an axis of the shaft;

means for redirecting light along an axis of the shaft from one end of the shaft via a notch coated with a reflective substance, the edges of the notch are at an angle to the light received;

means for capturing a fringe pattern created by the light after passing along the shaft axis; and

means for analyzing the fringe pattern.

44. An optical torque sensing system comprising:

a photo-elastic material that overlays a portion of a shaft;

a light-emitting component that delivers light at an angle orthogonal to an axis of the shaft to the photo-elastic material, the light is received at one end of the photo-elastic material and redirected through the photo-elastic material along at least two orthogonal directions within the medium via a notch coated with a reflective substance, the edges of the notch are at an angle to the light delivered; and

a computing system that analyzes data corresponding to light exiting the material, the exiting light manifesting information regarding state of the shaft.

45. The system of claim 44, the material being in the shape of a sleeve.

46. The system of claim 44, the material being in the shape of a collar.

47. A motor employing the system of claim 44.

48. A pump employing the system of claim 44.

49. An aircraft employing the system of claim 44.

50. A helicopter employing the system of claim 44.

51. The system of claim 44 further comprising an interferometer.

52. The system of claim 44 further comprising a classifier.

53. The system of claim 52, the classifier performing a utility-based analysis to generate a prognosis as to future state of the shaft.

54. The system of claim 52, the classifier performing a utility-based analysis to generate a diagnose present state of the shaft.