Photoelastic sensing device

• US 4,498,348 A
• Filed: 06/13/1983
• Issued: 02/12/1985
• Est. Priority Date: 06/13/1983
• Status: Expired due to Fees

• Current Assignee: Labinal Components and Systems, Inc.
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Wesson, Laurence N.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/503,429
• Time in Patent Office: 610 Days
• Field of Search: 73/517 R, 73/800, 73/862.38, 73/862.04, 73/862.05, 73/862.06, 73/189, 350/371, 356/371
• US Class Current: 73/862.05
• CPC Class Codes: G01L 1/241 by photoelastic stress analysis
• CPC Class Codes: G01L 5/166 using photoelectric means

Abstract

A photoelastic sensing device comprising a photoelastic member of transparent material, first means for supplying polarized light fluxes to the member for transmission therethrough along a plurality of respective paths, and second means for receiving and detecting the transmitted light fluxes. A third means applies stresses to the member in response to the application thereto of force which is variable and has a magnitude and direction represented by its components along a plurality of vector coordinates which define a space of at least two dimensions. The light fluxes which are transmitted respectively along the plurality of paths of the member are each responsive to the stresses in the member along its path, and the second means provides an output signal which is responsive to the force and to each of the components of the force applied to the third means. The output signal is representative of and provides a measure and indication of the force and each of its components applied to the sensing device, and is responsive to the magnitude and direction of the applied force for providing control means.

Claims

1. A photoelastic sensing device comprising a photoelastic member of transparent material, first means for providing light fluxes to the member for transmission therethrough as polarized light fluxes along respective first and second paths, second means for respectively receiving and detecting the light fluxes transmitted along the first and second paths, the light fluxes respectively transmitted along the first and second paths of the member each being responsive to stresses in the member along its path, and third means for applying stresses to the member in response to the application thereto of force, which force is variable and has a magnitude and a direction represented by its respective components along first and second vector coordinates defining a two dimensional space, the second means providing an output signal which is representative of the force and responsive to each of the components of the force applied to the third means.

2. The sensing device of claim 1 in which the light fluxes respectively transmitted along the paths are responsive to the magnitudes of the components of the applied force which are respectively in the directions of the first and second coordinates, and the second means by its output signal provides control means which is responsive to the magnitude and direction of the applied force.

3. The sensing device of claim 1 in which the light flux transmitted along the first path is responsive to the magnitude of the component of the applied force in the direction of the first coordinate and the light flux transmitted along the second path is responsive to the magnitude of the component of the applied force in the direction of the second coordinate, the first path for transmission of light flux by the member is in a direction transverse to the first coordinate and the second path for the transmission of light flux is in a direction transverse to the second coordinate, and the output signal of the second means is responsive to the magnitude and direction of the applied force.

4. The sensing means of claim 3 in which the first and second coordinates are orthogonal vector coordinates.

5. The sensing device of claim 4 in which the first path for transmission of light flux by the member is in a direction perpendicular to that of the first coordinate and the second path for transmission of light flux is in a direction perpendicular to that of the second coordinate.

6. The sensing device of claim 5 in which the directions of the first and second paths are each perpendicular to the direction of the second coordinate.

7. The sensing device of claim 1 in which the light flux transmitted along the first path is responsive to the magnitude of the component of the applied force in the direction of the first coordinate and the light fluxes transmitted along the first and second paths are responsive in the same sense to the magnitude of the component of force in the direction of the second coordinate, and the output signal of the second means is responsive to the magnitude and direction of the applied force provided by its components.

8. The sensing means of claim 7 in which the directions of the first and second paths for transmission of light fluxes are each transverse to the direction of the first coordinate and to the direction of the second coordinate.

9. The sensing means of claim 8 in which the first and second paths are parallel to each other and have a direction which is perpendicular to the direction of the first coordinate and to the direction of the second coordinate, and the first and second coordinates are orthogonal vector coordinates.

10. The sensing device of claim 1 in which the third means provides bending stresses to the member with the application of a moment of force thereto, the bending stresses comprise compressive and tensile stresses in a direction transverse to the first and second paths for affecting the light fluxes transmitted by the member.

11. The sensing device of claim 10 in which the third means comprises a body having a first end for receiving the applied moment of force, and a second end which is subjected to torque with the application of the moment of force to its first end and which applies the bending stresses to the member.

12. The sensing device of claim 11 in which the body of the third means is elongated and extends along a longitudinal axis, the bending stresses in the member produced by the torque at the second end of the body are in the direction of the longitudinal axis, and the paths for the transmission of light fluxes through the member are transverse in direction to the longitudinal axis of the body and the stresses produced by the body in the member.

13. The sensing device of claim 12 in which the member has a peripheral surface, the first means provides light fluxes to the peripheral surface of the member at respective first regions for the transmission of respective light fluxes along the first and second paths through the member to respective second regions of the peripheral surface, and the second means receives the transmitted light fluxes at the respective second regions of the peripheral surface of the member.

14. The sensing device of claim 13 in which the first means includes polarizing means providing polarized light fluxes having rectangular vector components which are respectively parallel and perpendicular to the direction of the stresses produced in the member, and the second means detects changes in the respective rectangular components of the light fluxes received for providing the output signal.

15. The sensing device of claim 14 in which the member has a rectangular configuration providing the peripheral surface with opposite spaced parallel portions for the first and second regions, the light flux transmitted along the first path is responsive to the magnitude of the component of the force in the direction of the first coordinate and the light flux transmitted along the second path is responsive to the magnitude of the component of the force in the direction of the second coordinate, and the output signal of the second means is responsive to and representative of the magnitude and direction of the applied force provided by its components.

16. The sensing device of claim 15 in which at least one of the paths is displaced from the longitudinal axis toward the peripheral surface of the member, the first path for transmission of light flux by the member is in a direction transverse to the first coordinate and the second path for the transmission of light flux is in a direction transverse to the second coordinate.

17. The sensing device of claim 16 in which the first and second coordinates are orthogonal vector coordinates, and the second means by its output signal provides control means which is responsive to the magnitude and direction of the applied force.

18. The sensing device of claim 17 in which the first path for transmission of light flux by the member is in a direction perpendicular to that of the first coordinate and the second path for the transmission of light flux is in the direction perpendicular to that of the second coordinate.

19. The sensing device of claim 18 in which the directions of the first and second paths are perpendicular to that of the second coordinate.

20. The sensing device of claim 11 in which the first end of the body includes handle means for manually applying force thereto, and the second means by its output signal is responsive to the magnitude and direction of the force applied to the handle of the body.

21. The sensing device of claim 11 in which the first end of the body has an enlarged portion for having applied thereto the force provided by a fluid current, and the output signal of the second means is indicative of the direction and magnitude of the fluid current to which the first end of the body is subjected.

22. The sensing device of claim 11 in which the first end of the body includes a mass for applying gravitational force to the body at its first end and the second end of the body is secured with a movable means, and the output signal of the second means is indicative of the inclination or acceleration of the movable means.

23. The sensing device of claim 11 which includes a unit movably positioned with respect to the first end of the body and having magnetic properties, the first end of the body has at least a portion with magnetic properties for having force exerted thereon by the unit, and the output signal is indicative of the position and movement of the unit with respect to the first end of the body.

24. The sensing device of claim 23 in which the body is elongated and extends along a longitudinal axis, the unit comprises a permanent magnet which rotates about the axis proximate to the first end of the body and the magnet angularly changes its position with the movement of the unit to apply force to the first end of the body in a direction corresponding to its angular position, and the output signal is indicative of the angular position and angular velocity of the unit.

25. The sensing device of claim 1 in which the member has an axial direction transverse its paths, the third means with the application of the force thereto having components along the first coordinate taken in the axial direction and the second coordinate normal thereto provides bending compressive and tensile stresses to the member for the moment of the applied force in the direction normal to the axial direction and axial compressive and tensile stresses for the component of the applied force in the axial direction, the bending stresses provide both compressive and tensile stresses at different locations of the member in the direction transverse to the paths for affecting the light fluxes transmitted by the member, and the axial stresses provide a respective one of the compressive and tensile stresses to the member in a direction transverse to the first and second paths for affecting the light fluxes transmitted by the member.

26. The sensing device of claim 25 in which the third means comprises a body having a first end for receiving the applied force, and a second end which is subjected to torque, compressive and tensile forces with the application of the force to its first end and respectively applies the bending, compressive and tensile stresses to the member.

27. The sensing device of claim 26 in which the body of the third means is elongated and extends along a longitudinal axis in the axial direction of the member, the components of the force applied to the first end of the body in directions normal to the longitudinal axis produce the torque and apply the bending, compressive and tensile stresses to the member in the direction of the longitudinal axis, and the components of the applied force in the direction of the longitudinal axis respectively away from and towards the second end of the body correspondingly provide axial compressive and tensile stresses in the member in the direction of the longitudinal axis, and the paths for the transmission of light fluxes through the member are transverse in direction to the longitudinal axis of the body and the stresses produced in the member.

28. The sensing device of claim 27 in which the member has a peripheral surface, the first means provides light fluxes to the peripheral surface of the member at respective first regions for the transmission of respective light fluxes along the first and second paths through the member to respective second regions of the peripheral surface, and the second means receives the transmitted light fluxes at the respective second regions of the peripheral surface of the member.

29. The sensing device of claim 28 in which the first means includes polarizing means providing polarized light fluxes having rectangular vector components which are respectively parallel and perpendicular to the direction of the stresses produced in the member, and the second means detects changes in the respective rectangular components of the light fluxes received for producing the output signal which provides control means responsive to the magnitude and direction of the applied force.

30. The sensing device of claim 29 in which the member has a rectangular configuration providing the peripheral surface with opposite spaced parallel portions for the first and second regions, the first and second paths are displaced from the longitudinal axis toward the peripheral surface, the light flux transmitted along the first path is responsive to the magnitude of the component of the applied force in the direction of the first coordinate and the light flux transmitted along the second path is responsive to the magnitude of the component of the applied force in the direction of the second coordinate, and the output signal of the second means is responsive to the magnitude and direction of the applied force provided by its components.

31. The sensing device of claim 29 in which the member has a rectangular configuration providing the peripheral surface with opposite spaced parallel portions for the first and second regions, the first and second paths are displaced from the longitudinal axis toward the peripheral surface, the light flux transmitted along the first path is responsive to the magnitude of the component of the applied force in the direction of the first coordinate and the light fluxes transmitted along the first and second paths are responsive in the same sense to the magnitude of the component of the applied force in the direction of the second coordinate, and the output signal of the second means is responsive to the magnitude and direction of the applied force provided by its components.

32. The sensing device of claim 31 in which the first and second paths are parallel to each other and have a direction which is perpendicular to the direction of the first coordinate and to the direction of the second coordinate, and the first and second coordinates are orthogonal vector coordinates.

33. The sensing device of claim 29 in which the first end of the body includes handle means for manually applying force thereto, and the second means by its output signal is responsive to the magnitude and direction of the force applied to the handle of the body.

34. A photoelastic sensing device comprising a photoelastic member of transparent material, first means for providing light fluxes to the member for transmission therethrough as polarized light fluxes along respective first, second and third paths, second means for respectively receiving and detecting the light fluxes transmitted along the first, second and third paths, the light fluxes respectively transmitted along the first, second and third paths of the member each being responsive to stresses in the member along its path, and third means for applying stresses to the member in response to the application thereto of force which is variable and has a magnitude and a direction represented by its respective components along first, second and third vector coordinates defining a three dimensional space, the second means providing an output signal which is responsive to each of the components of the force applied to the third means.

35. The sensing device of claim 34 in which the light fluxes respectively transmitted along the paths in the member are responsive to the magnitudes of the components of the applied force which are respectively in the directions of the first, second and third coordinates, and the second means by its output signal provides control means which is responsive to the magnitude and direction of the applied force.

36. The sensing device of claim 34 in which the light flux transmitted along the first path is responsive to the magnitude of the component of the applied force in the direction of the first coordinate, the light flux transmitted along the second path is responsive to the magnitude of the component of the applied force in the direction of the second coordinate, and the light fluxes transmitted along the second and third paths are responsive to the magnitude of the component of the applied force in the direction of the third coordinate;

the first path for transmission of light flux by the member is in a direction transverse to the first coordinate, the second path for the transmission of light flux is in a direction transverse to the second coordinate, and the third path for the transmission of light flux is in a direction transverse to the third coordinate; and

the output signal of the second means is responsive to the magnitude and direction of the applied force.

37. The sensing device of claim 36 in which the first, second and third coordinates are orthogonal vector coordinates.

38. The sensing device of claim 37 in which the first path for transmission of light flux by the member is in a direction perpendicular to that of the first coordinate, the second path for transmission of light flux is in a direction perpendicular to that of the second coordinate, and the third path for transmission of light flux is in a direction perpendicular to that of the third coordinate.

39. The sensing device of claim 38 in which the directions of the first, second and third paths are each perpendicular to the direction of the third coordinate, and the second means by its output signal provides control means which is responsive to the magnitude and direction of the applied force.

40. The sensing device of claim 34 in which the light flux transmitted along the first path is responsive to the magnitude of the component of applied force in the direction of the first coordinate, the light fluxes transmitted along the second and third paths are respectively responsive in opposite senses to the magnitude of the component of the applied force in the direction of the second coordinate and are responsive in the same sense to the magnitude of the component of force in the direction of the third coordinate, and the output signal of the second means is responsive to the magnitude and direction of the applied force provided by its components.

41. The sensing device of claim 40 in which the directions of the first, second and third paths for the transmission of light fluxes are respectively transverse to the directions of the first, second and third coordinates.

42. The sensing means of claim 41 in which the second and third paths are parallel to each other and have a direction which is perpendicular to the direction of the second coordinate and to the direction of the third coordinate, and the first, second and third coordinates are orthogonal vector coordinates.

43. The sensing device of claim 34 in which the third means with the application of the force thereto provides bending, compressive and tensile stresses to the member for the moment of the force and axial compressive and tensile stresses for the axial component of the force, the bending stresses provide both compressive and tensile stresses at different locations of the member in the direction transverse to the paths for affecting the light fluxes transmitted by the member, the axial stresses provide a respective one of the compressive and tensile stresses to the member in a direction transverse to the first and second paths for affecting the light fluxes transmitted by the member.

44. The sensing device of claim 43 in which the third means comprises a body having a first end for receiving the applied force, and a second end which is subjected to torque, compressive and tensile forces with the application of the force to its first end and respectively applies the bending, compressive and tensile stresses to the member, and the second means by its output signal provides control means which is responsive to the magnitude and direction of the applied force.

45. The sensing device of claim 43 in which the third means comprises a body which is elongated and extends along a longitudinal axis having a first end for receiving the applied force and a second end, the components of the force applied to the first end of the body in directions normal to the longitudinal axis produce torque at the second end and apply the bending, compressive and tensile stresses to the member in the direction of the longitudinal axis, and the components of the force applied to the first end of the body in the direction of the longitudinal axis respectively away from and towards the second end of the body correspondingly provide axial compressive and tensile stresses in the member in the direction of the longitudinal axis, and the paths for the transmission of light fluxes through the member are transverse in direction to the longitudinal axis of the body and the stresses produced in the member, and the output signal of the second means is responsive to and representative of the magnitude and direction of the applied force.

46. The sensing device of claim 45 in which the member has a peripheral surface, the first means provides light fluxes to the peripheral surface of the member at respective first regions for transmission of respective light fluxes along the first, second and third paths through the member to respective second regions of the peripheral surface, and the second means receives the transmitted light fluxes at the respective second regions of the peripheral surface of the member.

47. The sensing device of claim 46 in which the first means includes polarizing means providing polarized light fluxes having rectangular vector components which are respectively parallel and perpendicular to the direction of the stresses produced in the member, and the second means detects changes in the respective rectangular components of the light fluxes received for providing the output signal.

48. The sensing device of claim 47 in which the member has a rectangular configuration providing the peripheral surface with opposite spaced parallel portions for the first and second regions, the first and second paths are positioned on opposite sides of and are displaced from the longitudinal axis toward the peripheral surface, the light flux transmitted along the first path is responsive to the magnitude of the component of the applied force in the direction of the first coordinate, the light flux transmitted along the second path is responsive to the magnitude of the component of the applied force in the direction of the second coordinate and the light flux transmitted along the third path is responsive to the magnitude of the component of the applied force in the direction of the third coordinate, and the output signal of the second means is responsive to the direction and magnitude of the applied force provided by its components.

49. The sensing device of claim 47 in which the member has a rectangular configuration providing the peripheral surface with opposite spaced parallel portions for the first and second regions, the first and second paths are positioned on opposite sides of and are displaced from the longitudinal axis toward the peripheral surface, the light flux transmitted along the first path is responsive to the magnitude of the component of the applied force in the direction of the first coordinate, the light fluxes transmitted along the second and third paths are respectively responsive in opposite senses to the magnitude of the component of the applied force in the direction of the second coordinate and are responsive in the same sense to the magnitude of the component of the applied force in the direction of the third coordinate, and the output signal of the second means is responsive to the direction and magnitude of the applied force provided by its components.

50. The sensing device of claim 49 in which the second and third paths are parallel to each other and have a direction which is perpendicular to the direction of the second coordinate and to the direction of the third coordinate, the first, second and third coordinates are orthogonal vector coordinates, and the second means by its output signal provides control means which is responsive to the magnitude and direction of the applied force.

51. The sensing device of claim 45 in which the first end of the body includes handle means for manually applying force thereto, and the second means by its output signal is responsive to the magnitude and direction of the force applied to the handle of the body.