Multidimensional force sensor

• US 5,095,762 A
• Filed: 05/11/1990
• Issued: 03/17/1992
• Est. Priority Date: 07/14/1988
• Status: Expired due to Fees

• Current Assignee: University of Hawai'i
• Original Assignee: University of Hawai'i
• Inventors: Holm-Kennedy, James W., Lee, Gordon P., Kaneshiro, Michael H.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/522,515
• Time in Patent Office: 676 Days
• Field of Search: 73/517 R, 73/517 A, 73/517 B, 73/862.04, 324/660, 324/661, 324/662, 340/870.37, 361/278, 361/280
• US Class Current: 73/862.041
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/123 by piezo-resistive elements, e.g. semiconductor strain gauges
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0817 for pivoting movement of the mass, e.g. in-plane pendulum
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends

Abstract

A multibeam structure measures displacement of one or more response elements to detect multiple components of applied force. The flexible beams are each coupled to a response element which may be displaced by a force arising from linear acceleration, angular acceleration, fluid flow, electric/magnetic/gravitational fields, and others sources. The displacement of the response element is detected with a variety of sensing methods including capacitive and piezoresistive sensing.

Claims

1. A multidimensional force sensor, comprising:

a substantially planar main body having first, second and third apertures and a center of rotation about which said main body is adapted to rotate;

a wide and thin first beam having opposing wide sides attached at a first end to said main body and projecting into said first aperture in a first direction substantially parallel to said main body and substantially outward from said center of rotation, with a normal of the wide sides of said first beam oriented substantially perpendicular to said main body;

a wide and thin second beam having opposing wide sides attached at a first end to said main body and projecting into said second aperture in a second direction substantially parallel to said main body, substantially perpendicular to said first direction and substantially outward from said center of rotation, with a normal of the wide sides of said second beam oriented substantially perpendicular to said main body;

a wide and thin third beam having opposing wide sides attached at a first end to said main body and projecting into said third aperture in a third direction substantially parallel to said main body, substantially perpendicular to said second direction and substantially outward from said center of rotation, with a normal of the wide sides of said third beam oriented substantially parallel to said main body; and

sensing means for sensing displacement of each of said first, second and third beams, respectively, coupled to each of said first, second and third beams, respectively.

2. A multidimensional force sensor, as described in claim 1, further comprising:

first, second and third response elements attached to the second ends of each of said first, second and third beams, respectively.

3. A multidimensional force sensor, as described in claim 2, wherein said sensing means comprises sensing means coupled to each of said first, second and third response elements, respectively, for sensing displacement of each of said first, second and third response elements, respectively.

4. A multidimensional force sensor, as described in claim 3, wherein said sensing means comprises first, second and third capacitive sensor elements, each of said first, second and third sensor elements producing a change in capacitance in response to displacement of said first, second and third response elements, respectively.

5. A multidimensional force sensor, as described in claim 4, wherein each of said sensor elements includes a movable plate and a fixed plate and said movable plates of said first, second and third capacitive sensor elements are mounted on said first, second and third response elements, respectively.

6. A multidimensional force sensor, as described in claim 2, further comprising limiting means partially surrounding one of said response elements for limiting displacement of said response element.

7. A multidimensional force sensor, as described in claim 6, wherein said limiting means comprises a casing.

8. A multidimensional force sensor, as described in claim 2, further comprising limiting means completely surrounding one of said response elements for limiting displacement of said response element.

9. A multidimensional force sensor, as described in claim 1, wherein said sensing means comprises first, second and third discrete electromechanical sensor elements, said first, second and third sensor elements producing electrical signals in response to displacement of said first, second and third beams respectively.

10. A multidimensional force sensor, as described in claim 9, wherein said first, second and third sensor elements are mounted on said first, second and third beams, respectively.

11. A multidimensional force sensor, as described in claim 1, wherein said main body and said beams comprise an integrally formed piece of semiconducting material.

12. A multidimensional force sensor, as described in claim 11, wherein said semiconducting material is silicon.

13. A multidimensional force sensor, as described in claim 11, wherein said semiconducting material is germanium.

14. A multidimensional force sensor, as described in claim 1, wherein said main body and said beams comprise an integrally formed piece of material selected from the group consisting of quartz, glass and ceramics.

15. A multidimensional force sensor, as described in claim 1, further comprising damping means surrounding one of said beams, for damping vibration of said beam.

16. A multidimensional force sensor, as described in claim 15, wherein said damping means comprise a fluid.

39. A multidimensional force sensor, as described in any one of claims 4, 5, 9 or 10, wherein one of said sensor elements for sensing displacement of one of said beams comprises:

a first sensor component for sensing displacement of said one beam, coupled to said one beam; and

a second sensor component for sensing displacement of said one beam, coupled to said one beam, wherein said second sensor component responds differently from said first sensor component to displacement of said one beam in one direction.

40. A multidimensional force sensor, as described in any one of claims 9, 10, 17, 18, 28, or 29, wherein one of said sensor elements for sensing displacement of one of said beams comprises a piezoresistor mounted on a surface of said one beam.

41. A multidimensional force sensor, as described in any one of claims 9, 10, 17, 18, 28, or 29, wherein one of said sensor elements for sensing displacement of one of said beams comprises a piezoresistor embedded in the longitudinal axis of said one beam for sensing stress in said one beam.

17. A multidimensional force sensor, comprising:

a substantially planar main body having first, second, third, fourth and fifth apertures;

a first beam attached to said main body at a first end and projecting into said first aperture in a first direction substantially parallel to said main body;

a first sensor element for sensing displacement of said first beam, coupled to said first beam;

a second sensor element for sensing displacement of said first beam, coupled to said first beam, that responds differently from said first sensor element to displacement of said first beam in one direction;

a second beam attached to said main body at a first end and projecting into said second aperture in a second direction substantially parallel to said main body and substantially perpendicular to said first direction;

a third sensor element for sensing displacement of said second beam, coupled to said second beam, that responds differently from said third sensor element to displacement of said second beam in one direction;

a third beam attached to said main body at a first end and projecting into said third aperture in a third direction substantially parallel to said main body and substantially perpendicular to said second direction;

a fifth sensor element for sensing displacement of said third beam, coupled to said third beam;

a sixth sensor element for sensing displacement of said third beam, coupled to said third beam, that responds differently from said fifth sensor element to displacement of said third beam in one direction;

a fourth beam attached to said main body at a first end and projecting into said fourth aperture in a fourth direction substantially parallel to said main body and substantially perpendicular to said third direction;

a seventh sensor element for sensing displacement of said fourth beam, coupled to said fourth beam;

an eighth sensor element for sensing displacement of said fourth beam, coupled to said fourth beam, that responds differently from said seventh sensor element to displacement of said fourth beam in one direction;

a fifth beam attached to said main body at a first end and projecting into said fifth aperture in a fifth direction substantially parallel to said main body and between said fourth direction and said first direction; and

a ninth sensor element for sensing displacement of said fifth beam, coupled to said fifth beam.

18. A multidimensional force sensor, as described in claim 17, further comprising:

first, second, third, fourth and fifth response elements attached to the second ends of said first, second, third, fourth and fifth beams, respectively.

19. A multidimensional force sensor, as described in claim 18, further comprising limiting means partially surrounding one of said response elements for limiting displacement of said response element.

20. A multidimensional force sensor, as described in claim 19, wherein said limiting means comprises a casing.

21. A multidimensional force sensor, as described in claim 18, further comprising limiting means completely surrounding one of said response elements for limiting displacement of said response element.

22. A multidimensional force sensor, as described in claim 17, wherein said main body and said beams comprise an integrally formed piece of semiconducting material.

23. A multidimensional force sensor, as described in claim 22, wherein said semiconducting material is silicon.

24. A multidimensional force sensor, as described in claim 22, wherein said semiconducting material is germanium.

25. A multidimensional force sensor, as described in claim 17, wherein said main body and said beams comprise an integrally formed piece of material selected from the group consisting of quartz, glass and ceramics.

26. A multidimensional force sensor, as described in claim 17, further comprising damping means surrounding one of said beams, for damping vibration of said beam.

27. A multidimensional force sensor, as described in claim 26, wherein said damping means comprises a fluid.

42. A multidimensional force sensor, as described in any one of claims 4, 18, or 29, further comprising a plate support member attached to said main body and extending towards one of said response elements, and wherein said sensor element coupled to said beam attached to said one response element comprises:

a first capacitor plate mounted on said one response element;

a second capacitor plate mounted on said plate support member in close proximity and substantially parallel to said first capacitor plate; and

capacitance measuring means coupled to said first and second capacitor plates for measuring the change in capacitance between said first capacitor plate and said second capacitor plate as said one response element is displaced.

43. A multidimensional force sensor, as described in claim 42, wherein each of said first and second capacitor plates comprises a plurality of electrically conductive strips parallel to each other and electrically connected to each other.

44. A multidimensional force sensor, as described in claim 42, wherein said capacitor plates are substantially rectangular.

45. A multidimensional force sensor, as described in claim 42, wherein said first capacitor plate and said second capacitor plate only partially overlap.

46. A multidimensional force sensor, as described in claim 42, wherein said first capacitor plate is of a different shape from said second capacitor plate.

47. A multidimensional force sensor, as described in claim 46, wherein each of said first and second capacitor plates comprises a plurality of electrically conductive strips parallel to each other and electrically connected to each other, and each of said first and second capacitor plates only partially overlaps the other.

48. A multidimensional force sensor, as described in claim 46, wherein said first capacitor plate is substantially triangular in shape, wherein said second capacitor plate is substantially rectangular in shape, and wherein only a portion of said first capacitor plate overlaps said second capacitor plate.

49. A multidimensional force sensor, as described in claim 48, wherein each of said first and second capacitor plates comprises a plurality of electrically conductive strips parallel to each other and electrically connected to each other.

50. A multidimensional force sensor, as described in any one of claims 4, 18, or 29, further comprising a plate support member attached to said main body and extending towards one of said response elements, and wherein said sensor element coupled to said beam attached to said one response element comprises:

a first capacitor plate mounted on said plate support member in close proximity to said one response element and offset to one side of said one response element;

a second capacitor plate mounted on said plate support member in close proximity to said one response element, substantially parallel to said first capacitor plate, and offset to the opposite side of said one response element from said first capacitor plate;

a third capacitor plate mounted on said one response element, substantially parallel to said first capacitor plate and said second capacitor plate, and partially overlapping said first capacitor plate and said second capacitor plate; and

capacitance measuring means coupled to said first, second and third capacitor plates for measuring the change in capacitance between said first capacitor plate and said third capacitor plate and between said second capacitor plate and said third capacitor plate as said one response element is displaced.

51. A multidimensional force sensor, as described in claim 50, wherein each of said first, second and third capacitor plates comprises a plurality of electrically conductive strips parallel to each other and electrically connected to each other.

52. A multidimensional force sensor, as described in claim 50, further comprising:

piezoresistor means embedded in the longitudinal axis of said beam for sensing stress in said beam.

53. A multidimensional force sensor, as described in any one of claims 4, 18, or 29, further comprising a plate support member attached to said main body and extending towards one of said response elements, and wherein said sensor element coupled to said beam attached to said one response element comprises:

a first capacitor plate mounted on said plate support member in close proximity to said one response element and offset to one side of said one response element;

a second capacitor plate mounted on said plate support member adjacent to said first capacitor plate, substantially parallel to said first capacitor plate, and having its center in close proximity to said one response element;

a third capacitor plate mounted on said plate support member in close proximity to said one response element, substantially parallel to said first capacitor plate and said second capacitor plate, and offset to the opposite side of said one response element from said first capacitor plate;

a fourth capacitor plate that is substantially larger than said second capacitor plate mounted on said one response element, substantially parallel to said first capacitor plate, said second capacitor plate and said third capacitor plate, centered over and completely overlapping said second capacitor plate and partially overlapping said first capacitor plate and said third capacitor plate; and

capacitance measuring means coupled to said first, second, third and fourth capacitor plates for measuring the change in capacitance between said first capacitor plate and said fourth capacitor plate, between said second capacitor plate and said fourth capacitor plate, and between said third capacitor plate and said fourth capacitor plate, as said one response element is displaced.

54. A multidimensional force sensor, as described in claim 53, wherein each of said first, second, third and fourth capacitor plates comprises a plurality of electrically conductive strips parallel to each other and electrically connected to each other.

55. A multidimensional force sensor, as described in claim 53, further comprising:

piezoresistor means embedded in the longitudinal axis of said beam for sensing stress in said beam.

56. A multidimensional force sensor, as described in any one of claims 2, 18, or 29, wherein one of said response elements comprises a mass.

57. A multidimensional force sensor, as described in any one of claims 2, 18, or 29, wherein one of said response elements comprises a material responsive to a magnetic field.

58. A multidimensional force sensor, as described in any one of claims 2, 18, or 29, wherein one of said response elements comprises a material responsive to an electric field.

59. A multidimensional force sensor, as described in any one of claims 2, 18, or 29, wherein one of said response elements comprises an electrically charged material.

60. A multidimensional force sensor, as described in any one of claims 2, 18, or 29, wherein one of said response elements comprises a magnetized material.

28. A multidimensional force sensor, comprising:

a substantially planar main body having an aperture;

a first beam attached to said main body at a first end and projecting into said aperture in a first direction substantially parallel to said main body;

a first sensor element for sensing displacement of said first beam, coupled to said first beam;

a second sensor element for sensing displacement of said first beam, coupled to said first beam, that responds differently from said first sensor element to displacement of said first beam in one direction;

a second beam attached to said main body at a first end and projecting into said aperture in a second direction substantially parallel to said main body and substantially perpendicular to said first direction;

a third sensor element for sensing displacement of said second beam, coupled to said second beam;

a fourth sensor element for sensing displacement of said second beam, coupled to said second beam, that responds differently from said third sensor element to displacement of said second beam in one direction;

a third beam attached to said main body at a first end and projecting into said aperture in a third direction substantially parallel to said main body and substantially perpendicular to said second direction;

a fifth sensor element for sensing displacement of said third beam, coupled to said third beam;

a sixth sensor element for sensing displacement of said third beam, coupled to said third beam, that responds differently from said fifth sensor element to displacement of said third beam in one direction;

a fourth beam attached to said main body at a first end and projecting into said aperture in a direction substantially parallel to said main body and substantially perpendicular to said third direction;

a seventh sensor element for sensing displacement of said fourth beam, coupled to said fourth beam;

an eighth sensor element for sensing displacement of said fourth beam, coupled to said fourth beam, that responds differently from said seventh sensor element to displacement of said fourth beam in one direction;

a fifth beam attached to said main body at a first end and projecting into said aperture in a direction substantially parallel to said main body and between said fourth direction and said first; and

a ninth sensor element for sensing displacement of said fifth beam, coupled to said fifth beam.

29. A multidimensional force sensor, as described in claim 28, further comprising:

first, second, third, fourth and fifth response elements attached to the second ends of said first, second, third, fourth and fifth beams, respectively.

30. A multidimensional force sensor, as described in claim 29, further comprising limiting means partially surrounding one of said response elements for limiting displacement of said response element.

31. A multidimensional force sensor, as described in claim 30, wherein said limiting means comprises a casing.

32. A multidimensional force sensor, as described in claim 29, further comprising limiting means completely surrounding one of said response elements for limiting displacement of said response element.

33. A multidimensional force sensor, as described in claim 28, wherein said main body and said beams comprise an integrally formed piece of semiconducting material.

34. A multidimensional force sensor, as described in claim 33, wherein said semiconducting material is silicon.

35. A multidimensional force sensor, as described in claim 33, wherein said semiconducting material is germanium.

36. A multidimensional force sensor, as described in claim 28, wherein said main body and said beams comprise an integrally formed piece of material selected from the group consisting of quartz, glass and ceramics.

37. A multidimensional force sensor, as described in claim 28, further comprising damping means surrounding one of said beams, for damping vibration of said beam.

38. A multidimensional force sensor, as described in claim 37, wherein said damping means comprises a fluid.