Multidimensional force sensor

• US 4,951,510 A
• Filed: 07/14/1988
• Issued: 08/28/1990
• 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): Ruehl, Charles A.
• Application Number:
  US07/220,073
• Time in Patent Office: 775 Days
• Field of Search: 73/510, 73/517 A, 73/517 R, 73/651, 73/654, 73/862.04, 73/862.64, 73/505
• 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 an aperture;

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

sensing means coupled to each of said first, second and third beams, respectively, for sensing displacement of 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 is 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 which includes a movable plate element and a fixed plate element, each of said first, second and third capacitive 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 said movable plate elements of said first, second and third capacitance 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 one response elements for limiting displacement of said one 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 one response element.

9. A multidimensional force sensor, as described in claim 2, wherein one of said response elements comprises a mass.

10. A multidimensional force sensor, as described in claim 2, wherein one of said response elements comprises a material responsive to a magnetic field.

11. A multidimensional force sensor, as described in claim 2, wherein one of said response elements comprises a material responsive to an electric field.

12. A multidimensional force sensor, as described in claim 2, wherein one of said response elements comprises an electrically charged material.

13. A multidimensional force sensor, as described in claim 2, wherein one of said response elements comprises a magnetized material.

14. 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.

15. A multidimensional force sensor, as described in claim 14, wherein said first, second and third sensor elements are mounted on said first, second and third beams, respectively.

16. A multidimensional force sensor, as described in claim 14, 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, as described in any one of claims 14 or 15, 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.

18. A multidimensional force sensor, as described in any one of claims 14 or 15, 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.

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

20. A multidimensional force sensor, as described in claim 19, wherein said semiconducting material is silicon.

21. A multidimensional force sensor, as described in claim 19, wherein said semiconducting material is germanium.

22. 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.

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

24. A multidimensional force sensor, as described in claim 23, wherein said damping means comprises a fluid.