Multidimensional force sensor

• US 5,101,669 A
• Filed: 05/11/1990
• Issued: 04/07/1992
• 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.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/523,715
• Time in Patent Office: 697 Days
• Field of Search: 73/517 R, 73/517 A, 73/517 B, 73/654, 73/651, 73/862.64, 361/280, 361/278, 340/870.37, 324/660, 324/661, 324/662
• US Class Current: 73/862.626
• 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 other sources. The displacement of the response element is detected with a variety of sensing methods including capacitive and piezoresistive sensing.

Claims

1. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, comprising:

a first set of electrically conductive strips electrically connected to each other mounted on said response element;

a second set of electrically conductive strips electrically connected to each other mounted on said main body in close proximity and substantially parallel to said first set of electrically conductive strips, said first set of electrically conductive strips and said second set of electrically conductive strips producing a change in capacitance in response to displacement of said response element; and

capacitance measuring means, coupled to said first set of electrically conductive strips and said second set of electrically conductive strips, for measuring said change in capacitance.

13. A sensor, as described in any one of claims 1, 2, 3, 5 or 9, wherein said main body and said beam comprise an integrally formed piece of semiconducting material.

14. A sensor, as described in claim 13, wherein said semiconducting material is silicon.

15. A sensor, as described in claim 13, wherein said semiconducting material is germanium.

16. A sensor, as described in any one of claims 1, 2, 3, 5 or 9, wherein said main body and said beam comprise an integrally formed piece of material selected from the group consisting of quartz, glass and ceramics.

17. A sensor, as described in any one of claims 1, 2, 3, 5 or 9, further comprising limiting means partially surrounding said response element for limiting displacement of said response element.

18. A sensor, as described in claim 17, wherein said limiting means comprises a casing.

19. A sensor, as described in any one of claim 1, 2, 3, 5 or 9, further comprising limiting means completely surrounding said response element for limiting displacement of said response element.

20. A sensor, as described in any one of claims 1, 2, 3, 5 or 9, further comprising damping means surrounding said beam, for damping vibration of said beam.

21. A sensor, as described in claim 20, wherein said damping means comprises a fluid.

22. A senor, as described in any one of claims 1, 2, 3, 5 or 9, wherein said response element comprises a mass.

23. A sensor, as described in any one of claim 1, 2, 3, 5 or 9, wherein said response element comprises a material responsive to a magnetic field.

24. A sensor, as described in any one of claim 1, 2, 3, 5 and 9, wherein said response element comprises a material response to an electric field.

25. A sensor, as described in any one of claim 1, 2, 3, 5 or 9, wherein said response element comprises an electrically charged material.

26. A sensor, as described in any one of claims 1, 2, 3, 5 or 9, wherein said response element comprises a magnetized material.

27. A multidimensional force sensor, as described in any one of claims 1, 2, 3, 5 or 9, further comprising a piezoresistor mounted on a surface of said beam.

28. A sensor, as described in any one of claims 1, 2, 3, 5 or 9, wherein said beam comprises a piezoresistive material, whereby said beam comprises a sensor element for sensing displacement of said beam.

29. A multidimensional force sensor, as described in any one of claims 1, 2, or 3, further comprising piezoresistor means embedded in the longitudinal axis of said beam for sensing stress in said beam.

2. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam comprising:

a first capacitor plate attached to said response element;

a second capacitor plate having a different shape from said first capacitor plate attached to said main body and only partially overlapping said first capacitor plate substantially parallel to and in close proximity to said first capacitor plate, said first capacitor plate and said second capacitor plate producing a change in capacitance in response to displacement of said response element; and

capacitance measuring means, coupled to said first capacitor plate and said second capacitor plate, for measuring said change in capacitance.

3. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, comprising:

a first triangular capacitor plate mounted on said response element;

a second rectangular capacitor plate mounted on said main body in close proximity and substantially parallel to said first capacitor plate, said first triangular capacitor plate and said second rectangular capacitor plate producing a change in capacitance as said response element is displaced; and

capacitance measuring means coupled to said first triangular capacitor plate and said second rectangular capacitor plate for measuring said change in capacitance.

4. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, as described in claim 3, wherein each of said first triangular capacitor plate and said second rectangular capacitor plate comprises a plurality of electrically conductive strips, parallel to each other and electrically connected to each other.

5. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, comprising:

a first capacitor plate mounted on said main body in close proximity to said response element and offset to one side from said response element;

a second capacitor plate mounted on said main body in close proximity to said response element, substantially coplanar to said first capacitor plate, and offset to the opposite side of said response element from said first capacitor plate;

a third capacitor plate mounted on said response element, spaced apart from and parallel to said first capacitor plate and said second capacitor plate, and partially overlapping said first capacitor plate and said second capacitor plate, said first capacitor plate and said third capacitor plate and said second capacitor plate and said third capacitor plate producing changes in capacitances in response to displacement of said response element; and

capacitance measuring means, coupled to said first, second and third capacitor plates, for measuring said changes in capacitance.

6. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, as described in claim 5, wherein said capacitance measuring means comprises:

a first capacitance measuring means coupled to said first and third capacitor plates for measuring the change in capacitance between said first and third capacitor plates as said response element is displaced; and

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

7. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam as described in claim 5, 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.

8. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, as described in claim 5, further comprising:

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

9. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam comprising:

a first capacitor plate mounted on said main body in close proximity to said response element and offset to one side from said response element;

a second capacitor plate mounted on said main body adjacent to said first capacitor plate, substantially coplanar to said first capacitor plate, and having its center in closest proximity to said response element;

a third capacitor plate mounted on said main body in close proximity to said response element, substantially coplanar to said first capacitor plate and said second capacitor plate, and offset to the opposite side of said response element from said first capacitor plate;

a fourth capacitor plate that is substantially larger than said second capacitor plate mounted on said response element, spaced apart from and 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,

said first capacitor plate and said fourth capacitor plate, said second capacitor plate and said fourth capacitor plate, and said third capacitor plate and said fourth capacitor plate producing changes in capacitance as said beam is displaced; and

capacitance measuring means, coupled to said first, second, third and fourth capacitor plates, for measuring said changes in capacitance.

10. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, as described in claim 9, wherein said capacitance measuring means comprises:

a first capacitance measuring means coupled to said first and fourth capacitor plates for measuring the change in capacitance between said first and fourth capacitor plates as said response element is displaced;

a second capacitance measuring means coupled to said second and fourth capacitor plates for measuring the change in capacitance between said second and fourth capacitor plates as said response element is displaced; and

a third capacitance measuring means coupled to said third and fourth capacitor plates for measuring the change in capacitance between said third and fourth capacitor plates as said response element is displaced.

11. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, as described in claim 9, 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.

12. A sensor for sensing displacement of a beam attached to a main body at a first end and having a response element attached to a second end of said beam, as described in claim 9, further comprising:

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