Z-axis vibratory gyroscope

• US 6,539,801 B1
• Filed: 06/29/2000
• Issued: 04/01/2003
• Est. Priority Date: 06/29/1999
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Gutierrez, Roman C., Tang, Tony K.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US09/617,599
• Time in Patent Office: 1,006 Days
• Field of Search: 735/041.2, 735/041.4, 735/041.5, 735/041.6, 735/040.4, 735/040.2
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 2015/084 the mass being suspended at more than one of its sides, e.g. membrane-type suspension, so as to permit multi-axis movement of the mass

Abstract

A microgyroscope having a suspended vertical post uses the Coriolis force to detect the rotation rate. The microgyroscope consists of a single vertical post which senses the rotation rate. The vertical post is supported by multiple silicon suspensions. The vertical post is driven electrostatically to oscillatory in-plane (x and y directions) by vertical capacitors. The Coriolis force induced motions of the vertical post is detected capacitively by the vertical capacitors.

Claims

1. A gyroscope comprising:

a frame;

a vertical post positioned within the frame;

a plurality of suspensions that suspend the vertical post near a center of the frame;

a first set of capacitors positioned proximate to the vertical post, the first set being positioned vertically above the suspensions; and

a second set of capacitors positioned proximate to the vertical post, the second set being positioned vertically below the suspensions, wherein each capacitor has a height that is significantly greater than a height of each suspension.

2. The gyroscope of claim 1, wherein the plurality of capacitors provide an excitation force for the vertical post.

3. The gyroscope of claim 1, wherein the vertical post is free to move in a z-axis, which is an axis parallel to a longitudinal axis of the vertical post.

4. The gyroscope of claim 1, wherein the plurality of suspensions are positioned at approximately the mid-point of the vertical post.

5. The gyroscope of claim 1, wherein the plurality of suspensions are silicon suspensions.

6. The gyroscope of claim 1, wherein at least one capacitor has a height that is substantially equal to half of a height of the vertical post.

7. The gyroscope of claim 1, wherein the first set of capacitors are bonded to the second set of capacitors.

8. The gyroscope of claim 1, wherein each capacitor is proximate to a corner of the vertical post, the vertical post having a rectangular cross-section.

9. The gyroscope of claim 1, wherein each capacitor has an L-shaped cross-section and is proximate to a corner of the vertical post, the vertical post having a rectangular cross-section.

10. The gyroscope of claim 1, wherein each suspension comprises a thin elongated member with a substantially rectangular cross-section.

11. The gyroscope of claim 1, wherein the suspensions, a first portion of the frame, a first portion of the vertical post and the first set capacitors are formed from a first silicon wafer, and a second portion of the frame, a second portion of the vertical post and the second set of capacitors are formed from a second silicon wafer, the first and second portions of the frame being bonded together to form the gyroscope.

12. The gyroscope of claim 1, wherein each capacitor is positioned between a first vertical plane formed by a first suspension and a second vertical plane formed by a second suspension.

13. The gyroscope of claim 1, wherein the capacitors capacitively detect Coriolis force induced motions of the vertical post.

14. The gyroscope of claim 1, wherein the capacitors electrostatically drive the vertical post to oscillate in a horizontal plane.

15. The gyroscope of claim 1 wherein the gyroscope is operable to detect forces in x-, y- and z-directions.

16. A gyroscope comprising:

a frame;

a vertical post positioned within the frame;

a plurality of suspensions that suspend the vertical post near a center of the frame; and

four capacitors positioned proximate to the vertical post, each capacitor having a height that is substantially similar to a height of the vertical post, each capacitor being positioned between a first vertical plane formed by a first suspension and a second vertical plane formed by a second suspension.