Micro-machined angle-measuring gyroscope

• US 6,481,285 B1
• Filed: 04/20/2000
• Issued: 11/19/2002
• Est. Priority Date: 04/21/1999
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Howe, Roger T., Shkel, Andrei M.
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US09/556,023
• Time in Patent Office: 943 Days
• Field of Search: 735/040.4, 735/041.2, 735/041.3, 735/041.4, 735/143.2, 735/141.8, 735/142.4, 361/280
• US Class Current: 73/504.13
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

A micro-machined angle measurement gyroscope. In one implementation, the gyroscope includes a substrate; a proof mass coupled to the substrate by an isotropic suspension such that the proof mass can move in any direction in the plane of the substrate; a plurality of drive electrodes configured to cause the proof mass to oscillate in the plane of the substrate; and a plurality of sense electrodes configured to sense the motion of the proof mass in the plane of the substrate. In another implementation, the gyroscope includes a substrate; a proof mass suspended above the substrate by an isotropic suspension such that the proof mass can move in any direction in an oscillation plane normal to the substrate; a plurality of drive electrodes configured to cause the proof mass to oscillate in the oscillation plane; and a plurality of sense electrodes configured to sense the motion of the proof mass in the oscillation plane.

Claims

1. A micro-machined angle measurement gyroscope comprising:

a substrate;

a proof mass coupled to the substrate by an isotropic suspension such that the proof mass can move in any direction in the plane of the substrate;

a plurality of drive electrodes configured to cause the proof mass to oscillate in the plane of the substrate; and

a plurality of sense electrodes configured to sense the motion of the proof mass in the plane of the substrate.

2. The gyroscope of claim 1, wherein each drive electrode moves the proof mass along a drive axis, and at least two of the drive axes are mutually orthogonal.

3. The gyroscope of claim 2, wherein each sense electrode senses the motion of the proof mass along a sense axis, and at least two of the sense axes are mutually orthogonal.

4. The gyroscope of claim 3, wherein the proof mass comprises a rigid ring.

5. The gyroscope of claim 4, wherein the proof mass comprises one or more concentric rings.

6. The gyroscope of claim 4, wherein the substrate has an anchor at the center of the ring, and the ring is connected to the anchor by one or more flexures.

7. The gyroscope of claim 6, wherein each drive and sense electrode includes an inner electrode located inside the ring and an outer electrode located outside the ring.

8. The gyroscope of claim 3, wherein

each drive and sense electrode includes a plurality of comb teeth;

the proof mass includes a plurality of comb teeth; and

the comb teeth of the drive and sense electrodes and the proof mass are adjacent.

9. The gyroscope of claim 1 wherein the suspension comprises a ring attached between the proof mass and the substrate.

10. The gyroscope of claim 9, wherein the substrate has an anchor at the center of the ring, and the suspension further comprises one or more flexures connected between the proof mass and the anchor.

11. The gyroscope of claim 1 wherein the suspension comprises a plurality of concentric rings attached between the proof mass and the substrate.

12. The gyroscope of claim 11, further comprising one or more central drive electrodes located near the center of the rings.

13. The gyroscope of claim 1, wherein the proof mass, drive and sense electrodes, suspension and substrate are micro-machined from a single crystal of material.

14. The gyroscope of claim 13, wherein the material is silicon.

15. A micro-machined angle measurement gyroscope comprising:

a substrate;

a proof mass suspended above the substrate by an isotropic suspension such that the proof mass can move in any direction in an oscillation plane normal to the substrate;

a plurality of drive electrodes configured to cause the proof mass to oscillate in the oscillation plane; and

a plurality of sense electrodes configured to sense the motion of the proof mass in the oscillation plane.

16. The gyroscope of claim 15, wherein each drive electrode moves the proof mass along a drive axis, and the drive axes of a pair of the drive electrodes are mutually orthogonal.

17. The gyroscope of claim 16, wherein each sense electrode senses the motion of the proof mass along a sense axis, and the sense axes of a pair of the sense electrodes are mutually orthogonal.

18. The gyroscope of claim 17, wherein

each drive and sense electrode includes a plurality of comb teeth;

the proof mass includes a plurality of comb teeth; and

the comb teeth of the drive and sense electrodes and the proof mass are adjacent.

19. The gyroscope of claim 15, wherein the suspension comprises one or more suspension units each having a flexible beam disposed between the proof mass and an anchor attached to the substrate.

20. The gyroscope of claim 19, wherein each suspension unit further comprises:

a flexible frame attached between the beam and the anchor;

a suspension tuning electrode attached to the frame; and

an anchored electrode attached to the substrate;

wherein

a bias voltage between the suspension tuning electrode and the anchored electrode imposes a bias force on the beam.

21. The gyroscope of claim, 15 wherein the proof mass, electrodes, suspension and substrate are micro-machined from a single block of material.

22. The gyroscope of claim 21, wherein the material is silicon.

23. The gyroscope of claim 22, further comprising one or more tuning electrodes configured to adjust the frequency of oscillation of the proof mass.