ELECTROSTATIC SPRING SOFTENING IN REDUNDANT DEGREE OF FREEDOM RESONATORS

• US 20040226370A1
• Filed: 04/25/2003
• Published: 11/18/2004
• Est. Priority Date: 04/26/2002
• Status: Active Grant

• Current Assignee: California Institute of Technology, The Boeing Co.
• Original Assignee: California Institute of Technology, The Boeing Co.
• Inventors: Humphreys, Todd E., Shcheglov, Kirill V., Challoner, A. Dorian, Hayworth, Ken J.
• Granted Patent: US 6,823,734 B1
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 3/0062 Devices moving in two or more dimensions, i.e. having special features which allow movement in more than one dimension
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: Y10T 74/1275 Electrical

Abstract

The present invention discloses an isolated electrostatic biased resonator gyroscope. The gyroscope includes an isolated resonator having a first and a second differential vibration mode, a baseplate supporting the isolated resonator, a plurality of excitation affixed to the baseplate for exciting the first differential vibration mode, a plurality of sensing electrodes affixed to the baseplate for sensing movement of the gyroscope through the second differential vibration mode and a plurality of bias electrodes affixed to the baseplate for trimming isolation of the resonator and substantially minimizing frequency split between the first and second differential vibration modes. Typically, the isolated resonator comprises a proof mass and a counterbalancing plate with the bias electrodes disposed on the baseplate below.

Claims

1. A resonator gyroscope, comprising:

an isolated resonator having a first and a second differential vibration mode;

a baseplate supporting the isolated resonator;

a plurality of excitation electrodes affixed to the baseplate for exciting the first differential vibration mode;

a plurality of sensing electrodes affixed to the baseplate for sensing movement of the gyroscope through the second differential vibration mode; and

a plurality of bias electrodes affixed to the baseplate for trimming isolation of the resonator and substantially minimizing frequency split between the first and second differential vibration modes.

2. The resonator gyroscope of claim 1, wherein the isolated resonator provides redundant degrees of freedom in a structure comprising:

an inner resonant post;

an outer resonant plate;

the baseplate supporting the isolated resonator; and

baseplate frame.

3. The resonator gyroscope of claim 1, further comprising a mounting frame attached to the baseplate through one or more isolation flexures to provide redundant degrees of freedom to the isolated resonator.

4. The resonator gyroscope of claim 1, wherein the isolated resonator comprises two bodies with transverse inertia symmetry and centers of mass about a substantially coincident axis and the first and second differential vibration modes are transverse to the substantially coincident axis with substantially equal frequencies.

5. The resonator gyroscope of claim 4, wherein the two bodies of the isolated resonator comprise a proof mass and a counterbalancing plate.

6. The resonator gyroscope of claim 5, wherein the sense and excitation electrodes and at least one of the bias electrodes are disposed to react with the counterbalancing plate.

7. The resonator gyroscope of claim 5, further comprising one or more flexures joining the proof mass and the counterbalancing plate and attached to the baseplate.

8. The resonator gyroscope of claim 7, wherein the one or more flexures are arranged around a perimeter of the proof mass, each with a first end attached to the counterbalancing plate and a second end attached to the proof mass.

9. The resonator gyroscope of claim 5, wherein the proof mass comprises a vertical portion attached to a support plate portion elastically connected to the counterbalancing plate.

10. The resonator gyroscope of claim 9, wherein the vertical portion is longer than required to isolate the resonator in the absence of trimming isolation with the plurality of bias electrodes.

11. The resonator gyroscope of claim 9, wherein the vertical portion comprises a post attached to the support plate portion.

12. The resonator gyroscope of claim 9, wherein:

a length of the vertical portion is imbalanced; and

spring softening compensates for the imbalance.

13. The resonator gyroscope of claim 9, wherein at least one of the bias electrodes reacts with the support plate portion.

14. A method of producing a resonator gyroscope, comprising:

providing an isolated resonator having a first and a second differential vibration mode;

supporting the isolated resonator with a baseplate;

affixing a plurality of excitation electrodes to the baseplate for exciting the first differential vibration mode;

affixing a plurality of sensing electrodes to the baseplate for sensing movement of the gyroscope through the second differential vibration mode; and

affixing a plurality of bias electrodes to the baseplate for trimming isolation of the resonator and substantially minimizing frequency split between the first and second differential vibration modes.

15. The method of claim 14, wherein the isolated resonator provides redundant degrees of freedom in a structure comprising:

an inner resonant post;

an outer resonant plate;

the baseplate supporting the isolated resonator; and

baseplate frame.

16. The method of claim 14, further comprising a mounting frame attached to the baseplate through one or more isolation flexures to provide redundant degrees of freedom to the isolated resonator.

17. The method of claim 14, wherein the isolated resonator comprise two bodies with transverse inertia symmetry and centers of mass about a substantially coincident axis and the first and second differential vibration modes are transverse to the substantially coincident axis with substantially equal frequencies.

18. The method of claim 17, wherein the two bodies of the isolated resonator comprise a proof mass and a counterbalancing plate.

19. The method of claim 18, wherein the sense and excitation electrodes and at least one of the bias electrodes are disposed to react with the counterbalancing plate.

20. The method of claim 18, further comprising one or more flexures joining the proof mass and the counterbalancing plate and attached to the baseplate.

21. The method of claim 20, wherein the one or more flexures are arranged around a perimeter of the proof mass, each with a first end attached to the counterbalancing plate and a second end attached to the proof mass.

22. The method of claim 18, wherein the proof mass comprises a vertical portion attached to a support plate portion elastically connected to the counterbalancing plate.

23. The method of claim 22, wherein the vertical portion is longer than required to isolate the resonator in the absence of trimming isolation with the plurality of bias electrodes.

24. The method of claim 22, wherein the vertical portion comprises a post attached to the support plate portion.

25. The method of claim 22, wherein the resonator isolation is tuned by changing a length of the vertical portion.

26. The method of claim 22, wherein at least one of the bias electrodes reacts with the support plate portion.