Capacitive bulk acoustic wave disk gyroscopes with self-calibration

• US 7,874,209 B2
• Filed: 01/08/2008
• Issued: 01/25/2011
• Est. Priority Date: 01/08/2008
• Status: Active Grant

• Current Assignee: Litton Systems Incorporated
• Original Assignee: Northrop Grumman Guidance And Electronics Company, Inc.
• Inventors: Stewart, Robert E.
• Primary Examiner(s): Kwok; Helen C.
• Application Number:
  US12/006,982
• Publication Number:
  US 20090173157A1
• Time in Patent Office: 1,113 Days
• Field of Search: 73/13.7, 73/13.8, 735/040.2, 735/040.4, 735/041.2, 735/041.3, 735/041.4, 735/041.5, 735/040.1
• US Class Current: 73/504.01
• CPC Class Codes: G01C 19/5698 using acoustic waves, e.g. surface acoustic wave gyros

Abstract

The apparatus in one embodiment may have capacitive bulk acoustic wave disk gyro operated in a closed loop mode. A self-calibration system may be operatively coupled to the capacitive bulk acoustic wave disk gyroscope. Self-calibration of gyro bias of the gyro may be implemented by interchanging an anti-nodal axis with a nodal axis of the gyro.

Claims

1. An apparatus comprising:

a capacitive bulk acoustic wave disk gyro operated in a closed loop mode; and

a self-calibration system operatively coupled to the capacitive bulk acoustic wave disk gyroscope;

wherein self-calibration of gyro bias of the gyro is implemented by interchanging an anti-nodal axis with a nodal axis of the gyro.

2. The apparatus according to claim 1, wherein the gyro has a plurality of electrodes having nodal pickoff electrodes and forcing electrodes, and wherein anti-nodal forcer electrodes are interchanged with the nodal pickoff electrodes and anti-nodal pickoff electrodes are interchanged with nodal forcer electrodes to effect the interchanging of the anti-nodal axis with the nodal axis of the gyro.

3. An apparatus comprising:

a capacitive bulk acoustic wave disk gyro having a resonator having a mechanical symmetry of (100) single crystal silicon;

a drive system that drives the resonator in an n=3 mode, the drive system operatively coupled to the resonator;

a self-calibration system operatively coupled to the resonator and the drive system;

wherein self-calibration of gyro bias of the gyro is implemented by interchanging an anti-nodal axis with a nodal axis of the gyro.

4. The apparatus according to claim 3, wherein the gyro is operated in a degenerative bulk acoustic mode.

5. The apparatus according to claim 3, wherein the gyro has drive and sense axes, wherein the gyro has a plurality of electrodes, and wherein each of the drive and sense axes has respectively, of the plurality of electrodes, three electrodes that are pickoff electrodes and three further electrodes that are forcing electrodes.

6. The apparatus according to claim 3, wherein the gyro has a plurality of electrodes having pickoff electrodes and forcing electrodes, and wherein anti-nodal forcer electrodes are interchanged with nodal pickoff electrodes and anti-nodal pickoff electrodes are interchanged with nodal forcer electrodes to effect the interchanging of the anti-nodal axis with the nodal axis of the gyro.

7. The apparatus according to claim 3, wherein in an inertial system under dynamic operating conditions the apparatus further comprises two gyros with alternating polarities.

8. The apparatus according to claim 3, wherein in an inertial system under dynamic operating conditions the apparatus further comprises a single gyro with two resonators with alternating polarities per axis.

9. The apparatus according to claim 3, wherein interchanging the anti-nodal axis with a nodal axis in the gyro causes a gyro scale factor to reverse polarity while a gyro bias polarity remains unchanged.

10. An apparatus comprising:

a capacitive bulk acoustic wave disk gyro having a resonator having a mechanical symmetry of (111) single crystal silicon;

a drive system that drives the resonator in an n=2 mode, the drive system operatively coupled to the resonator;

a self-calibration system operatively coupled to the resonator and the drive system;

wherein self-calibration of gyro bias of the gyro is implemented by interchanging an anti-nodal axis with a nodal axis of the gyro.

11. The apparatus according to claim 10, wherein the gyro is operated in a degenerative bulk acoustic mode.

12. The apparatus according to claim 10, wherein the gyro has drive and sense axes, wherein the gyro has a plurality of electrodes, and wherein each of the drive and sense axes has respectively, of the plurality of electrodes, two electrodes that are pickoff electrodes and two further electrodes that are forcing electrodes.

13. The apparatus according to claim 10, wherein the gyro has a plurality of electrodes having pickoff electrodes and forcing electrodes, and wherein anti-nodal forcer electrodes are interchanged with nodal pickoff electrodes and anti-nodal pickoff electrodes are interchanged with nodal forcer electrodes to effect the interchanging of the anti-nodal axis with the nodal axis of the gyro.

14. The apparatus according to claim 10, wherein in an inertial system under dynamic operating conditions the apparatus further comprises two gyros with alternating polarities.

15. The apparatus according to claim 10, wherein in an inertial system under dynamic operating conditions the apparatus further comprises a single gyro with two resonators with alternating polarities per axis.

16. The apparatus according to claim 10, wherein interchanging the anti-nodal axis with a nodal axis in the gyro causes a gyro scale factor to reverse polarity while a gyro bias polarity remains unchanged.

17. A method comprising:

operating a capacitive bulk acoustic wave disk gyro in a closed loop mode; and

interchanging an anti-nodal axis with a nodal axis of the gyro to effect self-calibration of gyro bias of the gyro.

18. The method according to claim 17, wherein the gyro has a plurality of electrodes having pickoff electrodes and forcing electrodes, and wherein anti-nodal forcer electrodes are interchanged with nodal pickoff electrodes and anti-nodal pickoff electrodes are interchanged with nodal forcer electrodes to effect the interchanging of the anti-nodal axis with the nodal axis of the gyro.

19. The method according to claim 17, wherein interchanging the anti-nodal axis with a nodal axis in the gyro causes a gyro scale factor to reverse polarity while a gyro bias polarity remains unchanged.

20. The method according to claim 17, wherein the capacitive bulk acoustic wave disk gyro is implemented in single crystal silicon.