XY-axis shell-type gyroscopes with reduced cross-talk sensitivity and/or mode matching

• US 9,091,544 B2
• Filed: 05/29/2012
• Issued: 07/28/2015
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Johari-Galle, Houri
• Primary Examiner(s): KWOK, HELEN C
• Application Number:
  US13/482,186
• Publication Number:
  US 20130319116A1
• Time in Patent Office: 1,155 Days
• Field of Search: 735/041.3, 735/041.2, 735/040.2, 735/040.4
• US Class Current: 1/1
• CPC Class Codes: G01C 19/5684 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5698 using acoustic waves, e.g. surface acoustic wave gyros

Abstract

Cross-talk sensitivity in an xy-axis shell-type gyroscope can be rejected or reduced by operating the gyroscope with a single in-plane flexural or bulk resonance mode and sensing two out-of-plane degenerate or non-degenerate resonance modes resulting from rotations about two axes in the plane of the resonator. Mode matching in an xy-axis shell-type gyroscope can be achieved by configuring the resonator (e.g., size, shape, thickness) to match the in-plane and out-of-plane resonance frequencies for the drive and sense modes of interest.

Claims

1. A shell-type gyroscope with improved cross-talk sensitivity, the shell-type gyroscope comprising:

a resonator substantially disposed in a resonator plane;

a plurality of drive electrodes disposed substantially in the resonator plane; and

a plurality of sense electrodes disposed in a plane apart from and parallel to the resonator plane, wherein the resonator is driven via the drive electrodes in an in-plane bulk resonance mode substantially in the resonator plane, and wherein rotations about two orthogonal sense axes in the resonator plane are sensed via the sense electrodes using two out-of-plane bulk modes of the resonator caused by rotation about the axes, the inplane mode substantially rejecting cross-talk between the two orthogonal sense axes.

2. A shell-type gyroscope according to claim 1, wherein the out-of-plane modes are degenerate modes.

3. A shell-type gyroscope according to claim 1, wherein the two out-of-plane modes are non-degenerate modes.

4. A shell-type gyroscope according to claim 1, wherein the two axes include orthogonal x and y axes, the drive and sense electrodes are aligned with the x and y axes, and the in-plane mode is an elliptical mode having anti-nodes substantially along the x and y axes, and wherein the sense electrodes that are parallel to the resonator plane and aligned with the x axis are configured for sensing rotation rate about the y axis and the sense electrodes that are parallel to the resonator plane and aligned with the y axis are configured for sensing rotation rate about the x axis.

5. A shell-type gyroscope according to claim 1, wherein the resonator is configured such that a frequency of the in-plane mode substantially matches a frequency of the out-of-plane mode.

6. A shell-type gyroscope according to claim 5, wherein at least one of the size, shape, or thickness of the resonator is specially configured to substantially match the frequencies.

7. A shell-type gyroscope according to claim 1, further comprising:

a second plurality of sense electrodes disposed substantially in the resonator plane, wherein rotations about a z-axis normal to the resonator plane are sensed via the second plurality of sense electrodes.

8. A shell-type gyroscope according to claim 7, wherein the in-plane mode is a first elliptical mode having anti-nodes substantially along x and y axes, and wherein the second plurality of sense electrodes are located substantially at the anti-nodes of a second elliptical mode having anti-nodes along axes offset substantially 45 degrees from the x and y axes.

9. A method for operating a shell-type gyroscope having a resonator substantially disposed in a resonator plane, a plurality of drive electrodes disposed substantially in the resonator plane, and a plurality of sense electrodes disposed in a plane apart from and parallel to the resonator plane, the method comprising:

driving, via the drive electrodes, resonance of the resonator in an in-plane bulk resonance mode substantially in the resonator plane; and

sensing, via the sense electrodes, rotations about two orthogonal sense axes in the resonator plane using two out-of-plane bulk modes of the resonator caused by rotation about the axes, the in-plane mode substantially rejecting cross-talk between the two orthogonal sense axes.

10. A method according to claim 9, wherein the out-of-plane modes are degenerate modes.

11. A method according to claim 9, wherein the two out-of-plane modes are non-degenerate modes.

12. A method according to claim 9, wherein the two axes include orthogonal x and y axes, the drive and sense electrodes are aligned with the x and y axes, and the inplane mode is an elliptical mode having anti-nodes substantially along the x and y axes, and wherein the sense electrodes that are parallel to the resonator plane and aligned with the x axis are configured for sensing rotation rate about the y axis and the sense electrodes that are parallel to the resonator plane and aligned with the y axis are configured for sensing rotation rate about the x axis.

13. A method according to claim 9, further comprising:

sensing rotations about a z-axis normal to the resonator plane via a second plurality of sense electrodes disposed substantially in the resonator plane.

14. A method according to claim 13, wherein the in-plane mode is a first elliptical mode having anti-nodes substantially along x and y axes, and wherein the second plurality of sense electrodes are located substantially at the anti-nodes of a second elliptical mode having anti-nodes along axes offset substantially 45 degrees from the x and y axes.

15. Apparatus for operating a shell-type gyroscope having a resonator substantially disposed in a resonator plane, a plurality of drive electrodes disposed substantially in the resonator plane, and a plurality of sense electrodes disposed in a plane apart from and parallel to the resonator plane, the apparatus comprising:

a drive circuit configured to drive, via the drive electrodes, resonance of the resonator in an in-plane bulk resonance mode substantially in the resonator plane; and

a sense circuit configured to sense, via the sense electrodes, rotations about two orthogonal sense axes in the resonator plane using two out-of-plane bulk modes of the resonator caused by rotation about the axes, the in-plane mode substantially rejecting cross-talk between the two orthogonal sense axes.

16. Apparatus according to claim 15, wherein the out-of-plane modes are degenerate modes.

17. Apparatus according to claim 15, wherein the two out-of-plane modes are non-degenerate modes.

18. Apparatus according to claim 15, wherein the two axes include orthogonal x and y axes, the drive and sense electrodes are aligned with the x and y axes, and the in-plane mode is an elliptical mode having anti-nodes substantially along the x and y axes, and wherein the sense circuit is configured to sense rotation rate about the y axis using the sense electrodes aligned with the x axis and to sense rotation rate about the x axis using the sense electrodes aligned with the y axis.

19. Apparatus according to claim 18, where in the sense circuit includes:

a first circuit configured to receive signals from the sense electrodes aligned with the y-axis indicative of a first resonant sense mode in a z-direction caused by rotation rate about the x-axis and output a signal indicative of rotation rate about the x-axis based on the signals from the sense electrodes in the z-direction and aligned with the y-axis and a velocity signal indicative of velocity of the resonator along the y-axis; and

a second circuit configured to receive signals from the sense electrodes aligned with the x-axis indicative of a second resonant sense mode in the z-direction caused by rotation rate about the y-axis and output a signal indicative of rotation rate about the y-axis based on the signals from the sense electrodes in the z-direction and aligned with the x-axis and a velocity signal indicative of velocity of the resonator along the x-axis.

20. Apparatus according to claim 15, wherein the gyroscope further comprises a second plurality of sense electrodes disposed substantially in the resonator plane, and wherein the sense circuit is configured to receive signals from the second plurality of sense electrodes indicative of a resonant sense mode in the resonator plane caused by rotation rate about a z-axis normal to the resonator plane and output a signal indicative of rotation rate about the z-axis based on the signals from the second plurality of sense electrodes.

21. Apparatus according to claim 20, wherein the in-plane mode is a first elliptical mode having anti-nodes substantially along x and y axes, and wherein the second plurality of sense electrodes are located substantially at the anti-nodes of a second elliptical mode having anti-nodes along axes offset substantially 45 degrees from the x and y axes.

22. A method for reducing cross-talk sensitivity in an xy-axis shell-type gyroscope having a resonator substantially disposed in a resonator plane, the method comprising:

operating the gyroscope with a single in-plane bulk resonance mode; and

sensing two out-of-plane degenerate or non-degenerate bulk resonance modes resulting respectively from rotations about two sense axes in the resonator plane.