Axi-Symmetric Small-Footprint Gyroscope with Interchangeable Whole-Angle and Rate Operation

• US 20150354959A1
• Filed: 06/09/2015
• Published: 12/10/2015
• Est. Priority Date: 06/09/2014
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Senkal, Doruk, Shkel, Andrei M.
• Granted Patent: US 10,180,323 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01C 19/5684 the devices involving a micromechanical structure

Abstract

A toroidal ring gyroscope with a robust outer perimeter anchor and a distributed suspension system. The vibrational energy in the design is concentrated towards the innermost ring, and the device is anchored at the outer perimeter. The distributed support structure prevents vibrational motion propagating to the outer anchor, which helps trap the vibrational energy within the gyroscope and provides a Q-factor of >100,000 at a compact size of 1760 μm. Due to the parametric pumping effect, energy added to each mode is proportional to the existing amplitude of the respective mode. As a result, errors associated with finding the orientation of the standing wave and x-y drive gain drift are bypassed. The toroidal ring gyroscope can be fabricated using any standard silicon on insulator process. Due to the high Q-factor and robust support structure, the device can potentially be instrumented in high-g environments that require high angular rate sensitivity.

Claims

1. A micromachined Coriolis vibratory ring gyroscope comprising:

a toroidal outer anchor;

a distributed suspension system having an innermost portion, disposed within the toroidal outer anchor, and concentrically coupled to the outer anchor; and

an electrode assembly disposed in the center of the distributed suspension system and having a capacitive gap between the electrode assembly and the innermost portion of the distributed suspension system, the electrode assembly driving the distributed suspension system into oscillation by electrostatic forces.

2. The gyroscope of claim 1 where the distributed suspension comprises a plurality of concentrically disposed rings coupled to one another.

3. The gyroscope of claim 2 where the plurality of concentrically disposed rings comprises a concentrically disposed innermost ring which has a greater thickness than the other ones of the plurality of concentrically disposed rings.

4. The gyroscope of claim 3 wherein the capacitive gap between the innermost portion of the distributed suspension system and the electrode assembly comprises a capacitive gap between the innermost ring of the distributed suspension system which has greater thickness and the driving electrode assembly.

5. The gyroscope of claim 1 where the electrode assembly comprises:

a central star electrode; and

at least eight discrete electrodes symmetrically disposed radially around the central star electrode.

6. The gyroscope of claim 5 wherein at least four of the at least eight discrete electrodes are forcer electrodes.

7. The gyroscope of claim 5 wherein at least four of the at least eight discrete electrodes are pick-off electrodes.

8. The gyroscope of claim 5 wherein the central star electrode is configured for parametric pumping of the distributed suspension system.

9. The gyroscope of claim 1 further comprising a micro-controller configured to drive the gyroscope at a constant amplitude, suppress a quadrature error, and track and control orientation of a precession pattern of the gyroscope.

10. The gyroscope of claim 1 further comprising a Q factor of at least 100,000 and an overall diameter of no more than 1760 μ

m.

21. The gyroscope of claim 1 where the electrode assembly driving the distributed suspension system into oscillation by electrostatic forces comprises an electrode assembly driving the gyroscope in any of a plurality of wineglass modes provided that the wineglass mode shape has a degenerate mode pair.

22. The gyroscope of claim 2 where the plurality of concentrically disposed rings are coupled to one another via a plurality of radially disposed spokes.

11. A method of operating a gyroscope comprising

anchoring a distributed suspension system to a toroidal outer anchor;

defining a capacitive gap between the distributed suspension system and an electrode assembly disposed within the toroidal outer anchor; and

driving the distributed suspension system with the electrode assembly into oscillation via electrostatic forces.

12. The method of claim 11 where anchoring a distributed suspension system to a toroidal outer anchor comprises concentrically coupling the distributed suspension system to the toroidal outer anchor.

13. The method of claim 11 where defining a capacitive gap between the distributed suspension system and an electrode assembly comprises disposing the electrode assembly adjacently to an innermost concentrically disposed ring of a plurality of concentric rings comprising the distributed suspension system.

14. The method of claim 11 where driving the distributed suspension system with the electrode assembly into oscillation via electrostatic forces comprises driving the distributed suspension system with the electrode assembly using a plurality of discrete electrodes disposed symmetrically around a central star electrode.

15. The method of claim 14 where driving the distributed suspension system with the electrode assembly into oscillation via electrostatic forces comprises using the central star electrode to drive the distributed suspension system by parametric pumping.

16. A method for driving a toroidal ring gyroscope comprising:

driving the gyroscope to a predetermined amplitude using an at resonance drive signal;

stabilizing the phase lock loop and amplitude gain control;

disabling the at resonance drive signal; and

driving the gyroscope through a parametric drive signal.

17. The method of claim 16 where driving the gyroscope through the parametric drive signal comprises driving the gyroscope in any of a plurality of wineglass modes provided that the wineglass mode shape has a degenerate mode pair.

18. The method of claim 16 where driving the gyroscope through the parametric drive signal comprises driving the gyroscope by an electrode assembly configured for parametric pumping.

19. The method of claim 18 where driving the gyroscope by an electrode assembly configured for parametric pumping comprises driving the gyroscope by an electrode assembly comprised of at least four forcer electrodes.

20. The method of claim 18 where driving the gyroscope by an electrode assembly configured for parametric pumping comprises driving the gyroscope by an electrode assembly comprised of at least four pick-off electrodes.