Multi-mode coriolis vibratory gyroscopes having high order rotationally symmetric mechanical structure and 32 electrodes

Patent metadata

Field	Value
Publication number	US-10436587-B2
Application number	US-201816004310-A
Country	US
Kind code	B2
Filing date	Jun 8, 2018
Priority date	Aug 11, 2017
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

An angular sensor, comprising a Coriolis vibratory gyroscope (CVG) resonator, capable of oscillating along a first pair of normal n=1 modes comprising a first normal mode and a second normal mode; and a second pair of normal n=2 modes comprising a third normal mode and a fourth normal mode; the sensor further comprising one drive electrode and one sense electrode aligned along an anti-nodal axis of each mode; and a pair of bias tune electrodes aligned with an anti-nodal axis of each mode if no drive and sense electrode pair is aligned with said anti-nodal axis.

First claim

The invention claimed is:

1. An angular sensor, comprising:
a Coriolis vibratory gyroscope (CVG) resonator, provided for oscillating along:
a first pair of normal n-=modes comprising a first normal mode and a second normal mode; each of the first and second normal modes having one anti-nodal axis; and
a second pair of normal n=2 modes comprising a third normal mode and a fourth normal mode; each of the third and fourth normal modes having two anti-nodal axis;
at least one of a drive electrode and a sense electrode aligned along the anti-nodal axis of each of the first and second normal modes;
at least one of a drive electrode and a sense electrode aligned along a first anti-nodal axis of each of the third and fourth normal modes mode; and
a pair of bias tune electrodes aligned with a second anti-nodal axis of each of the third and fourth modes if no drive or sense electrode is aligned with said second anti-nodal axis.

2. The angular sensor of claim 1 , wherein said at least one of a drive electrode and a sense electrode aligned along the first and second anti nodal axis are each part of a pair comprising one sense electrode and one drive electrode.

3. The angular sensor of claim 2 , comprising:
a coarse readout circuit configured for:
driving the first pair of modes,
measuring motion of the first pair of modes with a first sensitivity, and
deriving from the measured motion of the first pair of modes a coarse measurement of a true angular rate of the CVG resonator; and
a fine readout circuit configured for:
receiving the coarse measurement,
driving the second pair of modes,
measuring motion of the second pair of modes with a second sensitivity higher than the first sensitivity; said measuring being offset by said coarse measurement and
deriving, from the measured motion of the second pair of modes and the received coarse measurement, a fine measurement of the true angular rate of the CVG resonator.

4. The angular sensor of claim 3 , wherein the coarse readout circuit comprises, for said driving the first pair of modes:
a first frequency reference configured to generate a first reference signal; and
a first phase control circuit configured to:
measure a first phase difference between a first phase target, and the difference between: a phase of an oscillation of the first normal mode and a phase of the first reference signal;
apply a first phase correction signal to the CVG resonator, to reduce the first phase difference; and
a second phase control circuit configured to:
measure a second phase difference between a second phase target, and the difference between: a phase of an oscillation of the second normal mode and the phase of the first reference signal; and
apply a second phase correction signal to the CVG resonator, to reduce the second phase difference.

5. The angular sensor of claim 4 , wherein the fine readout circuit comprises, for said driving the second pair of modes:
a second frequency reference configured to generate a second reference signal;
a third phase control circuit configured to:
measure a third phase difference between a third phase target, and the difference between: a phase of an oscillation of the third normal mode and a phase of the second reference signal; and
apply a third phase correction signal to the CVG resonator, to reduce the third phase difference; and
a fourth phase control circuit configured to:
measure a fourth phase difference between a fourth phase target, and the difference between: a phase of an oscillation of the fourth normal mode and the phase of the second reference signal; and
apply a fourth phase correction signal to the CVG resonator, to reduce the fourth phase difference.

6. The angular sensor of claim 4 , wherein the frequency reference comprises an atomic frequency reference; or an ovenized crystal oscillator (OCXO) or a temperature controlled crystal oscillator (TCXO).

7. The angular sensor of claim 6 , wherein the atomic frequency reference is a rubidium, cesium, or hydrogen or strontium based dock.

8. The angular sensor of claim 6 , wherein the atomic frequency reference is a chip-scale atomic clock (CSAC).

9. The angular sensor of claim 4 , wherein the first phase control circuit is configured to apply a first phase correction signal to the CVG resonator by adjusting a natural frequency of the first normal mode.

10. The angular sensor of claim 4 , wherein the first phase control circuit is configured to adjust the natural frequency of the first normal mode by applying a bias voltage to a first tuning electrode of the CVG resonator.

11. The angular sensor of claim 4 , wherein the second phase control circuit is configured to adjust a natural frequency of the second normal mode by applying a bias voltage to a second tuning electrode of the CVG resonator.

12. The angular sensor of claim 3 , wherein the fine readout circuit is configured to drive the third normal mode at a first drive frequency and to drive fourth normal mode at a second drive frequency, and
wherein the fine readout circuit is configured to derive the fine measurement of the true angular rate of the CVG resonator by adjusting the first drive frequency and the second drive frequency so that the difference between the first drive frequency and the second drive frequency is proportional to the coarse measurement.

13. The angular sensor of claim 3 , wherein the fine readout circuit is configured to derive the fine measurement of the true angular rate of the CVG resonator by adjusting a natural frequency of the third normal mode and a natural frequency of fourth normal mode so that the difference between the natural frequency of the third normal mode and the natural frequency of the fourth normal mode is proportional to the coarse measurement.

14. The angular sensor of claim 13 , wherein the fine readout circuit is configured to adjust the natural frequency of the third normal mode by adjusting a bias voltage applied to a tuning electrode coupled to the third normal mode.

15. The angular sensor of claim 3 , wherein the fine readout circuit is configured to generate a measurement of the difference between the true angular rate of the CVG resonator and the coarse measurement with a resolution of 19 bits.

16. The angular sensor of claim 3 , wherein the coarse readout circuit is configured to generate a measurement of the difference between the true angular rate of the CVG resonator and the coarse measurement with a resolution of 19 bits.

17. The angular sensor of claim 16 wherein the fine readout circuit is configured to generate a measurement of the difference between the true angular rate of the CVG resonator and the coarse measurement with a resolution of 19 bits.

18. The angular sensor of claim 3 , wherein the coarse readout circuit is configured to drive the first pair of modes so that an amplitude of motion of first normal mode is about 10 times an amplitude of motion of the second normal mode.

19. The angular sensor of claim 3 , wherein the coarse readout circuit is configured to drive the first pair of modes so that a phase of motion of first normal mode is about 90 degrees different from a phase of motion of the second normal mode.

20. The angular sensor of claim 3 , wherein the fine readout circuit is configured to drive the first pair of modes so that an amplitude of motion of the third normal mode is about 10 times an amplitude of motion of the fourth normal mode.

21. The angular sensor of claim 3 , wherein the fine readout circuit is conf

Assignees

• Hrl Lab Llc

Inventors

• Sorenson Logan D
• Nguyen Hung
• Perahia Raviv
• Huang Lian X
• Chang David T

Classifications

• G01C19/5684 Primary

  the devices involving a micromechanical structure · CPC title

• G01C19/025

  Gyroscopes functioning for short periods · CPC title

• G01C19/5712

  the devices involving a micromechanical structure · CPC title