TORSIONAL RATE MEASURING GYROSCOPE

• US 20150114115A1
• Filed: 06/04/2012
• Published: 04/30/2015
• Est. Priority Date: 06/04/2012
• Status: Active Grant

• Current Assignee: Emcore Corporation
• Original Assignee: Systron Donner Inertial, Inc. (Emcore Corporation)
• Inventors: Painter, Chris
• Granted Patent: US 9,581,445 B2
• Time in Patent Office: Days
• US Class Current: 73/504.16
• 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: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass
• CPC Class Codes: Y10T 74/1275 Electrical

Abstract

A torsional gyroscope is provided that includes: a pickup tine and a drive tine of piezoelectric material, pickup electrodes disposed along the pickup tine, drive electrodes disposed along the drive tine, and a drive mass. The drive tine has a first end attached to the pickup tine and is transverse to the drive tine. The drive mass is attached to a second end of the drive tine opposite the first end of the drive tine. An electric field applied to the drive electrodes induces a rotational oscillation of the drive tine causing the drive tine to rotate about the first axis, inducing the drive mass to rotate about the first axis. Angular rotation of the drive mass along a third axis induces a torque in the pickup tine that induces an electric field in the pickup tine that induces an electrical charge to build up in the pickup electrodes.

Claims

1. A torsional gyroscope comprising:

a drive tine having a length along a first axis, the drive tine comprising a piezoelectric material;

a pickup tine having a length along a second axis, the pickup tine comprising a piezoelectric material, the pickup tine being transverse to the drive tine, the drive tine having a first end attached to the pickup tine;

a plurality of pickup electrodes disposed along the pickup tine;

a plurality of drive electrodes disposed along the drive tine; and

a drive mass attached to a second end of the drive tine opposite the first end of the drive tine;

wherein the drive electrodes and the drive tine are configured such that an electric field applied to the drive electrodes will induce a rotational oscillation of the drive tine such that the drive tine will rotate about the first axis, inducing the drive mass to rotate about the first axis; and

wherein angular rotation of the drive mass about a third axis will induce a torque in the pickup tine that will induce an electric field in the pickup tine that will induce an electrical charge to build up in the plurality of pickup electrodes.

2. The torsional gyroscope of claim 1 wherein the piezoelectric material comprising at least one of the drive tine and the pickup tine is quartz.

3. The torsional gyroscope of claim 1 wherein the drive tine has a rectilinear cross-section, and wherein a drive electrode of the plurality of drive electrodes is disposed at each corner of the rectilinear cross-section.

4. The torsional gyroscope of claim 3 wherein the drive tine and the drive electrodes are configured such that the electric field applied to the drive electrodes induces a mechanical shear in the piezoelectric material comprising the drive tine.

5. The torsional gyroscope of claim 4 wherein the drive tine and the drive electrodes are configured such that the electric field applied to the drive electrodes will induce the drive tine to rotate about a centroid of the cross-section of the drive tine.

6. The torsional gyroscope of claim 1 wherein the pickup tine has a rectilinear cross-section, and wherein a pickup electrode of the plurality of pickup electrodes is disposed on each side of the rectilinear cross-section of the pickup tine.

7. The torsional gyroscope of claim 6 wherein the pickup tine and the drive tine are configured such that angular rotation of the drive mass about the third axis will induce angular rotation of the pickup tine that will induce the electric displacement field in the pickup tine.

8. The torsional gyroscope of claim 1 wherein the pickup tine is configured such that the charge induced on the plurality of pickup electrodes is proportional to the angular rotation rate of the drive mass about the third axis.

9. A planar three-dimensional inertial sensor system comprising:

a first gyroscopic sensor configured to measure rotation about a first axis of rotation;

a second gyroscopic sensor configured to measure rotation about a second axis of rotation;

a torsional gyroscopic sensor configured to measure rotation about a third axis of rotation;

wherein the first gyroscopic sensor, the second gyroscopic sensor, and the torsional gyroscopic sensor are disposed along a same plane.

10. The planar three-dimensional inertial sensor system of claim 9 wherein at least one of the first gyroscopic sensor and the second gyroscopic sensor is a tuning fork gyroscopic sensor.

11. The planar three-dimensional inertial sensor system of claim 9 wherein the torsional gyroscopic sensor is configured to measure angular rotation of a drive mass induced into rotational oscillation about the first axis of rotation, the torsional gyroscopic sensor being configured to measure angular rotation about the third axis of rotation.

12. The planar three-dimensional inertial sensor system of claim 9 wherein the torsional gyroscopic sensor comprises:

a drive tine having a length along a first axis, the drive tine comprising a piezoelectric material;

a pickup tine having a length along a second axis, the pickup tine comprising a piezoelectric material, the pickup tine being transverse to the drive tine, the drive tine having a first end attached to the pickup tine;

a plurality of pickup electrodes disposed along the pickup tine;

a plurality of drive electrodes disposed along the drive tine;

a drive mass attached to a second end of the drive tine opposite the first end of the drive tine;

wherein the drive electrodes and the drive tine are configured such that an electric field applied to the drive electrodes will induce a rotational oscillation of the drive tine such that the drive tine will rotate about the first axis, inducing the drive mass to rotate about the first axis; and

wherein angular rotation of the drive tine about a third axis will induce a torque in the pickup tine that will induce an electric field in the pickup tine that will induce an electrical charge to build up in the plurality of pickup electrodes.

13. A torsional gyroscope comprising:

a pickup frame having a central opening;

an anchor point disposed within the central opening of the pickup frame;

a plurality of pickup beams connecting the pickup frame to the anchor point, the pickup beams comprising a piezoelectric material;

a plurality of pickup electrodes attached to the pickup beams;

a drive frame having a central opening, the pickup frame being disposed within the central opening of the drive frame;

a plurality of drive beams, the drive beams connecting the drive frame to the pickup frame, the drive beams comprising a piezoelectric material; and

a plurality of drive electrodes disposed on the drive beams,

wherein the drive beams and the drive electrodes are configured such that an applying an electric field to the drive electrodes induces a rotational oscillation of the drive beams about a first axis, the rotation of the drive beams inducing the drive frame to rotate about the first axis;

wherein angular rotation of the drive frame about a third axis will induce a torque about a second axis, the torque being applied to the pickup frame which induces a strain in the pickup tines that will induce an electric displacement field pickup tines that will in turn induce an electric charge to build up in the plurality of pickup electrodes.

14. The torsional gyroscope of claim 13 wherein the piezoelectric material comprising at least one of the drive tine and the pickup tine is quartz.

15. The torsional gyroscope of claim 13 wherein the drive beams have a rectilinear cross-section, and wherein a drive electrode of the plurality of drive electrodes is disposed at each corner of the rectilinear cross-section.

16. The torsional gyroscope of claim 15 wherein the drive beams and the drive electrodes are configured such that the electric field applied to the drive electrodes induces a mechanical shear in the piezoelectric material comprising the drive beams.

17. The torsional gyroscope of claim 16 wherein the drive beams and the drive electrodes are configured such that the electric field applied to the drive electrodes induces the drive beams to rotate about a centroid of the cross-section of each of the drive tines.

18. The torsional gyroscope of claim 13 wherein the pickup beams have a rectilinear cross-section, and wherein a pickup electrode of the plurality of pickup electrodes is disposed on each side of the rectilinear cross-section of the pickup beams.

19. The torsional gyroscope of claim 18 wherein the pickup beams and the drive frame are configured such that angular rotation of the drive frame about the third axis will induce angular rotation of the pickup tines that will induce the electric displacement field in the pickup beams.

20. The torsional gyroscope of claim 13 wherein the pickup beams comprise a plurality of beams oriented such that the beams are oriented according to the crystalline structure of the piezoelectric material comprising the beams.

21. The torsional gyroscope of claim 20 wherein the plurality of beams are oriented to cancel at least a portion of anisotropic properties of the piezoelectric material comprising the beams.

22. The torsional gyroscope of claim 20 wherein the plurality of beams comprises quartz and the beams are oriented along an X crystal axis of the crystalline quartz.

23. The torsional gyroscope of claim 20 wherein the cross-members are aligned with the crystalline structure of the quartz to reduce the torsion of the cross-members along the second axis of rotation.

24. A differential torsional gyroscopic sensor comprising:

a first drive tine having a length along a first axis, the first drive tine comprising a first piezoelectric material;

a first pickup tine having a length along a second axis, the first pickup tine comprising a second piezoelectric material, the first pickup tine being transverse to the first drive tine, the first drive tine having a first end attached to the first pickup tine;

a plurality of first pickup electrodes disposed along the first pickup tine;

a plurality of first drive electrodes disposed along the drive tine;

a first drive mass attached to a second end of the first drive first tine opposite the first end of the first drive tine;

a second drive tine having a length along the first axis, the second drive tine comprising a third piezoelectric material;

a second pickup tine having a length along the second axis, the second pickup tine comprising a fourth piezoelectric material, the second pickup tine being transverse to the second drive tine, the second drive tine having a first end attached to the second pickup tine;

a plurality of second pickup electrodes disposed along the second pickup tine;

a plurality of second drive electrodes disposed along the second drive tine; and

a second drive mass attached to a second end of the second drive tine opposite the first end of the second drive tine;

wherein the first pickup tine and the second pickup tine share a common anchor point;

wherein the first drive electrodes and the first drive tine are configured such that an electric field applied to the first drive electrodes will induce a rotational oscillation of the first drive tine such that the first drive tine will rotate about the first axis, inducing the first drive mass to rotate about the first axis;

wherein angular rotation of the first drive tine about a third axis will induce a torque in the first pickup tine that will induce an electric field in the first pickup tine that will induce an electrical charge to build up in the first pickup electrodes;

wherein the second drive electrodes and the second drive tine are configured such that an electric field applied to the second drive electrodes will induce a rotational oscillation of the second drive tine such that the second drive tine will rotate about the first axis, inducing the second drive mass to rotate about the first axis; and

wherein displacement of the second drive tine along a third axis will induce a torque in the second pickup tine that will induce an electric field in the second pickup tine that will induce an electrical charge to build up in the second pickup electrodes.

25. The sensor of claim 24 wherein the first, second, third, and fourth piezoelectric materials comprise the same piezoelectric material.

26. The sensor of claim 24 wherein the first drive tine has a rectilinear cross-section, and wherein a drive electrode of the plurality of first drive electrodes is disposed at each corner of the rectilinear cross-section.

27. The sensor of claim 26 wherein the first drive tine and the first drive electrodes are configured such that the electric field applied to the first drive electrodes induces a mechanical shear in the piezoelectric material comprising the first drive tine.

28. The sensor of claim 27 wherein the first drive tine and the first drive electrodes are configured such that the electric field applied to the first drive electrodes induces the first drive tine to rotate about a centroid of the cross-section of the first drive tine.

29. The sensor of claim 24 wherein the first pickup tine has a rectilinear cross-section, and wherein a pickup electrode of the plurality of first pickup electrodes is disposed on each side of the rectilinear cross-section of the first pickup tine.

30. The sensor of claim 29 wherein the first pickup tine and the first drive tine are configured such that angular rotation of the first drive mass about the third axis will induce angular rotation of the first pickup tine that will induce the electric displacement field in the first pickup tine.

31. The sensor of claim 24 wherein the first drive tine and the second drive tine are configured such that applying an electrical field to the first drive electrodes and the second drive electrodes induces rotational oscillation of the first drive tine in a first direction and the second drive tine in a second direction opposite the first direction.