Twin axis gyroscope

• US 6,401,534 B1
• Filed: 10/13/1999
• Issued: 06/11/2002
• Est. Priority Date: 03/14/1998
• Status: Expired due to Fees

• Current Assignee: Atlantic Inertial Systems Ltd (Rtx Corporation)
• Original Assignee: BAE Systems Plc
• Inventors: Fox, Colin Hnery John, Fell, Christopher
• Primary Examiner(s): MOLLER, RICHARD ALAN
• Application Number:
  US09/417,302
• Time in Patent Office: 972 Days
• Field of Search: 735/041.3, 735/041.2, 735/040.2, 735/041.4
• US Class Current: 73/504.13
• CPC Class Codes: G01C 19/5677 of essentially two-dimensional vibrators, e.g. ring-shaped vibrators

Abstract

A two axis gyroscope has a substantially planar vibratory resonator having a substantially ring or hoop-like shape structure, carrier mode drive means for causing the resonator to vibrate in a Cosnθ out-of-plane carrier mode, where n has an integer value of 2 or more, support means for flexibly supporting the resonator, carrier mode pick-off means for sensing out-of-plane movement of the resonator, X axis response mode pick-off means for sensing in-plane Cosn₁θ response mode movement of the resonator in response to rotation of the gyroscope about the X axis, where n₁ has a value of n+1 or n−1, and Y axis response mode pick-off means for sensing in-plane Sinn₁θ response mode movement of the resonator in response to rotation of the gyroscope about the Y axis where n₁ has a value of n+1 or n−1, identical to that for the X axis response mode.

Claims

1. A two axis gyroscope including a substantially planar vibratory resonator having a substantially ring or hoop-like shape structure with inner and outer peripheries extending around a common axis, carrier mode drive means for causing the resonator to vibrate in a Cosnθ

out-of-plane carrier mode, where n has an integer value of 2 or more, support means for flexibly supporting the resonator and for allowing the resonator to vibrate, in response to the carrier mode drive means, relative to the support means, carrier mode pick-off means for sensing out-of-plane movements of the resonator, X axis response mode pick-off means for sensing in-plane Cosn₁θ

response mode movement of the resonator in response to rotation of the gyroscope about the X axis where n₁ has a value of n plus 1 or n minus 1, and Y axis response mode pick-off means for sensing in-plane Sinn₁θ

response mode movement of the resonator in response to rotation of the gyroscope about the Y axis, where n₁ has a value of n plus 1 or n minus 1, identical to that for the X axis response mode.

2. A gyroscope according to claim 1, including X axis response mode drive means for nulling the X axis response mode movement of the resonator to permit the gyroscope to be operated in a forced feedback configuration.

3. A gyroscope according to claim 1 including Y axis response mode drive means for nulling the Y axis response mode movement of the resonator to permit the gyroscope to be operated in a forced feedback configuration.

4. A gyroscope according to claim 1 wherein the support means includes a plurality of flexible legs flexibly connecting the resonator to a support, with the number of legs being given by N equals 4n₁ and with the angular separation between the legs being given by 360°

divided by N.

5. A gyroscope according to claim 1 wherein the resonator is made from metal, quartz, polysilicon or bulk silicon.

6. A gyroscope according to claim 1 wherein the drive means and/or the pick-off means are electrostatic, electromagnetic, piezo or optical.

7. A gyroscope according to claim 1 wherein the carrier mode is a Cos2θ

out-of-plane mode, the X axis response mode is an in-plane Cosθ

mode, and the Y axis response mode is an in-plane Sinθ

mode, with the carrier mode drive means including two drive elements located at 0° and

180°

with respect to a fixed reference axis in the plane of the resonator, with the carrier mode pick-off means including two pick-off elements located at 90° and

270°

with respect to the fixed reference axis, with the X axis pick-off means including a pick-off element located at 0°

with respect to the fixed reference axis, with the Y axis pick-off means including a pick-off element located at 90°

with respect to the fixed reference axis, with the X axis drive means including a drive element located at 180°

with respect to the fixed reference axis and with the Y axis drive means including a drive element located at 270°

with respect to the fixed reference axis.

8. A gyroscope according to claim 1 wherein the carrier mode is a Cos2θ

out-of-plane mode, the X axis response mode is an in-plane Cos3θ

mode, and the Y axis response mode is an in-plane Sin3θ

mode, with the carrier mode drive means including two drive elements located at 0° and

180°

with respect to a fixed reference axis in the plane of the resonator, with the carrier mode pick-off means including two pick-off elements located at 90° and

270°

with respect to the fixed reference axis, with the X axis pick-off means including three pick-off elements located at 0°

, 120° and

240°

with respect to the fixed reference axis, with the Y axis pick-off means including three pick-off elements located at 30°

, 150° and

270°

with respect to the fixed reference axis, with the X axis drive means including three drive elements located at 60°

, 180° and

300°

with respect to the fixed reference axis and with the Y axis drive means including three drive elements located at 90°

, 210° and

330°

with respect to the fixed reference axis.

9. A gyroscope according to claim 1 wherein the carrier mode is a Cos3θ

out-of-plane mode, the X axis response mode is an in-plane Cos2θ

mode, and the Y axis response mode is an in-plane Sin2θ

mode, with the carrier mode drive means including three drive elements located at 0°

, 120° and

240°

with respect to a fixed reference axis in the plane of the resonator, with the carrier mode pick-off means including three pick-off elements located at 60°

, 180° and

300°

with respect to the fixed reference axis, with the X axis pick-off means including two pick-off elements located at 0° and

180°

with respect to the fixed reference axis, with the Y axis pick-off means including two pick-off elements located at 45° and

225°

with respect to the fixed reference axis, with the X axis drive means including two drive elements located at 90° and

270°

with respect to the fixed reference axis, and with the Y axis drive means including two drive elements located at 135° and

315°

with respect to the fixed reference axis.

10. A gyroscope according to claim 1 wherein the carrier mode is a Cos3θ

out-of-plane mode, the X axis response mode is an in-plane Cos4θ

mode, and the Y axis response mode is an in-plane Sin4θ

mode, with the carrier mode drive means including three drive elements located at 0°

, 120° and

240°

with respect to a fixed reference axis in the plane of the resonator, with the carrier mode pick-off means including three pick-off elements located at 60°

, 180° and

300°

with respect to the fixed reference axis, with the X axis pick-off means including four pick-off elements located at 0°

, 90°

, 180° and

270°

with respect to the fixed reference axis, with the Y axis pick-off means including four pick-off elements located at 22.5°

, 112.5°

, 202.5° and

292.5°

with respect to the fixed reference axis, with the X axis drive means including four drive elements located at 45°

, 135°

, 225° and

315°

with respect to the fixed reference axis, and with the Y axis drive means including four drive elements located at 67.5°

, 157.5°

, 247.5° and

337.5°

with respect to the fixed reference axis.

11. A gyroscope according to claim 2, including Y axis response mode drive means for nulling the Y axis response mode movement of the resonator to permit the gyroscope to be operated in a forced feedback configuration.

12. A gyroscope according to claim 2, wherein the support means includes a plurality of flexible legs flexibly connecting the resonator to a support, with the number of legs being given by N equals 4n₁ and with the angular separation between the legs being given by 360°

divided by N.

13. A gyroscope according to claim 3, wherein the support means includes a plurality of flexible legs flexibly connecting the resonator to a support, with the number of legs being given by N equals 4n₁ and with the angular separation between the legs being given by 360°

divided by N.

14. A gyroscope according to claim 2, wherein the resonator is made from metal, quartz, polysilicon or bulk silicon.

15. A gyroscope according to claim 3, wherein the resonator is made from metal, quartz, polysilicon or bulk silicon.

16. A gyroscope according to claim 4, wherein the resonator is made from metal, quartz, polysilicon or bulk silicon.

17. A gyroscope according to claim 2, wherein the drive means and/or the pick-off means are electrostatic, electromagnetic, piezo or optical.

18. A gyroscope according to claim 3, wherein the drive means and/or the pick-off means are electrostatic, electromagnetic, piezo or optical.

19. A gyroscope according to claim 4, wherein the drive means and/or the pick-off means are electrostatic, electromagnetic, piezo or optical.