IMPROVEMENTS IN OR RELATING TO A GYROSCOPE

• US 20100218606A1
• Filed: 12/06/2007
• Published: 09/02/2010
• Est. Priority Date: 12/15/2006
• Status: Active Grant

• Current Assignee: Atlantic Inertial Systems Incorporated (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Atlantic Inertial Systems Incorporated (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Fell, Christopher Paul
• Granted Patent: US 7,958,781 B2
• Time in Patent Office: Days
• US Class Current: 73/504.130
• CPC Class Codes: G01C 19/5684 the devices involving a micromechanical structure

Abstract

A gyroscope structure 41 includes ring structure 42 supported from a central hub 43 by eight compliant support legs 44a to 44h. Primary drive transducers 45a and 45b and secondary drive transducers 46a and 46b are all located around and in spaced relationship with the external periphery of the ring structure 42 to create capacitive gaps and primary pick-off transducers 47a and 47b and secondary pick-off transducers 48a and 48b are all located around and in spaced relationship with the internal periphery of the ring structure 42 to create capacitive gaps. The gyroscope structure 41 includes sixteen capacitor plates 49a to 49p in spaced relationship to the ring structure 42 to create capacitive gaps. Two groups of capacitive plates 49a to 49d and 49i to 49l are all located around the internal periphery of the ring structure 42 and two groups of capacitor plates 49e to 49h and 49m to 49p are all located around the external periphery of the ring structure 42. Each capacitor plate 49a to 49p is arranged to generate a predetermined electrostatic force, which acts upon the ring structure 42 to locally adjust the stiffness of the ring structure 42.

The positioning of the transducers 45a to 48b and capacitor plates 49a to 49p reduces the effect of variation a capacitive gap with ring structure 42 due to temperature change, thereby improving the scalefactor of the gyroscope structure.

Claims

1. A vibrating structure gyroscope, including a semiconductor substrate, a vibrating planar ring structure, support means arranged to support the ring structure relative to the semiconductor substrate, the semiconductor substrate, ring structure and support means being arranged substantially co-planar with one another, at least one primary drive transducer arranged to cause the ring structure to oscillate in a primary mode at the resonant frequency of the primary mode, at least one primary pick-off transducer arranged to detect oscillation of the ring structure in the primary mode, at least one secondary pick-off transducer arranged to detect oscillation of a secondary mode induced when angular velocity is applied around an axis substantially perpendicular to the ring structure, at least one secondary drive transducer arranged to null the induced secondary mode oscillation, the primary and secondary drive transducers and the primary and secondary pick-off transducers all being arranged around the periphery of the ring structure and at least two oscillation frequency adjusting capacitor plates arranged around the periphery of the ring structure such that when a voltage is applied between at least one capacitor plate and the ring structure an electrostatic force is generated between the capacitor plate and the ring structure to differentially adjust the frequencies of the primary and secondary modes to reduce the difference between the frequencies of the primary and secondary modes, wherein at least one of the capacitor plates is located externally of the periphery of the ring structure and the other capacitor plate or capacitor plates are located internally of the periphery of the ring structure and wherein at least one of the drive transducers or pick-off transducers are located internally of the periphery of the ring structure and the other drive transducer or drive transducers or pick-off transducer or pick-off transducers are located externally of the periphery of the ring structure.

2. A vibrating structure gyroscope, as claimed in claim 1, wherein the capacitor plates are arranged in cooperating pairs and at least one capacitor plate of each cooperating pair of capacitor plates is located externally of the periphery of the ring structure and the other capacitor plate of each cooperating pair of capacitor plates is located internally of the periphery of the ring structure.

3. A vibrating structure gyroscope, as claimed in claim 1, wherein either the drive transducers or the pick-off transducers are arranged in pairs of cooperating transducers, and at least one transducer of each pair of cooperating transducers is located internally of the periphery of the ring structure and the other transducer of each pair of cooperating transducers is located externally of the periphery of the ring structure.

4. A vibrating structure gyroscope, as claimed in claim 1, wherein the capacitor plates are arranged in cooperating pairs and at least one cooperating pair of capacitor plates is located externally of the periphery of the ring structure and one or more other cooperating pair or cooperating pairs of capacitor plates are located internally of the periphery of the ring structure.

5. A vibrating structure gyroscope, as claimed in claim 1, wherein the capacitor plates are arranged in groups of four and at least one group of four capacitor plates is located externally of the periphery of the ring structure and the other group or groups of capacitor plates are arranged internally of the periphery of the ring structure.

6. A vibrating structure gyroscope, as claimed in claim 1, wherein the drive transducers or pick-off transducers are arranged in cooperating pairs and at least one cooperating pair of drive transducers or pick-off transducers is located internally of the periphery of the ring structure and the other cooperating pair or cooperating pairs of drive transducers or pick-off transducers are located externally of the periphery of the ring structure.

7. A vibrating structure gyroscope, as claimed in claim 1, including sixteen capacitor plates arranged in groups of four, wherein two of the groups of capacitor plates are located externally of the periphery of the ring structure and the other two groups of capacitor plates are located internally of the periphery of the ring structure.

8. A vibrating structure gyroscope, as claimed in claim 7, wherein the drive transducers or pick-off transducers are arranged in cooperating pairs, and two cooperating pairs of drive transducers or pick-off transducers are located internally of the periphery of the ring structure and the other two cooperating pairs of drive transducers or pick-off transducers are located externally of the periphery of the ring structure.

9. A vibrating structure gyroscope, as claimed in claim 7, wherein each capacitor plate of a group of four capacitor plates has a corresponding capacitor plate in each of the other groups of four capacitor plates, and corresponding capacitor plates are arranged to be connected to a common voltage supply.

10. A vibrating structure gyroscope, as claimed in claim 1, wherein the primary and secondary drive transducers, the primary and secondary pick-off transducers, and the capacitor plates are arranged substantially co-planar with one another and substantially co-planar with the semiconductor substrate.

11. A vibrating structure gyroscope, as claimed in claim 1, wherein the support means includes two or more radially compliant legs, each leg being supported at one end from a central hub of the semiconductor located internally of the ring structure and each leg connected at the other end to the internal periphery of the ring structure.

12. A vibrating structure gyroscope, as claimed in claim 1, wherein the support means includes two or more radially compliant legs, each leg being supported at one end from the semiconductor substrate externally of the ring structure and each leg connected at the other end to the external periphery of the ring structure.

13. A vibrating structure gyroscope, as claimed in claim 1, wherein the semiconductor substrate is sealed between two support substrates to form a sealed cavity encapsulating the ring structure, the support means, the primary and secondary drive transducers, the primary and secondary pick-off transducers and the capacitor plates.

14. A vibrating structure gyroscope, as claimed in claim 13, wherein the primary and secondary drive transducers, primary and secondary pick-off transducers and the capacitor plates are each carried by one of the two support substrates.

15. A vibrating structure gyroscope, as claimed in any claim 1, wherein the capacitor plates are arranged in groups of four capacitor plates, the groups of four capacitor plates being angularly located about the ring structure so that a first group of four capacitor plates substantially coincides with an angle θ

of the ring structure, a second group of four capacitor plates substantially coincides with the angle θ

offset by 90°

, a third group of four capacitor plates substantially coincides with the angle θ

offset by 180° and

a fourth group of four capacitor plates substantially coincides with the angle θ

offset by 270°

.