Vibratory Gyroscope Balanced by an Electrostatic Device

• US 20080282833A1
• Filed: 12/07/2006
• Published: 11/20/2008
• Est. Priority Date: 12/13/2005
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Chaumet, Bernard
• Granted Patent: US 8,104,364 B2
• Time in Patent Office: Days
• US Class Current: 74/5R
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01C 19/5762 the sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: Y10T 74/12 Gyroscopes
• CPC Class Codes: Y10T 74/125 by magnetic field
• CPC Class Codes: Y10T 74/1254 by motor torque
• CPC Class Codes: Y10T 74/1282 with rotor drive

Abstract

The invention relates to a gyroscope with a vibrating structure, produced by micromachining in a thin wafer, which comprises a movable inertial assembly (1) comprising at least one movable mass (50) able to vibrate in the plane of the wafer along a drive axis x and along a sense axis y roughly perpendicular to the x-axis, an interdigital sensor comb (90) and an interdigital drive comb (70). It furthermore comprises at least one additional interdigital comb (10a), called the quadrature-error compensation comb, connected to the mass (50) and which has two asymmetric air gaps e and λe, λ being a positive real number, for subjecting the mass to an adjustable electrostatic stiffness due to coupling between the x-axis and the y-axis by applying a variable DC voltage V to this comb, the adjustable stiffness allowing compensation for the quadrature error of the gyroscope.

Claims

1. A gyroscope with a vibrating structure, produced by micromachining in a thin wafer, which comprises a movable inertial assembly comprising at least one movable mass able to vibrate in the plane of the wafer along a drive axis x and along a sense axis y roughly perpendicular to the x-axis, an interdigital sensor comb and an interdigital drive comb, at least one additional interdigital comb, called the quadrature-error compensation comb, connected to the mass and which has two asymmetric air gaps e and λ

e, λ

being a positive real number, for subjecting the mass to an adjustable electrostatic stiffness due to coupling between the x-axis and the y-axis by applying a variable DC voltage V to this comb, the adjustable stiffness allowing compensation for the quadrature error of the gyroscope.

2. The gyroscope as claimed in claim 1, wherein the quadrature-error compensation comb(s) (10a) is (are) arranged along the y-axis.

3. The gyroscope as claimed in claim 1, wherein when the movable inertial assembly has a symmetry axis parallel to the x-axis, it comprises a second quadrature-error compensation comb, the two compensation combs being arranged symmetrically in relation to the symmetry axis and wherein the second comb has along y two air gaps symmetrical to the air gaps of the first comb relative to the symmetry axis.

4. The gyroscope as claimed in claim 2, wherein when the movable inertial assembly has a symmetry axis parallel to the y-axis, it comprises a third and a fourth quadrature-error compensation comb, these two compensation combs being respectively symmetrical to the first and second combs in relation to the symmetry axis parallel to y.

5. The gyroscope as claimed in claim 3, wherein when the movable inertial assembly has a symmetry axis parallel to the y-axis, it comprises a third and a fourth quadrature-error compensation comb, these two compensation combs being respectively symmetrical to the first and second combs in relation to the intersection between the symmetry axis parallel to x and the symmetry axis parallel to y.

6. The gyroscope as claimed in claim 1, wherein the movable inertial assembly includes a second mass able to vibrate along the sense axis y.

7. The gyroscope as claimed in claim 6, including a third mass able to vibrate in opposite phase to the second mass along the sense axis y.

8. The gyroscope as claimed in claim 1, wherein the movable inertial assembly furthermore comprises at least one interdigital comb for adjusting the sensing frequency which has two identical air gaps e′

and which is linked with a mass able to vibrate along the sense axis y.

9. The gyroscope as claimed in claim 8, wherein the comb for adjusting the sensing frequency is positioned along the y-axis.

10. The gyroscope as claimed in claim 6, wherein the movable assembly is designated the first movable assembly, it comprises a second movable assembly which comprises the same elements as the first movable assembly (1) and a coupling structure that links these two assemblies to each other and allows a transfer of mechanical vibration energy between them.

11. A simple or double tuning fork gyroscope as claimed in the claim 10.