Micro-machined gyrometric sensor for differential measurement of the movement of vibrating masses

• US 7,707,886 B2
• Filed: 06/19/2006
• Issued: 05/04/2010
• Est. Priority Date: 07/05/2005
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Le Verrier, Bertrand, Chaumet, Bernard, Willemin, Jerome, Rougeot, Claude
• Primary Examiner(s): Kwok; Helen C.
• Application Number:
  US11/994,825
• Publication Number:
  US 20080210005A1
• Time in Patent Office: 1,415 Days
• Field of Search: 735/041.2, 735/041.4, 735/040.4, 735/041.5, 735/041.6, 735/040.2
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

The invention relates to a microgyroscope, that is to say an inertial micromechanical sensor dedicated to the measurement of angular velocities, which is produced by micromachining techniques, and has a novel arrangement of the modules for measuring the movement of the vibrating masses. The gyroscope comprises two symmetrical moving assemblies (30, 50; 30′, 50′) that are coupled by a coupling structure (20, 20′, 22). Each of the two assemblies comprises a moving mass (30) surrounded by a moving intermediate frame (50). The frame (50) is connected to the coupling structure (20, 20′, 22) and can vibrate in two degrees of freedom in orthogonal directions Ox and Oy of the plane of the wafer. The mass (30) is connected, on one side, to the frame and, on the other side, to fixed anchoring regions (34, 36) via linking means (40-46; 52-58) that allow the vibration movement in the Oy direction to be transmitted to the mass without permitting any movement of the mass in the Ox direction. An excitation structure (70) is associated with the frame in order to excite its vibration along Ox. A movement detection structure (90) is associated with the mass (30) in order to detect its vibration along Oy.

Claims

1. A gyroscope with a vibrating structure, produced by micromachining a thin planar wafer, comprising:

two symmetrical moving assemblies that are symmetrical with respect to a central axis parallel to a direction Oy of the plane of the wafer and are coupled by a coupling structure that connects these two assemblies in order to allow mechanical vibration energy to be transferred between them, each of the two symmetrical moving assemblies comprises two moving elements, an inertial first moving element being connected to the coupling structure and able to vibrate in two degrees of freedom in orthogonal directions Ox and Oy of the plane of the wafer, and a second moving element being connected, on one side, to the first element and, on the other side, to fixed anchoring regions via linking means that allow the vibration movement of the first element in the Oy direction to be transmitted to the second element without permitting any movement of the second element in the Ox direction, an excitation structure being associated with the first moving element in order to excite a vibration of the first element along Ox, and a double movement detection structure comprising first and second elementary detection structures being associated with the second moving element of each of the two assemblies in order to detect a vibration of the second elements along Oy, the first moving element being an intermediate frame surrounding the second moving element, denoted by the name moving mass, and the coupling structure comprising two outer frames, each of which surrounds the intermediate frame of a respective moving assembly, wherein each elementary detection structure comprises a first detection module and a second detection module which are symmetrical with respect to an axis of symmetry parallel to the Ox direction, the first detection modules of each elementary structure on the one hand and the second detection modules of each elementary structure on the other hand being symmetrical with respect to the central axis parallel to the Oy direction, the first and second modules of each elementary structure delivering separate detection signals that vary inversely with respect to one another, these being first and second signals S1M1, S1M2 in the case of the first and second modules of the first elementary structure and third and fourth signals S2M1, S2M2 in the case of the first and second modules of the second elementary structure, and means being provided for producing the linear combination S1M1+S2M2−

S1M2−

S2M1.

2. The gyroscope as claimed in claim 1, wherein the first module of the first elementary structure is electrically connected to the second module of the second elementary structure in order to produce a first sum S1M1+S2M2, and reciprocally the second module of the first elementary structure is electrically connected to the first module of the second elementary structure in order to produce a second sum S1M2+S2M1, and in that means are provided for subtracting the second sum from the first sum.

3. The gyroscope as claimed in claim 1, wherein the excitation structure of the first moving element is a capacitive comb with interdigitated electrodes, said comb being machined in the thin planar wafer.

4. The gyroscope as claimed in claim 1, wherein the detection modules of the elementary detection structure comprise at least one capacitive comb with interdigitated electrodes, said comb being machined in the thin planar wafer.

5. The gyroscope as claimed in claim 1, comprising at least one interdigitated comb associated with each second moving element, in order to exert an adjustable torque on the second moving element.

6. The gyroscope as claimed in claim 1, comprising at least an interdigitated comb associated with each second moving element, in order to adjust the detection frequency.

7. The gyroscope as claimed in claim 1, comprising at least one interdigitated comb associated with each second moving element, in order to slave the position of the second moving element on a position which may be that which the second moving element occupies when it is at rest.

8. The gyroscope as claimed in claim 2, wherein the excitation structure of the first moving element is a capacitive comb with interdigitated electrodes, said comb being machined in the thin planar wafer.

9. The gyroscope as claimed in claim 2, wherein the detection modules of the elementary detection structure comprise at least one capacitive comb with interdigitated electrodes, said comb being machined in the thin planar wafer.

10. The gyroscope as claimed in claim 4, comprising at least one interdigitated comb associated with each second moving element, in order to exert an adjustable torque on the second moving element.

11. The gyroscope as claimed in claim 2, comprising at least an interdigitated comb associated with each second moving element, in order to adjust the detection frequency.

12. The gyroscope as claimed in claim 2, comprising at least one interdigitated comb associated with each second moving element, in order to slave the position of the second moving element on a position which may be that which the second moving element occupies when it is at rest.

13. The gyroscope as claimed in claim 8, wherein the detection modules of the elementary detection structure comprise at least one capacitive comb with interdigitated electrodes, said comb being machined in the thin planar wafer.

14. The gyroscope as claimed in claim 3, comprising at least one interdigitated comb associated with each second moving element, in order to exert an adjustable torque on the second moving element.

15. The gyroscope as claimed in claim 3, comprising at least an interdigitated comb associated with each second moving element, in order to adjust the detection frequency.

16. The gyroscope as claimed in claim 3, comprising at least one interdigitated comb associated with each second moving element, in order to slave the position of the second moving element on a position which may be that which the second moving element occupies when it is at rest.

17. The gyroscope as claimed in claim 4, comprising at least one interdigitated comb associated with each second moving element, in order to slave the position of the second moving element on a position which may be that which the second moving element occupies when it is at rest.