Micro-machined gyro sensor with detection in the machined plate plane

• US 20060037396A1
• Filed: 11/03/2003
• Published: 02/23/2006
• Est. Priority Date: 11/05/2002
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Rougeot, Claude, Leverrier, Bertrand, Inglese, Jerome, Nicu, Liviu
• Granted Patent: US 7,159,460 B2
• Time in Patent Office: Days
• US Class Current: 73/504.120
• 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 on a silicon wafer. The gyroscope comprises two symmetrical moving assemblies coupled via a coupling structure. Each of the two assemblies comprises a moving mass surrounded by a moving intermediate frame. The frame is connected to the coupling structure and can vibrate in two degrees of freedom in orthogonal directions Ox and Oy in the plane of the wafer. The mass is connected on one side to the frame and on the other side to fixed anchoring regions via linking means that allow the vibration movement along the Oy direction to be transmitted to the mass without permitting movement of the mass along the Ox direction. An excitation structure is associated with the frame in order to excite its vibration along Ox. A movement detection structure is associated with the mass in order to detect its vibration along Oy.

Claims

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

two symmetrical moving assemblies coupled by a coupling structure that connects these two assemblies in order to allow mechanical vibration energy to be transferred between them, wherein 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 movement detection structure being associated with the second moving element in order to detect a vibration of the second element along Oy, the first moving element being a rectangular 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.

2. The gyroscope as claimed in claim 1, wherein the moving mass is connected to the intermediate frame via at least two first narrow and elongate flexure arms that exhibit high resistance to elongation in the Oy direction and low stiffness in the Ox direction, and the moving mass is connected to at least one anchoring region via at least two second narrow and elongate flexure arms that exhibit high resistance to elongation in the Ox direction and low stiffness in the Oy direction.

3. The gyroscope as claimed in claim 2, wherein each first flexure arm is bent over in the form of a U and has two elongate portions extending along the Oy direction, these two portions being connected by a short linking element.

4. The gyroscope as claimed in claim 3, wherein the short linking element of one of the first arms is connected to the similar linking element of another first arm via a crosspiece elongated in the Ox direction.

5. The gyroscope as claimed in claim 1, wherein the coupling structure is connected to the first moving element of each assembly via short rigid links.

6. The gyroscope as claimed in claim 1, wherein the coupling structure comprises, around each moving assembly, an outer frame and a short linking bar between the outer frames.

7. The gyroscope as claimed in claim 1, wherein the structure for exciting the first moving element is a capacitive comb with interdigitated electrodes, which is machined in the thin flat wafer.

8. The gyroscope as claimed in claim 1, wherein the structure for detecting movement of the second moving element is a capacitive comb with interdigitated electrodes, which is machined in the thin flat wafer.

9. The gyroscope as claimed in claim 1, wherein the gyroscope includes at least one interdigitated comb associated with the second moving element of each assembly, for detecting the movement of the latter along Oy, and at least one additional interdigitated comb, electrically separated from the first, for exerting, on the second moving element, by applying an adjustable voltage to this additional comb, an adjustable force allowing the natural resonant frequency of the moving assembly to be modified.

10. The gyroscope as claimed in claim 1, wherein the gyroscope includes at least one interdigitated comb associated with the second moving element of each assembly, for detecting the movement of the latter along Oy, and at least one additional interdigitated comb associated with the second moving element (30) of each assembly, in order to exert, by applying an adjustable voltage to this additional comb, an adjustable torque on the second moving element about an axis Oz perpendicular to Ox and Oy.

11. The gyroscope as claimed in claim 1, wherein the gyroscope includes at least three interdigitated combs associated with the second moving element, the first one for detecting the movement of the second moving assembly along Oy, the second one for adjusting the detection frequency and the third one for exerting an adjustable torque on the second moving element.