INERTIAL SENSOR HAVING AN OSCILLATING ROTATING DISK

• US 20120006123A1
• Filed: 07/06/2011
• Published: 01/12/2012
• Est. Priority Date: 07/07/2010
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: WALTHER, Arnaud, ROBERT, Philippe
• Granted Patent: US 9,010,193 B2
• Time in Patent Office: Days
• US Class Current: 73/774
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

The present invention relates to an inertial rotary movement microsensor for detecting a rotational movement around what is referred to as an axis of rotation (X), provided with a part that is movable relative to a fixed part, the movable part comprising an excitation mass configured to undergo an oscillating movement in an excitation direction (Z) by an exciter so as to generate a Coriolis force induced by the rotational movement, a detection mass kinematically connected to the excitation mass by a linkage configured to transmit the Coriolis force at least partly without transmitting the oscillating movement around the excitation axis at least partly, a detector configured to measure the Coriolis force transmitted to the detection mass, characterized in that the detector is provided with at least one strain gauge suspended between the detection mass and an anchoring part integral with the fixed part.

Application to the technologies known as MEMS.

Claims

1. An inertial rotary movement microsensor for detecting a rotational movement around what is referred to as an axis of rotation (X), provided with a part that is movable relative to a fixed part, the movable part comprising:

an excitation mass configured to undergo an oscillating movement around what is referred to as an excitation axis (Z) by an exciter so as to generate a Coriolis force induced by the rotational movement,

a detector kinematically connected to the excitation mass by a linkage configured to transmit the Coriolis force at least partly without transmitting the oscillating movement around the excitation axis (Z) at least partly, and having one degree of freedom in rotation around what is known as an oscillation axis (Y), perpendicular to the axis of rotation (X),

a detector configured to measure the Coriolis force transmitted to the detection mass,

and wherein the detector is provided with at least one strain gauge suspended between the detection mass and an anchoring part integral with the fixed part, and wherein the at least one strain gauge is connected to the detection mass at a height level in the excitation axis (Z) different from that of the oscillation axis (Y) of the detection mass.

2. A microsensor according to claim 1, wherein at least one strain gauge is a piezoresistive gauge.

3. A microsensor according to claim 1, wherein the fixed part is provided with a substrate from which all or part of the movable part is constructed, the strain gauge extending in a plane parallel to the plane of the substrate, in a direction parallel to the axis of rotation (X).

4. A microsensor according to claim 3, wherein the detection mass is superposed on the fixed part in the excitation axis (Z) and is provided with an inside face opposite one face of the fixed part, the strain gauge being located in the extension of the inside face.

5. A microsensor according to the preceding claim 1, provided with an intermediate movable mass connected to the excitation mass so as to be subjected at least partly to the oscillating movement around the excitation axis (Z) and to the Coriolis force, and connected to the detection mass so as to transmit the Coriolis force at least partly and to be movable in rotation integrally with the detection mass in its oscillation axis (Y).

6. A microsensor according to claim 1, wherein the strain gauge is suspended from the anchoring part integral with the fixed part by way of an individual electrical contact.

7. A microsensor according to claim 1, wherein the detection mass is provided with a hole, at the position of which there is suspended the at least one strain gauge.

8. A microsensor according to the preceding claim, wherein the detection mass exhibits axial symmetry in the excitation axis (Z), the hole being located at the center of the detection mass.

9. A microsensor according to the preceding claim, wherein the detection mass is provided with a series of beams provided with at least one beam projecting toward the inside of the hole and to which the strain gauge is connected.

10. A microsensor according to the preceding claim, wherein the beam is oriented in the oscillation axis (Y) of the detection mass.

11. A microsensor according to the preceding claim, wherein the detection mass is provided with a second strain gauge connected to the beam in symmetrical relationship with the first strain gauge relative to the oscillation axis (Y) of the detection mass.

12. A microsensor according to claim 9, wherein the series of beams includes a second beam to form a pair of beams comprising at least one strain gauge connected to the second beam, the said second beam and the said at least one gauge being symmetric respectively relative to the first beam and to the at least one strain gauge connected to the first beam, in the axis of symmetry of the detection mass.

13. A microsensor according to claim 1, wherein the excitation mass and the detection element are configured to generate and transmit a second Coriolis force induced by a rotational movement around a second axis of rotation (Y) perpendicular to the axis of rotation (X), the micro sensor being provided with a second detector configured to measure the second Coriolis force transmitted to the detection mass, the detection mass having one degree of freedom in rotation around a second axis (X) referred to as oscillation axis.

14. A microsensor according to the preceding claim in combination with claim 5, wherein the intermediate mass has one degree of freedom in rotation around the second axis (X) referred to as oscillation axis.

15. A microsensor according to claim 13 in combination with claim 9, wherein the detection mass is provided with a second series of beams turned by 90°

relative to the first series of beams around the point of intersection of the first and second oscillation axes (X, Y) of the detection mass, and wherein the second detector is provided with piezoresistive gauges turned by 90°

relative to the piezoresistive gauges of the first detector around the point of intersection of the first and second oscillation axes (X, Y) of the detection mass.

16. A microsensor according to claim 1, wherein the excitation mass surrounds the detection mass.

17. A microsensor according to claim 1, provided with:

an additional mass connected to the excitation mass so as to exhibit a vibration movement in a direction perpendicular to the excitation axis (Z) and so as to generate a Coriolis force induced by a rotational movement of the additional mass in the excitation axis (Z),

an additional detector configured to measure the Coriolis force induced by a rotational movement of the additional mass in the excitation axis (Z).

18. A microsensor according to the preceding claim, wherein the additional mass has two parts constructed symmetrically relative to the excitation axis (Z), the additional detector cooperating with the two parts of the additional mass to achieve a differential measurement of the Coriolis force induced by the rotational movement of the additional mass in the excitation axis.

19. A microsensor according to the preceding claim, wherein each part of the additional mass is provided with a portion configured to be subjected to the vibration movement and a portion anchored to the fixed part so that it is not subjected to the vibration movement, the two parts being connected by an arm, the additional detector being provided with at least one strain gauge on each arm.

20. A microsensor according to claim 1, consisting of a micro electromechanical system.

21. A microsensor according to the preceding claim, wherein the at least one strain gauge comprises a deposit of electrically conductive material having piezoresistive properties.

22. A microsensor according to the preceding claim, wherein the deposit of material is obtained by engraving in a layer of material, and at least one electrically conductive organ is also obtained by engraving in the said layer of material.

23. An inertial rotary movement microsensor for detecting a rotational movement around what is referred to as an axis of rotation (X), provided with a part that is movable relative to a fixed part, the movable part comprising:

an excitation mass configured to undergo an oscillating movement around what is referred to as an excitation axis (Z) by an exciter so as to generate a Coriolis force induced by the rotational movement,

a detection mass kinematically connected to the excitation mass by a linkage configured to transmit the Coriolis force at least partly without transmitting the oscillating movement around the excitation axis (Z) at least partly, and having one degree of freedom in rotation around what is known as an oscillation axis (Y), perpendicular to the axis of rotation (X),

a detector configured to measure the Coriolis force transmitted to the detection mass, wherein the detector is provided with at least one strain gauge suspended between the detection mass and an anchoring part integral with the fixed part,

an additional mass connected to the excitation mass so as to exhibit a vibration movement in a direction perpendicular to the excitation axis (Z) and so as to generate a Coriolis force induced by a rotational movement of the additional mass in the excitation axis (Z),

an additional detector configured to measure the Coriolis force induced by a rotational movement of the additional mass in the excitation axis (Z).

24. A microsensor according to claim 23, wherein the additional mass has two parts constructed symmetrically relative to the excitation axis (Z), the additional detector cooperating with the two parts of the additional mass to achieve a differential measurement of the Coriolis force induced by the rotational movement of the additional mass in the excitation axis.

25. A microsensor according to claim 24, wherein each part of the additional mass is provided with a portion configured to be subjected to the vibration movement and a portion anchored to the fixed part so that it is not subjected to the vibration movement, the two parts being connected by an arm, the additional detector being provided with at least one strain gauge on each arm.