Modal decoupling via flexure-based transmissions as applied to a micromachined tuning fork gyroscope

• US 9,546,868 B2
• Filed: 07/24/2014
• Issued: 01/17/2017
• Est. Priority Date: 07/26/2013
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated, Massachusetts Institute of Technology
• Original Assignee: Charles Stark Draper Laboratory Incorporated, Massachusetts Institute of Technology
• Inventors: DiBiasio, Christopher Michael, Culpepper, Martin Luther, Thomas, Marcel, Panas, Robert Matthew
• Primary Examiner(s): CULLER, JILL E
• Application Number:
  US14/340,042
• Publication Number:
  US 20150168145A1
• Time in Patent Office: 908 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

A gyroscope includes a first mass, a second mass, and a drive structure configured to drive each of the first mass and the second mass in a drive mode. The drive structure includes a first portion and a second portion, with the first portion being configured to drive the first mass in a direction along a drive axis and the second portion being configured to drive the second mass in a direction opposite to the first mass along the drive axis. The gyroscope further includes a sense structure configured to sense motion of each of the first mass and the second mass in a sense mode along a direction substantially perpendicular to the drive axis, and a plurality of flexures configured to couple the first portion to the second portion and further configured to decouple the drive mode and the sense mode.

Claims

1. A gyroscope comprising:

a first mass and a second mass;

a drive structure configured to drive each of the first mass and the second mass in a drive mode, the drive structure including a first portion and a second portion, the first portion being configured to drive the first mass in a direction along a drive axis and the second portion being configured to drive the second mass in a direction opposite to the first mass along the drive axis;

a sense structure configured to sense motion of each of the first mass and the second mass in a sense mode along a direction substantially perpendicular to the drive axis; and

a plurality of flexures configured to couple the first portion to the second portion and further configured to decouple the drive mode and the sense mode,

wherein the gyroscope is a planar gyroscope, the drive structure and the sense structure being disposed in a plane of the gyroscope and the plurality of flexures being oriented substantially perpendicular to the plane,

wherein at least one flexure is configured to couple the first mass to the first portion, the at least one flexure being oriented substantially parallel to the plane, and

wherein the at least one flexure is configured to be compliant to allow displacement of the first mass along the drive axis and along the direction substantially perpendicular to the drive axis out of the plane of the gyroscope and further configured to be stiff to motion of the first mass in other directions.

2. The gyroscope of claim 1, wherein the drive structure further includes a third portion coupled to the first portion and the second portion by a first subset of the plurality of flexures.

3. The gyroscope of claim 2, wherein the drive structure further includes a fourth portion coupled to the first portion and the second portion by a second subset of the plurality of flexures.

4. The gyroscope of claim 3, wherein the first portion and the second portion are arranged along the drive axis in a plane of the gyroscope and the third portion and the fourth portion are arranged substantially perpendicular to the drive axis in the plane.

5. The gyroscope of claim 4, wherein the third portion is configured to move towards the fourth portion substantially perpendicular to the drive axis in response to the first portion moving away from the second portion along the drive axis.

6. The gyroscope of claim 4, further comprising an anchor positioned around the drive structure, at least some flexures of the plurality of flexures being coupled to the anchor.

7. The gyroscope of claim 1, further comprising at least one flexure configured to couple the first mass to the first portion, the at least one flexure being oriented substantially perpendicular to the plane.

8. The gyroscope of claim 7, wherein the at least one flexure is configured to allow displacement of the first mass along the drive axis and along the direction substantially perpendicular to the drive axis in the plane of the gyroscope.

9. The gyroscope of claim 8, wherein the at least one flexure is further configured to be stiff to motion of the first mass in other directions.

10. The gyroscope of claim 8, further comprising at least one other flexure configured to couple the second mass to the second portion, the at least one other flexure being oriented substantially perpendicular to the plane and being configured to allow displacement of the second mass along the drive axis and along the direction substantially perpendicular to the drive axis in the plane of the gyroscope.

11. The gyroscope of claim 1, further comprising at least one other flexure configured to couple the second mass to the second portion, the at least one other flexure being oriented substantially parallel to the plane and being configured to be compliant to displacement of the second mass along the drive axis and along the direction substantially perpendicular to the drive axis out of the plane of the gyroscope.

12. The gyroscope of claim 1, wherein the gyroscope is a macromachined gyroscope.

13. The gyroscope of claim 1, wherein the gyroscope is a MEMS gyroscope.

14. The gyroscope of claim 1, wherein the sense structure includes a first prong coupled to the first mass and a second prong coupled to the second mass.

15. The gyroscope of claim 1, wherein the sense structure is coupled to a first anchor and centered in a plane of the gyroscope and the drive structure is disposed around the sense structure, the drive structure being coupled to a second anchor by at least one of the plurality of flexures.

16. The gyroscope of claim 1, wherein the drive structure is decoupled from the sense structure.

17. The gyroscope of claim 1, wherein each of the drive mode and the sense mode is independently tunable.