EXTENSION-MODE ANGULAR VELOCITY SENSOR

• US 20140047921A1
• Filed: 08/13/2013
• Published: 02/20/2014
• Est. Priority Date: 09/11/2009
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: SEEGER, Joseph, BOROVIC, Bruno
• Granted Patent: US 9,052,194 B2
• Time in Patent Office: Days
• US Class Current: 73/504.14
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion

Abstract

An angular velocity sensor including a drive extension mode. In one aspect, an angular rate sensor includes a base and at least three masses disposed substantially in a plane parallel to the base, the masses having a center of mass. At least one actuator drives the masses in an extension mode, such that in the extension mode the masses move in the plane simultaneously away or simultaneously towards the center of mass. At least one transducer senses at least one Coriolis force resulting from motion of the masses and angular velocity about at least one input axis of the sensor. Additional embodiments can include a linkage that constrains the masses to move in the extension mode.

Claims

1. An angular rate sensor comprising:

a base;

at least three masses disposed substantially in a plane parallel to the base, said masses having a center of mass;

at least one actuator that drives said masses in an extension mode, wherein in the extension mode said masses move in the plane simultaneously away or simultaneously towards said center of mass; and

at least one transducer that senses at least one Coriolis force resulting from motion of said masses and angular velocity about at least one input axis of the sensor.

2. The angular rate sensor of claim 1 further comprising:

a linkage that constrains said masses to move in said extension mode.

3. The angular rate sensor of claim 2 wherein the linkage further comprises:

a frame substantially parallel to the plane and flexibly coupled to said masses, wherein said masses surround an outside of said frame within said plane.

4. The angular rate sensor of claim 3 wherein said transducer comprises a capacitive sensor connected to said base and to said frame.

5. The angular rate sensor of claim 2 wherein the linkage further comprises:

a frame substantially parallel to the plane and flexibly coupled to said masses, wherein said frame surrounds an outside of said masses within said plane.

6. The angular rate sensor of claim 2 wherein said linkage is substantially stiff along an axis normal to the plane.

7. The angular rate sensor of claim 1 further comprising at least one frame flexibly connected to said masses.

8. The angular rate sensor of claim 7 wherein said masses surround at least one frame.

9. The angular rate sensor of claim 7 wherein said at least one frame surrounds said masses.

10. The angular rate sensor of claim 7 wherein said transducer comprises a capacitive sensor connected to said base and said frame.

11. The angular rate sensor of claim 7 wherein said frame is flexibly coupled to the base.

12. The angular rate sensor of claim 1 wherein the extension mode is a mechanical resonant mode in which the masses are moved at a resonant frequency.

13. The angular rate sensor of claim 1 wherein said at least three masses are substantially planar masses.

14. The angular rate sensor of claim 1 wherein said at least one actuator drives said masses as a single-drive system having a single drive mode, in which only a single drive circuit is used to control the at least one actuator, and wherein said at least one transducer senses a plurality of Coriolis forces resulting from motion of said masses and angular velocities about a plurality of input axes of the sensor.

15. The angular rate sensor of claim 1 wherein at least one of said masses is flexibly coupled to said base through an associated anchoring linkage.

16. The angular rate sensor of claim 15 wherein each of said anchoring linkages further comprises:

an actuator mass suspended to the base via an anchoring flexure; and

a coupling flexure flexibly coupling said associated mass to said actuator mass.

17. The angular rate sensor of claim 16 wherein said anchoring flexure is substantially stiff to rotation about said input axis, and said anchoring flexure is substantially compliant to motion in said extension mode.

18. The angular rate sensor of claim 16 wherein

said coupling flexure is substantially compliant to rotation about said input axis,

said coupling flexure is substantially stiff to translation along a line radiating from a center point of the angular rate sensor outwards, and

said coupling flexure is substantially compliant to rotation about said line radiating from said center point outwards.

19. The angular rate sensor of claim 1 wherein said center of mass does not move when said masses are moving in said extension mode.