Torsional rate sensor with momentum balance and mode decoupling

• US 20060272411A1
• Filed: 06/06/2005
• Published: 12/07/2006
• Est. Priority Date: 06/06/2005
• Status: Active Grant

• Current Assignee: Emcore Corporation
• Original Assignee: Custom Sensors & Technologies Incorporated (Schneider Electric SE)
• Inventors: Acar, Cenk, Mao, Minyao
• Granted Patent: US 7,240,552 B2
• Time in Patent Office: Days
• US Class Current: 73/504.40
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

Rate sensor comprising two generally planar proof masses, means for driving the masses to oscillate in phase opposition about parallel drive axes in the planes of the masses, an input axis perpendicular to the drive axes, sense axes perpendicular to the drive axes and the input axis, means mounting the masses for torsional movement about the sense axes in response to Coriolis forces produced by rotation of the masses about the input axis, means constraining the two masses for anti-phase movement about both the drive axes and the sense axes, sensing frames coupled to the masses for movement in response to the torsional movement of the masses about the sense axes, and means responsive to movement of the sensing frames for monitoring rate of rotation about the input axis.

Claims

1. A rate sensor comprising two generally planar proof masses, means for driving the masses to oscillate in phase opposition about parallel drive axes in the planes of the masses, an input axis perpendicular to the drive axes, sense axes perpendicular to the drive axes and the input axis, means mounting the masses for torsional movement about the sense axes in response to Coriolis forces produced by rotation of the masses about the input axis, means constraining the two masses for anti-phase movement about both the drive axes and the sense axes, sensing frames coupled to the masses for movement in response to the torsional movement of the masses about the sense axes, and means responsive to movement of the sensing frames for monitoring rate of rotation about the input axis.

2. The rate sensor of claim 1 wherein the means constraining the two masses comprises a mechanical link between adjacent edges of the masses.

3. The rate sensor of claim 1 wherein the means for monitoring the rate of rotation comprises capacitors having plates which move relative to other plates in response to the movement of the sensing frames.

4. The rate sensor of claim 1 wherein the sensing frames are constrained for linear movement in response to the torsional movement of the masses.

5. The rate sensor of claim 1 wherein the sensing frames are constrained for rotational movement in response to the torsional movement of the masses.

6. A rate sensor comprising two generally planar proof masses mounted side-by-side for anti-phase torsional movement about a pair of spaced apart drive axes, an input axis perpendicular to the drive axes, sense axes perpendicular to the drive axes and the input axis, means mounting the masses for torsional movement about the sense axes in response to Coriolis forces produced by rotation of the masses about the input axis, means connecting adjacent inner edge portions of the two masses together for movement in concert about both the drive axes and the sense axes, a sensing frame constrained for linear movement, and links connecting the masses to the sensing frame for transforming torsional motion of the masses about the sense axes to linear motion of the sensing frame.

7. The rate sensor of claim 6 wherein the masses are mounted on gimbals which are rotatable about the drive axes, with flexures mounting the masses to the gimbals for torsional movement about the sense axes.

8. The rate sensor of claim 6 wherein the masses are mounted on gimbals for torsional movement about the drive axes, and the gimbals are mounted on flexures which permit torsional movement of the gimbals and the masses about the sense axes.

9. The rate sensor of claim 8 wherein the flexures are connected to anchors outside the masses.

10. The rate sensor of claim 8 wherein the flexures are connected to anchors near the centers of the masses.

11. The rate sensor of claim 6 wherein the means connecting the inner edge portions of the two masses together comprises a coupling link.

12. The rate sensor of claim 11 wherein the sensing frame and the coupling link have equal masses and linear acceleration of the sensing frame and the coupling link in a direction parallel to the drive axes balance each other out.

13. The rate sensor of claim 11 wherein the sensing frame has a greater mass than the coupling link and the sensor is responsive to linear acceleration of the sensing frame in a direction parallel to the drive axes as well as to rotation about the input axis.

14. A rate sensor comprising two generally planar proof masses, a drive axis in the plane of each of the masses, means for driving the masses to oscillate in phase opposition about the drive axes, an input axis perpendicular to the drive axes, sense axes perpendicular to the drive axes and the input axis, means mounting the masses for torsional movement about the sense axes in response to Coriolis forces produced by rotation of the masses about the input axis, means constraining the two masses for anti-phase movement about both the drive axes and the sense axes, a pair of sensing frames coupled to opposite sides of each of the masses for movement in opposite directions in response to the torsional movement of the masses about the sense axes, and electrode plates on the sensing frames which move in opposite directions relative to fixed plates on the opposite sides of the masses to form capacitors which change value in opposite directions in response to the torsional movement of the masses about the sense axes.

15. The rate sensor of claim 14 wherein the drive axes are spaced apart and parallel to each other.

16. The rate sensor of claim 14 wherein the sensing frames are constrained for movement in directions perpendicular to the drive axes.

17. The rate sensor of claim 14 wherein the means mounting the masses comprises a pair of gimbals on which the masses are pivotally mounted for movement about the drive axes, and flexures mounting the gimbals for rotational movement about the sense axes.

18. The rate sensor of claim 17 wherein the flexures are connected to anchors near the centers of the masses.

19. A rate sensor comprising a pair of spaced apart, parallel drive axes, an input axis perpendicular to the drive axes, sense axes perpendicular to the drive axes and the input axis, a pair of generally planar proof masses pivotally mounted on inner frames for see-saw movement about the drive axes, with the inner frames being located entirely with the lateral confines of the masses and being mounted for rotational movement about the sense axes, sensing frames mounted on opposite sides of the masses for rotation about axes parallel to the sense axes, means for transferring rotational movement of the masses to the sensing frames, and electrode plates on the sensing frames which are interleaved with fixed plates to form capacitors which change in value in response to rotational movement of the masses about the sensing axes.

20. The rate sensor of claim 19 wherein the inner frames are mounted by flexures which extend from anchors at the centers of the masses.

21. The rate sensor of claim 19 wherein the masses and the inner frames are symmetrical about the drive axes and the input axes.

22. The rate sensor of claim 19 including a mechanical link connecting adjacent edge portions of the masses together for movement in concert about the drive axes and the sensing axes.

23. A rate sensor comprising a pair of spaced apart, parallel drive axes, an input axis perpendicular to the drive axes, sense axes perpendicular to the drive axes and the input axis, a pair of generally planar proof masses pivotally mounted on sensing frames for see-saw movement about the drive axes, means mounting the sensing frames for rotational movement about the sense axes, means for transferring rotational movement of the masses to the sensing frames, and electrode plates on the sensing frames which are interleaved with fixed plates to form capacitors which change in value in response to rotational movement of the masses about the sensing axes, with both the sensing frames and the capacitors being located entirely with the lateral confines of the masses.

24. The rate sensor of claim 23 wherein the sensing frames are mounted by flexures which extend from anchors at the centers of the masses.

25. The rate sensor of claim 23 wherein the masses and the inner frames are symmetrical about the drive axes and the input axes.

26. The rate sensor of claim 23 including a mechanical link connecting adjacent edge portions of the masses together for movement in concert about the drive axes and the sensing axes.

27. A rate sensor comprising a pair of generally planar proof masses pivotally mounted within generally circular gimbals for see-saw movement about a pair of spaced apart, parallel drive axes, an input axis perpendicular to the drive axes, sense axes perpendicular to the drive axes and the input axis, means mounting the gimbals and the masses for torsional movement about the sense axes, and electrode plates extending radially from the gimbals interleaved with fixed electrodes to form capacitors which change in value in accordance with torsional movement of the masses about the sense axes in response to Coriolis forces produced by rotation of the masses about the input axis.

28. The rate sensor of claim 27 wherein the sensing frames are mounted by flexures which extend outward from anchors near the centers of the masses.

29. The rate sensor of claim 27 wherein the plates form separate capacitors on opposite sides of the masses, and the values of the capacitors on the opposite sides change in opposite directions.

30. The rate sensor of claim 27 including a mechanical link connecting adjacent edge portions of the masses together for movement in concert about the drive axes and the sensing axes.