Quadrature reduction in MEMS gyro devices using quad steering voltages

• US 7,213,458 B2
• Filed: 03/22/2005
• Issued: 05/08/2007
• Est. Priority Date: 03/22/2005
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Weber, Mark W., Smith, Robert B.
• Primary Examiner(s): Chapman; John E.
• Application Number:
  US10/907,131
• Publication Number:
  US 20060213265A1
• Time in Patent Office: 777 Days
• Field of Search: 735/041.2, 735/041.4, 735/041.6
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

Devices and methods for reducing quadrature motion in a MEMS-type gyroscope are disclosed. A MEMS-type gyroscope in accordance with an illustrative embodiment of the present invention can include one or more proof masses configured to oscillate in a drive plane above a sense electrode for measuring Coriolis forces exerted on the one or more proof masses resulting from motion of the gyroscope about an input axis. One or more quad steering voltage members can be positioned adjacent each of the one or more proof masses and activated to electrostatically attract the proof masses toward the sense electrodes to reduce quadrature motion of the proof masses. A levitation force can be induced in certain embodiments to further reduce quadrature motion of the proof masses, if desired.

Claims

1. A MEMS gyroscope, comprising:

one or more proof masses configured to oscillate in a drive plane above a support substrate;

a sense electrode positioned adjacent to each of the one or more proof masses;

a sense bias voltage source for inducing a charge between the one or more proof masses and corresponding sense electrode; and

one or more quad steering voltage members positioned adjacent to each of the one or more proof masses, each of said one or more quad steering voltage members being electrically coupled to a quad steering voltage for electrostatically reducing quadrature motion of the one or more proof masses.

2. The MEMS gyroscope of claim 1, wherein each of said one or more proof masses is adapted to oscillate back and forth.

3. The MEMS gyroscope of claim 2, wherein the one or more quad steering voltage members are positioned such that an overlap between a quad steering voltage member and a corresponding proof mass changes as the proof mass oscillates back and forth.

4. The MEMS gyroscope of claim 3, wherein the quad steering voltage is a DC signal.

5. The MEMS gyroscope of claim 3, wherein the quad steering voltage is an AC signal.

6. The MEMS gyroscope of claim 3, wherein two or more of the one or more quad steering voltage members are provided with different quad steering voltage signals.

7. The MEMS gyroscope of claim 1, further comprising one or more suspension springs for allowing movement of the one or more proof masses in the drive plane.

8. The MEMS gyroscope of claim 1, wherein said one or more quad steering voltage members comprises a single quad steering voltage member.

9. The MEMS gyroscope of claim 1, wherein said one or more quad steering voltage members comprises a plurality of quad steering voltage members.

10. The MEMS gyroscope of claim 1, wherein each of said one or more quad steering voltage members comprises a first quad steering voltage member and a second quad steering voltage member.

11. The MEMS gyroscope of claim 10, wherein the polarity of the quad steering voltage applied to the first quad steering voltage member is opposite that applied to the second quad steering voltage member.

12. The MEMS gyroscope of claim 1, wherein the quad steering voltages applied to the quad steering voltage members are nulled.

13. The MEMS gyroscope of claim 1, wherein each of the one or more quad steering voltage members includes a rectangular-shaped electrode plate.

14. The MEMS gyroscope of claim 1, wherein each of the one or more quad steering voltage members includes a number of inwardly projecting fingers.

15. The MEMS gyroscope of claim 1, wherein each of the one or more quad steering voltage members includes an inwardly projecting finger positioned within a cutout portion of the sense electrode.

16. The MEMS gyroscope of claim 1, wherein each of the one or more quad steering voltage members includes a plurality of quad steering voltage electrodes each positioned within a corresponding cutout portion of the sense electrode.

17. The MEMS gyroscope of claim 1, further comprising sensing means for sensing the Coriolis force exerted on the one or more proof masses and outputting a rate signal corresponding to the rate of rotation of the gyroscope about an input axis.

18. The MEMS gyroscope of claim 17, wherein said sensing means includes a charge amplifier.

19. A MEMS gyroscope, comprising:

one or more proof masses configured to oscillate in a drive plane above a support substrate, each of said one or more proof masses being electrically grounded to the support substrate by one or more suspension springs;

a sense electrode positioned adjacent to and parallel with each of the one or more proof masses;

a sense bias voltage for inducing a charge between the one or more proof masses and corresponding sense electrode;

one or more quad steering voltage members positioned adjacent to and parallel with each proof mass, each of said one or more quad steering voltage members being electrically coupled to a quad steering voltage, the quad steering voltage adapted to electrostatically reduce quadrature motion of the one or more proof masses; and

sensing means for measuring the Coriolis force exerted on the one or more proof masses and outputting a rate signal corresponding to the rate of rotation of the gyroscope about an input axis.

20. The MEMS gyroscope of claim 19, wherein each of said one or more proof masses is adapted to oscillate back and forth.

21. The MEMS gyroscope of claim 19, wherein said one or more quad steering voltage members comprises a single quad steering voltage member.

22. The MEMS gyroscope of claim 19, wherein said one or more quad steering voltage members comprises a plurality of quad steering voltage members.

23. The MEMS gyroscope of claim 19, wherein each of said one or more quad steering voltage members comprises a first quad steering voltage member and a second quad steering voltage member.

24. The MEMS gyroscope of claim 23, wherein the polarity of the quad steering voltage applied to the first quad steering voltage member is opposite that applied to the second quad steering voltage member.

25. The MEMS gyroscope of claim 19, wherein the quad steering voltages applied to the quad steering voltage members are nulled.

26. The MEMS gyroscope of claim 19, wherein each of the one or more quad steering voltage members includes a rectangular-shaped electrode plate.

27. The MEMS gyroscope of claim 19, wherein each of the one or more quad steering voltage members includes a number of inwardly projecting fingers.

28. The MEMS gyroscope of claim 19, wherein each of the one or more quad steering voltage members includes an inwardly projecting finger positioned within a cutout portion of the sense electrode.

29. The MEMS gyroscope of claim 19, wherein each of the one or more quad steering voltage members includes a plurality of quad steering voltage members each positioned within a corresponding cutout portion of the sense electrode.

30. A method for reducing quadrature motion in a gyroscope using quad steering voltages, comprising the steps of:

providing a gyroscope having a proof mass configured to oscillate back and forth in a drive plane above a sense electrode;

providing one or more quad steering voltage members adjacent the proof mass; and

applying a quad steering voltage to the one or more quad steering voltage members to electrostatically attract the proof mass towards the sense electrode in a manner that reduces the quadrature motion of the proof mass.

31. The method of claim 30, wherein the quad steering voltage is a DC voltage.

32. The method of claim 30, wherein the quad steering voltage is an AC voltage.

33. The method of claim 30, wherein a different quad steering voltage is applied to at least two of the quad steering voltage members.

34. The method of claim 30, wherein at least two of the one or more quad steering voltage members are positioned adjacent one side of the proof mass, and the applying step applies a common quad steering voltage to the at least two quad steering voltage members.

35. The method of claim 30, wherein at least two of the one or more quad steering voltage members are positioned adjacent one side of the proof mass, and the applying step applies a different quad steering voltage to the at least two quad steering voltage members.

36. The method of claim 30, wherein the gyroscope further includes a drive electrode and a motor pickoff comb.

37. The method of claim 36, wherein the drive electrode and motor pickoff comb each include a number of comb fingers interdigitated with a number of comb fingers of the proof mass.

38. The method of claim 37, wherein, during said step of applying a quad steering voltage to the one or more quad steering voltage members, a levitation force is further induced on the proof mass.

39. A method for reducing quadrature motion in a gyroscope using quad steering voltages, comprising the steps of:

providing a gyroscope having a proof mass configured to oscillate back and forth in a

drive plane above a sense electrode;

providing a quad steering voltage member laterally adjacent a first end of the sense electrode; and

applying a quad steering voltage to the quad steering voltage member to electrostatically attract the proof mass towards the sense electrode when quadrature of the proof mass occurs.

40. The method of claim 39, wherein two or more quad steering voltage members are positioned adjacent the first end of the sense electrode, and said applying step applies a quad steering voltage to the two or more quad steering voltage members.

41. The method of claim 40, wherein the applying step applies a different quad steering voltage to at least two of the two or more quad steering voltage members.