Isolated planar gyroscope with internal radial sensing and actuation

• US 20040055380A1
• Filed: 08/12/2003
• Published: 03/25/2004
• Est. Priority Date: 08/12/2002
• Status: Active Grant

• Current Assignee: California Institute of Technology, The Boeing Co.
• Original Assignee: California Institute of Technology
• Inventors: Shcheglov, Kirill V., Challoner, A. Dorian
• Granted Patent: US 7,040,163 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5684 the devices involving a micromechanical structure
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/4908 Acoustic transducer
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

The present invention discloses an inertial sensor comprising a planar mechanical resonator with embedded sensing and actuation for substantially in-plane vibration and having a central rigid support for the resonator. At least one excitation or torquer electrode is disposed within an interior of the resonator to excite in-plane vibration of the resonator and at least one sensing or pickoff electrode is disposed within the interior of the resonator for sensing the motion of the excited resonator. In one embodiment, the planar resonator includes a plurality of slots in an annular pattern; in another embodiment, the planar mechanical resonator comprises four masses; each embodiment having a simple degenerate pair of in-plane vibration modes.

Claims

1. An inertial sensor, comprising:

a planar mechanical resonator for substantially in-plane vibration and having a central mounting point;

a rigid support for the resonator at the central mounting point;

at least one excitation electrode within an interior of the planar mechanical resonator to excite in-plane vibration of the resonator; and

at least one sensing electrode within the interior of the resonator for sensing the motion of the excited resonator.

2. The inertial sensor of claim 1, wherein planar resonator vibration is substantially isolated from the rigid support.

3. The inertial sensor of claim 1, wherein the in-plane vibration comprises substantially radial motion about the central mounting point.

4. The inertial sensor of claim 1, further comprising a baseplate supporting the rigid support, excitation electrode and sensing electrode.

5. The inertial sensor of claim 4, wherein producing the sensor comprises the steps of:

etching the baseplate;

bonding a wafer to the etched baseplate; and

through etching the wafer to form the resonator, excitation elements and sensing elements.

6. The inertial sensor of claim 5, further comprising grinding and polishing the through-etched wafer to a desired thickness.

7. The inertial sensor of claim 5, wherein through etching the wafer also forms a case wall for the inertial sensor.

8. The inertial sensor of claim 1, wherein the planar mechanical resonator comprises a plurality slots.

9. The inertial sensor of claim 8, wherein the plurality of slots are arranged in an annular pattern around the central mounting point.

10. The inertial sensor of claim 8, wherein the plurality of slots are arranged with substantially uniform radial spacing around the central mounting point.

11. The inertial sensor of claim 8, wherein the plurality of slots are arranged in a symmetric pattern.

12. The inertial sensor of claim 8, wherein the at least one excitation electrode is disposed within one or more of the plurality of slots.

13. The inertial sensor of claim 12, wherein the at least one excitation electrode is disposed within one or more inner slots of the plurality of slots.

14. The inertial sensor of claim 8, wherein the at least one sensing electrode is disposed within one or more of the plurality of slots.

15. The inertial sensor of claim 14, wherein the at least one sensing electrode is disposed within one or more outer slots of the plurality of slots.

16. The inertial sensor of claim 1, wherein the planar mechanical resonator comprises four masses, each having a simple degenerate pair of in-plane vibration modes.

17. The inertial sensor of claim 16, wherein the planar mechanical resonator has two degenerate in-plane system modes producing symmetric motion of the four masses for Coriolis sensing.

18. The inertial sensor of claim 1, further comprising an integral case vacuum wall formed from a same wafer as the resonator.

19. The inertial sensor of claim 1, further comprising an end cap wafer bonded to the case wall with a vacuum seal.

20. The inertial sensor of claim 19, wherein the end cap wafer includes readout electronics for the inertial sensor.

21. A method producing an inertial sensor, comprising the steps of:

providing a planar mechanical resonator for substantially in-plane vibration and having a central mounting point;

supporting the resonator at the central mounting point;

providing at least one excitation electrode within an interior of the resonator to excite in-plane vibration of the resonator; and

providing at least one sensing electrode within the interior of the resonator for sensing the motion of the excited resonator.

22. The method of claim 21, wherein planar resonator vibration is substantially isolated from the rigid support.

23. The method of claim 21, wherein the vibration comprises substantially in-plane vibration about the central mounting point.

24. The method of claim 21, further comprising a baseplate supporting the rigid support, excitation electrodes and sensing electrode.

25. The method of claim 24, wherein the sensor is produced by etching the baseplate, bonding a wafer to the etched baseplate and through-etching the wafer to form the resonator, excitation electrode and sensing electrode.

26. The method of claim 25, further comprising grinding and polishing the through-etched wafer to a desired thickness.

27. The method of claim 25, wherein through etching the wafer also forms a case vacuum wall for the inertial sensor.

28. The method of claim 21, wherein the planar mechanical resonator comprises a plurality slots.

29. The method of claim 28, wherein the plurality of slots are arranged in an annular pattern around the central mounting point.

30. The method of claim 28, wherein the plurality of slots are arranged with substantially uniform radial spacing around the central mounting point.

31. The method of claim 28, wherein the plurality of slots are arranged in a symmetric pattern.

32. The method of claim 28, wherein the at least one excitation electrode is disposed within one or more of the plurality of slots.

33. The method of claim 32, wherein the at least one excitation electrode is disposed within one or more inner slots of the plurality of slots.

34. The method of claim 28, wherein the at least one sensing electrode is disposed with one or more of the plurality of slots.

35. The method of claim 34, wherein the at least one sensing electrode is disposed within one or more outer slots of the plurality of slots.

36. The method of claim 21, wherein the planar mechanical resonator comprises four masses, each having a simple degenerate pair of in-plane vibration modes.

37. The method of claim 36, wherein the planar mechanical resonator has two degenerate in-plane system modes producing symmetric motion of the four masses for Coriolis sensing.

38. The method of claim 21, further comprising providing an integral case vacuum wall formed from a same wafer as the resonator.

39. The method of claim 21, further comprising providing an end cap wafer bonded to the case wall with a vacuum seal.

40. The method of claim 39, wherein the end cap wafer includes readout electronics for the inertial sensor.

41. A resonator for an inertial sensor, comprising:

a plurality of concentric rings; and

interleaved segments connecting the concentric rings.

42. The resonator of claim 41, wherein the concentric rings are substantially circular.

43. The resonator of claim 41, wherein the resonator is supported at a central mounting point.

44. The resonator of claim 41, wherein the resonator is supported circumferentially.

45. The resonator of claim 41, wherein the resonator exhibits substantially in-plane vibration when excited.

46. The resonator of claim 41, wherein the resonator includes at least one excitation electrode within an interior of the plurality of the concentric rings and the interleaved segments to excite in-plane vibration of the resonator;

and

at least one sensing electrode within the interior of the concentric rings and the interleaved segments for sensing the motion of the excited resonator.