Integral resonator gyroscope

• US 20040055381A1
• 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: The Boeing Co.
• Inventors: Shcheglov, Kirill V., Challoner, A. Dorian, Hayworth, Ken J., Wiberg, Dean V., Yee, Karl Y.
• Granted Patent: US 6,944,931 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: B81C 3/001 Bonding of two components
• 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 29/49007 Indicating transducer
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

The present invention discloses an inertial sensor having an integral resonator. A typical sensor comprises a planar mechanical resonator for sensing motion of the inertial sensor and a case for housing the resonator. The resonator and a wall of the case are defined through an etching process. A typical method of producing the resonator includes etching a baseplate, bonding a wafer to the etched baseplate, through etching the wafer to form a planar mechanical resonator and the wall of the case and bonding an end cap wafer to the wall to complete the case.

Claims

1. An inertial sensor, comprising:

a planar mechanical resonator for sensing motion of the inertial sensor; and

a case for housing the resonator;

wherein the resonator and a wall of the case are defined through an etching process.

2. The inertial sensor of claim 1, wherein the case comprises a vacuum housing.

3. The inertial sensor of claim 1, wherein the resonator and the wall are produced from a common wafer.

4. The inertial sensor of claim 1, wherein connect pins pass electrical signals from a baseplate to an end cap wafer of the case to provide electrical connection for exciting the resonator and sensing motion of the resonator.

5. The inertial sensor of claim 1, further comprising control electronics within the case for exciting and sensing movement of the resonator.

6. The inertial sensor of claim 1, wherein metal traces pass through the case to provide electrical connection for exciting the resonator and sensing motion of the resonator.

7. The inertial sensor of claim 1, further comprising 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.

8. The inertial sensor of claim 7, wherein the at least one excitation electrode, the at least one sensing electrode and the resonator are produced from a common wafer.

9. The inertial sensor of claim 7, wherein the at least one excitation electrode, the at least one sensing electrode, the resonator and the wall of the case are produced from a common wafer.

10. The inertial sensor of claim 1, wherein the case further comprises a baseplate supporting the resonator and the wall and an end cap wafer disposed on the wall of the case.

11. The inertial sensor of claim 10, wherein connect pins pass electrical signals from the baseplate to the end cap wafer of the case to provide electrical connection for exciting and sensing movement of the resonator.

12. The inertial sensor of claim 10, wherein the resonator and the wall are produced from a common etching process.

13. The inertial sensor of claim 10, wherein metal bonding is used to fuse the baseplate to the wall and the wall to the end cap wafer to vacuum seal the case.

14. The inertial sensor of claim 10, wherein the resonator and the wall are produced from a common wafer.

15. The inertial sensor of claim 10, wherein the end cap wafer includes control electronics for exciting the resonator and sensing motion of the resonator.

16. The inertial sensor of claim 15, wherein the control electronics are within the case.

17. The inertial sensor of claim 15, wherein electrical signals of exciting and sensing electrodes of the resonator are connected from baseplate metal traces by connect pins to the end cap wafer of the case to provide electrical connection with the control electronics on the end cap wafer.

18. The inertial sensor of claim 17, wherein end cap metal traces pass through the case between the wall and the end cap to communicate sensing information from the control electronics.

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

20. The inertial sensor of claim 19, wherein the plurality of slots are arranged in an annular pattern around the central mounting point.

21. The inertial sensor of claim 19, wherein the plurality of slots are arranged with substantially uniform radial spacing around the central mounting point.

22. The inertial sensor of claim 19, wherein the plurality of slots are arranged in a symmetric pattern.

23. The inertial sensor of claim 19, wherein at least one excitation electrode is disposed within one or more of the plurality of slots.

24. The inertial sensor of claim 23, wherein the at least one excitation electrode is disposed within one or more inner slots of the plurality of slots.

25. The inertial sensor of claim 19, wherein at least one sensing electrode is disposed within one or more of the plurality of slots.

26. The inertial sensor of claim 25, wherein the at least one sensing electrode is disposed within one or more outer slots of the plurality of slots.

27. The inertial sensor of claim 1, further comprising a rigid support for the planar resonator at a central mounting point of the resonator.

28. The inertial sensor of claim 27, wherein the in-plane vibration comprises substantially radial motion about the central mounting point.

29. The inertial sensor of claim 27, wherein vibration of the planar resonator is substantially isolated from the rigid support.

30. 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.

31. The inertial sensor of claim 30, wherein the planar mechanical resonator has two degenerate in-plane system modes producing symmetric motion of the four masses for Coriolis sensing.

32. A method of producing a sensor comprising the steps of:

etching a baseplate;

bonding a wafer to the etched baseplate;

through etching the wafer to form a planar mechanical resonator;

through etching the wafer to form the wall of the case; and

bonding an end cap wafer to the wall to complete the case.

33. The method of claim 32, further comprising grinding and polishing the through-etched wafer to a desired thickness.

34. The method of claim 32, wherein the case comprises a vacuum housing.

35. The method of claim 32, wherein connect pins pass electrical signals from a baseplate to an end cap wafer of the case to provide electrical connection for exciting the resonator and sensing motion of the resonator.

36. The method of claim 32, further comprising control electronics within the case for exciting and sensing movement of the resonator.

37. The method of claim 32, wherein metal traces pass through the case to provide electrical connection for exciting the resonator and sensing motion of the resonator.

38. The method of claim 32, further comprising through etching the wafer to produce at least one excitation electrode within an interior of the planar mechanical resonator to excite in-plane vibration of the resonator;

and

through etching the wafer to produce at least one sensing electrode within the interior of the resonator for sensing the motion of the excited resonator.

39. The method of claim 32, further comprising through etching connect pins from the wafer to pass electrical signals from the baseplate to the end cap wafer of the case to provide electrical connection for exciting and sensing movement of the resonator.

40. The method of claim 32, wherein the resonator and the wall are produced from a common etching process.

41. The method of claim 32, further comprising fusing the baseplate to the wall and the wall to the end cap wafer with metal bonding to vacuum seal the case.

42. The method of claim 32, wherein the end cap wafer includes control electronics for exciting the resonator and sensing motion of the resonator.

43. The method of claim 42, wherein the control electronics are within the case.

44. The method of claim 42, wherein electrical signals of exciting and sensing electrodes of the resonator are connected from baseplate metal traces by connect pins to the end cap wafer of the case to provide electrical connection with the control electronics on the end cap wafer.

45. The method of claim 44, wherein end cap metal traces pass through the case between the wall and the end cap to communicate sensing information from the control electronics.

46. The method of claim 32, wherein through etching the wafer to form a planar mechanical resonator comprises through etching a plurality slots.

47. The method of claim 46, wherein the plurality of slots are arranged in an annular pattern around the central mounting point.

48. The method of claim 46, wherein the plurality of slots are arranged with substantially uniform radial spacing around the central mounting point.

49. The method of claim 46, wherein the plurality of slots are arranged in a symmetric pattern.

50. The method of claim 46, wherein through etching to form a plurality of slots also forms at least one excitation electrode disposed within one or more of the plurality of slots.

51. The method of claim 50, wherein the at least one excitation electrode is disposed within one or more inner slots of the plurality of slots.

52. The method of claim 46, wherein through etching to form a plurality of slots also forms at least one sensing electrode disposed within one or more of the plurality of slots.

53. The method of claim 52, wherein the at least one sensing electrode is disposed within one or more outer slots of the plurality of slots.

54. The method of claim 32, bonding the wafer to the baseplate and through etching the wafer forms a rigid support for the planar resonator at a central mounting point of the resonator for in-plane vibration.

55. The method of claim 54, wherein the in-plane vibration comprises substantially radial motion about the central mounting point.

56. The method of claim 54, wherein vibration of the planar resonator is substantially isolated from the rigid support.

57. The method of claim 32, wherein the planar mechanical resonator comprises four masses, each having a simple degenerate pair of in-plane vibration modes.

58. The method of claim 57, wherein the planar mechanical resonator has two degenerate in-plane system modes producing symmetric motion of the four masses for Coriolis sensing.