Motion-responsive coupled masses

• US 20050183502A1
• Filed: 02/22/2005
• Published: 08/25/2005
• Est. Priority Date: 02/23/2004
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Rodney, Paul F.
• Granted Patent: US 7,197,929 B2
• Time in Patent Office: Days
• US Class Current: 73/504.20
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

In some embodiments, an apparatus and a system, as well as a method and an article, may include coupling a plurality of masses to provide a plurality of output signals responsive to motion relative to a common axis. Moving the plurality of masses at a substantially common frequency, moving a subset of the plurality of masses out of phase with the remainder of the plurality of masses, and combining the plurality of output signals to provide a combined signal associated with a response property of at least one of the plurality of masses may also be included.

Claims

1. A method, comprising:

coupling a plurality of masses to provide a corresponding plurality of output signals responsive to motion relative to a common axis;

periodically moving the plurality of masses at a substantially common frequency;

periodically moving a subset of the plurality of masses at the substantially common frequency and out of phase with a remainder of the plurality of masses; and

combining the corresponding plurality of output signals to provide a combined signal associated with a response property of at least one of the plurality of masses.

2. The method of claim 1, further comprising:

determining a bias drift as the response property of the at least one of the plurality of masses.

3. The method of claim 1, further comprising:

determining, from the combined signal, an angular rate of rotation about the common axis.

4. The method of claim 1, wherein the combined signal comprises an indication of linear acceleration relative to a rest frame, further comprising:

measuring the linear acceleration using at least one accelerometer.

5. The method of claim 4, further comprising:

compensating for a bias drift of the response property by subtracting the linear acceleration from the combined signal.

6. The method of claim 1, wherein coupling the plurality of masses further comprises:

deriving a first feedback signal from the corresponding plurality of output signals; and

transmitting the first feedback signal to at least one driver coupled to a first group of the plurality of masses.

7. The method of claim 6, wherein the first feedback signal is derived from a substantially linear combination of the corresponding plurality of output signals.

8. The method of claim 6, wherein the first feedback signal is derived from a substantially nonlinear combination of the corresponding plurality of output signals.

9. The method of claim 6, further comprising:

deriving a second feedback signal from the corresponding plurality of output signals; and

transmitting the second feedback signal to at least another driver coupled to a second group of the plurality of masses.

10. The method of claim 9, wherein the second feedback signal is derived from a second substantially linear combination of the corresponding plurality of output signals different from a first combination of the corresponding plurality of output signals from which the first feedback signal is derived.

11. The method of claim 9, wherein the second feedback signal is derived from a second substantially nonlinear combination of the corresponding plurality of output signals different from a first combination of the corresponding plurality of output signals from which the first feedback signal is derived.

12. The method of claim 1, wherein periodically moving the subset of the plurality of masses further comprises:

periodically moving the subset of the plurality of masses at the substantially common frequency and about 180 degrees out of phase with the remainder of the plurality of masses.

13. The method of claim 1, wherein the common axis comprises an alignment axis of substantially maximum response sensitivity associated with each one of the plurality of masses.

14. The method of claim 13, further comprising:

determining an amount of mass response misalignment from the combined signal.

15. The method of claim 13, wherein the alignment axis of substantially maximum response sensitivity for each one of the plurality of masses is aligned within about five angular degrees of the alignment axis of substantially maximum response sensitivity for every other one of the plurality of masses.

16. The method of claim 1, wherein the common axis comprises an alignment axis of substantially maximum response sensitivity associated with a first group of the plurality of masses, and wherein the alignment axis of substantially maximum response sensitivity for a second group of the plurality of masses is aligned within about five angular degrees of the alignment axis of substantially maximum response sensitivity for the first group of the plurality of masses or within about five angular degrees of an axis substantially orthogonal to the alignment axis of substantially maximum response sensitivity for the first group of the plurality of masses.

17. The method of claim 1, further comprising:

determining the substantially common frequency from a response of at least two of the plurality of masses to an excitation; and

tuning a driver coupled to the plurality of masses to excite the plurality of masses at the substantially common frequency.

18. An apparatus, comprising:

a plurality of masses coupled to provide a corresponding plurality of output signals responsive to motion relative to a common axis;

a driver module to periodically move the plurality of masses at a substantially common frequency, and to periodically move a subset of the plurality of masses out of phase with a remainder of the plurality of masses; and

a combination module to combine the corresponding plurality of output signals to provide a combined signal associated with a response property of at least one of the plurality of masses.

19. The apparatus of claim 18, wherein the plurality of masses comprise:

at least one pair of masses coupled to a common coupling beam.

20. The apparatus of claim 18, wherein the plurality of masses comprise:

a single MEMS gyroscope.

21. The apparatus of claim 18, wherein the plurality of masses comprise:

a first proof mass in a first MEMS gyroscope and a second proof mass in a second MEMS gyroscope.

22. The apparatus of claim 18, further comprises:

a first driver circuit to receive a first feedback signal derived from the corresponding plurality of output signals and to drive a first group of the plurality of masses.

23. The apparatus of claim 22, wherein the first feedback signal is derived from a substantially linear combination of the corresponding plurality of output signals.

24. The apparatus of claim 22, wherein the first feedback signal is derived from a substantially nonlinear combination of the corresponding plurality of output signals.

25. The apparatus of claim 22, further comprising:

a second driver circuit to receive a second feedback signal derived from the corresponding plurality of output signals and to drive a second group of the plurality of masses.

26. The apparatus of claim 25, wherein the second feedback signal is derived from a second substantially linear combination of the corresponding plurality of output signals different from a first combination of the corresponding plurality of output signals from which the first feedback signal is derived.

27. The apparatus of claim 25, wherein the second feedback signal is derived from a second substantially nonlinear combination of the corresponding plurality of output signals different from a first combination of the corresponding plurality of output signals from which the first feedback signal is derived.

28. The apparatus of claim 18, wherein the driver module operates to periodically move the subset of the plurality of masses at the substantially common frequency and about 180 degrees out of phase with the remainder of the plurality of masses.

29. The apparatus of claim 18, wherein the common axis comprises an alignment axis of substantially maximum response sensitivity.

30. The apparatus of claim 29, wherein the alignment axis of substantially maximum response sensitivity for each one of the plurality of masses is aligned within about five angular degrees of the alignment axis of substantially maximum response sensitivity for every other one of the plurality of masses.

31. The apparatus of claim 18, wherein the common axis comprises an alignment axis of substantially maximum response sensitivity associated with a first group of the plurality of masses, and wherein the alignment axis of substantially maximum response sensitivity for a second group of the plurality of masses is aligned within about five angular degrees of the alignment axis of substantially maximum response sensitivity for the first group of the plurality of masses or within about five angular degrees of an axis substantially orthogonal to the alignment axis of substantially maximum response sensitivity for the first group of the plurality of masses.

32. The apparatus of claim 18, further comprising:

an accelerometer to measure, as a portion of the combined signal, linear acceleration relative to a rest frame.

33. An article comprising a machine-accessible medium having associated information, wherein the information, when accessed, results in a machine performing:

coupling a plurality of masses to provide a corresponding plurality of output signals responsive to motion relative to a common axis;

periodically moving the plurality of masses at a substantially common frequency;

periodically moving a subset of the plurality of masses at the substantially common frequency and out of phase with a remainder of the plurality of masses; and

combining the corresponding plurality of output signals to provide a combined signal associated with a response property of at least one of the plurality of masses.

34. The article of claim 33, wherein the machine-accessible medium further includes data, which when accessed by the machine, results in the machine performing:

deriving a first feedback signal from the corresponding plurality of output signals; and

transmitting the first feedback signal to at least one driver coupled to a first group of the plurality of masses.

35. The article of claim 33, wherein the common axis comprises an alignment axis of substantially maximum response sensitivity associated with a first group of the plurality of masses, and wherein the alignment axis of substantially maximum response sensitivity for a second group of the plurality of masses is aligned within about five angular degrees of the alignment axis of substantially maximum response sensitivity for the first group of the plurality of masses or within about five angular degrees of an axis substantially orthogonal to the alignment axis of substantially maximum response sensitivity for the first group of the plurality of masses.

36. A system, comprising:

an apparatus including a plurality of masses coupled to provide a corresponding plurality of output signals responsive to motion relative to a common axis, a driver module to periodically move the plurality of masses at a substantially common frequency, and to periodically move a subset of the plurality of masses out of phase with a remainder of the plurality of masses, and a combination module to combine the corresponding plurality of output signals to provide a combined signal associated with a response property of at least one of the plurality of masses; and

one of a drill collar, a downhole tool, and a tool body to house the apparatus.

37. The system of claim 36, wherein the downhole tool comprises a tool selected from one of a wireline logging tool and a logging while drilling (LWD) tool.

38. The system of claim 36, wherein the plurality of masses comprise:

a single MEMS gyroscope.