USE OF ELECTRODES TO CANCEL LIFT EFFECTS IN INERTIAL SENSORS

• US 20060213266A1
• Filed: 05/10/2006
• Published: 09/28/2006
• Est. Priority Date: 03/22/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Weber, Mark W., French, Howard B.
• Granted Patent: US 7,231,824 B2
• Time in Patent Office: Days
• US Class Current: 73/504.20
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

Devices and methods for reducing errors 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 any undesired motion of the proof masses due to quadrature and/or temperature effects. The voltage applied to each of the quad steering voltage members can be time-varying, and, in some cases, can be derived from the same voltage signal used to drive the proof masses.

Claims

1. A MEMS-type gyroscope, comprising:

one or more proof masses coupled to a time-varying drive voltage source, said one or proof masses configured to oscillate in a drive plane above a support substrate;

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

a sense bias voltage source coupled to the one or more proof masses, said sense bias voltage source adapted to produce a charge between the one or more proof masses and a corresponding sense electrode;

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; 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 voltage.

2. The MEMS-type gyroscope of claim 1, wherein the voltage coupled to the one or more quad steering voltage members is a DC voltage.

3. The MEMS-type gyroscope of claim 1, wherein the voltage coupled to the one or more quad steering voltage members is an AC voltage.

4. The MEMS-type gyroscope of claim 3, wherein the AC voltage is in phase with the drive voltage source.

5. The MEMS-type gyroscope of claim 4, wherein the voltage coupled to the one or more quad steering voltage members is a component of the drive voltage source.

6. The MEMS-type gyroscope of claim 5, wherein the magnitude of the voltage applied to the one or more quad steering voltage members is less than the magnitude of the drive voltage source.

7. The MEMS-type gyroscope of claim 5, wherein the magnitude of the voltage applied to the one or more quad steering voltage members is substantially equal to the magnitude of the drive voltage source.

8. The MEMS-type gyroscope of claim 5, further comprising a resistive element disposed in series between the drive voltage source and each quad steering voltage member.

9. The MEMS-type gyroscope of claim 8, wherein the resistive element is a variable resistor.

10. The MEMS-type gyroscope of claim 8, wherein the resistive element is a fixed-type resistor.

11. The MEMS-type gyroscope of claim 1, wherein the voltages applied to the one or more quad steering voltage members are nulled.

12. The MEMS-type gyroscope of claim 1, wherein said sensing means includes a charge amplifier.

13. A MEMS-type gyroscope, comprising:

one or more proof masses coupled to a time-varying drive voltage source, said one or more proof masses configured to oscillate in a drive plane above a support substrate;

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

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

one or more quad steering voltage members positioned adjacent to each proof mass, each of said one or more quad steering voltage members being electrically coupled to a resistive element in series with the drive voltage source; 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.

14. A method for reducing errors in a gyroscope, comprising the steps of:

providing a gyroscope including a time-varying drive voltage source coupled to one or more proof masses each adapted 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 time-varying voltage to the one or more quad steering voltage members to electrostatically attract the proof mass towards the sense electrode to reduce any undesired quadrature motion of the one or more proof masses.

15. The method of claim 14, wherein the time-varying voltage coupled to the one or more quad steering voltage members is an AC voltage.

16. The method of claim 15, wherein the AC voltage is in phase with the drive voltage source.

17. The method of claim 14, wherein the time-varying voltage coupled to the one or more quad steering voltage members is a component of the drive voltage source.

18. The method of claim 17, wherein the magnitude of the time-varying voltage coupled to the one or more quad steering voltage members is less than the magnitude of the drive voltage source.

19. The method of claim 17, wherein the magnitude of the time-varying voltage coupled to the one or more quad steering voltage members is substantially equal to the magnitude of the drive voltage source.

20. The method of claim 14, further comprising the steps of:

providing a sense bias voltage on each of the one or more proof masses; and

measuring any Coriolis forces 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.