MEMS tuning fork gyro sensitive to rate of rotation about two axes

• US 7,703,324 B2
• Filed: 05/11/2007
• Issued: 04/27/2010
• Est. Priority Date: 05/11/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Sutton, Michael S., Weber, Mark W.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US11/747,629
• Publication Number:
  US 20080276707A1
• Time in Patent Office: 1,082 Days
• Field of Search: 735/040.4, 735/041.2, 735/041.4, 735/041.6
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5726 Signal processing

Abstract

A two-axes rate sensing MEMS system. The system includes two proof masses, two drive components, two drive sense components, two orthogonal sets of substrate electrodes, and a processing device. The processing device is in signal communication with the two proof masses, the two sense components, or the two sets of substrate electrodes. The processing device determines the rate of rotation about two orthogonal axes based on signals received from the two proof masses, the two sense components, or the two substrate electrodes. Rotation about one axis will induce proofmass motion in the plane of the substrate. Rotation about an orthogonal axis will induce proofmass motion out-of-plane of the proofmasses. The sensing scheme independently detects these proof mass motion, which can infer rate of rotation.

Claims

1. A two-axes MEMS gyroscope system comprising:

two proof masses;

two drive components;

two drive sense components;

four Coriolis sense electrodes, two of the Coriolis sense electrodes are sensitive to in-plane proof mass motion and two of the Coriolis sense electrodes are sensitive to out-of-plane proof mass motion; and

a processing device in signal communication with at least one of the two proof masses, or the four Coriolis sense electrodes, the processing device being configured to determine rate of rotation about two orthogonal axes based on signals received from at least one of the two proof masses, or the four Coriolis sense electrode, wherein the processing device is configured to demodulate the signals received from the proof masses based on two previously defined modulation frequencies.

2. The system of claim 1, wherein the two drive components and the two drive sense components form comb capacitors with a respective proof mass.

3. The system of claim 1, wherein the two of the Coriolis sense electrodes are biased at a first modulation frequency and the other two Coriolis sense electrodes are biased at a second modulation frequency.

4. The system of claim 2, wherein the proof masses are biased to a predefined voltage, if the processing device receives signals from the four Coriolis sense electrodes.

5. A method for determining rate of rotation about two orthogonal axes in a single

MEMS gyroscope system, the method comprising:

driving two proof masses to resonate in plane based on a drive signal;

modulating the two of the four Coriolis sense electrodes at a first frequency;

modulating the other two of the four Coriolis sense electrodes at a second frequency;

receiving signals from at least one of two proof masses or four Coriolis sense electrodes; and

determining rate of rotation about two orthogonal axes based on the received signals.

6. The method of claim 5, wherein two drive components and the two drive sensing electrodes form comb capacitors with a respective proof mass.

7. The method of claim 6,

wherein determining the rate of rotation includes demodulating the signals received from the proof masses based on the first and the second modulation frequencies.

8. The method of claim 6, further comprising:

biasing the proof masses to a predefined voltage, if the received signals are received from the four Coriolis sense electrodes.