Gyroscope with auxiliary self-test

• US 10,139,229 B2
• Filed: 08/01/2016
• Issued: 11/27/2018
• Est. Priority Date: 12/10/2015
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Coronato, Luca, Gafforelli, Giacomo, Ruohio, Jaakko
• Primary Examiner(s): Schmitt, Benjamin R
• Application Number:
  US15/225,281
• Publication Number:
  US 20170167876A1
• Time in Patent Office: 848 Days
• Field of Search: 73 137, 73 138, 7350402, 7350412, 7351416
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/5733 Structural details or topology
• CPC Class Codes: G01C 19/5762 the sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719
• CPC Class Codes: G01C 19/5783 Mountings or housings not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719

Abstract

A gyroscope includes drive electrodes that drive a drive mass at a drive frequency. A sense mass is responsive to a Coriolis force caused by rotation of the gyroscope and oscillates based on the drive frequency. Electrodes adjacent to the sense mass drive the sense mass at test frequencies. The response to the driving at the test frequencies is measured and a gyroscope failure is identified based on this response.

Claims

1. A system for performing a self-test for a gyroscope, the system comprising:

one or more drive masses located in a device plane;

one or more drive electrodes adjacent to the one or more drive masses;

a drive circuit, wherein the drive circuit is configured to cause the one or more drive electrodes to drive the one or more drive masses to oscillate at a drive frequency;

one or more sense masses located in the device plane, wherein the one or more sense masses are coupled to the one or more drive masses to oscillate at the drive frequency in response to a rotation about an axis perpendicular to the device plane;

one or more sense electrodes adjacent to the one or more sense masses, wherein a voltage between the one or more sense electrodes and the one or more sense masses changes based on the oscillation of the one or more sense masses;

one or more auxiliary electrodes adjacent to the one or more sense masses, wherein the one or more auxiliary electrodes drive the one or more sense masses at a first test frequency and a second test frequency, wherein the first test frequency is distinct from the drive frequency, wherein the second test frequency is distinct from the drive frequency and the first test frequency, and wherein the one more sense electrodes sense a first test response signal at the first test frequency and a second test response signal at the second test frequency; and

processing circuitry configured to identify a gyroscope failure based on at least one of the first test response signal and the second test response signal,

wherein the gyroscope failure is identified based on a first gain change for the first test response signal, a second gain change for the second test response signal, and a ratio of the first gain change and the second gain change.

2. The system of claim 1, wherein the first gain change is determined based on a difference between a magnitude of the first test response signal and a first baseline magnitude, and the second gain change is determined based on a difference between a magnitude of the second test response signal and a second baseline magnitude.

3. The system of claim 1, wherein the gyroscope failure is identified when the first gain change exceeds a first threshold, the second gain change exceeds a second threshold, and the ratio exceeds a ratio threshold.

4. The system of claim 1, wherein the gyroscope failure is identified when the ratio exceeds a ratio threshold and at least one of the first gain change or the second gain change exceeds gain threshold.

5. The system of claim 1, wherein the gyroscope failure is identified when the first gain change exceeds a first threshold, the second gain change exceeds a second threshold, and the ratio is less than a ratio threshold.

6. The system of claim 1, wherein the processing circuitry is further configured to cause the drive circuit to no longer cause the one or more drive electrodes to drive the one or more drive masses when the gyroscope failure is identified.

7. The system of claim 6, wherein the processing circuitry is further configured to provide a notification when the gyroscope failure is identified.

8. The system of claim 1, wherein the first test frequency and the second test frequency are both located at least 6 percent away of a sense mode resonant frequency of the sense oscillator away from the sense mode resonant frequency.

9. The system of claim 8, wherein the drive frequency is located at least 6 percent away from the sense mode resonant frequency of the sense oscillator.

10. The system of claim 1, wherein both a first test gain associated with the first test frequency and a second test gain associated with the second test frequency are within 75% of a sense gain at the drive frequency.

11. The system of claim 1, wherein one of a first test gain associated with the first test frequency or a second test gain associated with the second test frequency is within 25% of a sense gain at the drive frequency.

12. The system of claim 1, wherein the processing circuitry is further configured to determine angular velocity based on the voltage at the one or more sense electrodes.

13. The system of claim 1, wherein a change in a gain of the one or more sense masses at the drive frequency due to the driving of the sense oscillator at the first test frequency and the second test frequency is less than a threshold.

14. The system of claim 13, wherein the driving of the sense oscillator at the first test frequency is at a first magnitude, and the driving of the sense oscillator at the second test frequency is at a second magnitude.

15. The system of claim 1, wherein the one or more auxiliary electrodes comprise the one or more sense electrodes.

16. The system of claim 1, wherein both of the first test frequency and the second test frequency are located on the same side of a sense mode resonant frequency.

17. The system of claim 16, wherein the difference between the first test frequency and the second test frequency is greater than 2 percent of the sense mode resonant frequency and less than 6 percent of the sense mode resonant frequency.

18. The system of claim 16, wherein the drive frequency is located on the other side of the sense mode resonant frequency from the first test frequency and the second test frequency.

19. A method for performing a self-test for a gyroscope, the method comprising:

providing a drive signal from a drive circuit to one or more drive electrodes, wherein the drive electrodes are adjacent to one or more drive masses;

driving the one or more drive masses at a drive frequency based on the drive signal;

receiving a rotation about an axis perpendicular to the device plane at one or more sense masses, wherein the one or more sense masses and the one or more drive masses are located in a device plane, and wherein the one or more sense masses are coupled to the one or more drive masses to oscillate at the drive frequency in response to the received rotation;

driving the one or more sense masses at a first test frequency and a second test frequency, wherein the first test frequency is distinct from the drive frequency, and wherein the second test frequency is distinct from the drive frequency and the first test frequency;

measuring a sense voltage at one or more sense electrodes, wherein the sense voltage is responsive to the oscillation of the one or more sense masses at the drive frequency, the first test frequency, and the second test frequency;

identifying a gyroscope failure based on sense voltage response to the oscillation of the one or more sense masses at the first test frequency and the second test frequency, wherein the gyroscope failure is identified based on a first gain change for the sense voltage at the first test frequency, a second gain change for the sense voltage at the second test frequency, and a ratio of the first gain change and the second gain change.