MEMS gyroscope self-test using a technique for deflection of the sensing mobile mass

Patent metadata

Field	Value
Publication number	US-11255670-B2
Application number	US-201916452967-A
Country	US
Kind code	B2
Filing date	Jun 26, 2019
Priority date	Jun 26, 2019
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

A microelectromechanical system (MEMS) gyroscope sensor has a sensing mass and a quadrature error compensation control loop for applying a force to the sensing mass to cancel quadrature error. To detect fault, the quadrature error compensation control loop is opened and an additional force is applied to produce a physical displacement of the sensing mass. A quadrature error resulting from the physical displacement of the sensing mass in response to the applied additional force is sensed. The sensed quadrature error is compared to an expected value corresponding to the applied additional force and a fault alert is generated if the comparison is not satisfied.

First claim

What is claimed is:

1. A method for self-testing a microelectromechanical system (MEMS) gyroscope sensor having a sensing mass and a quadrature error compensation control loop for applying a force to the sensing mass to cancel quadrature error, comprising:
opening the quadrature error compensation control loop;
applying an additional force to produce a physical displacement of the sensing mass;
sensing a quadrature error due to the physical displacement of the sensing mass in response to the applied additional force;
comparing the sensed quadrature error to an expected value corresponding to the applied additional force; and
generating a fault alert if the comparison is not satisfied.

2. The method of claim 1 , wherein sensing the quadrature error comprises generating a quadrature error signal having an in-phase component and a quadrature phase component, and wherein comparing comprises comparing a magnitude of one of the in-phase and quadrature-phase components to a magnitude expected due to the physical displacement of the sensing mass, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

3. The method of claim 1 , wherein sensing the quadrature error comprises generating a quadrature error signal having an in-phase component and a quadrature phase component, and wherein comparing comprises comparing a magnitude of the in-phase component to a magnitude of the quadrature-phase component, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

4. The method of claim 1 , wherein the MEMS gyroscope sensor further has a driving mass coupled to the sensing mass, the method further comprising:
applying force to the driving mass to induce oscillation;
sensing oscillation of the driving mass to generate a reference clock phase;
sensing movement of the sensing mass to generate a sensing signal; and
demodulating the sensing signal in response to the reference clock phase to generate the quadrature error.

5. The method of claim 4 , wherein demodulating the sensing signal comprises generating an in-phase component and a quadrature phase component for the quadrature error.

6. The method of claim 5 , wherein comparing comprises comparing a magnitude of one of the in-phase and quadrature-phase components to a magnitude expected due to the physical displacement of the sensing mass, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

7. The method of claim 5 , wherein comparing comprises comparing a magnitude of the in-phase component to a magnitude of the quadrature-phase component, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

8. The method of claim 5 , wherein the reference clock phase has an in-phase component and a quadrature-phase component, the method further comprising phase shifting both the in-phase component and a quadrature-phase component of the reference clock phase so that both the in-phase component and quadrature phase component of the quadrature error have non-zero magnitudes.

9. The method of claim 8 , wherein comparing comprises comparing the non-zero magnitudes of the in-phase component and quadrature-phase component of the quadrature error, and wherein generating comprises asserting the fault alert if the non-zero magnitudes are not substantially equal.

10. The method of claim 1 , further comprising, prior to opening, closing the quadrature error compensation control loop to zero out quadrature error.

11. The method of claim 1 , wherein sensing the quadrature error comprises generating a quadrature error signal having an in-phase component, and further comprising converting the in-phase component to a rate signal indicative of angular velocity, wherein comparing comprises comparing a magnitude of the rate signal to a magnitude expected due to the physical displacement of the sensing mass, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

12. A method for self-testing a microelectromechanical system (MEMS) gyroscope sensor, comprising:
using a quadrature error compensation functionality of the MEMS gyroscope sensor to excite a sensing mass in a mode of operation where a control loop for quadrature error compensation is opened;
sensing a quadrature error in the open control loop condition; and
detecting fault in the MEMS gyroscope sensor by processing in-phase and quadrature phase components of the quadrature error.

13. The method of claim 12 , wherein detecting fault comprises comparing a magnitude of the in-phase component to an expected magnitude due the excitation of the sensing mass and indicating a fault condition if the magnitudes are not substantially equal.

14. The method of claim 12 , wherein detecting fault comprises comparing a magnitude of the in-phase component to a magnitude of the quadrature phase component indicating a fault condition if the magnitudes are not substantially equal.

15. A method for self-testing a microelectromechanical system (MEMS) gyroscope sensor having a sensing mass and a quadrature error compensation control loop for applying a quadrature error compensation force to the sensing mass to cancel quadrature error, comprising:
opening the quadrature error compensation control loop to prevent application of the quadrature error compensation force;
applying a testing force to the sensing mass in substitution for the quadrature error compensation force in order to produce a testing physical displacement of the sensing mass;
sensing a quadrature error due to the testing physical displacement of the sensing mass in response to the applied testing force;
comparing the sensed quadrature error to an expected value corresponding to the applied testing force; and
generating a fault alert if the comparison is not satisfied.

16. The method of claim 15 , wherein sensing the quadrature error comprises generating a quadrature error signal having an in-phase component and a quadrature phase component, and wherein comparing comprises comparing a magnitude of one of the in-phase and quadrature-phase components to a magnitude expected due to the testing physical displacement of the sensing mass, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

17. The method of claim 15 , wherein sensing the quadrature error comprises generating a quadrature error signal having an in-phase component and a quadrature phase component, and wherein comparing comprises comparing a magnitude of the in-phase component to a magnitude of the quadrature-phase component, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

18. The method of claim 15 , wherein sensing the quadrature error comprises generating a quadrature error signal having an in-phase component, and further comprising converting the in-phase component to a rate signal indicative of angular velocity, wherein comparing comprises comparing a magnitude of the rate signal to a magnitude expected due to the physical displacement of the sensing mass, and wherein generating comprises asserting the fault alert if the magnitudes are not substantially equal.

19. The method of claim 15 , wherein the MEMS gyroscope sensor further has a driving mass coupled to the sensing mass, the method further comprising:
applying force to the driving mass to induce oscillation;
sensing movement of the sensing mass to

Assignees

• St Microelectronics Inc

Inventors

• Hu Yamu
• Fang Deyou
• Mcclure David
• Zhang Huantong
• Sahoo Naren K

Classifications

• G01C19/5719 Primary

  using planar vibrating masses driven in a translation vibration along an axis · CPC title

• H04L27/364 Primary

  Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels · CPC title

• H04L27/3863

  Compensation for quadrature error in the received signal · CPC title

• G01C19/5776

  Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 · CPC title