Composite vibratory in-plane accelerometer

Patent metadata

Field	Value
Publication number	US-10234477-B2
Application number	US-201615275188-A
Country	US
Kind code	B2
Filing date	Sep 23, 2016
Priority date	Jul 27, 2016
Publication date	Mar 19, 2019
Grant date	Mar 19, 2019

Abstract

Systems and methods are described herein for detecting and measuring inertial parameters, such as acceleration. In particular, the systems and methods relate to vibratory inertial sensors implementing time-domain sensing techniques. Within a composite mass sensor system, a sense mass may oscillate at a frequency different from its actuation frequency, allowing flexibility when integrating the sensor into drive systems without sacrificing sensitivity.

First claim

What is claimed is:

1. A composite mass system, comprising:
a sense mass, wherein the sense mass responds to an inertial parameter in a first direction at a first frequency in the first direction;
a drive mass flexibly coupled to the sense mass, wherein the drive mass is driven in the first direction at a second frequency;
a first time-domain switch configured to generate an output voltage based on a first current generated in part by the sense mass moving relative to a support structure; and
logic circuitry in signal communication with the first time-domain switch and configured to:
determine a time interval based on the output voltage; and
calculate the inertial parameter based on the time interval.

2. The composite mass system of claim 1 , wherein a resonant frequency of the sense mass is different from a resonant frequency of the drive mass.

3. The composite mass system of claim 2 , wherein the first frequency is the resonant frequency of the sense mass, and the second frequency is the resonant frequency of the drive mass.

4. The composite mass system of claim 1 , wherein the drive mass is flexibly coupled to the sense mass via coupling springs that are compliant in the first direction.

5. The composite mass system of claim 4 , further comprising an anchor structure rigidly coupled to the support structure, wherein the drive mass is mechanically coupled to the anchor structure via drive springs.

6. The composite mass system of claim 5 , wherein a spring constant of the coupling springs is lower than a spring constant of the drive springs.

7. The composite mass system of claim 5 , further comprising an arm having a major axis that passes radially from the anchor structure to the drive mass, wherein the drive springs are coupled to the arm and configured to cause the drive mass to move substantially in the first direction as the arm is rotated about an axis perpendicular to a plane defined by the first direction and the major axis.

8. The composite mass system of claim 7 , wherein the first direction is substantially tangential to the rotation of the arm.

9. The composite mass system of claim 5 , wherein a spring constant of the coupling springs increases as oscillation frequency increases and decreases as oscillation frequency decreases.

10. The composite mass system of claim 1 , wherein the drive mass is driven via a comb drive.

11. The composite mass system of claim 1 , wherein the time-domain switch comprises a first half coupled to the sense mass and a second half coupled to the support structure.

12. The composite mass system of claim 1 , wherein the time-domain switch comprises a plurality of time-domain switches.

13. The composite mass system of claim 1 , further comprising a second time-domain switch configured to generate a second voltage based on a second current generated in part by the sense mass, wherein the first current is out of phase with the second current.

14. The composite mass system of claim 13 , wherein the logic circuitry is further configured to linearly combine a signal generated from the first time-domain switch with a signal generated from the second time-domain switch.

15. The composite mass system of claim 1 , wherein the second frequency is higher than the first frequency.

16. The composite mass system of claim 15 , wherein the inertial parameter is acceleration.

17. A method for determining an inertial parameter, comprising:
responding to an inertial parameter in a first direction with a sense mass in the first direction at a first frequency;
driving, in the first direction at a second frequency, a drive mass that is flexibly coupled to the sense mass;
generating, from a first time-domain switch, an output voltage based on a first current generated in part by the sense mass moving relative to a support structure;
determining a time interval based on the output voltage; and
calculating the inertial parameter based on the time interval.

18. The method of claim 17 , further comprising oscillating the sense mass at a resonant frequency of the sense mass and driving the drive mass at a resonant frequency of the drive mass.

19. The method of claim 17 , wherein the drive mass is flexibly coupled to the sense mass via coupling springs that are compliant in the first direction.

20. The method of claim 19 , wherein the drive mass is mechanically coupled to an anchor structure via drive springs; and
wherein the anchor structure is rigidly coupled to the support structure.

21. The method of claim 20 , wherein a spring constant of the coupling springs is lower than a spring constant of the drive springs.

22. The method of claim 17 , wherein the drive mass is driven via a comb drive.

23. The method of claim 17 , wherein a first half of the time-domain switch is coupled to the sense mass and a second half of the time-domain switch is coupled to the support structure.

24. The method of claim 23 , further comprising generating, from a second time-domain switch, a second voltage based on a second current generated in part by the sense mass, wherein the first current is out of phase with the second current.

25. The method of claim 24 , further comprising linearly combining a signal generated from the first time-domain switch with a signal generated from the second time-domain switch.

26. The method of claim 17 , wherein a resonant frequency of the sense mass is different from a resonant frequency of the drive mass.

27. The method of claim 17 , wherein the inertial parameter comprises an acceleration.

Assignees

• Lumedyne Tech Incorporated
• Google Llc

Inventors

• Anac Ozan
• Huang Xiaojun

Classifications

• B81B7/008

  MEMS characterised by an electronic circuit specially adapted for controlling or driving the same (B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00) · CPC title

• G01C19/5776

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

• G01P15/097 Primary

  by vibratory elements · CPC title

• G01C19/5726

  Signal processing · CPC title

• G01P15/14

  by making use of gyroscopes (gyroscopes per se G01C19/00) · CPC title