Micromachined Gyroscopes with 2-DOF Sense Modes Allowing Interchangeable Robust and Precision Operation

• US 20130233076A1
• Filed: 04/19/2013
• Published: 09/12/2013
• Est. Priority Date: 10/23/2009
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Schofield, Adam, Trusov, Alexander, Shkel, Andrei
• Granted Patent: US 9,310,199 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5733 Structural details or topology

Abstract

A z-axis gyroscope design is presented with a 2-degree of freedom (DOF) sense mode allowing interchangeable operation in either precision (mode-matched) or robust (wide-bandwidth) modes. This is accomplished using a complete 2-DOF coupled system which allows for the specification of the sense mode resonant frequencies and coupling independent of frequency. By decoupling the frame connecting the sense system to a central anchor, x-y symmetry is preserved while enabling a fully coupled 2-DOF sense mode providing control over both the bandwidth and the amount of coupling independent of operational frequency. The robust mode corresponds to operation between the 2-DOF sense mode resonant frequencies providing a response gain and bandwidth controlled by frequency spacing. Precision mode of operation, however, relies on mode-matching the drive to the second, anti-phase sense mode resonant frequency which can be designed to provide a gain advantage over a similar 1-DOF system.

Claims

1. A micromachined z-axis vibratory rate gyroscope formed on a substrate comprising:

an outer decoupling drive frame restrained to oscillate substantially only in a drive direction;

an inner decoupling drive frame restrained to oscillate substantially only in a drive direction, the inner and outer decoupling drive frames being decoupled from each other and both resiliently coupled to the substrate;

a first sense mass m_a resiliently coupled to the outer decoupling drive frame and restrained to oscillate substantially only in the sense direction;

a second sense mass m_b resiliently coupled to the outer decoupling drive frame and restrained to oscillate substantially only in the sense direction, the first and second sense masses m_a and m_b being independently resiliently coupled to each other to allow relative oscillation in the sense direction;

a drive electrostatic comb coupled to either the inner decoupling drive frame or the outer decoupling frame or both; and

a sense electrostatic comb coupled to either the first sense mass or the second sense mass or both.