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Session A2: Advances in MEMS-based Inertial Sensors and Inertial Measurement Units (Invited Session)

State-of-the-Art in MEMS Coriolis Vibratory Gyroscopes with Multi-Degree-of-Freedom Architectures Designed for Dynamic Range, Robustness, and Sensitivity
Andrei M. Shkel, Cenk Acar, Chris Painter, Alex Trusov, Adam Schofield, Sergei Zotov, Igor Prikhodko, Brent Simon, Doruk Senkal, Alexandra Efimovskaya, Danmeng Wang, Sina Askari, Mohammad Asadian, University of California, Irvine
Location: Pavilion Ballroom East
Date/Time: Tuesday, Apr. 21, 2:58 p.m.

Peer Reviewed

An overview of multi-mass solutions for MEMS Coriolis vibratory gyroscopes will be presented in this paper. The advantages and challenges associated with increasing the number of Degrees-of- Freedom (DOF) of the mechanical element are discussed.
Conceptually, a single proof-mass is sufficient to measure the Coriolis-acceleration-induced angular rate signal along a single axis of rotation. Over the last two decades, however, a variety of multi-mass solutions emerged, offering advantages, such as a dynamic structural balance, an increased bandwidth of detection, and a dynamic amplification of response.
Dynamically balanced systems, such as, for example, a Dual Foucault Pendulum (DFP) gyroscope, utilized two or more dynamically equivalent, mechanically coupled proof-masses, oscillating in the anti-phase motion, for improved vibration immunity and anchor loss mitigation, resulting in the ultra-high quality factor. The concepts of a dynamic balance for anchor loss mitigation and a common-mode rejection of shock and vibration are employed in the design of the Tuning Fork (TF) Gyroscope, where two dynamically equivalent, mechanically coupled proof-masses are utilized. A similar principle is employed in the design of a Quadruple Mass Gyroscope (QMG), where the structural element is formed by four mechanically coupled proof masses, and thus enabling a dynamic balance of forces and moments in drive and sense modes, as opposed to a dynamic balance of forces in a single-axis TF architecture.
This group also introduced a family of designs pursuing an increased bandwidth, inherently robust dual-mass gyroscope. The mechanical element was comprised of a two DOF sense mode oscillator, formed by two interconnected masses. These devices were operated in a flat region of the sense-mode response curve, where the amplitude and phase of the response are insensitive to environmental fluctuations. For example, it was experimentally demonstrated that a temperature variation from 25 to 75C resulted in only 1.62% change in the output of a wide-bandwidth gyroscope, which was 12.2 times smaller as compared to a conventional 1-DOF sense mode gyroscope.
Another example of a multi-mass solution developed by the group is a dual-mass dynamically amplified system, where an increased number of DOF resulted in dynamic amplification of motion and improved sensitivity. In a dynamically amplified gyroscope, the first, the “drive mass", was actively driven to oscillate at a small amplitude of motion, in a linear operational regime. Meanwhile, the mechanically coupled “slave mass" was used for sensing the Coriolis signal. The amplitude of motion of the “slave mass" was dynamically amplified, resulting in an increased scale factor of the device.
This paper offers a review of different multi-degree of freedom gyroscope concepts. The advantages of such systems are analyzed, and potential challenges are discussed.



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