Doruk Senkal - Whole-angle MEMs gyroscopes: challenges and opportunities

1. List of Abbreviations
2. Chapter 5
3. Chapter 7
4. Chapter 8

1. Chapter 1
2. Chapter 2
3. Chapter 3
4. Chapter 4
5. Chapter 5
6. Chapter 6
7. Chapter 7
8. Chapter 8
9. Chapter 9

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Ekram Hossain, Editor in Chief

Doruk Senkal

Andrei M. Shkel

Copyright 2020 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.

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ISBN 9781119441885

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Cover Image: Courtesy of Doruk Senkal

Table 1 Control system abbreviations.

Table 2 Mechanical parameters of the resonator.

Symbol	Description
f	Mean frequency of the two primary modes of the resonator
Mean energy decay time constant of the resonator
Qfactor	Ratio of stored energy to energy loss per vibration cycle (Q = f)
f	Frequency split between primary modes in Hz (f = fxfy)
Frequency split between primary modes in rad/s ( = xy)
1	Measure of anisodamping within the gyroscope ()
Angle defining the orientation of actual versus intended axes of elasticity
Angle defining the orientation of actual versus intended axes of damping
(x, y, z)	Coordinate frame oriented along intended axes of symmetry x and y
n = 2 mode	A 4node degenerate mode pair of a wineglass or ring/disk system
n = 3 mode	A 6node degenerate mode pair of a wineglass or ring/disk system
Precession pattern	Vibration pattern formed by superposition of x and y vibratory modes, which is capable of changing its orientation (precesses) when subjected to Coriolis forces or an external forcing function
Pattern angle ()	Orientation of the precession pattern in degrees, which is a measure of angular rotation in a Rate Integrating Gyroscope

Coriolis Vibratory Gyroscopes (CVGs) can be divided into two broad categories based on the gyroscope's mechanical element: degenerate mode gyroscopes (type 1), which have xy symmetry, and nondegenerate mode gyroscopes (type 2), which are designed intentionally to be asymmetric in x and y modes.

Currently, nondegenerate mode gyroscopes fulfill the needs of a variety of commercial applications, such as tilt detection, activity tracking, and gaming. However, when it comes to inertial navigation, where sensitivity and stability of the sensors are very important, commercially available MEMS sensors fall short by three orders of magnitude. Degenerate mode gyroscopes, on the other hand, offer a number of unique advantages compared to nondegenerate vibratory rate gyroscopes, including higher rate sensitivity, ability to implement wholeangle mechanization with mechanically unlimited dynamic range, exceptional scale factor stability, and a potential for selfcalibration. For this reason, as the MEMS gyroscope development is reaching maturity, the Research and Development focus is shifting from highvolume production of lowcost nondegenerate mode gyroscopes to high performance degenerate mode gyroscopes. This paradigm shift in MEMS gyroscope research and development creates a need for a reference book to serve both as a guide and an entry point to the field of degenerate mode gyroscopes.