Whole-Angle MEMS Gyroscopes

Challenges and Opportunities

Doruk Senkal, Andrei M. Shkel

• Publisher: Wiley-IEEE Press
• Year: 2020
• Print ISBN: 9781119441885
• eBook ISBN: 9781119441922
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Presents the mathematical framework, technical language, and control systems know-how needed to design, develop, and instrument micro-scale whole-angle gyroscopes

This comprehensive reference covers the technical fundamentals, mathematical framework, and common control strategies for degenerate mode gyroscopes, which are used in high-precision navigation applications. It explores various energy loss mechanisms and the effect of structural imperfections, along with requirements for continuous rate integrating gyroscope operation. It also provides information on the fabrication of MEMS whole-angle gyroscopes and the best methods of sustaining oscillations.

Whole-Angle Gyroscopes: Challenges and Opportunities begins with a brief overview of the two main types of Coriolis Vibratory Gyroscopes (CVGs): non-degenerate mode gyroscopes and degenerate mode gyroscopes. It then introduces readers to the Foucault Pendulum analogy and a review of MEMS whole angle mode gyroscope development. Chapters cover: dynamics of whole-angle coriolis vibratory gyroscopes; fabrication of whole-angle coriolis vibratory gyroscopes; energy loss mechanisms of coriolis vibratory gyroscopes; and control strategies for whole-angle coriolis vibratory gyro- scopes. The book finishes with a chapter on conventionally machined micro-machined gyroscopes, followed by one on micro-wineglass gyroscopes. In addition, the book:

• Lowers barrier to entry for aspiring scientists and engineers by providing a solid understanding of the fundamentals and control strategies of degenerate mode gyroscopes
• Organizes mode-matched mechanical gyroscopes based on three classifications: wine-glass, ring/disk, and mass spring mechanical elements
• Includes case studies on conventionally micro-machined and 3-D micro-machined gyroscopes

Whole-Angle Gyroscopes is an ideal book for researchers, scientists, engineers, and college/graduate students involved in the technology. It will also be of great benefit to engineers in control systems, MEMS production, electronics, and semi-conductors who work with inertial sensors.

Part I
Fundamentals of Whole‐Angle Gyroscopes

1
Introduction

Coriolis Vibratory Gyroscopes (CVGs) are mechanical transducers that detect angular rotation around a particular axis. In its most fundamental form, a CVG consists of two or more mechanically coupled vibratory modes, a forcing system to induce vibratory motion and a sensing system to detect vibratory motion. Angular rotation can be detected by sensing the energy transfer from one vibratory mode to another in the presense of Coriolis forces, Figure 1.1.

Historically, first examples of CVGs can be found in the Aerospace Industry, which were primarily used for navigation and platform stabilization applications. Later, advent of Micro‐electromechanical System (MEMS) fabrication techniques brought along orders of magnitude reduction in cost, size, weight, and power (CSWaP), which made CVGs truly ubiquitous. Today CVGs are used in a wide variety of civilian applications, examples include:

• Industrial applications, such as robotics and automation;
• Automobile stabilization, traction control, and roll‐over detection;
• Gesture recognition and localization in gaming and mobile devices;
• Optical image stabilization (OIS) of cameras;
• Head tracking in Augmented Reality (AR) and Virtual Reality (VR);
• Autonomous vehicles, such as self‐driving cars and Unmanned Aerial Vehicles (UAVs).

1.1 Types of Coriolis Vibratory Gyroscopes

CVGs can be divided into two broad categories based on the gyroscope's mechanical element [1]: degenerate mode (i.e.

‐axis) gyroscopes, which have

–

symmetry (

of 0 Hz), and nondegenerate mode gyroscopes, which are designed intentionally to be asymmetric in

and

modes (

). Degenerate mode

‐axis gyroscopes offer a number of unique advantages compared to nondegenerate vibratory rate gyroscopes, including higher rate sensitivity, ability to implement whole‐angle mechanization with mechanically unlimited dynamic range, exceptional scale factor stability, and a potential for self‐calibration.

Figure 1.1 Coriolis Vibratory Gyroscopes, in their simplest form, consist of a vibrating element with two or more mechanically coupled vibratory modes. Illustration shows a

‐axis gyroscope and its vibratory modes along

‐ and

‐axis.

1.1.1 Nondegenerate Mode Gyroscopes

Nondegenerate mode CVGs are currently being used in a variety of commercial applications due to ease of fabrication and lower cost. Most common implementations utilize two to four vibratory modes for sensing angular velocity along one to three axes. This is commonly achieved by forcing a proof mass structure into oscillation in a so‐called “drive” mode and sensing the oscillation on one or more “sense” modes. For example, the

‐axis of the gyroscope in Figure 1.1, can be instrumented as a drive...

Table of contents

• Cover
• Table of Contents
• List of Abbreviations
• Preface
• About the Authors
• Part I: Fundamentals of Whole‐Angle Gyroscopes
• Part II: 2‐D Micro‐Machined Whole‐Angle Gyroscope Architectures
• Part III: 3‐D Micro‐Machined Whole‐Angle Gyroscope Architectures
• References
• Index
• IEEE Press Series on Sensors
• End User License Agreement