Whole-Angle MEMS Gyroscopes: Challenges and Opportunities (IEEE Press Series on Sensors)

"Coriolis Vibratory Gyroscopes (CVGs) can be divided into two broad categories based on the gyroscope's mechanical element: (Type 1) degenerate mode gyroscopes, which have x-y symmetry, and (Type 2) non-degenerate mode gyroscopes, which are designed intentionally to be asymmetric in x and y modes. Currently, non-degenerate 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, have a number of unique advantages compared to non-degenerate 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. For this reason, as the MEMS gyroscope development is reaching maturity, the Research and Development focus is shifting from high-volume production of low-cost non-degenerate 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 world of degenerate mode gyroscopes"-- Provided by publisher Cover -- Title Page -- Copyright Page -- Contents -- List of Abbreviations -- Preface -- About the Authors -- Part I Fundamentals of Whole-Angle Gyroscopes -- Chapter 1 Introduction -- 1.1 Types of Coriolis Vibratory Gyroscopes -- 1.1.1 Nondegenerate Mode Gyroscopes -- 1.1.2 Degenerate Mode Gyroscopes -- 1.2 Generalized CVG Errors -- 1.2.1 Scale Factor Errors -- 1.2.2 Bias Errors -- 1.2.3 Noise Processes -- 1.2.3.1 Allan Variance -- 1.3 Overview -- Chapter 2 Dynamics -- 2.1 Introduction to Whole-Angle Gyroscopes -- 2.2 Foucault Pendulum Analogy -- 2.2.1 Damping and Q-factor 2.2.1.1 Viscous Damping -- 2.2.1.2 Anchor Losses -- 2.2.1.3 Material Losses -- 2.2.1.4 Surface Losses -- 2.2.1.5 Mode Coupling Losses -- 2.2.1.6 Additional Dissipation Mechanisms -- 2.2.2 Principal Axes of Elasticity and Damping -- 2.3 Canonical Variables -- 2.4 Effect of Structural Imperfections -- 2.5 Challenges of Whole-Angle Gyroscopes -- Chapter 3 Control Strategies -- 3.1 Quadrature and Coriolis Duality -- 3.2 Rate Gyroscope Mechanization -- 3.2.1 Open-loop Mechanization -- 3.2.1.1 Drive Mode Oscillator -- 3.2.1.2 Amplitude Gain Control -- 3.2.1.3 Phase Locked Loop/Demodulation 3.2.1.4 Quadrature Cancellation -- 3.2.2 Force-to-rebalance Mechanization -- 3.2.2.1 Force-to-rebalance Loop -- 3.2.2.2 Quadrature Null Loop -- 3.3 Whole-Angle Mechanization -- 3.3.1 Control System Overview -- 3.3.2 Amplitude Gain Control -- 3.3.2.1 Vector Drive -- 3.3.2.2 Parametric Drive -- 3.3.3 Quadrature Null Loop -- 3.3.3.1 AC Quadrature Null -- 3.3.3.2 DC Quadrature Null -- 3.3.4 Force-to-rebalance and Virtual Carouseling -- 3.4 Conclusions -- Part II 2-D Micro-Machined Whole-Angle Gyroscope Architectures -- Chapter 4 Overview of 2-D Micro-Machined Whole-Angle Gyroscopes 4.1 2-D Micro-Machined Whole-Angle Gyroscope Architectures -- 4.1.1 Lumped Mass Systems -- 4.1.2 Ring/Disk Systems -- 4.1.2.1 Ring Gyroscopes -- 4.1.2.2 Concentric Ring Systems -- 4.1.2.3 Disk Gyroscopes -- 4.2 2-D Micro-Machining Processes -- 4.2.1 Traditional Silicon MEMS Process -- 4.2.2 Integrated MEMS/CMOS Fabrication Process -- 4.2.3 Epitaxial Silicon Encapsulation Process -- Chapter 5 Example 2-D Micro-Machined Whole-Angle Gyroscopes -- 5.1 A Distributed Mass MEMS Gyroscope -- Toroidal Ring Gyroscope -- 5.1.1 Architecture -- 5.1.1.1 Electrode Architecture 5.1.2 Experimental Demonstration of the Concept -- 5.1.2.1 Fabrication -- 5.1.2.2 Experimental Setup -- 5.1.2.3 Mechanical Characterization -- 5.1.2.4 Rate Gyroscope Operation -- 5.1.2.5 Comparison of Vector Drive and Parametric Drive -- 5.2 A Lumped Mass MEMS Gyroscope -- Dual Foucault Pendulum Gyroscope -- 5.2.1 Architecture -- 5.2.1.1 Electrode Architecture -- 5.2.2 Experimental Demonstration of the Concept -- 5.2.2.1 Fabrication -- 5.2.2.2 Experimental Setup -- 5.2.2.3 Mechanical Characterization -- 5.2.2.4 Rate Gyroscope Operation -- 5.2.2.5 Parameter Identification

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.

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.