This book provides the latest theoretical analysis and design methodologies of different types of Coriolis vibratory gyroscopes (CVG). Together, the chapters analyze different types of sensitive element designs and their kinematics, derivation of motion equations, analysis of sensitive elements dynamics in modulated and demodulated signals, calculation and optimization of main performance characteristics, and signal processing and control. Essential aspects of numerical simulation of CVG using Simulink® are also covered. This is an ideal book for graduate students, researchers, and engineers working in fields that require gyroscope application, including but not limited to: inertial sensors and systems, automotive and consumer electronics, small unmanned aircraft control systems, personal mobile navigation systems and related software development, and augmented and virtual reality systems.
MEMS Vibratory Gyroscopes provides a solid foundation in the theory and fundamental operational principles of micromachined vibratory rate gyroscopes, and introduces structural designs that provide inherent robustness against structural and environmental variations. In the first part, the dynamics of the vibratory gyroscope sensing element is developed, common micro-fabrication processes and methods commonly used in inertial sensor production are summarized, design of mechanical structures for both linear and torsional gyroscopes are presented, and electrical actuation and detection methods are discussed along with details on experimental characterization of MEMS gyroscopes. In the second part, design concepts that improve robustness of the micromachined sensing element are introduced, supported by constructive computational examples and experimental results illustrating the material.
This book provides a unified approach for the two versions of Coriolis vibratory gyroscopes: Micro-Electro-Mechanical System (MEMS) and non-MEMS. It describes a new, differential mode of operation, analyzing the new triple mode gyro—rate, rate-integrating, and differential. The latter provides the gyro with an increased versatility by providing the maximum possible accuracy under changeable motion parameters and environmental conditions. The book also presents computer simulation, experiments, and test results on the rejection of external disturbances, and considers the fabrication processes of MEMS, metallic and quartz resonators. It will interest researchers, scientists, engineers, and students specializing in the field of inertial sensors, as well as engineers of digital control systems, and inertial sensors test-engineers. It can also be used as a reference book when designing vibratory gyros.
This book introduces readers to the shell structure, operating principle, manufacturing process, and control theory for cylindrical vibratory gyroscopes. The cylindrical vibratory gyroscope is an important type of Coriolis vibratory gyroscope that holds considerable potential for development and application. The main aspects addressed include: operating principle and structure, theoretical analysis and modeling, dynamic analysis and modeling, manufacturing process, parameter testing methods, closed-loop control, and the error compensation mechanism in cylindrical vibratory gyroscopes.
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.
Micro-machined vibratory gyroscopes are very small devices (up to a few millimeters in dimension) that work based on Coriolis force coupling between two resonance modes. The small size, low power consumption, and cheap price make these sensors popular in automotive, gaming, smart phones, and robotics industries. These sensors referred to as MEMS (microelectromechanical system) gyroscopes are currently not used for navigation applications because due to their miniature size and imperfections in fabrication methods they do not have enough accuracy. In this thesis, we present methods in design and control algorithms for MEMS vibratory gyroscopes to cancel the effect of imperfections in fabrication and improve gyroscopes' performance. First chapter of this thesis is an introduction on MEMS vibratory gyroscopes and their principles and standard operations modes.The second chapter presents the structural design and analysis of a single-structure 3-axis MEMS gyroscope. The gyroscope has four resonant modes of interest and uses a decoupling mechanism whereby auxiliary masses are used to actuate the drive mode of the gyroscope in order to reduce drive-force coupling to sense modes' motion (one of the sources of errors in MEMS gyroscopes). The use of auxiliary masses results in a two degree-of-freedom (DOF) mechanism of the drive mode. To compare the effectiveness of using auxiliary masses two gyroscope types has been design one actuated from auxiliary masses (type A) and one actuated from major masses (type B). The two designs are simulated analytically to study the displacement of each mass in each design while comparing the force required to achieve that displacement for drive mode. Experimental data from fabricated devices show how using auxiliary masses will decrease drive force coupling and as a result improve the gyroscope's performance. Third chapter describes the operation of a high quality factor gyroscope in various regimes where electromechanical nonlinearities introduce different forms of amplitude-frequency (A-f) dependence. Experiments are conducted using an epitaxially-encapsulated 2 x 2 mm2 quad-mass gyroscope (QMG) with a quality factor of 85,000. The device exhibits third-order Duffing nonlinearity at low bias voltages (15 V) due to the mechanical nonlinearity in the flexures and at high bias voltages (35 V) due to third-order electrostatic nonlinearity. At intermediate voltages (26 V), these third-order nonlinearities cancel and the amplitude-frequency dependence is greatly reduced. A model is developed to demonstrate the connection between the electromechanical nonlinearities and the amplitude-frequency dependence, also known as the backbone curve. Gyroscope operation is demonstrated in each nonlinear operating regime and the key performance measures of the gyroscope's performance, angle random walk (ARW) and bias instability, are measured as a function of drive-mode vibration amplitude. While the bias instability is nearly independent of the drive-mode’s nonlinearity, we find that ARW increases when the third-order nonlinearities are minimized, and the decrease in ARW due to increase of amplitude is independent of drive mode's type of nonlinearity.In the fourth chapter we present a direct angle measurement method in gyroscopes. Towards the objective of direct angle measurement using a rate integrating gyroscope (RIG) without a minimum rate threshold and performance limited only by electrical and mechanical thermal noise, in this chapter we present the implementation of a generalized electronic feedback method for the compensation of MEMS gyroscope damping asymmetry (anisodamping) and stiffness asymmetry (anisoelasticity) on a stand-alone digital signal processing (DSP) platform. Using the new method, the precession angle dependent bias error and minimum rate threshold, two issues identified by Lynch for a MEMS RIG due to anisodamping are overcome. To minimize angle dependent bias, we augment the electronic feedback force of the amplitude regulator with a non-unity gain output distribution matrix selected to correct for anisodamping. Using this method, we have decreased the angle dependent bias error by a factor of 30, resulting a minimum rate threshold of 2.5 dps. To further improve RIG performance, an electronically-induced self-precession rate is incorporated and successfully demonstrated to lower the rate threshold.
