Date of Award
Spring 2009
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Mechanical & Aerospace Engineering
Program/Concentration
Mechanical Engineering
Committee Director
Zhili Hao
Committee Member
Jen K. Huang
Committee Member
Shirshak Dhali
Call Number for Print
Special Collections; LD4331.E56 D87 2009
Abstract
Over the past two decades, micromachined gyroscopes fabricated using MicroElectroMechanical Systems (MEMS) technology have attracted a great deal of attention from various industrial and military sectors due to their significant advantages over traditional bulky gyroscopes, including small size, batch fabrication, low power consumption, and low cost. Among the various micromachined gyroscopes developed so far, tuning-fork gyroscopes with integrated electrostatic transducers have been extremely attractive because of their significant advantages over other structural forms and other types of transducers., including larger proof mass, large vibration amplitude in the drive-mode, and relative ease of fabrication.
This thesis presents the advanced design and performance characterization of a new tuning-fork gyroscope with high Quality Factors (Qs). This gyroscope design is comprised of a tuning-fork mechanical structure with high. Qs in both its drive-mode and sense-mode, comb-drive transducers for excitation of the drive-mode vibrations, parallel-plate sense electrodes for detection of a rotation rate signal, and tuning electrodes for minimizing the frequency difference between the two operation modes. The detailed finite element analysis of the tuning-fork structure is conducted in ANSYS. Through the use of an electrical analogy, the overall dynamic behavior of the tuning-fork structure and its integrated transducers is modeled as an equivalent electrical circuit model in P-SPICE. This design is fabricated using a one-mask fabrication technology based on silicon-on-insulator (SOI) wafers. The fabrication process consists of two steps: 1) a Deep-Reactive-Ion-Etching (DRlE) step of an aspect ratio of 10:1 and 2) a Hydrogen fluoride (HF) etching step. One batch of 30µm-thick gyroscopes is fabricated. These fabricated devices are tested under a vacuum in a two-port configuration using an Agilent 4395A network analyzer to characterize the frequency response of the drive-mode and sense-mode. The measured best Qs of a fabricated gyroscope are 106,000 for the drive-mode and 102,000 for the sense-mode. Since the gyroscope design is based on matched mode operation, a DC bias voltage applied to the device is adjusted in order to minimize the frequency difference between the drive-mode and the sense-mode. A minimum frequency difference of 4Hz over l 9.49kHz is achieved. However, due to the presence of Quadrature error, the rate sensitivity of the gyroscope is not successfully measured. In addition, due to the critical importance of minimizing frequency difference, a preliminary study on mode coupling and its associated dynamics of the gyroscope is also conducted.
Rights
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DOI
10.25777/w9xr-1w27
Recommended Citation
Durgam, Shiva K..
"Advanced Design and Performance Characterization of A Micromachined Tuning-Fork Gyroscope With High Quality Factors"
(2009). Master of Science (MS), Thesis, Mechanical & Aerospace Engineering, Old Dominion University, DOI: 10.25777/w9xr-1w27
https://digitalcommons.odu.edu/mae_etds/487