Support Loss and Q Factor Enhancement for a Rocking Mass Microgyroscope

A rocking mass gyroscope (RMG) is a kind of vibrating mass gyroscope with high sensitivity, whose driving mode and sensing mode are completely uniform. MEMS RMG devices are a research hotspot now because they have the potential to be used in space applications. Support loss is the dominant energy loss mechanism influencing their high sensitivity. An accurate analytical model of support loss for RMGs is presented to enhance their Q factors. The anchor type and support loss mechanism of an RMG are analyzed. Firstly, the support loads, powers flowing into support structure, and vibration energy of an RMG are all developed. Then the analytical model of support loss for the RMG is developed, and its sensitivities to the main structural parameters are also analyzed. High-Q design guidelines for rocking mass microgyroscopes are deduced. Finally, the analytical model is validated by the experimental data and the data from the existing literature. The thicknesses of the prototypes are reduced from 240 μm to 60 μm, while Q factors increase from less than 150 to more than 800. The derived model is general and applicable to various beam resonators, providing significant insight to the design of high-Q MEMS devices.

[1]  A. Pierce.  An Introduction to its Physical Principles and Applications , 1981 .

[2]  Kenneth J. Hayworth,et al.  High Performance Microgyros for Space Applications , 1999 .

[3]  Tayfun Akin,et al.  A high-performance silicon-on-insulator MEMS gyroscope operating at atmospheric pressure , 2007 .

[4]  S. Kotru,et al.  Design and Fabrication of a Meso-Scale Gyroscope , 2008, 2008 IEEE Workshop on Microelectronics and Electron Devices.

[5]  Hakan Urey,et al.  Vibration mode frequency formulae for micromechanical scanners , 2005 .

[6]  Paul Ashley,et al.  Feasibility study of a micromachined single-axis vibratory gyroscope using piezoelectric PNZT thin films for actuation and sensing , 2010 .

[7]  Karl Yee,et al.  High-performance MEMS microgyroscope , 2002, Symposium on Design, Test, Integration, and Packaging of MEMS/MOEMS.

[8]  A. T. Moorhouse,et al.  A closed form solution for the mobility of an edge-excited, semi-infinite plate , 2004 .

[9]  N. Jalili,et al.  Coupled vibration and parameter sensitivity analysis of rocking-mass vibrating gyroscopes , 2009 .

[10]  Andrei M. Shkel,et al.  MEMS Vibratory Gyroscopes: Structural Approaches to Improve Robustness (MEMS Reference Shelf) , 2008 .

[11]  Benjamin Chouvion,et al.  Vibration Transmission and Support Loss in MEMS Sensors , 2010 .

[12]  P. Ward,et al.  Quality factors of MEMS gyros and the role of thermoelastic damping , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[13]  F. Ayazi,et al.  Support loss in micromechanical disk resonators , 2005, 18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005..

[14]  Reza Abdolvand,et al.  Quality factor in trench-refilled polysilicon beam resonators , 2006, Journal of Microelectromechanical Systems.

[15]  Xuezhong Wu,et al.  Support loss for beam undergoing coupled vibration of bending and torsion in rocking mass resonator , 2011 .

[16]  Christiaan Kauffmann.  Input mobilities and power flows for edge excited, semi‐infinite plates , 1991 .

[17]  Ewald Eichler.  Plate-Edge Admittances , 1964 .

[18]  Brian H. Houston,et al.  Attachment loss of micromechanical and nanomechanical resonators in the limits of thick and thin support structures , 2007 .

[19]  C. Zener.  INTERNAL FRICTION IN SOLIDS II. GENERAL THEORY OF THERMOELASTIC INTERNAL FRICTION , 1938 .

[20]  D. Keymeulen,et al.  Tuning of MEMS Gyroscope using Evolutionary Algorithm and “ switched drive-angle” method , 2006, 2006 IEEE Aerospace Conference.

[21]  F. Ayazi,et al.  An analytical model for support loss in micromachined beam resonators with in-plane flexural vibrations , 2003 .