An approach for increasing drive-mode bandwidth of MEMS vibratory gyroscopes

The limitations of the photolithography-based micromachining technologies defines the upper-bound on the performance and robustness of micromachined gyroscopes. Conventional gyroscope designs based on matching (or near-matching) the drive and sense modes are extremely sensitive to variations in oscillatory system parameters that shift the natural frequencies and introduce quadrature errors. Nonconventional design concepts have been reported that increase bandwidth to improve robustness, but with the expense of response gain reduction. This paper presents a new approach that may yield robust vibratory MEMS gyroscopes with better gain characteristics while retaining the wide bandwidth. The approach is based on utilizing multiple drive-mode oscillators with incrementally spaced resonance frequencies to achieve wide-bandwidth response in the drive-mode, leading to improved robustness to structural and thermal parameter fluctuations. Enhanced mode-decoupling is achieved by distributing the linear drive-mode oscillators radially and symmetrically, to form a multidirectional linear drive-mode and a torsional sense-mode; minimizing quadrature error and zero-rate output. The approach has been implemented on bulk-micromachined prototypes fabricated in a silicon-on-insulator (SOI)-based process, and experimentally demonstrated.

[1]  Yong-Kweon Kim,et al.  A few deg/hr resolvable low noise lateral microgyroscope , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[2]  Andrei M. Shkel,et al.  FOUR DEGREES-OF-FREEDOM MICROMACHINED GYROSCOPES , 2001 .

[3]  A. Shkel.  Modeling and simulation of micromachined gyroscopes in the presence of imperfections , 1999 .

[4]  Farrokh Ayazi,et al.  Micromachined inertial sensors , 1998, Proc. IEEE.

[5]  Gary K. Fedder,et al.  A DRIE CMOS-MEMS gyroscope , 2002, Proceedings of IEEE Sensors.

[6]  Weichen Xue,et al.  Design and characteristics of two-gimbals micro-gyroscopes fabricated with quasi-LIGA process , 1997, Proceedings of International Solid State Sensors and Actuators Conference (Transducers '97).

[7]  J. Frech,et al.  Decoupled microgyros and the design principle DAVED , 2001, Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090).

[8]  Y. Mochida,et al.  A micromachined vibrating rate gyroscope with independent beams for the drive and detection modes , 2000 .

[9]  Robert P. Leland.  Adaptive tuning for vibrational gyroscopes , 2001, Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228).

[10]  A. Shkel,et al.  Nonresonant micromachined gyroscopes with structural mode-decoupling , 2003 .

[11]  Roberto Horowitz,et al.  Dynamics and control of micromachined gyroscopes , 1999, Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251).

[12]  R. Horowitz,et al.  Adaptive control for z-axis MEMS gyroscopes , 2001, Proceedings of the 2001 American Control Conference. (Cat. No.01CH37148).

[13]  Andrei M. Shkel,et al.  Distributed-mass micromachined gyroscopes for enhanced mode-decoupling , 2003, Proceedings of IEEE Sensors 2003 (IEEE Cat. No.03CH37498).

[14]  Y. Mochida,et al.  A micromachined vibrating rate gyroscope with independent beams for the drive and detection modes , 2000, Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.99CH36291).

[15]  Jong-Hyun Lee,et al.  A laterally driven symmetric micro-resonator for gyroscopic applications , 2000 .