Dynamics and Control Problems in Micromechanical Resonators

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Friday, October 4, Giedt 1003, 12:10pm-1:00pm

Speaker: David Horsley
University of California, Davis
Professor, Mechanical & Aerospace Engineering
Electrical & Computer Engineering Graduate Program

Host: Professor Erkin Seker

Abstract:

Micro electromechanical systems (MEMS), an academic curiosity fifteen years ago, is now an over $10B industry. The relative maturity of the MEMS manufacturing base means that it is now possible to for academics to pose more sophisticated questions about the intriguing dynamics and control problems posed by these devices. In a large class of MEMS devices including timing oscillators and gyroscopes, it is desirable to maximize the oscillation amplitude and therefore the stored mechanical strain energy to improve the device’s signal-to-noise ratio (SNR). One approach, parametric excitation, is a nonlinear phenomenon described by the Mathieu equation and is implemented by modulating the device’s stiffness at a harmonic of the oscillation frequency. We used parametric excitation to achieve an 80-fold increase in SNR in a resonant sensor, showing this to be a promising approach for low-power MEMS sensors. A second issue is that large-amplitude nonlinearities described by the Duffing equation are associated with bifurcations that are known to result in dramatic jump instabilities in open-loop resonators. These nonlinearities were previously understood to pose a limit to stable large-amplitude operation. Using a disk resonator gyroscope, we recently demonstrated that closed-loop operation above the critical bifurcation point does not result in increased instability of the gyroscope’s scale factor or bias error, motivating more study of closed-loop nonlinear oscillators in MEMS applications.

Biography:

David Horsley is a Professor in the Department of Mechanical and Aerospace Engineering at the University of California, Davis, USA, and has been a co-director of the Berkeley Sensor and Actuator Center (BSAC) since 2005. His research interests include micromechanical devices with applications as physical sensors, filters and oscillators. Dr. Horsley received the Ph.D. degree in Mechanical Engineering from the University of California, Berkeley in 1998 for his thesis work pioneering dual-stage microactuators in hard disk drives. Prior to joining the faculty at UC Davis, he held positions at Dicon Fiberoptics, Hewlett Packard Laboratories and was involved in founding an optical components start-up, Onix Microsystems. Prof. Horsley is a recipient of the NSF CAREER Award and the UC Davis College of Engineering’s Outstanding Junior Faculty Award.


Speaker contact information

* Please contact Erkin Seker , if you would like to meet the speaker.

About the seminar:
This seminar is part of the Fall EEC 290 seminar series and is open to all.