Semester

Fall

Date of Graduation

2004

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Lane Department of Computer Science and Electrical Engineering

Committee Chair

Parviz Famouri.

Abstract

Applying closed-loop control to a MEMS devices not only can handle the abnormal behaviors caused by manufactory imprecision or device failure, enabling MEMS devices to survive in critical conditions, but also can increase the application where MEMS devices are used to drive components under varying load conditions. This study mainly focuses on the effort of closed-loop control on the Lateral Comb Resonator (LCR) MEMS device. The success of closed-loop control has been achieved on lateral comb resonator with novel integrated through wafer optical monitoring technique.;Availability of a system model and feedback signals are mandatory conditions for the implementation of closed-loop control. Because of the fabrication process tolerance, the parameters of the Lateral Comb Resonator (LCR)'s model cannot be determined accurately based merely on theoretical analysis. Three different system identification methods in both the time domain and frequency domain have been implemented, and the results agree.;Noise analysis on the optical monitoring signal shows that more than 90% of the noise in the signal is due to the optical monitoring setup, and a wavelet thresholding method and FFT based low pass filter have been adopted in this study to remove this Gaussian distributed noise.;Different designs are developed to monitor the LCR, both for single opening and grating structure LCRs, resulting in monitoring signals that are very different in nature. The optical monitoring signal for single opening device can be used directly as a feedback signal to perform closed-loop control on the shuttle for damping shock effect or to perform stroke-length control on the shuttle. The optical monitoring signal for the grating structure LCR is a frequency modulation of the shuttle's displacement. Based on this signal, both position and velocity signals can be reconstructed in real time. Experimental successes on force estimation and tracking control have been achieved based on this signal reconstruction method.;The signal reconstruction method, which can decouple the noise from the optical signal, has been implemented. 2mum's resolution can be achieved with the current single beam optical monitoring method. The resolution can be improved with the implementation of multi-beam optical monitoring in the near future.

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