Title page for ETD etd-11142006-145204


Type of Document Master's Thesis
Author Younis, Mohamed Abdelrahman
Author's Email Address myouni1@lsu.edu
URN etd-11142006-145204
Title A Generalized Approach for the Control of Micro-Electromechanical Relays
Degree Master of Science in Mechanical Engineering (M.S.M.E.)
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Marcio S. de Queiroz Committee Chair
Wanjun Wang Committee Member
Yitshak Ram Committee Member
Keywords
  • relay
  • pull-in
  • MEMS
  • closed-loop
  • feedback
Date of Defense 2006-11-13
Availability unrestricted
Abstract
MEMS (Micro-Electromechanical Systems) is an area of research and applications that is becoming increasingly popular. It's mainly concerned with integrating micro-mechanical transducers with micro-electronic circuits on common substrates, traditionally silicon, through micro-fabrication. Instead of traditionally having the transducer and the communicating (or control) circuit as two separate entities, MEMS miniaturizes and combines them on a single chip, giving it several advantages, saving space, money, and increasing the sensitivity and accuracy of the integrated system.

A micro-electromechanical relay is a type of MEM devices that is becoming increasingly important in a wide range of industries such as the computer industry, the medical industry and the automotive industry, to name a few. However, micro-relays, both electrostatic and electromagnetic, share a common dynamic structure that causes an unfavorable phenomenon called pull-in in which the movable electrode comes crashing down to the fixed electrode once it reaches a certain gap spacing, possibly damaging the relay and creating undesirable output effects. To eliminate this phenomenon and have better control over the switching of the micro-relays, improving transient response and output error, a feedback control scheme is desired.

In this work, it is shown that voltage-controlled electromechanical micro-relays have a common dynamic structure allowing for the formulation of a generalized model. It is also shown that open-loop control of MEM relays naturally leads to pull-in during closing. An attempt has been made to control the relays eliminating this phenomenon and tracking a command signal that dictates the motion of the movable electrode over time with improved transient response. In doing so, two control schemes were adopted, a Lyapunov-based and a feedback linearization-based one.

Simulation results clearly show the superiority of the closed-loop control compared to the open-loop one. It's also shown that the Lyapunov-based controller was limited in the extent to which it improved the transient response and that the feedback linearization-based controller performed much better. The latter eliminated pull-in and significantly lowered transient response and settling times, leading to very good tracking of the command signal.

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