Electrical & Computer Engineering     |     Carnegie Mellon

Tuesday, May 29, 12:00-1:00 p.m. HH-1112

David Guillou
Carnegie Mellon University

Control of MEMS Electrostatic Parallel-Plate Actuators

Microelectromechanical system (MEMS) technology seeks to leverage and extend the classical VLSI paradigm by integrating components that operate in multiple energy domains (e.g. electronic, mechanical, optical, fluidic, chemical components) on a single die. The use of VLSI fabrication techniques and the scaling of physical laws enable both the design of MEMS devices which have higher performance than their macro-scale counterparts, and the design of new devices or systems which could not be implemented with conventional manufacturing technology.

As a discipline, MEMS is much less mature than VLSI electronics. Many basic aspects of MEMS fabrication technologies, MEMS component and system design, and MEMS design methodology are still topics for research. For example, many MEMS devices incorporate electrostatic "parallel-plate" actuators (PPAs) to implement transport functions (e.g. tilt an optical mirror or displace a payload) and force-feedback functions (e.g. as used in many inertial sensors) because PPAs generate comparatively high forces. However, PPAs have a limited range of stable motion when driven in open loop, which severely limits their practical use and performance.In this talk, we show that a PPA can be stabilized past its open-loop instability limit, and can be operated with both controlled stiffness and controlled damping, by use of position feedback control. We analyze the performance achieved with an ideal proportional-derivative controller, and we derive closed-form design equations. In addition, we discuss the effects of a finite controller gain-bandwidth product. Finally, we show that a PPA with feedback control can be employed as read/write head actuator in a MEMS-based data storage system.

David Guillou is a Ph.D. candidate in the Department of Electrical and Computer Engineering at Carnegie Mellon University, advised by Prof. L. Richard Carley. He received a B.S. in Electrical Engineering from Institut National des Sciences Appliquees, Rennes, France, and a M.S. in Electrical and Computer Engineering from the State University of New York at Buffalo. His research interests are in analog circuit design for instrumentation, low-noise and high-precision applications, and microelectromechanical systems.