SUBJECT: Ph.D. Dissertation Defense
BY: Joshua Schultz
TIME: Friday, August 10, 2012, 10:00 a.m.
PLACE: Love Building, 210
TITLE: Mathematical Modeling and Control of a Piezoelectric Actuator Exhibiting Quantization and Flexibility
COMMITTEE: Dr. Jun Ueda, Chair (ME)
Dr. Nazanin Bassiri-Gharb (ME)
Dr. Magnus Egerstedt (ECE)
Dr. William Singhose (ME)
Dr. Yang Wang (CE)


This thesis presents a mathematical framework and methods for understanding, modeling, and deploying biologically inspired cellular actuators. Cellular actuators are so named because they are modular units that can be connected in series and parallel bundles to actuate a given degree of freedom, much like muscle cells in biological systems. Two important biological principles of these actuators are expounded upon in this work: compliance, and quantization in actuation effort. Methods for modeling and designing nested hierarchical strain amplifying mechanisms are presented. These mechanisms serve the dual purpose of introducing natural compliance and adapting the force-displacement operating characteristic of the active material to one more suitable for robotics applications. This thesis presents a systematic understanding and design method, whereas previous work in this area has resorted to ad hoc methods. Cellular actuator driven systems have a number of on-off inputs, similar to motor units in human muscle. Methods are presented in this thesis to selectively activate these units in time to produce smooth motion despite a natural tendency toward oscillatory behavior. The effectiveness of the design and control methods presented are demonstrated on a biologically inspired camera positioning mechanism that is driven by a pair of cellular actuators in an antagonistic configuration.