21 August 2012
4 - 5pm
Venue: Ground Floor Seminar Room (G010), UniServices House, 70 Symonds Street, Auckland
A Bioengineering research seminar by Bryan Ruddy, PhD Graduand, Bioinstrumentation Lab, Massachusetts Institute of Technology
Actuator performance represents a key constraint on the capability of many engineered devices. Performance of these devices is often exceeded by their muscle-powered natural counterparts, inspiring the development of new, 'active material' actuators. In this talk, I will show how we can reconsider a traditional actuator, the linear permanent magnet motor, as a form of active material actuator, and present new, unified scaling and magnetic field models for its performance. These models comprise a hierarchical set of analytical solutions to the thermal and electromagnetic field relations of the motor, with a new presentation of the solutions to the magnetoquasistatic form of Maxwell’s equations in cylindrical coordinates with improved numerical stability. This active material motor model predicts that motors composed of large numbers of very small, actively-cooled repeat units, similar to the architecture of biological muscles, can provide greatly enhanced force density over extant designs. I will also present some preliminary experimental results from a motor built according to these principles, with continuous force production per unit mass of approximately 140 N/kg, about double that available in previously-reported motors of similar size.