Maximal Performance of an Antagonistically Coupled Dielectric Elastomer Actuator System

Dielectric elastomer actuators (DEAs) have been shown to produce electrically induced strains beyond 500%. The ability to undergo large deformation allows the DEA to store large amounts of elastic energy by electrical actuation; it also allows the DEA to perform flexibly in a diverse range of motions. Existing studies used different methods to maximize actuation strain for soft robotic applications. In this article, we examine the actuation of our antagonistically coupled DEAs, reminiscent to that of human muscles. We perform an analysis to reveal optimal conditions that maximize its actuation stroke, actuation force, and output energy. We quantify actuation stroke by the displacement sweep due to electrical actuation, between two fixed points, expressed as a percentage, and refer to this as "actuation sweep." From the analysis, we predicted an optimal prestretch for the DEA that corresponds to a 59% actuation sweep. In our experiment, we realized a 55% actuation sweep. We further characterized the output force and the mechanical work done for complete performance appraisal of the antagonistic system both theoretically and experimentally. We realized an antagonistic soft actuator system with simple geometry that provides significant electrically induced displacement, force, and work done, similar to that of biological muscle systems, and demonstrated its efficacy.