Use of aligned fibers to enhance the performance of dielectric elastomer inchworm robots

Inchworm based on the voltage actuation of dielectric elastomer actuators (DEAs) are amongst the simplest types of robots. We demonstrate a proof-of-concept inchworm robot that incorporates a few aligned fibers to suppress undesirable actuator bulging and more effectively convert the bending of a dielectric elastomer unimorph to forward motion. Finite element modeling confirms the role of the fibers in suppressing bulging but also shows that a threshold actuation voltage is required to convert the unimorph bending to forward motion of the inchworm. Based on the modeling results for unimorphs having different fiber spacing a simple inchworm is constructed and locomotion is demonstrated for actuation above the threshold voltage. Although not optimized, the inchworm illustrates the importance of using selectively positioned stiffening fibers as well as elastomers having lower viscoelastic losses.