A compliantly coupled dielectric elastomer actuator using magnetic repulsion

Dielectric elastomer actuators (DEAs) have attracted growing research interest over the past two decades for their large actuation strain, inherent compliance, and low cost. The conical DEA configuration is particularly attractive thanks to their simple structure and high force/stroke actuation. A double cone DEA design with two antagonistic membranes allows active bidirectional actuation. However, in existing double cone DEA designs, the two membranes are rigidly coupled, which restricts their relative actuation response under periodic electrical input to 180° out-of-phase operation. This work presents a magnetically coupled DEA with compliant coupling by a magnetic repulsion. The compliant coupling allows two separate inputs with a fully adjustable phase difference. The current prototype demonstrates a peak normalized stroke of 14% (relative to the nominal DEA height) at a phase shift of 180° and a normalized linear expansion between the two membranes of up to 8.3% (relative to the nominal DEA height) at a phase shift of 0° at 0.5 Hz. This results in several emerging actuation behaviors, which could potentially be suitable for controllable shape changing actuations, active vibration damping, and bioinspired locomotion.