In this paper we present the design of a fin-like dielectric elastomer actuator (DEA) that drives a miniature autonomous underwater vehicle (AUV). The fin-like actuator is modular and independent of the body of the AUV. All electronics required to run the actuator are inside the 100 mm long 3D-printed body, allowing for autonomous mobility of the AUV. The DEA is easy to manufacture, requires no pre-stretch of the elastomers, and is completely sealed for underwater operation. The output thrust force can be tuned by stacking multiple actuation layers and modifying the Young's modulus of the elastomers. The AUV is reconfigurable by a shift of its center of mass, such that both planar and vertical swimming can be demonstrated on a single vehicle. For the DEA we measured thrust force and swimming speed for various actuator designs ran at frequencies from 1 Hz to 5 Hz. For the AUV we demonstrated autonomous planar swimming and closed-loop vertical diving. The actuators capable of outputting the highest thrust forces can power the AUV to swim at speeds of up to 0.55 body lengths per second. The speed falls in the upper range of untethered swimming robots powered by soft actuators. Our tunable DEAs also demonstrate the potential to mimic the undulatory motions of fish fins.

A multilayer fabrication method has been used to create crawling soft robots based on dielectric elastomer actuators. These actuators are created without the need for pre-stretch, eliminating the need for rigid components. A four-legged, multi-gait capable crawler can be fabricated in a matter of hours and shows promise for future untethered systems. Studies on inchworm robots show them to be the fastest dielectric elastomer actuator-based systems reported to date, capable of traveling faster than 1 body length/second for the best elastomer available. Most importantly, the devices are primarily soft and deformable, with few rigid attachments.