A Soft Actuation Method for Underwater Robot Based on Dielectric Elastomer Actuator

Soft underwater robots have attracted widespread attention from researchers due to their excellent lightweight, low noise actuation, and excellent environmental interaction capabilities. A potential challenge is to develop a suitable flexible driving method for underwater robots using soft materials, which can not only successfully replicate the driving characteristics of biological muscles, but also replicate the swimming characteristics of aquatic organisms as much as possible. Here, through bionic the deformation feature of fish muscles, an underwater flexible actuating method based on dielectric elastomer actuators (DEAs) has been proposed, which can realize the large bending amplitude of the robotic fish caudal fin. By controlling the two driving units of a single soft actuator, the periodic swinging motion of the caudal fin can be simulated. In addition, the oscillation characteristics of the robotic fish caudal fin are simulated and analyzed by COMSOL software The results show that the maximum unidirectional bending angle of the robotic fishtail can reach 20° and the simulation results show that alternating anti-Carmen vortex structures can be generated, which proves the effectiveness of the proposed flexible actuating method. Finally, a robotic fish design concept composed of 3D-printed flexible shells and two soft actuators has been proposed, which can realize continuous C-shaped and S-shaped body curves by controlling the amplitude and phase of the soft actuator. This study not only provides a suitable driving method for the design and development of soft underwater robots, but also has guiding significance for the design of other soft actuators, dexterous operations, and soft robots.