Robotic jellyfish actuated with a shape memory alloy spring

摘要

We demonstrate a new approach to the design of a synthetic jellyfish that imitates the morphology and kinematicsof the actual animal. Since jellyfish usually move at low speeds, the locomotion can be mimicked using shapememory alloy (SMA) springs as artificial muscles. Compared to previous attempts at biomimetic underwaterrobots, the current research aims to simplify the design, generate larger stroke, and lower the actuation cyclefor propulsion. The robot consists of a soft silicone rubber disk with an embedded pre-stretched SMA springalong its circumference, which when heated contracts to initiate large shape changes in the structure. Ourapproach harnesses the buckling instability of the main body to create a relatively quick motion that producesa pulsed jet of water to generate thrust. The rubber disk is also equipped with several aps that contributeto the swimming motion by displacing the surrounding water through a rowing-like mechanism. The inuenceof different operation parameters, including the amplitude of the input power and the actuation frequency, areinvestigated on the swimming motion and propulsive thrust.