Development of a novel robotic jellyfish based on mechanical structure drive and barycenter adjustment

Jellyfish-inspired jet propulsion and robotic implementation have drawn much attention among the scientific community. In this paper, we report a novel robotic jellyfish synthesizing mechanical structure drive and barycenter adjustment mechanism. The robotic jellyfish relies on six-bar linkage mechanisms as actuators to realize the contraction-relaxation jet propulsion motion. To imitate the real jellyfish and to reduce drag, the robotic jellyfish is comprised of a streamlined head, a cavity shell, and a latex skin is enwraped around the drive units. To achieve free switch between different motion modes and transform attitude arbitrarily, a barycenter adjustment mechanism is embedded in the robot body. Through the upward, downward, balancing, as well as leaning-down motion of clump weights, the center of gravity of the robot can enwrap its center of buoyancy. Experimental tests on the actual robotic jellyfish verify the great 3D swimming ability.