A Tensegrity Robotic Fish Driven by a Sliding Crank-Pendulum Mechanism

This paper develops a tensegrity robotic fish, composed of the tensegrity structure and sliding crank-pendulum mechanism. The fish body is made of tensegrity structures and the sliding crank-pendulum mechanism transforms rotation of the motion into the swing of a pendulum rod. By connecting the two parts with joints and elastic cables, the robotic fish can realize flexible swing motion by changing the balance of internal forces of the tensegrity structure using the motor. The driving torque of the motor is analyzed by simulating the connection parameters between the pendulum rod and the fish body. Then a prototype is designed and fabricated. Experimental results present that with the increase of stiffness, the speed-frequency curve gradually presents an approximate linear growth, and higher stiffness means better swimming performance at a higher driving frequency zone.