Modeling of Robotic Fish Propelled by a Servo/IPMC Hybrid Tail

This paper presents modeling of robotic fish propelled by a hybrid tail with Servo and IPMC actuated two joints. The first joint is driven by a servo motor, which generates flapping motion for main propulsion. The second joint is actuated by a soft actuator, or ionic polymer-metal composite (IPMC) artificial muscle, which directs the propelled fluid for steering. A dynamic model is developed to capture the 2D motion dynamics of the robotic fish. The model fully captures the actuation dynamics of the IPMC soft actuator, two-link tail motion dynamics, and body motion dynamics. Experimental results have shown that the robotic fish is capable of swimming forward (up to 0.45 body length/second) and turning left and right (up to 40 degree/sec) with a small turning radius (less than half a body length). Finally, the dynamic model has been validated with experimental data, in terms of steady-state forward speed and turning speed versus the flapping frequency.