Hybrid tail excitation for robotic fish: Modeling and performance analysis

Abstract

We investigate the potential of a novel hybrid excitation of the tail for a robotic fish. The tail consists of an ionic polymer-metal composite (IPMC) beam excited at its base. A model of the beam dynamics under base excitation, IPMC actuation mechanism, and hydrodynamic forces is derived. Lighthill's theory of elongated bodies is used to estimate the forward speed from the tail's oscillations and associated power for different tail dimensions and actuation configurations. The model of the robotic fish propelled by only an IPMC actuator is validated using previously reported experimental frequency responses. Our results show that incorporating a small-amplitude base excitation has the potential to significantly improve the forward speed of the robotic fish over a broader range of frequency excitations while consuming minimal additional power. The results also show that this improvement is very significant at specific aspect ratios.