Dynamic Modeling of Robotic Fish Using Schiehien´s Method

This paper provides a preliminary study on dynamic modeling of a multi-link robotic fish based on Schiehlen´s multi-body dynamic equation. According to propulsive mechanism of real fish, the robotic fish propels itself using lateral oscillation and achieves a climb or descent maneuver employing a pair of pectoral fins. The designed robotic fish is mechanically composed of stiff anterior body, flexible rear body, and an oscillating lunate caudal fin, which can simply be viewed as an open, treed multi-body system. The kinematic analysis is then integrated with dynamic analysis to build complete dynamic equations in a form suited for controller design and computer simulation. Finally, simulations and experimental results are compared for straight swim and circular motion, which partially shows the validity of the proposed model.