A Dynamic Analysis and Realization of Diodontiform Fish Robot

Aquatic fish have remarkable agility and maneuverability when swimming, which results from long evolutionary adaptations. This paper introduces a novel structure for an underwater robot that imitates the natural locomotion of pectoral fins in Diodontiform fish. The proposed design is simple, requiring only one degree of freedom (DOF) for the actuator to generate the undulating motion of the fan-shaped fin membrane. The mechanism of the crankshaft and swing arm is exploited to convert the rotary motion of a motor into the oscillatory motion of the fin rays. To accurately describe the effect of fluid flow on each segment of the fin membrane, we employ Morison’s formula, which takes into account the components of inertia and damping of surrounding fluid. A dynamic model of a robot fish propelled by two pectoral fins is established based on the proposed approach. Simulation results demonstrate that this distinctive design can generate a continuous propulsive force with high efficiency. Moreover, several preliminary experiments have been conducted to verify the primary motion of the robot fish.