Optimization of Motion of a Mechanical Pectoral Fin

This paper describes the use of a mechanical pectoral fin as a new device for maneuvering and stabilizing an underwater vehicle. The mechanical pectoral fin consists of three servo-motors, which respectively generate a rowing motion, a feathering motion, and a flapping motion. We focused on the comparison of load characteristics of the mechanical pectoral fin between the drag-based swimming mode and the lift-based swimming mode, undertaken under the conditions of uniform flow and still water, respectively. Optimization of the parameters of fin motion so as to generate maximum propulsive force in terms of flow condition and motion pattern revealed that the lift-based rather than the drag-based swimming mode is suitable for generation of propulsive force in uniform flow, whereas the drag-based rather than the lift-based swimming mode is suitable for generation of propulsive force in still water within the range of motion of the mechanical pectoral fin.