Design study of flapping foil propulsion for an Odyssey Class autonomous underwater vehicle

Abstract

A design study was conducted to examine the feasibility of implementing fish-like flapping foil propulsion on an Odyssey Class autonomous underwater vehicle (AUV). Theoretically, fish-like propulsion offers higher efficiencies, greater maneuverability, and the potential for faster accelerations than the conventional propulsion system currently in use on the Odyssey Class AUV. Previous laboratory research has shown promising results, and retrofitting an Odyssey Class AUV with a flapping foil is a cost-effective way to step up the learning curve toward applying this technology in a field setting. Based primarily on MIT's RoboTuna research on the swimming motions of fish, the proposed design hopes to achieve a speed of 1.5 m/s. Oscillating two tail links independently at a tail flapping frequency of about 1 Hz should provide this performance. The links are driven with DC brushless motor systems through a Scotch yoke linkage and a linear actuator. Pitch and roll motion is accomplished with the addition of servo actuated pectoral fins, while dorsal and anal fins provide additional directional stability. A variety of motion schemes were contemplated, but the final design was chosen with an emphasis on simplicity, practicality, and robustness for use in a field setting.