Dynamic Control of a Pulsatile Jet Propelled Aquatic Robot

Abstract

Deriving inspiration from the propulsion methods of squids, a pulsatile jet propulsion system is adopted in a robotic model. A squid-like direction control mechanism, which can direct the jet along any direction on a hemispherical work volume, is also implemented. To obtain a suitable robot velocity (v) and a propulsive efficiency (ηp) for testing this mechanism, the stroke ratio (L/D) and outlet diameter are varied and the v and the ηp of various alternatives are estimated experimentally using vision analysis. A Stroke ratio of 3.78 and an outlet diameter of 25.4 mm were found suitable and employed for testing the mechanism. When the jet is deflected by 60° in the horizontal plane, the robot rotates about its centroid, signifying excellent maneuverability. Reverse motion was also demonstrated by removing inlet valves and blocking the outlet through the direction control mechanism. The performance of the direction control mechanism indicates that the robotic model was a feasible alternative to conventional screw-propelled aquatic robots.