Modeling and Control of a Bio-Inspired Underwater Vessel with Undulating-Fin Propulsion

Undulating-fin propulsion, where an elongated membrane is used to generate thrust, can enhance the mobility and station keeping capabilities of underwater vessels. Fish using this type of propulsion are able to maneuver in multiple directions including forward, backward, rapid reverse, upward, forward-lateral and station-keeping. Despite this potential, the use of undulating fin propulsion to control the six-degree of freedom of an underwater vessel has remained elusive, in part due to the lack of platform that allows studying the dynamics in free-swimming conditions. In this work, we present a self-contained physical model equipped with a bio-inspired fin-based propulsion. The propulsive mechanism is a single undulating fin running along the length of the robot, which controls both forward motion and directional maneuvers. We present a hydrodynamic characterization of the vessel in addition to a modeling framework to estimate forces, torques and motion control. As first step, we focus on the control for surge, sway and yaw.