Biomimetic Propulsion Systems for Mini-Autonomous Underwater Vehicles

This paper describes work carried out as part of a PhD research project investigating biomimetic propulsion systems for underwater vehicles at the University of Glasgow. The work focuses on the development of a vehicle called the RoboSalmon, which is a low-cost prototype allowing for different types of fish-like biomimetic propulsion systems to be investigated. The potential benefits of using a biomimetic propulsion system are highlighted and some applications discussed. RoboSalmon is a custom built vehicle based on the approximate dimensions of an Adult Atlantic Salmon. The first type of biomimetic propulsion system investigated is a tendon drive system which utilizes two tendon wires actuated by a single DC servo motor to produce an approximate fish-like tail movement. Development of an initial low cost prototype of the tendon drive RoboSalmon vehicle has been completed and experimentation with this prototype shows that the tendon drive propulsion system produces a forward thrust and allows for basic straight line and turning maneuvers. In parallel with the vehicle development, this investigation has also involved the development of a mathematical model of the RoboSalmon which draws on methods used for modeling conventional marine craft. Simulation results indicate good vehicle performance. From the initial surge velocity simulation results the RoboSalmon vehicle model is comparable to that of the experimentally observed velocity from the prototype using a similar tail beat frequency. Use of this prototype has also shown the limitations of this propulsion system and highlighted a number of areas where the overall vehicle design could be improved. Design work has started on an updated version of the RoboSalmon which takes into account the lessons learned from the development of the initial prototype and the parallel work on the SHARC vehicle. The next propulsion system under investigation is a tail with a number of segments individually actuated by geared DC motors. Comparisons are made and discussed between the two propulsions systems investigated thus far. Finally, the conclusions that can be drawn for the work completed to date on biomimetic propulsion systems are discussed.