The development of a multi-functional bio-robotic pectoral fin

Fish have the ability to propel and maneuver themselves with tremendous agility. In addition to swimming forwards, they move backwards, brake, hover in place, and perform a variety of turns, in still or turbulent waters. They rely heavily on their pair of pectoral fins when performing these maneuvers. Engineers and scientists have long sought to grant this level of agility to unmanned underwater vehicles (UUVs). This thesis discusses the development of a bio-robotic fin that models the pectoral fin of the bluegill sunfish as the fish maneuvered to avoid an obstacle. A design process was used which modeled the kinematics and physical properties of the biological fin. Analysis of biological fin motions, supported by computational fluid dynamics simulations, aided in the identification of key components of the fin motions and dynamics. The fin motions were simplified such that a robot could be designed in order to implement them. The stiffness of the bio-robotic fin was modeled after that of the biological fin, in order to ensure a proper dynamic interaction with the water. Experimentation involving high speed video, force collection, and the identification of hydrodynamics using digital particle image velocimetry were used to assess the fin's performance. The bio-robotic fin was able to create the motions, forces, and flows associated with the yaw turn, while retaining the ability to create other bluegill swimming motions. The results of the research indicate that for robotic fins to produce a level of performance on par with biological fins, that both the kinematics and the mechanical properties of the fin must be controlled.