Meeting Abstract

6.2  Thursday, Jan. 3  Pectoral fin biorobotics in fishes LAUDER, G. V.*; TANGORRA, J.; MITTAL, R.; MADDEN, P.; Harvard; MIT; George Washington; Harvard glauder@oeb.harvard.edu

Many fishes are able to generate both propulsive (thrust) forces and maneuvering torques using their pectoral fins. Previous analyses of pectoral fin function in bluegill sunfish have demonstrated that the pectoral fin surface undergoes complex deformations and that fin kinematics change dramatically during maneuvers. Flapping propulsion in fishes has often been compared to the motion of engineered heaving and pitching foils where two thrust peaks are seen as the foil moves up and down, with a shorter period of drag as the foil reverses direction between the downstroke and upstroke. We have analyzed the function of bluegill sunfish pectoral fins during both propulsion and maneuvering and compared fin function to the performance of engineered foils. Three-dimensional kinematic analyses of pectoral fin motion and the study of fin wake hydrodynamics during propulsion using transverse light sheet particle image velocimetry (PIV) and scanning PIV suggest that the sunfish pectoral fin generates continuous thrust without any drag at the transition of the fin from outstroke to instroke. Computational fluid dynamic analyses of sunfish pectoral fin function corroborate this conclusion. We have designed a self-propelled biorobotic pectoral fin with individually actuated fin rays and programmable movements that allows exploration of a diversity of fin movement patterns and the resulting forces to be investigated. This robotic fin can replicate the thrust pattern found in bluegill pectoral fins during propulsion, and also allows examination of fin movement patterns not used by sunfish. Experimental hydrodynamic analysis of the robotic fin allows direct comparison of thrust generating mechanisms with the bluegill sunfish pectoral fin.