Meeting Abstract
40.4 Monday, Jan. 5 Biorobotic analyses of fish fin function TANGORRA, J. T.; GOTTLIEB, J.; ESPOSITO, C.; LAUDER, G. V.*; Drexel University; Drexel University; Drexel University; Harvard University glauder@oeb.harvard.edu
A hallmark of aquatic propulsion in bony fishes is the use of multiple control surfaces to modulate locomotor forces and body position. Studying the in vivo function of fish fins has revealed a great deal about how fish use fins to generate locomotor forces. But in vivo analyses of fish fins are limited by the inability to prescribe movement patterns and difficulties in directly measuring force. Such difficulties can be overcome by using robotic models. Furthermore, biorobotic models of teleost fish fin function can be used to explore a wide parameter space of kinematics not possible using only experiments on live fishes, while simultaneously measuring forces, kinematics, and hydrodynamic patterns. We have constructed self-propelled robotic models of the pectoral, dorsal, and caudal fins that closely replicate key biological features of fish fins, and have also used a dual-flapping foil robotic device to examine the effect of fin surface flexibility on swimming speed. We constucted two different pectoral fin robotic models based on the fins of bluegill sunfish (Lepomis macrochirus): one that reproduces steady swimming kinematics, and a separate model that generates manuevering kinematics. An array of non-biological movement patterns were also studied for steady swimming, and fin kinematics, biaxial forces, and flow hydrodynamics were measured simultaneously during pectoral fin motion. During steady swimming, clear dual leading edge vortices were visible on the dorsal and ventral edges of the fin, on both the outstroke and instroke. Continuous accelerated flow was observed throughout the fin beat, as was a pattern of continous thrust generation during both outstroke and instroke. Movement of the dorsal half of the fin only reproduced thrust during the outstroke but generated very little thrust during the instroke.
