Meeting Abstract
One of the most-studied unsteady locomotor behaviors exhibited by fishes is the c-start escape response. Although the kinematics of these responses have been studied extensively, only a few studies have focused on hydrodynamic patterns generated by fishes executing escape behaviors. No study, to our knowledge, has employed robotic models of impulsive c-start escape behaviors to investigate how body stiffness changes escape hydrodynamics and to determine if simple robotic models can reproduce in vivo complex c-start hydrodynamic flow patterns: escape responses by bluegill sunfish have been shown generate three distinct vortex rings each with central orthogonal jet flows. In this study we used a robotic controller to impulsively move passively flexible plastic panels of three different known stiffnesses in heave, pitch, and heave+pitch motions to study the effects of stiffness on unsteady escape hydrodynamics. The heave+pitch motion imitated the center of mass trajectory used by the escape response of fish. We were able to reproduce the three-jet hydrodynamic pattern of the fish c-start using a panel of medium flexural stiffness and the combined heave+pitch motion. Both more flexible and stiffer panels resulted in non-biological flow patterns for all motions. The use of simple robotic models is a promising approach for studying the dynamics of unsteady fish behavior which can be difficult to manipulate experimentally in live animals.
