Meeting Abstract

S7-2.2  Friday, Jan. 6  Separating behavioral and passive dynamics in the pitch maneuvers of hawkmoths HEDRICK, TL; Univ. of North Carolina at Chapel Hill

Flying animals are widely appreciated as having amazing capabilities of flight maneuverability and control. Some types of these maneuvers, especially those beginning in a hovering or slow forward flight state, are now regularly recorded in attempts to understand the basis for these capabilities. However, many factors contribute to the observed dynamics of the animal, complicating analysis of the recordings. These factors include sensory feedback which results in the animal making changes to its wing kinematics and body configuration to produce the maneuver or compensate for a perturbation, making the observed motions the result of a “closed-loop” feedback process. Additionally, passive effects such as drag and the passive damping due to the interaction of basic (i.e. hovering) flapping kinematics with body motion also produce forces which influence the dynamics of the animal. These “open-loop” or uncontrolled effects on the dynamics of the animal must be isolated and removed from the observations to assess the animal’s active contribution to the observed movements. Because animals tend to respond to their environment or to imposed perturbations, open-loop properties are best measured by mathematical model, computational simulation or mechanical model. Here I use a comparison of two similar maneuvers or changes in state in the hawkmoth Manduca sexta to show how closed- and open-loop effects combine in different ways. The first of these cases is an animal initiated pitch maneuvers and the second a response to pitch perturbations. Despite the similarity of the maneuvers, the open- and closed-loop breakdown shows that the response to a pitch perturbation is not identical to the response of a moth stabilizing itself following an animal initiated pitch maneuver.