Dynamics, Control, And Stability Of Fruit Fly Flight

Abstract

The flight of insects is a beautiful example of an organism's complex interaction with its physical environment. Consider, for example, a fly's evasive dodge of an approaching swatter. The insect must orchestrate a cascade of events that starts with the visual system perceiving information that is then processed and transmitted through neural circuits. Next, muscle actions are triggered that induce changes to the insect's wing motions, and these motions interact with fluid flows to generate aerodynamic forces. Though not as obvious to appreciate, simply flying straight and keeping upright require similarly complex events in order to overcome unexpected disturbances and suppress intrinsic instabilities. Here, I present recent progress in dissecting the many layers that comprise maneuvering and stabilization in the flight of the fruit fly, D. melanogaster. My emphasis is on aspects of flight at the interface of biology and physics, and I seek to understand how physical effects both constrain and simplify biological strategies. This body of work roughly divides into three thrusts: the development of experimental and modeling methods, studies of actuation and control of maneuvering flight, and studies of control during flight stabilization. In Chapter 2, I discuss the experimental techniques we have developed for gathering many three-dimensional high-speed videos of insect flight. In addition, I outline our approach for automated extraction of body and wing motions from such videos. In Chapter 3, I show how experimental observations can be combined with aero- dynamic models to reveal that fruit flies use paddling motions to drive forward flight. In Chapter 4, I review our work on turning maneuvers with an emphasis on how the wing motions themselves arise through an actuation mechanism. In Chapter 5, I outline a set of experimental and modeling techniques for understanding how insects recover from in-flight perturbations to their heading. In Chapter 6, I use a similar approach to analyze the intrinsic instability of body pitch and predict the reaction time needed to stabilize flight. In Chapter 7, I include work on the hydrodynamic interactions between flapping bodies in a fluid flow.