Maneuvers and Stability in the Free Flight of Hawkmoth Manduca Sexta

DAMPING AT EVERY TURN: MANEUVERS AND STABILITY IN THE FREE FLIGHT OF HAWKMOTH MANDUCA SEXTA Jeremy Stuart Michael Greeter A dissertation submitted to the faculty at the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biology. Chapel Hill 2017 Approved by: Tyson L. Hedrick William M. Kier Kenneth J. Lohmann Laura A. Miller Gregory S. Sawicki © 2017 Jeremy Stuart Michael Greeter ALL RIGHTS RESERVED ii ABSTRACT Jeremy Stuart Michael Greeter: Damping at Every Turn: Maneuvers and Stability in the Free Flight of Hawkmoth Manduca sexta (Under the direction of Tyson L. Hedrick) Here I identify novel stability features in flapping flight. Implications may shift the current scientific consensus that flying animals, particularly insects, must actively monitor and respond to even slight perturbations to maintain control in pitch and roll, and allow engineers to recreate these capabilities in flying robots. Results are consistent with co-directional inertial and viscous effects working together to damp rotations. This could explain flight stability across a broad range of body sizes, speeds, and flapping frequencies. I propose a previously undescribed, likely ubiquitous class of passive “inertio-viscous” damping. Flapping wings move, so rotational perturbations on the time scale of halfstrokes manifest as wing position/orientation changes later in the flapping cycle. My novel results show these (at least partially) passive (inertia-based) kinematic responses push on the air to produce torques that oppose the initial perturbation. I then identify key design elements which future flapping-wing micro air vehicles could employ to exploit these stability effects. This emerges from a series of three experiments exploring roll and pitch dynamics in hawkmoth Manduca sexta. In the first, I coaxed moths to follow a light and described their lateral maneuver mechanics. I concluded roll is heavily damped, and positive coupling between roll and lateral acceleration, negative coupling between roll and lateral velocity, and countertorque from wing motion around the roll axis, are relevant (viscous/velocity) damping factors. In the second, I launched miniature cannonballs at moths and described their pitch recovery mechanics. I concluded inertial (and viscous) resistance of wing stroke plane to the pitch impulse (and rotational velocity) helps create pendular stability in mid-air. Gyroscopic (and viscous) reactions to pitch impulses (and rotational velocity) manifest as deviations to wing kinematics that further damp pitch, indicating reinforcing roles for inertia and drag in flapping flight stability. iii In the third, I glued T-bars on moths to create weight imbalances during hover. Results reinforce my conclusions about damping and roll/pitch-associated wing kinematics, show flexibility helps compensate for off-axis loads, and associate a novel wing kinematic with roll torque that suggests gyroscopic and pendular damping mechanisms also complement viscous/velocity-based damping in roll. iv To my father. I hope you’ve enjoyed our many adventures as much as I have. To my mother. Thank you for pushing me to succeed. v ACKNOWLEDGEMENTS I thank my close family, my good friends, and my strict teachers. I thank: My father, Stuart, who taught me how to love science and nature and learning and to always question the world around me, and also for his heavy-handed algebra lessons at the kitchen table. My mother, Dorothy, who pushed me to succeed in school, taught me to hold myself to a standard of success based on my own capabilities rather than those of others, taught me how to read, and tried very hard (but to no avail) to teach me good organizational habits. My sister, Stacy, who provided me with wisdom and emotional support, a yardstick with which to measure my personal growth, countless creative adventures in imaginary lands, and a safe haven from our mother and father! Most importantly, my noble canine companion Stinky—with his boundless enthusiasm—for teaching me loyalty and love and patience and how to live in the moment. I also thank: My friends, among them Evan Kriminger, Sarah Shapiro, Sean Sherry, and Zach Lucy, for moral support, outrageous adventures, and for indulging in my company despite my many idiosyncrasies. My close colleagues, especially Brenna Hansen and Jonathan Rader, for always providing a sympathetic ear. My congenial roommates for putting up with my talkativeness and messiness. I thank: My advisor Tyson Hedrick—without whom this work would simply not exist—for his thoughtful criticism, intimidating work ethic, and patience while I plodded my way through my PhD, matured professionally, and explored non-academic career options. My committee for providing suggestions throughout my graduate studies. Funding agencies for believing in my ability at various points in my scientific career, among them the Department of Defense (via the National Defense Science and Engineering Graduate Fellowship administered by the American Society for Engineering Education), NASA (via the Research and Education Awards Project administered by the South Carolina Space Grant Consortium), and the University of North Carolina Department of Biology (via the Evolution, Ecology, and Organismal Biology program). vi And finally, for making learning engaging and challenging, I would like to thank every science, engineering, and math teacher and teaching assistant I ever had. vii TABLE OF CONTENTS TABLE OF CONTENTS ............................................................................................................................. vii LIST OF TABLES ....................................................................................................................................... xv LIST OF FIGURES .................................................................................................................................... xvi LIST OF SYMBOLS AND ABBREVIATIONS ........................................................................................... xix Abbreviations .......................................................................................................................................... xix Operators, Annotations, Subscripts, and Constants ............................................................................... xx Wing and Body Characteristics ............................................................................................................... xxi Model Coefficients ................................................................................................................................. xxiii CHAPTER 1: GENERAL INTRODUCTION ................................................................................................. 1 General Overview ..................................................................................................................................... 1 Movement and Stability ............................................................................................................................. 2 Passive vs. active stability ..................................................................................................................... 3 Stability in legged locomotion................................................................................................................ 4 What is a maneuver? ............................................................................................................................ 4 Flight in Animals ........................................................................................................................................ 5 How insect wings create lift ................................................................................................................... 5 Fluids and size ...................................................................................................................................... 7 Stability and Maneuvers in Flapping Flight ............................................................................................... 8 Flight maneuvers ................................................................................................................................... 8 Flight stability ...................................................................................................................................... 10 Quantifying wing and body dynamics ................................................................................................. 12 Summary of Chapters 2-4 ....................................................................................................................... 13 Chapter 2 summary ............................................................................................................................. 14 viii Chapter 3 summary ............................................................................................................................. 15 Chapter 4 summary ............................................................................................................................. 16 References .............................................................................................................................................. 17 CHAPTER 2: DIRECT LATERAL MANEUVERS IN MANDUCA SEXTA ................................................. 23 Summary ................................................................................................................................................

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