ABSTRACT Title of Thesis: Design, Analysis, and Testing of a Flapping Wing Miniature Air Vehicle Degree Candidate: John Gerdes
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ABSTRACT Title of Thesis: Design, Analysis, and Testing of a Flapping Wing Miniature Air Vehicle Degree Candidate: John Gerdes, Master of Science, 2010 Thesis Directed by: Professor Satyandra K. Gupta Department of Mechanical Engineering, Institute for Systems Research Flapping wing miniature air vehicles (MAVs) offer several advantageous performance benefits, relative to fixed-wing and rotary-wing MAVs. The goal of this thesis is to design a flapping wing MAV that achieves improved performance by focusing on the flapping mechanism and the spar arrangement in the wings. Two variations of the flapping mechanism are designed and tested, both using compliance as a technique for improved functionality. In the design of these mechanisms, kinematics and dynamics simulation is used to evaluate how forces encountered during wing flapping affect the mechanism. Finite element analysis is used to evaluate the stress and deformation of the mechanism, such that a lightweight yet functional design can be realized. The wings are tested using experimental techniques. These techniques include high speed photography, stiffness measurement, and lift and thrust measurements. Experimentally measured force results are validated with a series of flight tests. A framework for iterative improvement of the MAV is described, that uses the results of physical testing and simulations to investigate the underlying causes of MAV performance aspects; and seeks to capture those beneficial aspects that will allow for performance improvements. Wings and flapping mechanisms designed in this thesis are used to realize a bird-inspired flapping wing miniature air vehicle. This vehicle is capable of radio controlled flights indoors and outdoors in winds up to 6.7m/s with controlled steering, ascent, and descent, as well as payload carrying abilities. DESIGN, ANALYSIS, AND TESTING OF A FLAPPING WING MINIATURE AIR VEHICLE By John William Gerdes Thesis submitted to the Faculty of the Graduate School of the University of Maryland, College Park in partial fulfillment of the requirements for the degree of Master of Science 2010 Advisory Committee: Professor Satyandra K. Gupta, Chair/Advisor Associate Professor Hugh A. Bruck Assistant Professor Sarah Bergbreiter Dr. Stephen A. Wilkerson, U.S. Army Research Laboratory © Copyright by John William Gerdes III 2010 Acknowledgements Now that I am finished writing this thesis, I am more aware than ever of the importance of certain people to me and their profound impact on who I am. Therefore, this thesis would not be complete without a proper thank you to these people, as this work was created by many more people than just me. First and foremost, I want to thank Dr. Gupta, who was always a great advisor to me. During my time in his group, I have learned more than I ever thought possible. Every time I thought I would never graduate or I could not answer a question myself, he always had a new idea and a focused plan for my research. And while I certainly did become a more knowledgeable student, some of the most valuable lessons I learned were about life, the workplace, and how to navigate the hectic world of competing goals, funding, bosses, and emerge with everyone feeling satisfied. I feel that I have been well-prepared to start my career with a feeling of confidence and satisfaction with my academic accomplishments. I want to thank all of my labmates both in AML and CIM lab. There were many long hours spent together, and I was happy to be part of a group that is full of such lively and fun people. Work among friends like these really does not feel like work at all, and for that I feel very lucky. I have to offer a big thank you to Drew Wilkerson of Army Research Laboratory, because he may be the one person who has shaped my academic and career choices the most. If I had never met the group out on ‘the island’ run by Drew four summers ago, I would be doing something very different right now. Over the years, Drew has always had only the very best intentions for me and for all of his students, and in my case, great benefits have resulted. I never could have imagined the opportunities that would open up to me before I met Drew, and I will always be grateful for his support. This thesis has comprised a tremendous amount of testing and re-testing. Dr. Bruck, Li- Jen Chang, Brian Russ, Brian Porter, and Kelsey Cellon have all combined to spend many hours helping me with what seemed like an impossible amount of lab work. Without these people, I would have needed much longer than two years to graduate. They have all shown great dedication and attention to detail in helping me, and I thank all of them for taking the time to help. Most importantly, I want to thank my family. You are the most important people in my life, and I will always love you. Mom, Dad, Kim, Heather, and everyone else, this work is dedicated to you. ii Contents ABSTRACT ..................................................................................................................................... ii Acknowledgements .......................................................................................................................... ii Table of Figures .............................................................................................................................. vi Chapter 1 - Introduction ................................................................................................................... 1 1.1 Background ............................................................................................................................ 1 1.1.1 Motivation for Miniaturized Unmanned Air Vehicles .................................................... 1 1.1.2 Advantages and Disadvantages of Flapping Wing Flight ............................................... 3 1.2 Motivation .............................................................................................................................. 6 1.2.1 Wing Design ................................................................................................................... 6 1.2.2 Mechanism Design .......................................................................................................... 7 1.2.3 Modeling ......................................................................................................................... 9 1.3 Thesis Goal and Scope ......................................................................................................... 10 1.4 Organization ........................................................................................................................ 12 Chapter 2 - Literature Review ........................................................................................................ 15 2.1 Introduction .......................................................................................................................... 15 2.2 Directional Control Scheme ................................................................................................. 16 2.2.1 Static Tail ...................................................................................................................... 16 2.2.2 Rudder Tail ................................................................................................................... 18 2.2.3 Ruddervator Tails .......................................................................................................... 24 2.2.4 Independent Wing Control ............................................................................................ 25 2.3 Wing Designs ....................................................................................................................... 27 2.3.1 Flapping Wings ............................................................................................................. 27 2.3.2 Four Clapping Wings .................................................................................................... 30 2.3.3 Folding Wings ............................................................................................................... 32 2.4 Mechanism designs .............................................................................................................. 33 2.4.1 Front Mounted Double Pushrod .................................................................................... 34 2.4.2 Front Mounted Double Crank ....................................................................................... 36 2.4.3 Front Mounted Single Pushrod ..................................................................................... 36 2.4.4 Side Mounted Crank ..................................................................................................... 39 2.5 Summary ............................................................................................................................... 42 2.6 Future Flapping Wing Research Directions ........................................................................ 45 iii Chapter 3 – Wing Design and Selection ........................................................................................ 50 3.1 Introduction ......................................................................................................................... 50 3.2 Force Measurement ............................................................................................................. 51 3.2.1 Design Criteria .................................................................................................................