ABSTRACT Title of Document: DESIGN AND ANALYSIS OF EXAGGERATED RECTILINEAR GAIT-BASED SNAKE-INSPIRED ROBOTS James Kendrick Hopkins Doctor of Philosophy, 2014 Dissertation directed by: Professor S. K. Gupta Department of Mechanical Engineering Snake-inspired locomotion is much more maneuverable compared to conventional locomotion concepts and it enables a robot to navigate through rough terrain. A rectilinear gait is quite flexible and has the following benefits: functionality on a wide variety of terrains, enables a highly stable robot platform, and provides pure undulatory motion without passive wheels. These benefits make rectilinear gaits especially suitable for search and rescue applications. However, previous robot designs utilizing rectilinear gaits were slow in speed and required considerable vertical motion. This dissertation will explore the development and implementation of a new exaggerated rectilinear gait that which will enable high speed locomotion and more efficient operation in a snake-inspired robot platform. The exaggerated rectilinear gait will emulate the natural snake’s rectilinear gait to gain the benefit a snake’s terrain adaptability, but the sequence and range of joint motion will be greatly exaggerated to achieve higher velocities to support robot speeds within the range of human walking speed. The following issues will be investigated in this dissertation. First, this dissertation will address the challenge of developing a snake-inspired robot capable of executing exaggerated rectilinear gaits. To successfully execute the exaggerated rectilinear gait, a snake-inspired robot platform must be able to perform high speed linear expansion/contraction and pivoting motions between segments. In addition to high speed joint motion, the new mechanical architecture much also incorporate a method for providing positive traction during gait execution. Second, a new exaggerated gait dynamics model will be developed using well established kinematics and dynamics analysis techniques. In addition to the exaggerated rectilinear gaits which emphasize high speed, a set of exaggerated rectilinear gaits which emphasize high traction will also be developed for application on difficult terrain types. Finally, an exaggerated rectilinear that emphasizes energy efficiency is defined and analyzed. This dissertation provides the foundations for realizing a high speed limbless locomotion capable of meeting the needs of the search, rescue, and recovery applications. Design and Analysis of Exaggerated Rectilinear Gait-Based Snake-Inspired Robots By James Kendrick Hopkins Dissertation 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 Doctor of Philosophy 2014 Advisory Committee: Professor Satyandra K. Gupta, Chair/Advisor Professor Shapour Azarm Professor Hugh A. Bruck Professor Jaydev P. Desai Professor P.S. Krishnaprasad ©Copyright by James Kendrick Hopkins 2014 Dedication To my lost loved ones. Special dedication to my grandfather, Varnell Hopkins, Sr., my grandmother, Zetha Smith, and my father-in-law, Lee Hargrove, Sr. ii Acknowledgments First of all, I would like to thank my academic advisor, Dr. Satyandra K. Gupta, for accepting me as a student and guiding me throughout my research. Dr. Gupta’s knowledge and analytical skills are only matched by his dedication to his students. His inspiration and patience have helped me immensely during my most difficult times, while pursuing my doctoral degree. I would like to thank Dr. Shapour Azarm, Dr. Hugh A. Bruck, Dr. Jaydev P. Desai, and Dr. P.S. Krishnaprasad for serving on my dissertation committee in spite of their busy schedules. I am also thankful to my colleagues (past and current) in the Simulation Based System Design Laboratory (SBSD) and Advanced Manufacturing Laboratory (AML) for their guidance and advice. Special thanks given to Brent Spranklin, Krishnanand Kaipa, Luke Roberts, Atul Thakur, Arvind Ananthanarayanan, and Wojciech Bejgerowski. Finally, I would like to thank my wonderful family. I am especially thankful for the love and support given to me by my beautiful wife, Patrice Hopkins. Without her understanding, I would not have progressed this far. I am also very thankful to my parents, James and Zelma Hopkins, and my brother, Dexter Hopkins, for always being there whenever I needed a listening ear and for keeping me grounded. Finally, I give thanks to my second family, my mother-in-law and her husband, Patricia and William Hobbs, Jr., my sister-in-law, LaShonda Hargrove, and my brother-in-law, Lee Hargrove, Jr., for their understanding and encouragement throughout this journey. iii Supporting Published Work This dissertation is partially comprised of work, published in several revered conferences and journals, in support of this research. These supporting publications and their associated chapters are presented as follows: Chapter 2: Hopkins, J. K., Spranklin, B. W., and Gupta, S. K., 2009, “A Survey of Snake-Inspired Robot Designs,” Bioinspiration and Biomimetics, 4(2), 021001. Chapter 3: Hopkins, J. K., and Gupta, S. K., 2011, “Design of a Drive Mechanism for a Rectilinear Gait-Based Snake-Inspired Robot,” ASME Mechanisms and Robotics Conference, Washington DC, 6, pp. 817-825. Hopkins, J. K., and Gupta, S. K., 2012, “Characterization of Forward Rectilinear-Gait Performance for a Snake-Inspired Robot,” Performance Metrics for Intelligent Systems (PerMIS’12) Workshop, College Park, MD, pp. 136-144. Chapter 4: Hopkins, J. K., and Gupta, S. K., 2012, “Dynamics-Based Model for a New Class of Rectilinear-Gait for a Snake-Inspired Robot,” ASME Mechanisms and Robotics Conference, Chicago, IL, 4, pp. 151-160. Hopkins, J. K., and Gupta, S. K., 2014, “Design and Modeling of a New Drive System and Exaggerated Rectilinear-Gait for a Snake-Inspired Robot” ASME Journal of Mechanisms and Robotics, 6(2), 021001. iv Chapter 5: Hopkins, J. K., Spranklin, B. W., and Gupta, S. K., 2008, “System-Level Optimization Model for a Snake-Inspired Robot Based on a Rectilinear Gait,” ASME Mechanisms and Robotics Conference, Brooklyn, NY, 2, pp. 913-924. Hopkins, J. K., Spranklin, B. W., and Gupta, S. K., 2011, “A Case Study in Optimization of Gait and Physical Parameters for a Snake-Inspired Robot Based on a Rectilinear Gait,” ASME Journal of Mechanisms and Robotics, 3(1), 014503. Hopkins, J. K., and Gupta, S. K., 2013, “Analysis of a Low Effort Gait for a Snake-Inspired Robot,” ASME Mechanisms and Robotics Conference, Portland, OR. v Table of Contents ABSTRACT ......................................................................................................................... i 1 Introduction ..................................................................................................................1 2 Related Work .............................................................................................................13 2.1 Overview ............................................................................................................ 13 2.2 Serpentine Motion through Passive Wheels....................................................... 13 2.2.1 Active Cord Mechanism 3 (ACM III) .........................................................14 2.2.2 ACM-R3 ......................................................................................................16 2.2.3 ACM-R5 ......................................................................................................18 2.2.4 AmphiBot I ..................................................................................................19 2.2.5 AmphiBot II .................................................................................................21 2.3 Serpentine Motion with Active Wheels ............................................................. 22 2.3.1 Koryu-II (KR-II) ..........................................................................................23 2.3.2 GMD-SNAKE2............................................................................................25 2.3.3 ACM-R4 ......................................................................................................26 2.3.4 NTUA Robotic Snake ..................................................................................27 2.4 Snake-Like Robots with Active Treads ............................................................. 29 2.4.1 Koryu-I (KR-I) .............................................................................................30 2.4.2 OmniTread OT-8 .........................................................................................31 2.4.3 OmniTread OT-4 .........................................................................................33 2.4.4 Reconfigurable Robot JL-I ..........................................................................35 2.5 Rectilinear Motion through Vertical Traveling Waves ...................................... 37 2.5.1 Inchworm Robot Introduced by Kotay and Rus 1996 .................................39 vi 2.5.2 Snake Robot Introduced by Dowling 1997 ..................................................40 2.5.3 PolyBot Reconfigurable Robots ..................................................................42 2.5.4 CMU’s Modular Snake Robots ....................................................................44 2.6 Rectilinear Motion through Rigid Body Linear Expansion ............................... 46 2.6.1 Slim Slime Robot .........................................................................................47