DESIGN AND DEVELOPMENT OF A ROBOT MANIPULATOR FOR CITRUS HARVESTING By BABU SIVARAMAN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2006 Copyright 2006 by Babu Sivaraman To my mother, for showing me the importance of hard work and persistence in all aspects of life ACKNOWLEDGMENTS I thank my advisor, Dr. Thomas Burks, for providing me an opportunity to explore my interests in the design and development of a robotic system. His constant encouragement and thoughtful suggestions helped me to accomplish the multiple tasks set forth for my dissertation. Needless-to-say, the get-togethers Dr. Burks and his family kindly hosted served as a respite from my regular schedule. I thank all the committee members for showing great interest in my research work. I am thankful to Dr. Carl Crane III for introducing me to the subject of robotics through his course offerings and Dr. John Schueller for his continued support throughout my academic pursuit at the University of Florida. I also thank them for providing the hydraulic power unit for the test set-up. I express my sincere gratitude to Dr. Sencer Yeralan for sharing interesting discussions on a multitude of topics and Dr. John Harris for serving as the external committee member as well as for being the graduate advisor for my minor in electrical engineering. I thankfully acknowledge the support of the Florida Department of Citrus (FDOC) and the Institute of Food and Agricultural Sciences (IFAS) for the research work on robotic manipulator development for citrus harvesting. I also offer my sincere appreciation to Mr. Michael Zingaro and Mr. Gregory Pugh for their tremendous support in the lab. Thanks are due to Mr.Steve Feagle for his timely completion of the joint parts and for his help in assembling the manipulator. The prototype would not have come to fruition without their support. iv My appreciation goes to Dr. Haridas Nayar of Ophirtech for his RobotectPro software support and to Dr. Peter Corke of Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) for making available the Matlab Robotics Toolbox free of cost over the web. I offer many thanks to Dr. Michael Hannan, Samuel Flood, Rajesh Pydipathi, Paulo Younse, Aaron Franzen, Siddhartha Mehta, Vijay Subramanian, Satnam Singh, Duke Bulanon, Sanghoon Han, and Xu Zhao of the ARM group for their interaction both in and out of the laboratory. Sam also provided me with data from tests he conducted on fruit properties. I owe much to Madhavan Esayanur, Sudarsan Srinivasan, Xavier George, Shiva Ariyakula, Subramanian Arcot, Sharath Cugati, Inka Hublitz, Luis Nogueira, Noble Thomas, Min Min, and Bernard Cardenas for making my stay in Gainesville delightful. Finally, I am most thankful to my brother Raja for his eternal support and my loving wife Raji for her constant encouragement and patience, and for proof-reading the entire document. v TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES...............................................................................................................x LIST OF FIGURES ........................................................................................................... xi ABSTRACT.......................................................................................................................xv CHAPTER 1 INTRODUCTION ........................................................................................................1 Overview.......................................................................................................................1 Citrus Industry Economics ...........................................................................................1 Robotic Harvesting Economics ....................................................................................3 Dissertation Organization .............................................................................................4 2 OBJECTIVES...............................................................................................................7 Problem Statement........................................................................................................7 Scope.............................................................................................................................7 Limiting Assumptions ..................................................................................................8 3 LITERATURE REVIEW ...........................................................................................10 Robotic Harvesting Manipulators – Related Work ....................................................10 Manipulator Kinematics .............................................................................................15 Kinematic Performance Indices..................................................................................21 Workspace ...........................................................................................................22 Dexterity Indices .................................................................................................23 Robot manipulability....................................................................................24 Manipulability ellipsoid ...............................................................................26 Posture diversity...........................................................................................26 4 METHODS AND PROCEDURES ............................................................................35 Robot Manipulator Configuration Selection for Citrus Harvesting Task...................35 vi Mechanical Design of the Four DOF Manipulator Comprising the Distal Joints of the Selected Configuration......................................................................................36 Hydraulic Test Circuit and Joint Level Control System.............................................37 Manipulator Performance Tests..................................................................................38 5 ROBOT MANIPULATOR SYNTHESIS: MODELING TOOLS.............................40 Introduction.................................................................................................................40 Manipulator Synthesis ................................................................................................41 Kinematic Synthesis Tool Requirements ............................................................42 Matlab Robotics Toolbox and RobotectPro ........................................................44 Application example ....................................................................................44 Robot definition............................................................................................45 Forward and inverse kinematics...................................................................47 Trajectory generation ...................................................................................48 Performance measures..................................................................................49 Additional features .......................................................................................50 Robot synthesis tools comparison................................................................52 Summary and Conclusions .........................................................................................52 6 KINEMATIC DEXTERITY INDICES FOR CITRUS HARVESTING ROBOT CONFIGURATION SELECTION.............................................................................57 Introduction.................................................................................................................57 Robot Kinematic Performance Indices.......................................................................58 Proposed Indices for Agricultural Robot Design and Analysis...........................58 Translational and rotational manipulability .................................................58 Directional invariance of dexterity...............................................................61 Application Example ...........................................................................................62 Citrus tree layout and fruit distribution ........................................................62 Basic robotic system layout..........................................................................62 Analysis of citrus harvesting robot configurations ......................................63 Results and discussion..................................................................................64 Conclusions.................................................................................................................66 7 MANIPULATOR CONFIGURATION SELECTION FOR CITRUS HARVESTING...........................................................................................................75 Introduction.................................................................................................................75 Robotic Citrus Harvesting Task Description..............................................................76 Robot Configuration Selection ...................................................................................76 Kinematic Structures for Evaluation ...................................................................77