Computational Principles of Mobile Robotics Mobile robotics is a multidisciplinary field involving both computer science and engineering. Addressing the design of automated systems, it lies at the intersection of artificial intelligence, computational vision, and robotics. This textbook for advanced undergraduates and graduate students emphasizes computation and algorithms for a range of strategies for locomotion, sensing, and reasoning. It concentrates on wheeled and legged mobile robots but also discusses a variety of other propulsion systems. The new edition presents advances in robotics and intelligent machines over the last 10 years, including significant coverage of SLAM (simultaneous localization and mapping) and multi-robot systems. It includes additional mathematical background and an extensive list of sample problems. Various mathematical techniques that were assumed in the first edition are now briefly introduced in appendices at the end of the text to make the book more self-contained. Researchers and students in the field of mobile robotics will appreciate this comprehensive treatment of state-of-the-art methods and key technologies. Gregory Dudek is James McGill Professor of Computer Science and the Director of the School of Computer Science and of the Mobile Robotics Laboratory at McGill University. Michael Jenkin is a Professor of Computer Science and Engineering at York University. He has coedited eight books on human and machine vision.
Computational Principles of Mobile Robotics Second Edition Gregory Dudek McGill University Michael Jenkin York University
CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi, Dubai, Tokyo, Mexico City Cambridge University Press 32 Avenue of the Americas, New York, NY 10013-2473, USA Information on this title: /9780521692120 Cambridge University Press 2010 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2010 Printed in the United States of America A catalog record for this publication is available from the British Library. Library of Congress Cataloging in Publication data Dudek, Gregory, 1958 Computational principles of mobile robotics / Gregory Dudek, Michael Jenkin. 2nd ed. p. cm. Includes bibliographical references and index. ISBN 978-0-521-87157-0 1. Mobile robots. 2. Robotics Mathematics. I. Jenkin, Michael, 1959 II. Title. TJ211.415.D83 2010 629.8 932 dc22 2010020795 ISBN ISBN 978-0-521-87157-0 Hardback 978-0-521-69212-0 Paperback Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party Internet Web sites referred to in this publication and does not guarantee that any content on such Web sites is, or will remain, accurate or appropriate.
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Contents Acknowledgments Preface to the Second Edition page xi xiii 1 Overview and Motivation 1 1.1 From Mechanisms to Computation 4 1.2 Historical Context 5 1.3 Biological Inspiration 11 1.4 Operational Regimes 11 1.5 Operational Modes 11 1.6 A Guide to This Book 12 1.7 Further Reading 13 1.8 Problems 16 2 Fundamental Problems 18 2.1 Path Planning for a Point Robot 19 2.2 Localization for a Point Robot 21 2.3 Sensing for a Point Robot 23 2.4 Mapping for a Point Robot 25 2.5 SLAM for a Point Robot 25 2.6 Looking Forward 26 2.7 Further Reading 27 2.8 Problems 27 Part One: Locomotion and Perception 29 3 Mobile Robot Hardware 31 3.1 Locomotion 31 3.2 Off-Board Communication 71 3.3 Processing 75 3.4 Further Reading 76 3.5 Problems 77 4 Non-Visual Sensors and Algorithms 82 4.1 Basic Concepts 82 4.2 Contact Sensors: Bumpers 86 vii
viii Contents 4.3 Inertial Sensors 87 4.4 Infrared Sensors 90 4.5 Sonar 91 4.6 Radar 98 4.7 Laser Rangefinders 98 4.8 Satellite-Based Positioning 100 4.9 Data Fusion 102 4.10 Biological Sensing 118 4.11 Further Reading 120 4.12 Problems 121 5 Visual Sensors and Algorithms 123 5.1 Visual Sensors 124 5.2 Object Appearance and Shading 131 5.3 Signals and Sampling 132 5.4 Image Features and Their Combination 134 5.5 Obtaining Depth 149 5.6 Active Vision 155 5.7 Other Sensors 158 5.8 Biological Vision 162 5.9 Further Reading 163 5.10 Problems 164 Part Two: Representation and Planning 165 6 Representing and Reasoning About Space 167 6.1 Representing Space 167 6.2 Representing the Robot 176 6.3 Path Planning for Mobile Robots 179 6.4 Planning for Multiple Robots 208 6.5 Biological Mapping 209 6.6 Further Reading 210 6.7 Problems 210 7 System Control 212 7.1 Horizontal Decomposition 213 7.2 Vertical Decomposition 217 7.3 Hybrid Control Architectures 223 7.4 Middleware 226 7.5 High-Level Control 226 7.6 Alternative Control Formalisms 230 7.7 The Human Robot Interface 235 7.8 Mobile Robot Software Development as Experimentation 237 7.9 Standard Software Toolkits 237
Contents ix 7.10 Further Reading 238 7.11 Problems 239 8 Pose Maintenance and Localization 240 8.1 Simple Landmark Measurement 241 8.2 Servo Control 249 8.3 Recursive Filtering 250 8.4 Non-Geometric Methods: Perceptual Structure 260 8.5 Correlation-Based Localization 267 8.6 Global Localization 267 8.7 Biological Approaches to Localization 273 8.8 Further Reading 274 8.9 Problems 274 9 Mapping and Related Tasks 276 9.1 Sensorial Maps 278 9.2 Geometric Maps 279 9.3 Topological Maps 287 9.4 Exploration 291 9.5 Further Reading 294 9.6 Problems 294 10 Robot Collectives 295 10.1 Categorizing Collectives 296 10.2 Control Architectures 296 10.3 Collective Communication 299 10.4 Sensing 300 10.5 Planning for Action 301 10.6 Formation Control 302 10.7 Localization 303 10.8 Mapping 304 10.9 Further Reading 305 10.10 Problems 306 11 Robots in Practice 307 11.1 Delivery Robots 307 11.2 Intelligent Vehicles 309 11.3 Robots for Survey and Inspection 314 11.4 Mining Automation 316 11.5 Space Robotics 317 11.6 Autonomous Aircraft 319 11.7 Military Reconnaissance 320 11.8 Bomb/Mine Disposal 320 11.9 Underwater Inspection 322 11.10 Agriculture/Forestry 323 11.11 Aids for the Disabled 325
x Contents 11.12 Entertainment 326 11.13 Domestic Robots 327 11.14 Further Reading 327 11.15 Problems 328 12 The Future of Mobile Robotics 329 12.1 Locomotion 329 12.2 Sensors 331 12.3 Control 332 12.4 System Integration 332 12.5 Standardization 333 12.6 Future Directions 333 Appendix A: Probability and Statistics 335 A.1 Probabililty 335 A.2 Some Simple Statistics 338 A.3 Further Reading 339 A.4 Problems 339 Appendix B: Linear Systems, Matrices, and Filtering 341 B.1 Linear Algebra 341 B.2 Matrix Algebra 341 B.3 Signals and Systems 343 B.4 Fourier Theory 344 B.5 Sampling and the Nyquist Theorem 344 B.6 Further Reading 345 B.7 Problems 345 Appendix C: Markov Models 346 C.1 Discrete Markov Process 346 C.2 Hidden Markov Models 348 C.3 Markov Decision Process 349 C.4 POMDP 350 C.5 Further Reading 351 C.6 Problems 351 Bibliography 353 Index 381
Acknowledgments This book would not have been possible without the active support of our students and colleagues who suffered through early drafts, provided imagery and papers, and put up with us while this volume was being put together. The list of people who helped is much too long to include here, but some require special mention: International Joint Conferences on Artificial Intelligence (IJCAI), for letting us do a tutorial on mobile robotics that started us on the journey; students at McGill and York, including Eric Bourque, Andrew Hogue, and Yiannis Rekleitis, who suffered with photocopies of early drafts; Prof. Evangelos Milios for his helpful comments and Prof. Evangelos Papadopoulos for his help on space robots; Rob Sim for his figures; and Louis Dudek for his proofreading and helpful comments. Finally, we thank Lauren Cowles and Cambridge University Press for encouraging us do this in the first place. xi
Preface to the Second Edition The authors surrounded by a collection of some of their robots and sensors. The first edition of this book arose from a tutorial that was initially presented in 1993. It evolved over a number of years and finally appeared in 2000. Robotics is, of course, a rapidly changing field, and even as the first edition was appearing, it was apparent that it would become dated rather quickly. Thus in late 2002, the first steps were taken toward a second edition. The field of mobile robotics continues to evolve, and this book has (we hope) evolved with the field. Topics that were in their infancy when the first edition was published such as SLAM and multi-robot systems have evolved into much more mature disciplines. The mathematical foundations of much of mobile robotics has also matured, and this too is reflected in this volume. In addition to updating the various algorithms and methods described in the first edition, the second edition is somewhat more self-contained. Specifically, various mathematical techniques that were assumed in the first edition are now introduced, albeit briefly, in appendices at the end of the text. xiii