WHEELED MOBILE ROBOTICS WHEELED MOBILE ROBOTICS From Fundamentals Towards Autonomous Systems Edited by GREGOR KLANČAR ANDREJ ZDEŠAR SAŠO BLAŽIČ IGOR ŠKRJANC Butterworth-Heinemann is an imprint of Elsevier The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States © 2017 Elsevier Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.
This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein.
In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library ISBN: 978-0-12-804204-5 For information on all Butterworth-Heinemann publications visit our website at https://www.com/ Publisher: Joe Hayton Acquisition Editor: Sonnini R. Yura Editorial Project Manager: Ana Claudia Abad Garcia Production Project Manager: Kiruthika Govindaraju Cover Designer: Mark Rogers Typeset by SPi Global, India PREFACE This is an introductory book on the subject of wheeled mobile robotics, covering all the essential knowledge and algorithms that are required in order to achieve autonomous capabilities of mobile robots.
The book can serve both as a textbook for engineering students and a reference book for professionals in the field. As a textbook, it is suitable for courses in mobile robotics, especially if the courses’ main emphasis is on mobile robots with wheels. The book covers topics from mathematical modeling of motion, sensors and measurements, control algorithms, path planning, nondeterministic events, and state estimation. The theory is supported with examples that have solutions and excerpts of Matlab code listings in order to make it simple for the reader to try, evaluate, and modify the algorithms.
Furthermore, at the end of the book some interesting practical projects are depicted, which can be used for laboratory practice or to consolidate the theory learned. The field of autonomous mobile robotics is an extremely popular field of research and development. Within this field the majority of mobile robots use wheels for motion. Wheeled mobile robots leave tracks where no man has ever been (e., extraterrestrial explorations), man should not go (e., dangerous or contaminated areas), or act alongside humans (e., human support and assistance).
Wheeled mobile robots have already started to pen- etrate into our homes in the form of robotic floor cleaners and lawn mowers, automatic guided vehicles can be found inside many industrial facilities, prototype self-driving cars already drive in the normal traffic, and in the nearby future many new applications of autonomous wheeled mobile robots are expected to appear, even in some unforeseen ways. The purpose of this book is to shed some light onto the design and give a deeper insight into the algorithms that are required in order to implement autonomous capabilities of wheeled mobile robots. The book addresses essential problems in wheeled mobile robotics and presents to the reader various approaches that can be used to tackle them. The presented algorithms range from basic and simple solutions to more advanced and state-of-the-art approaches.
The complete Matlab code listings of the algorithms that are presented in this book are also available for download at the book companion web- site: http://booksite. Therefore it should be simple for the readers to try, evaluate, tweak and tune the algorithms by vii viii Preface themselves. The website also contains many animated videos from the examples that give an additional insight into the topics and algorithms covered in the book. Škrjanc Ljubljana, Slovenia August 2016 ACKNOWLEDGEMENTS The authors would like to recognize all the individuals who contributed, both directly and indirectly, to this book.
We wish to thank all our colleagues, the current and past members of the Laboratory of Autonomous Mobile Systems, and the Laboratory of Modelling, Simulation and Control, Faculty of Electrical Engineering, University of Ljubljana, Slovenia, who inspired and contributed to this book. We are grateful to our colleague Dr. Matevž Bošnak for providing some insight into the field of assistive mobile robotics in walking rehabilitation therapy. Special acknowledgement goes to our former Head of the Laboratory, Prof.
Drago Matko for introducing our laboratory into the field of mobile robotics. Our gratitude also goes to all graduate students, research associates and technical staff from the Faculty of Electrical Engineering, University of Ljubljana, and researchers from institutions around the world with whom we have been involved in a diverse range of projects that in a way also enabled creation of this book. We would like to thank Asst. Auat Cheein, Department of Electronics Engineering, Universidad Técnica Federico Santa María, Chile, for providing us with some material from his field of research, mobile robotics in agriculture.
This work would have not been possible without support of the Slovenian Research Agency that backed many of our research and application projects. ix CHAPTER 1 Introduction to Mobile Robotics 1.1 Robots The word robot has roots in Slavic languages. The meaning of “robota” in Polish is work or labor, while the word is more archaic in Czech or Slovenian language and means statute labor or corvée. The famous Czech writer Karel Čapek coined the word robot and used it in the science fiction play R., which stands for Rossum’s Universal Robots.
The robots in the play are a sort of artificial human; in modern terminology cyborgs or androids would be more appropriate. The play witnessed huge success and the word robot was adopted by the majority of world languages. While the word robot is not even 100 years old, the idea of mechanic creatures goes very deep into history. In Greek mythology we find many creatures that are used for particular tasks.
Spartoi are mythical, fierce, and armed men who sprang up from the dragon’s teeth sown by Cadmus. They assisted Cadmus in building the Cadmeia or citadel of Thebes. Talos, created by Hephaestus, was a giant automaton made of bronze to protect Europa in Crete from pirates and invaders. The Greek god of blacksmiths and craftsmen, Hephaestus, is also credited for some other mechanical structures.
Automata can be also found in ancient Jewish, Chinese, and Indian legends. The idea of mechanical automata that resembled either humans or animals was then present in literature throughout the history. It really became popular in the 19th century and, especially, the 20th century. In the 20th century robots found a new popular media to depict them and bring them to life: film.
Some of the ideas in literature and films were attributed as science fiction at the time of creation, and later this fiction became a reality. The robotic designs were not present only in fiction. Very early in- ventors tried to construct mechanical automata. The Greek mathematician Wheeled Mobile Robotics © 2017 Elsevier Inc.00001-9 All rights reserved.
1 2 Wheeled Mobile Robotics Fig.1 Model of a bicycle and a programmable cart built based on Leonardo da Vinci’s notes. Archytas is believed to have designed and built the first artificial, self- propelled flying device in the 4th century BC. A mechanical bird propelled by steam was said to have actually flown some 200 m. In the comprehensive heritage of Leonardo da Vinci several mechanical designs can be found.
Among the rough sketches scattered throughout Leonardo’s notes, Rosheim [1] has reconstructed a programmable cart (Fig.1) used as a base for Leonardo’s inventions, such as a robot lion and a robot knight. The spring of industrial revolution technological advancement resulted in the outburst of automation that gradually led to the mobile robotics we know today.2 Mobile The word mobile has its roots in the Latin word of the same meaning, “mōbilis.” The majority of animal species possess the ability of locomotion. While some animals use passive systems to do so (they can move with water or air motion), others have developed more or less sophisticated mechanisms for active movement. Some animals perform locomotion in the 3D space (swimming in the water, flying in the air, moving through the soil), and others more or less follow the 2D surface of the water or the ground, while some animals are capable of combining different ways of movement.
In the context of mobile robots we are concerned with systems that can move using their locomotion apparatus. The latter very often mimics the one of a human or a certain animal. Copying from biological Introduction to Mobile Robotics 3 Fig.2 A working replica of the radio-controlled electrical boat built by Nikola Tesla. systems also very often successfully solves some technical problems that arise during artificial locomotion system design.
The other important aspect of a mobile system is that being mobile also means that the distance to the human operator can become large. This implies that the system needs to either possess a certain level of autonomy, meaning that it has to move across the space without the help of the operator, or accept the commands from a distant operator, meaning that the system is able to move tele-operated. Nikola Tesla was the first to design and build a radio-controlled electrical boat (Fig.2) at the end of the 19th century. In the 20th and the 21st century the level of autonomy continuously rose.
Yet, all the existing mobile systems are human operated on a certain level.3 Wheels Although very primitive animal species are able to move, it is often a nontrivial task to design an artificial system that is able to mimic animal locomotion. While wheels or similar structures cannot be found in the animal world, the vehicles with wheels are known to enable energy- efficient motion over the ground. The surface has to be smooth enough although appropriately constructed wheeled vehicles can also move over rugged terrain, such as steps. It is not known where and when the wheel 4 Wheeled Mobile Robotics (A) (B) Fig.3 The 5200-year-old wooden wheel (A) with the axle (B) found in the Ljubljana Marshes pile dwelling is one of the world’s most significant cultural heritage items in terms of both its age and technological accomplishment.
The diameter of the wheel is 70 cm and the axle length is 120 cm. (Museum and Galleries of Ljubljana, photos by M.) was invented but the established belief is that the first wheels were used in Mesopotamia approximately 4000 BC. From there, they were spread around the world. Some experts attribute the wheel’s invention to prehistoric Europe.
The oldest wooden wheel with an axle, 5200 years old, was discovered in Slovenia in the Ljubljana Marshes (Fig.4 Autonomous Mobile Systems Mobile systems can be defined as systems that are not attached to the environment and can move in a certain space.