Beginning Robotics Programming in Java with LEGO Mindstorms

Transcription

1 Beginning Robotics Programming in Java with LEGO Mindstorms Wei Lu

2 Beginning Robotics Programming in Java with LEGO Mindstorms Wei Lu Keene, New Hampshire, USA ISBN-13 (pbk): ISBN-13 (electronic): DOI / Library of Congress Control Number: Copyright 2016 by Wei Lu This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Trademarked names, logos, and images may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, logo, or image we use the names, logos, and images only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. The use in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Managing Director: Welmoed Spahr Lead Editor: Aaron Black Developmental Editor: Gary Schwartz Technical Reviewer: Nanyan Wang Editorial Board: Steve Anglin, Pramila Balan, Laura Berendson, Aaron Black, Louise Corrigan, Jonathan Gennick, Robert Hutchinson, Celestin Suresh John, Nikhil Karkal, James Markham, Susan McDermott, Matthew Moodie, Natalie Pao, Gwenan Spearing Coordinating Editor: Jessica Vakili Copy Editor: Karen Jameson Compositor: SPi Global Indexer: SPi Global Artist: SPi Global Distributed to the book trade worldwide by Springer Science+Business Media New York, 233 Spring Street, 6th Floor, New York, NY Phone SPRINGER, fax (201) , orders-ny@springer-sbm.com, or visit Apress Media, LLC is a California LLC and the sole member (owner) is Springer Science + Business Media Finance Inc (SSBM Finance Inc). SSBM Finance Inc is a Delaware corporation. For information on translations, please rights@apress.com, or visit Apress and friends of ED books may be purchased in bulk for academic, corporate, or promotional use. ebook versions and licenses are also available for most titles. For more information, reference our Special Bulk Sales ebook Licensing web page at Any source code or other supplementary materials referenced by the author in this text are available to readers at For detailed information about how to locate your book s source code, go to Readers can also access source code at SpringerLink in the Supplementary Material section for each chapter. Printed on acid-free paper

3 My wife Ling, for her endless love and support over the past fi ve years when I worked on this book. My daughter Julia and son Ryan, for giving their dad the best fun times when testing all of the robot s programs with them.

4 Contents at a Glance About the Author... xi Acknowledgments... xiii Introduction...xv Chapter 1: Introduction to Lego Mindstorms and lejos... 1 Chapter 2: Introduction to Motor Sensors Chapter 3: Controlling Wheeled Vehicles Chapter 4: Coordinators and Navigator API Chapter 5: Depth-First Search Algorithm and Its Implementation with Lego EV Chapter 6: Breadth-First Search and Its Implementation with Lego Mindstorms Chapter 7: Hill-Climbing Search and Its Implementation with Lego Mindstorms Chapter 8: Dijkstra s Algorithm and Its Implementation with Lego Mindstorms Chapter 9: The A* Search Algorithm and Its Implementation with Lego Mindstorms Chapter 10: Introducing the Touch Sensor and Ultrasonic Sensor Chapter 11: Introducing the Light Sensor and Color Sensor Chapter 12: Introduction to Behavior Programming Chapter 13: Multithreading Programming with Java lejos Index v

5 Contents About the Author... xi Acknowledgments... xiii Introduction...xv Chapter 1: Introduction to Lego Mindstorms and lejos... 1 Introduction to Lego Mindstorms... 1 Introduction to lejos... 3 Lego Mindstorms EV Lego Mindstorms NXT... 4 Lego Mindstorms RCX... 4 JDK Installation... 5 Testing the JDK Installation... 8 Installation of lejos and Its Firmware on Lego EV Eclipse IDE and Eclipse Plug-In for LeJOS EV Summary...25 Chapter 2: Introduction to Motor Sensors Basic Concepts of Java Programming Introducing Motors Introducing the Motor Class Controlling Basic Movement Using Motors Using a Tachometer for Inertia Testing Controlling the Accurate Rotation of Motors Interrupting Rotation vii

6 CONTENTS Regulating the Motor Speed Tracing a Straight Line Other Motor Methods Summary...41 Chapter 3: Controlling Wheeled Vehicles Introduction to Navigation API Basic Movement Using Pilot Classes Tracing Out a Square Tracing Out an Equilateral Triangle Tracing Out a Regular Hexagon Summary...63 Chapter 4: Coordinators and Navigator API Cartesian Coordinate System Basics Navigator API Functions Controlling the EV3 Brick Hardware Programming Practice with the LCD Display Programming Practice with Key Presses Programming Practice with Navigator API Summary...81 Chapter 5: Depth-First Search Algorithm and Its Implementation with Lego EV Overview of DFS Algorithm lejos EV3-Based DFS Algorithm Summary Chapter 6: Breadth-First Search and Its Implementation with Lego Mindstorms Overview of BFS Algorithm lejos EV3-Based BFS Algorithm Summary viii

7 CONTENTS Chapter 7: Hill-Climbing Search and Its Implementation with Lego Mindstorms Introduction to Heuristic Search Overview of Hill-Climbing Search lejos EV3-Based Hill-Climbing Algorithm Summary Chapter 8: Dijkstra s Algorithm and Its Implementation with Lego Mindstorms Introduction to Dijkstra s Algorithm lejos EV3-Based Dijkstra s Algorithm Summary Chapter 9: The A* Search Algorithm and Its Implementation with Lego Mindstorms What Is the A* Algorithm? The Basic Idea of the A* Searching Strategy Practice for Path Planning Using the A* Algorithm Summary Chapter 10: Introducing the Touch Sensor and Ultrasonic Sensor Sensor Classes Touch Sensor Ultrasonic Sensor Programming Practice with Touch Sensor Programming Practice with Ultrasonic Sensor Summary Chapter 11: Introducing the Light Sensor and Color Sensor Light Sensor Color Sensor Programming Practice with the Color and Light Sensors Summary ix

8 CONTENTS Chapter 12: Introduction to Behavior Programming Introduction to Behavior Programming The Behavior API Functions Design Pattern of Behavior Programming Programming Practice with Behavior Programming Summary Chapter 13: Multithreading Programming with Java lejos The Thread Concept Using Threads in lejos Method start() Method isalive () Method sleep () Practice with Multithreading in Java lejos Summary Index x

9 About the Author Wei Lu is an Associate Professor of Computer Science at Keene State College in New Hampshire. He received his Ph.D. in Electrical and Computer Engineering from the University of Victoria, Canada. Prior to joining Keene State College, he was a Senior Researcher with the German Research Centre for Artificial Intelligence (DFKI GmbH) and worked with Q1 Labs Inc. (Security Systems Division, IBM since October 2011) as a Secure Software Engineer. His general areas of research interests include Artificial Intelligence and Cyber Security. He has had more than 50 papers published by peerreviewed journals, book chapters, and conference proceedings. In addition, he coauthored, Network Intrusion Detection and Prevention: Concepts and Techniques (Springer, 2010) and has served as a technical program committee member and a technical reviewer for more than 70 international conferences and journals. xi

10 Acknowledgments I would like to express my deepest gratitude to the following people: My wife, for her endless love and support over the past five years when I worked on this book. My daughter and son, for giving their dad the best fun times when testing all of the robot s programs with them. My parents, for giving me the encouragement to keep exploring new opportunities. My colleagues Michael and Shari, for promoting Java robotics programming computer science education. All my students, who participated the course, CS495 Artificial Intelligence and Robotics. This book would not be published without their motivation. Nanyan Wang, for sharing his experience and insights in engineering and computer science and his technical review of this book. The Apress team, for leading me through the entire jungle of authoring a book. Without their passion for publishing the best robotics programming book in Java for beginners, I would not have had an opportunity to write and publish this b o ok. xiii

11 Introduction There are many cognitive tasks that people can do easily and almost subconsciously, but that have proven extremely difficult to program on a computer. Artificial Intelligence (AI) is the process of developing computer systems that can carry out these tasks, and it is devoted to the computational study of intelligent behavior. Such intelligent behavior includes a wide range of phenomena, such as perception, problem solving, use of knowledge, planning, learning, and communication in order to take a complicated task and convert it into simpler steps that the robotics system can handle. Based on the Lego Mindstorms robotic system, this book develops a wide range of techniques in the Java programming language for modeling these phenomena, including state-space search, several knowledge representation schemes, and task-specific methods. The book begins with an introduction to Lego Mindstorms EV3 and lejos, an open source project created to develop the technological infrastructure, and a tiny Java virtual machine in which to implant software into Lego Mindstorms products using Java technology. It then continues with a discussion of problem- solving techniques, such as breadth-first search, depth-first search, heuristic search, hill-climbing search, and A star (A*) search, and finishes with robotics behavior programming in Java multithreading programming with a set of sensors. A major goal of AI is to give computers the ability to think, or in other words, mimic human behavior. The problem with this mimicry is that, unfortunately, computers don't function in the same way as the human brain; that is, they require a series of well reasoned-out steps in order to find a solution. Therefore, one challenge in robotics programming is how to convert something complex into something simple that can be done by algorithms. This book bridges the gap between the theoretical AI algorithms and practical robotics systems by developing a set of algorithms and building them into the well-known Lego Mindstorms EV3 system in order to achieve an enhanced intelligence. xv