LEGO MINDSTORMS - Building Robots part 1 ppt

KEY SERIAL NUMBER Building Robots with LEGO MINDSTORMS Copyright © 2002 by Syngress Publishing, Inc.. It seemed an entire world of potential robotics fans had just been waiting for thisp

Mario Ferrari Giulio Ferrari Ralph Hempel

Technical Editor

T h e U LT I M AT E To o l f o r M i n d s t o r m s M a n i a c s !

• Discover the Undocumented Secrets behind the Design

of the Mindstorms System

• Become Inspired by the Techniques of World-Class Mindstorms Masters

• Build a Competitive Edge for Your Next Mindstorms Robotic Competition

s o l u t i o n s @ s y n g r e s s c o m

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Mario Ferrari Giulio Ferrari Ralph Hempel Technical Editor

T h e U LTI MATE To o l fo r M I N D STO R M S M a n i a c s !

Building Robots

with

LEGO MINDSTORMS

®

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KEY SERIAL NUMBER

Building Robots with LEGO MINDSTORMS

Copyright © 2002 by Syngress Publishing, Inc All rights reserved Printed in the United States of America Except as permitted under the Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher, with the exception that the program listings may be entered, stored, and executed in a computer system, but they may not be reproduced for publication.

Printed in the United States of America

1 2 3 4 5 6 7 8 9 0

ISBN: 1-928994-67-9

Technical Editor: Ralph Hempel Cover Designer: Michael Kavish

Co-Publisher: Richard Kristof Page Layout and Art by: Shannon Tozier

Acquisitions Editor: Catherine B Nolan Copy Editor: Michael McGee

Developmental Editor: Kate Glennon Indexer: Robert Saigh

Freelance Editorial Manager: Maribeth Corona-Evans

Distributed by Publishers Group West in the United States and Jaguar Book Group in Canada.

However, the publication of Building Robots with LEGO MINDSTORMS entitles

me to a one-time exemption from our rule I am lucky enough to be the father ofnine-year-old Sam Williams, who has taught me (among many important things) thejoy of building with LEGO Since helping Sam put together his first bricks at twoyears old to programming our latest MINDSTORMS robot (the optimisticallynamed “Chore-Doer 3000”), I have derived hundreds of hours of pleasure creatingprojects with Sam Perhaps the most ingenious thing about LEGO products, particu-larly the MINDSTORMS, is that the same product can be as challenging and enjoy-able to a 43 year old as it is to a nine year old

When presented with the chance to publish Mario and Giulio Ferrari’s book, Ijumped at the opportunity As I read the manuscript, I could sense the authors hadthe same passion for creating with LEGO MINDSTORMS that Sam and I have Iknew immediately that there was a market of at least two people for the book!

I had the opportunity to meet Mario Ferrari at the Frankfurt Book Fair justweeks prior to this book’s publication I am American and Mario is Italian, but thelanguage we spoke was that of two parents who have discovered a common passion

to share with our nine and ten year old sons

I hope you enjoy reading this book as much as we have enjoyed publishing it

—Chris Williams President, Syngress Publishing

FPO

Letters from the Authors

October 1998 It was a warm and sunny October and I remember it as if it was justyesterday Giovanni, a colleague of mine, returns home to Italy from his honeymoon

in New York He carries in the office an enormous blue box whose cover reads

“LEGO MINDSTORMS Robotics Invention System.”When Giovanni opens thebox and shows me the contents, I already know I must have one

Let me go back to the late 70s I was a high school student and had left my manyyears of LEGO play behind me I was enthusiastically entering the rising personalcomputing era Many of you are probably simply too young to remember that

period, but “using” a computer mainly meant programming it.The computers of that

time had few resources and rather primitive user interfaces; they were essentially massstorage devices, or something like a large unreliable cassette recorder.We program-mers had to count and save every single byte, and even the most trivial tasks werevery challenging But at the same time, of course, it was great fun!

I developed a very strong interest in computer programming, and in ArtificialIntelligence in particular Machines and mechanical devices had always fascinated me,and it came quite naturally to me to turn to robotics as an expansion of this interest.There were some relatively cheap and compact computing devices that could provide

a brain for my creatures, but unfortunately I discovered very soon all the technicalproblems involved in building the hardware of even a very simple robot.Where could

I find motors? Which were the right ones? Where could I learn how to controlthem? What kind of gearing did I need? Imagine spending months folding aluminumplates, mounting bearings, assembling electronic circuits, connecting wires… andassuming you’re able to do all those things, what do you get? A simple tin box thatcan run across the room and change direction when it hits an obstacle.The effort wasdefinitely far greater than the results Another problem was that constructing a newproject meant starting again from scratch, with new materials I wasn’t patient

enough, so I decided that a hobby in robotics was not for me

The dream of robotics remained a dream Until Giovanni opened that box As

soon as I got my hands on my first LEGO MINDSTORMS Robotics InventionSystem (RIS) set, it proved to be the fast and flexible robotics system that I waslooking for I found that the microcomputer, called the RCX, was very simple to usebut powerful enough to let me drive complex devices I became more and more

vi

intrigued by this toy, and through the Internet I soon discovered that I was not alone

It seemed an entire world of potential robotics fans had just been waiting for thisproduct, and the LEGO company itself sold much more of them than expected.From that October on, many things happened: I discovered LUGNET, the fan-tastic LEGO Users Group Network, the best resource ever for LEGO fans of anykind I created a small Web site where I published pictures and information about

my robotic creatures.Through these channels every day I got in touch with newpeople, and with some of them friendships have sprung up that go beyond ourcommon interests in LEGO robotics.This is really the most special and valuablething MINDSTORMS have given to me: Good friends all over the world

—Mario Ferrari

October 1999 Another warm and sunny October, but on one particular day theMedia Lab at the Massachusetts Institute of Technology (MIT) in Cambridge, MAhas a different look One large room at the facility is filled with exhibition tableswith piles of colorful LEGO pieces and strange constructions on them and, there arehundreds of adults and children, LEGO bricks in hand, showing off their robotic cre-ations and discussing the characteristics of their favorites.This is the world’s biggestgathering of LEGO MINDSTORMS fans—the Mindfest!

When and how did all this start? It seems only yesterday to me, but a year hadpassed since I discovered MINDSTORMS for the first time My brother Mariocalled me on the phone one evening, knowing I was about to leave on a short trip toNew York, and asked me to bring him home a new product from LEGO, a sort of aprogrammable brick that could be controlled via a standard computer I have to saythat I was very curious, but nothing more: I thought it might be a great new toy toplay around with, but I didn’t completely understand its possibilities.When I saw theRobotics Invention System (RIS) in the toy store, though, I immediately realizedhow great it could be, and that I must have one, too My own addiction to theLEGO MINDSTORMS began in that moment

Like nearly everyone under the age of 40, I’d built projects from the manyLEGO theme kits in my childhood I had the advantage of using the large quantity

of bricks that my older brothers and sisters had accumulated during the years, plussome new pieces and sets of the 80s Castles, pirates, trains… hours and hours of pure

fun, creating a large number of any kind of building and adventures.When I was alittle older, I discovered the TECHNIC series, a wonderful world of machines, gears,mechanical tools, and vehicles, with endless construction possibilities.Then, like manyother people, I abandoned LEGO as a young adult, and it remained out of my life—until I bought that big blue box in New York that day

Why do I like LEGO MINDSTORMS so much? For me, it is mainly because itrequires different skills and combines different disciplines: computer programming,robotics, and hands-on construction.You have to combine theory and practice, and tocoordinate the design, construction, software, and testing processes.You can exerciseyour creativity and your imagination, and you have a great tool for doing this—atool that is at the same time easy to use and very powerful, and most important, thatdoesn’t limit your ideas

And there’s even more to the rewards of MINDSTORMS than that Let’s goback to Mindfest for a moment.Why would such an extraordinary group of people

of different ages, cultures, and nationalities travel from all over the world to spend anentire weekend playing with LEGO? What exactly do they have in common? Why

do some of the most famous Artificial Intelligence experts seriously discuss every ture of this product? There must be something really special about this “toy.”

fea-Joining an international community is one of the best things about playing withLEGO It is not only a toy, but also a way of thinking and living Just play with theMINDSTORMS for a while—you’ll see for yourself!

—Giulio Ferrari

Author Acknowledgements

We would first like to thank Brian Bagnall for suggesting our names to SyngressPublishing when he heard Syngress was looking for an author to write a bookfocused on ideas and techniques for building MINDSTORMS robots.We are verygrateful to Syngress Publishing for having turned this suggestion into a real opportu-nity, and for having allowed us the great freedom of deciding the shape and content

of the book

Additional appreciation goes to Jonathan Knudsen, who encouraged us inembarking upon the adventure of writing a book, and who helped us in under-standing the world of technical publishing Another friend, Guido Truffelli, patientlyread every page of the manuscript Many thanks, Guido—your comments and sug-gestions were very valuable in making the book more complete and more useful.When Ralph Hempel accepted the offer to perform the technical edit of thebook, we were really excited Ralph’s contributions to MINDSTORMS robotics areimpressive, and range from mechanical solutions to extreme programming Hisinvolvement proved to be even more significant that we had even imagined

This was our first authoring experience, and all the Syngress staff has beenincredibly patient with us and very supportive A very special thank you goes to KateGlennon, our Developmental Editor, for having taught us how to transform a collec-tion of concepts and ideas into a book Mario wants to also thank his employer,EDIS, which granted him the time to focus more attention on the book

This book would have not been written without the contributions of the entireLUGNET MINDSTORMS Robotics community Its members are incredibly cre-ative, competent, helpful, and friendly, and they are always willing to share ideas andsolutions with other people.We have attempted to give proper credit to all thepeople whose ideas we mentioned in the book, and we apologize in advance forthose people who have been unintentionally left out

Last but not least, we’d like to express enormous gratitude to our families, whoencouraged and supported us through every moment of these intense months ofwriting

Syngress Acknowledgements

We would like to acknowledge the following people for their kindness and support

in making this book possible

Richard Kristof and Duncan Anderson of Global Knowledge, for their generousaccess to the IT industry’s best courses, instructors, and training facilities

Karen Cross, Lance Tilford, Meaghan Cunningham, Kim Wylie, Harry Kirchner,Kevin Votel, Kent Anderson, and Frida Yara of Publishers Group West for sharingtheir incredible marketing experience and expertise

Mary Ging, Caroline Hird, Simon Beale, Caroline Wheeler,Victoria Fuller, JonathanBunkell, and Klaus Beran of Harcourt International for making certain that ourvision remains worldwide in scope

Anneke Baeten and Annabel Dent of Harcourt Australia for all their help

David Buckland,Wendi Wong, Daniel Loh, Marie Chieng, Lucy Chong, Leslie Lim,Audrey Gan, and Joseph Chan of Transquest Publishers for the enthusiasm withwhich they receive our books

Kwon Sung June at Acorn Publishing for his support

Ethan Atkin at Cranbury International for his help in expanding the Syngress

program

A special thanks to Sam Williams, who comes to the office every week with a

backpack full of LEGOs.Watching the look on his face when he opens a new kit is ajoyous event

Modena, Italy, where he lives with his wife Anna and his childrenSebastiano and Camilla.

Giulio Ferrariis a student in Economics at the University of Modenaand Reggio Emilia, where he also studied Engineering He is fond ofcomputers and has developed utilities, entertainment software, and Webapplications for several companies Giulio discovered robotics in 1998,with the arrival of MINDSTORMS, and held an important place in thecreation of the Italian LEGO community He shares a love for LEGObricks with his oldest brother Mario, and a strong curiosity for the phys-ical and mathematical sciences Giulio also has a collection of 1200 dice,including odd-faced dice and game dice He studies, works, and lives inModena, Italy

Technical Editor

Ralph Hempel(BASc.EE, P.Eng) is an Independent Embedded SystemsConsultant He provides systems design services, training, and program-ming to clients across North America His specialty is in deeply

embedded microcontroller applications, which include alarm systems,automotive controls, and the LEGO RCX system Ralph providestraining and mentoring for software development teams that are new toembedded systems and need an in-depth review of the unique require-ments of this type of programming Ralph holds a degree in ElectricalEngineering from the University of Waterloo and is a member of theOntario Society of Professional Engineers He lives in Owen Sound,Ontario with his family, Christine, Owen, Eric, and Graham

Summary 15

Chapter 2 Playing with Gears 17

Introduction 18

Riding That Train:The Geartrain 21Worming Your Way:The Worm Gear 23Limiting Strength with the Clutch Gear 24Placing and Fitting Gears 26Using Pulleys, Belts, and Chains 31

Chains 35Making a Difference:The Differential 36Summary 39

Learn about Lego Gears

xiv Contents

Chapter 3 Controlling Motors 41

Introduction 42Pacing,Trotting, and Galloping 43

Putting It All Together: Chassis, Modularity,

Summary 94

Explore LEGO Sensors

LEGO sensors come in two

families: active and

passive sensors Passive

simply means they don't

require any electric supply

to work The touch and

temperature sensors

belong to the passive

class, while the light and

rotation sensors are

members of the active

class.

Contents xv

Chapter 6 Programming the RCX 97

Introduction 98

A Small Family of Programmable Bricks 100

Using the NQC Language 102Using Other Programming Languages 103

Summary 124

Chapter 8 Becoming Mobile 127

Introduction 128Building a Simple Differential Drive 128Keeping a Straight Path 130Using Sensors to Go Straight 130Using Gears to Go Straight 131Using Casters to Go Straight 134Building a Dual Differential Drive 136Building a Skid-Steer Drive 138Building a Steering Drive 140Building a Tricycle Drive 144Building a Synchro Drive 146

Understand the Benefits of Designing Modular Code

■ Readability

■ Reusability

■ Testability

Introducing Some Specialized Components 155Buying Additional Parts 161Creating Custom Components 163Building Custom Sensors 164Solving Port Limitations 170Creative Solutions When

More RCX Ports Are Needed 172Summary 177

Chapter 10 Getting Pumped: Pneumatics 179

Introduction 180Recalling Some Basic Science 180

Controlling the Airflow 187Building Air Compressors 190Building a Pneumatic Engine 194Summary 198

Chapter 11 Finding and Grabbing Objects 199

Introduction 200Operating Hands and Grabbers 200Transferring Motion Using Tubing 203Understanding Degrees of Freedom 205

Summary 212

Chapter 12 Doing the Math 213

Introduction 214Multiplying and Dividing 215

Explore extra parts,

custom sensors, and tricks

for using the same motor

for more than one task:

■ Extra parts come from

either sets or service

packs

■ Custom sensors are a

new frontier, and

reveal a whole new

world of possibilities

■ Mechanical tricks

enable you to use the

same motor to power

multiple mechanisms.

Contents xvii

Understanding Hysteresis 229Summary 232

Chapter 13 Knowing Where You Are 233

Introduction 234Choosing Internal or External Guidance 234Looking for Landmarks: Absolute Positioning 236

Measuring Movement: Relative Positioning 243Summary 246

Part II Projects 247 Chapter 14 Classic Projects 249

xviii Contents

Chapter 16 Unconventional Vehicles 311

Introduction 312Creating Your Own SHRIMP 312

Creating Other Vehicles 328Elevator 328Train 328Cable Railway or Gondola 329Boat 329

Chapter 18 Replicating Renowned Droids 349

Introduction 350Building an R2-D2-Style Droid 350Programming the Droid 356Variations on the Construction 359Building a Johnny Five-Style Droid 361Variations on the Construction 366Summary 368

Chapter 19 Solving a Maze 371

Introduction 372

Using the Left Side—Right Side Strategy 374Applying Other Strategies 376

Use Angle Connectors

There are currently six

types of angle connectors

in the LEGO line,

numbered 1 to 6 In case

you’re wondering how the

numbers relate to angles,

here are the

Contents xix

Building a Maze Runner 377Constructing the Maze Runner 377Programming the Runner 380

Variations on the Maze Runner 381Building a Maze Solver 382Constructing the Maze Solver 383Programming the Solver 387Summary 389

Chapter 20 Board Games 391

Introduction 392

Building the Hardware 393

Improving Your Game 396

Building a Visual Interface 397Building a Mechanical Interface 400Connecting and Programming

Variations on the Construction 408Playing Other Board Games 409Summary 410

Chapter 21 Playing Musical Instruments 411

Introduction 412

Building the Drummer 413Programming the Drummer 416Variations 417

Building the Pianist 417Programming the Pianist 422Changes and Improvements 423

to withstand the forces involved in the

performance