Robotics Demystified. McGraw-Hill

EDWIN WISE


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Robotics Demystified


PREFACE
This book is for people who want to learn the basic concepts of robotics without
taking a formal course. This book seeks to give you an intuitive grasp of
the various technologies that make up the field of robotics. There is no one
‘‘robot technology,’’ so this book breaks the study of robots down into technology
categories: the mechanics and framework of the robot, the electronics
that make up its brain and nerves, and the control systems and programming
that gives the robot life.
To aid you in your learning, this work contains short quizzes that review
the main concepts in each chapter. Answers to the quizzes are given in the
back of the book.
This is a hands-on book, and it contains a number of experiments to
illustrate the concepts described in the text. These experiements can be
completed with easily found materials.
Though this is a hands-on book, it is not a ‘‘how to’’ book. Since it covers
several complex topics, it can only go so deep into each one.
Edwin Wise

ACKNOWLEDGMENTS
Of course, I have to acknowledge my wife Marla for letting me take the time
to write this book. My reviewers, Bob Comer and Matt Pinsonneault with
help from Nikolas Wise, helped me to remain coherent and stay on track.
The text was written in Microsoft Word, and the graphics and diagrams
were created and edited with Adobe’s Photoshop, Midnight Software’s
DeltaCAD, CadSoft’s Eagle electronics layout editor, Pacestar’s ever useful
EDGE Diagrammer, and MFSoft’s Equation Grapher. Facts were
checked against the Oxford English Dictionary and the Wikipedia at www.wikipedia.com
both of which are excellent sources of information.
Special appreciation goes out to the fine people at www.lugnet.com and
the tools their members have created, without which this book would look a
lot less interesting. MLCad by Michael Lachmann let me draw all of the
LEGO designs and LPub by Kevin Clague processed these models, using
geometry in Luts Uhlmann’s LGeo library, for rendering.
Electronic layout to POVRay model conversion was handled by Eagle3D,
which was written by Matthias Weisser. Eagle3D can be found on his
homepage at http://www.matwei.de/. All rendering was done by POVRay,
from www.povray.org.
LEGO is a trademark of the LEGO Group of companies, who reserve all
rights to their names and logos. This is not a LEGO book, a book about
LEGOs, nor is this work endorsed by LEGO. We do, however, use the
LEGO construction system to provide mechanical examples. These little
plastic blocks are available everywhere, and provide a familiar context for
our exploration. The LEGO Mindstorms system also provides motors and
computers that we use to learn about robotic systems.
All other product names are the trademark of their respective companies.
E. W.

Introduction
Robot
1.a. One of the mechanical men and women inCˇ apek’s play; hence, a machine
(sometimes resembling a human being in appearance) designed to function
in place of a living agent, esp. one which carries out a variety of
tasks automatically or with a minimum of external impulse.

b. A person whose work or activities are entirely mechanical; an automaton.
Oxford English Dictionary, Online Edition
KarelCˇ apek used the word Robot in his 1921 play Rossum’s Universal Robots,
derived from the Czech word robota, meaning ‘‘forced labor.’’ These Robots
were created to replace man and, in their simplified form, as cheap labor.
Robots had perfect memory but were incapable of thinking new thoughts.
They mirrored the Hebrew legends of the golem, a clay statue that has had
life breathed into to by mystical means. And, of course, this all sounds a lot
like Dr. Frankenstein’s monster, reanimated from the bits and pieces dug up
from the local graveyard.

One thing these stories have in common is that the creation is ultimately
the downfall of their creator—robots, golems, and reanimated flesh mean
trouble. They are an illustration of what happens when we reach too far and
are bitten by the unintended consequences.

We, however, are interested in the robot as an agent that carries out its
tasks automatically or with a minimum of external impulse rather than a
recreation of life itself. A smart machine.
In this chapter, we first look at some of the history behind the robot. From
there we explore the technologies that make up a robot, laying the groundwork
for later chapters on how these technologies work. Once we have a good
sense of what a robot is, we peek into the future to see what robots might
someday be like.

A Brief Tour of Robotics
AUTOMATA AND ANIMATRONICS
An automaton is a device that has the ability to move under its own power.
The mechanism of the motion is normally hidden, giving the illusion that the
device is self-motivated or alive. While this definition can apply to something
as mundane as a mechanical watch, automata are usually mechanisms that
try to mimic the look and behavior of living creatures.

We humans have long been fascinated by the workings of our own bodies
and the animals around us. With this fascination has come the urge to
recreate these things, to step into the role of divinity and try our hand at the game of life.

The ancient Greeks, at around 400 B.C. and continuing on into the common
era, are reputed to have used steam and water power to animate statues
or drive various mechanisms in their temples. Automatically opening doors,
statues that appear to drink offerings of wine, singing birds, self-lighting fires,
and other wonders are documented in the few remaining writings of that time.
There are hints of similar Egyptian and Chinese devices from that era as well.
Most of these technologies, the accumulated knowledge of ancient civilizations,
were lost until relatively recent times. During the Renaissance, Europe
started to drag itself out of the Dark Ages and began discovering (or, in
many cases, rediscovering) all manner of ideas, art, technologies, and sciences.
Among these, combining both art and technology, were the automata.
Some wild stories tell us about an iron fly and an artificial eagle made
of wood, constructed by Johannes Muller in the 1470s. In the fourteenth
and fifteenth centuries, automata were the playthings of royalty. Leonardo da
Vinci made an animated lion for King Louis XII, Gianello della Tour of
Cremona built a number of mechanical entertainers for Emperor Charles V,
and Christiaan Huygens created a robotic army sometime around 1680.
The first documented automaton in human form, or android, was made
by Hans Bullman in the early sixteenth century. Androids have been a
popular subject for automata builders ever since. Inventors built machines
to play musical instruments of all kinds, draw, write, and even play chess—
or at least, pretend to play chess.

The eighteenth century was the golden age of automata, with many intricate
machines. These were driven by clockwork gears and cylinders containing
hundreds, if not thousands, of complicated control tracks. These tracks
were composed of sequences of rods of different heights fixed to a cylinder, or
individual cams with complex shapes, that pushed on levers that moved rods
that adjusted the automaton creating a specific sequence of actions.
The Turk was a world-famous automaton from this time. Built in 1770 by
Wolfgang von Kepelen, and later purchased from Kepelen’s son by Johan
Nepomuk Maelzel in 1804, the Turk toured Europe and America amazing
audiences by playing chess!

By the time the Turk was on tour, audiences were familiar with the
workings of automata and had been exposed to many fine machines. But they
were also confident that these machines were just that, simple collections of
gears and levers whose rote actions were no challenge to the human intellect.
The automata may appear to be alive, but they are only vague shadows of
life. They couldn’t think.

The Turk challenged this view. It played, and often won, games of chess
against any number of famous figures of the time. Napolean, Charles
Babbage, and Edgar Allen Poe all took their turn against this mechanical
savant. Of course, it turned out that the machine could not play chess at all.
Instead, it provided cramped quarters for a human chess player who in turn
ran the machinery that made the Turk move.

One very complex automaton wasn’t an android, but a duck. Jacques
Vaucanson created this avian automaton in 1738 and then went on tour with
it. At the price of a week’s wages, audiences were invited to see this creation
move around, adjust its wings, preen, drink water, and even eat food, digest
it, and then defecate. All of this required thousands of moving parts within
both the duck and its large base. And yet, automata were just a hobby of
Vaucanson’s. He sold his collection in 1743 and went on to direct the stateowned
silk-mills in France. Among other innovations, he developed a way
to weave silk brocade using a machine guided by perforated cards. Owing to
hostility among the weavers of the time, his advances in factory automation
were ignored for decades.

In 1804, Joseph-Marie Jacquard improved and reintroduced the technique
and was later credited with its invention. While the automatic loom was still
despised by weavers, who went as far as burning down automated factories,
its improved efficiency led to its ultimate acceptance and led the way into the
industrial revolution.

In the nineteenth century improved manufacturing techniques brought
simple automata to the masses, typically in the form of toys, fancy clocks,
and other novelties. Clockwork mechanical toys were popular well into the
twentieth century. Today the springs, gears, and cams in toys have been
replaced by tiny motors and electronic controls.
The skills and techniques developed by the automata makers during the
Renaissance provided a foundation for the industrial revolution that
followed. Today, you can still find automata for sale. Automata are now in
the domain of the artist and pieces from modern craftsmen and artists can be
found for as little as a few dollars, up to hundreds or thousands of dollars.
Another use for these magical machines is entertainment. Walt Disney
introduced mechanical actors in the displays of his amusement park and
christened them Audio-Animatronics. This cumbersome name is normally
shortened to simply ‘‘animatronics.’’ Animatronics are machines driven by
motors and hydraulics and synchronized with an audio track to give the full illusion of life.

From the simplest Egyptian trick with water to the modern miracles of
Disney’s animatronics, these machine all share one characteristic. They can
only reproduce a preset sequence of motions.

FACTORY MACHINES
Ever since the advent of factories during the industrial revolution, specialized
machines have had an important role in creating the products of
civilization. The most common machine was the underpaid, overworked
citizen—men, women, and children. Early factory conditions were dangerous,
but the wages were good and nobody could argue with the efficiency
factories brought.

Water and steam power, and later gas and electric power, replaced and
enhanced human power, allowing us to make our products even faster
and cheaper. Complex machines were created to take over many aspects of
manufacture. The automatic loom is well known, but even today there are
specific machines for many tasks.

You don’t normally think about it, but there is a complex machine whose
only purpose is to bend wire into paperclips. There is another machine,
perhaps in the same factory, that makes nails. Other machines perform other
tasks. These machines, invaluable as they are for industry, are still forms of automata.

be programmed. But there is still a large gray area. Take that nail-making
machine and add a bunch of controls to it so it can make nails from different
sizes of wires, with different types of points, and different types of heads.
Is it an automaton or a robot? Does it make a difference if the controls are
mechanical levers and knobs or electronic circuits?
In the early factories, working alongside a machine made your job more
dangerous even if it made it less arduous. These early machines were large
assemblies of spinning, whirring, moving parts that continued to spin, whir,
and move even if a finger, foot, or other body part intruded into it. Even
today, people working with machines in factories and food-processing plants
face special risks. Machines are designed to be as safe as possible, but there
are limits to what can be done to a metal sheer or punch press, for example,
and have it remain useful.

As machines improved into robots, they made some aspects of factory
work safer. A robotic painter, spot welder, or assembly machine can operate
in an empty space without any help at all. A supervisor stands safely outside
its range of motion while the robot does the dirty and dangerous work
(Fig. 1-1).

The most visible type of factory robot is the robot arm (Fig. 1-2). These
can be given any type of specialized ‘‘hand’’ needed for their job (Fig. 1-3)
and programmed to perform complex activities. One arm, with a set of
different hands, can be programmed to perform any number of tasks. These
are the robots that we recognize as ‘‘smart’’ machines, beginning to realize
the dream promised to us by Kepelen’s Turk.


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 2005 by The McGraw-Hill Companies, Inc


Contents
Preface xv
Acknowledgments xvi
CHAPTER 1 Introduction 1
A Brief Tour of Robotics 2
Automata and Animatronics 2
Factory Machines 4
Fictional Robots 7
Future Dreams 8
Inside Robots 9
Tools and Supplies 10
Parting Words of Wisdom 11
CHAPTER 2 Mechanical Forces 13
Introduction 13
Energy 15
Units of Measurement 16
Position 16
Time: t 17
Length: l 17
Mass: m 18
Velocity: v 19
Acceleration: a 23
Force: F 24
Momentum: p 26
Energy: E 26
Storing Energy 27
Losing Energy 29
Summary 30
Quiz 30
CHAPTER 3 Simple Machines 32
Introduction 32
Structural Strength 33
Triangles and Squares 33
Hidden Triangles 35
Inclined Plane 36
Wedge 40
Screw 41
Levers 42
Lever Machine 42
Pulleys 44
Pulley Machine 45
Wheels and Torque 49
Gears and Sprockets 51
Summary 53
Quiz 53
CHAPTER 4 Electricity 54
Introduction 54
Pieces of Matter 55
Electrons in Metal 56
Electromagnetic Field 57
Units 59
Unit Prefixes 59
Electrical Charge 60
Current: I 61
Charge Difference 62
Electrical Energy 63
Power: P 63
Batteries and Generators 63
Speed of Electricity 64
Summary 65
Quiz 65
CHAPTER 5 Starting with Electronics 66
Introduction 66
Electronic Circuits 67
Schematic 67
Printed Circuit Board 68
Circuit Assembly 70
Prototyping Boards 70
Dead Bug and Wire Wrapping 71
Soldering 72
Suppliers 79
Resistors 80
Resistor 80
Ohm’s Law 81
Resistor Networks 83
Resistive Sensor 87
Light Bulb 94
Summary 94
Quiz 95
CHAPTER 6 Control 96
Introduction 96
Passive Control 97
Balancing Machine 98
Open-Loop Control 98
Feedback Control 99
CONTENTS vii
Centrifugal Feedback 100
Hysteresis 102
Mechanical Switch 104
Summary 105
Quiz 106
CHAPTER 7 Sequencing and Programs 107
Introduction 107
Switches and Cycles 108
Cam Control 111
Cardboard Cam 113
Card Control 113
Mechanical Card Reader 115
Programming Concepts 115
Computer Numbers 117
Computer Instructions 121
Summary 122
Quiz 123
CHAPTER 8 Joints 124
Introduction 124
Rotation and Bending 125
Rotation 125
Bearings and Bushings 126
Bending 127
Sliding 128
Complex Motion 128
Ball and Socket 128
Universal Joint 130
Robot Wrist 131
Others 134
Summary 134
Quiz 135
CHAPTER 9 Power Transmission 136
Introduction 136
Chains, Belts, and Cables 137
Gears 141
Gear Trains 142
More Gears 145
Couplers 149
Directional Transmission 150
Differential Transmission 150
Summary 154
Quiz 155
CHAPTER 10 Beyond Resistance: Capacitance 156
Introduction 156
AC/DC 157
Oscilloscope 160
Diodes 161
Signal Diode 161
Rectifier 162
Light-Emitting Diode 163
Zener Diode 163
Capacitors 165
Capacitor 165
Capacitors and Audio 168
Capacitor Networks 170
RC Circuits 171
RC Filters 172
Diode-Capacitor Circuits 176
Summary 178
Quiz 178
CHAPTER 11 Inductance and Magnetism 179
Introduction 179
CONTENTS ix
Electromagnets 180
Nail Electromagnet 181
Relay 182
Motors 182
Generators 184
Servos and Steppers 184
Inductors 185
Behavior 186
Component 186
Filters 187
Phase 187
Transformer 188
Summary 189
Quiz 189
CHAPTER 12 Semiconductors 190
Introduction 190
Conductor Physics 191
Semiconductor Physics 192
Doped Silicon 193
Diode Physics 195
Forward Bias 197
Reverse Bias 198
Electronic Switches 198
Analog Versus Digital 198
Transistor 200
FET 202
Integrated Circuits 204
Summary 205
Quiz 205
CHAPTER 13 Programming 207
Introduction 207
Programming Basics 208
RCX Programming 211
Programs 213
Simple Timed Sequence 213
Obstacle Avoidance 213
Line Following 218
Self-Calibration 221
Summary 221
Quiz 223
CHAPTER 14 Shaping Motion 224
Introduction 224
Looking Back 225
Single-Link Mechanisms 225
Two Links 228
More Links 229
Parallel Motion 229
Four-Bar Linkage 232
Complex Motions 234
Other Mechanisms 236
Cardan Gear 236
Quick-Return 237
Geneva Stop 237
Ratchet 237
Summary 238
Quiz 240
CHAPTER 15 Communication 241
Introduction 241
Telerobotics 241
Tethered Robots 242
Remote Control 243
Semi-Autonomous 243
Communication Technologies 245
Parallel 245
Serial 246
Wireless 249
Other Interfaces 250
Summary 251
Quiz 251
CHAPTER 16 Languages 252
Introduction 252
Programming Concepts 253
Turing Machine 255
Choosing a Language 258
Manufacturing Languages 260
Custom Languages 260
Human Language 261
Human Intelligence 261
Summary 262
Quiz 262
CHAPTER 17 Intelligent Behavior 263
Introduction 263
Reflexive Control 264
Thermostat 265
PID Motor Control 266
Serial Behaviors 269
Layered Behaviors 270
Logical Behavior 272
Scripting 272
Formal Logic 272
Natural Computation 273
Pattern Recognition 275
Statistics 275
Fuzzy Logic 276
Neural Networks 278
Summary 280
Quiz 281
CHAPTER 18 Advanced Control 282
Introduction 282
Decisions 283
Mapping 285
Odometry 287
Odometry Errors 289
Supervised Learning 289
Supervised Robotic Learning 292
Unsupervised Learning 293
Swarm Robots 294
Agents 294
Summary 295
Quiz 295
Answers 296
Index 309

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