From: J. R. Molloy (jr@shasta.com)
Date: Tue Jun 26 2001 - 10:34:33 MDT
"Mobile Robotics: A Practical Introduction" is an excellent introduction
to the foundations and methods used for designing completely autonomous
mobile robots.
A fascinating, cutting-edge research topic, autonomous mobile robotics is
now taught in more and more universities. In this book you are introduced
to the fundamental concepts of this complex field via twelve detailed case
studies which show how to build and program real working robots.
Topics covered include machine learning, autonomous navigation in
unmodified, noisy and unpredictable environments, and high fidelity mobile
robot simulation.
This book provides a very practical introduction to mobile robotics for a
general scientific audience, and is essential reading for final year
undergraduate students and postgraduate students studying Robotics,
Artificial Intelligence, Cognitive Science and Robot Engineering. Its
update and overview of core concepts in mobile robotics will assist and
encourage practitioners of the field, and set challenges to explore new
avenues of research.
Chapters Include:
Introduction, Foundations, Robot Hardware, Robot Learning: Making Sense of
Raw Sensor Data, Navigation, Simulation: Modeling Robot-Environment
Interaction, Analysis of Robot Behavior, Outlook, Answers to Exercises,
References, Index.
This is the first chapter in the book Mobile Robotics: A Practical
Introduction. This chapter sets the scene. It presents an introduction to the
scientific issues in mobile robotics, gives an overview of the contents of
each chapter, and encourages you to build your own robot to put this book into
action.
Autonomous mobile robotics is a fascinating research topic, for many reasons.
First, to change a mobile robot from a computer on wheels that is merely able
to sense some physical properties of the environment through its sensors into
an intelligent agent, able to identify features, to detect patterns and
regularities, to learn from experience, to localize, build maps and to
navigate requires the simultaneous application of many research disciplines.
In this sense, mobile robotics reverses the trend in science towards more and
more specialization, and demands lateral thinking and the combination of many
disciplines.
Engineering and computer science are core elements of mobile robotics,
obviously, but when questions of intelligent behavior arise, artificial
intelligence, cognitive science, psychology and foolosophy offer hypotheses
and answers. Analysis of system components, for example through error
calculations, statistical evaluations etc. are the domain of mathematics, and
regarding the analysis of whole systems physics proposes explanations, for
example through chaos theory.
Second, autonomous mobile robots are the closest approximation yet of
intelligent agents, the age-old dream. For centuries people have been
interested in building machines that mimic living beings. From mechanical
animals, using clockwork, to the software and physical agents of artificial
life - the question of "what is life?" and can we understand it has always
motivated research.
Perception and action are tightly coupled in living beings. To see, animals
perform specific head and eye movements. To interact with the environment,
they anticipate the result of their actions and predict the behavior of other
objects. They alter the environment in order to communicate (so-called
stigmergy) nest building in ants is an example of this.
Because of this tight coupling between perception and action there is a strong
argument for investigating intelligent behavior by means of situated agents,
i.e. mobile robots. In order to investigate simulations of life and lifelike
agents that interact intelligently with their environment, we need to close
the loop between perception and action, allowing the agent to determine what
it sees. Whether we will have autonomous robots that match human intelligence
within 50 years, or whether humans will even be obsolete by then (very fuzzy
statements, because the definitions of "intelligent" and "obsolete" are not at
all clear), as some writers predict, or whether we will have to wait another
100 years for truly intelligent household robots, as others reply, autonomous
mobile robots offer a uniquely suited research platform for investigating
intelligent behavior.
Third, there are commercial applications of mobile robots. Transportation,
surveillance, inspection, cleaning or household robots are just some examples.
However, autonomous mobile robots have not yet made much impact upon
industrial and domestic applications, mainly due to the lack of robust,
reliable and flexible navigation and behavior mechanisms for autonomous mobile
robots operating in unmodified, semi-structured environments. Installing
markers such as beacons, visual patterns or induction loops (guiding wires
buried in the ground) is one way round this problem, but it is expensive,
inflexible and sometimes outright impossible. The alternative navigation in
unmodified environments - requires sophisticated sensor signal processing
techniques which are still in their experimental evaluation phases. Case
studies in this book present some of these techniques. So, to let mobile
robots work in areas which are inaccessible to humans, or to perform
repetitive, difficult or dangerous tasks, is yet another strong motivation for
developing intelligent, autonomous robots.
And finally, there is also an aesthetic and artistic element to mobile
robotics. Swarms of robots collaborating to achieve a particular task, or
moving about avoiding collisions with one another and objects in their
environment, beautifully designed mobile robots, like for instance
micro-robots, or miniature legged robots, appeal to our sense of aesthetics.
It is not surprising that mobile robots and robot arms have been used for
artistic performances.
Construct Your Own Working Robot
Mobile robotics, by nature, has to be practiced. There are a range of
relatively cheap mobile robots available now, which can be used for student
practicals, student projects, or robotics projects at home (robotics as a
hobby is rapidly gaining ground). GRASMOOR, built at the University of
Manchester, is one example - it has its own on- board controller, infrared
sensors, light sensors, tactile sensors, and a differential drive system'.
GRASMOOR is controlled by a variant of the MIT 6270 controller, a controller
with analogue and digital inputs for sensors, and pulse- width-modulated
output to drive motors (the different types of sensors that can be used on
robots are discussed in chapter 3, and pulse width modulation generates
electric pulses of variable length to drive motors at variable speed). Like
many robot micro-controllers, the 6.270 controller is based on the Motorola
6811 microprocessor.
It is not difficult to get going for a few hundred dollars, using robot kits
or technical construction kits based on children's toys, some of which have
micro-controllers and the necessary software environment to program the
robots. A good introduction to building your own robot is Mobile Robots :
Inspiration to Implementation.
If you are competent at building electronic circuits - and they needn't be
very complicated - you can also use commercially available micro-controllers,
and interface sensors and motors to them to build your robot. The basic
message is: you don't have to invest large sums to build a mobile robot.
Experiments with Mobile Robots
This book contains 12 detailed case studies that cover the areas of robot
learning, navigation and simulation. Furthermore, there are examples,
exercises and pointers to open questions. One of their purposes is to indicate
interesting areas of robotics research, identifying open questions and
relevant problems.
A fascinating introduction to thought experiments with robots is Valentino
Braitenberg's book on "synthetic psychology" (Vehicles), which contains many
experiments that can be implemented and carried out on real robots.
Organization of the Book
Scientific progress rests on the successes and failures of the past, and is
only achieved if the history of a scientific area is understood. This book
therefore begins by looking at the history of autonomous mobile robotics
research, discussing early examples and their contributions towards our
understanding of the complex interaction between robots, the world they
operate in, and the tasks they are trying to achieve.
A robot, obviously, is made from hardware, and the functionality of a robot's
sensors and actuators influences its behavior greatly. The second chapter of
the book, therefore, looks at hardware issues specifically and discusses the
most common robot sensors and actuators.
A truly intelligent robot needs to be able to deal with uncertain, ambiguous,
contradictory and noisy data. It needs to learn through its own interaction
with the world, being able to assess events with respect to the goal it is
trying to achieve, and to alter its behavior if necessary. Chapter 4 presents
mechanisms that can support these fundamental learning competencies.
Mobility is (almost) pointless without the ability of goal-directed motion,
i.e. navigation. This book will therefore cover the area of mobile robot
navigation, taking some inspiration from the most successful navigators on
earth: living beings (chapter 5). Five case studies highlight the mechanisms
used in successful robot navigation systems: self-organization, emergent
functionality and autonomous mapping of the environment "as the robot
perceives it".
Scientific research is not only about matter, it is about method as well.
Given the complexity of robot-environment interaction, given the sensitivity
of a robot's sensors to slight changes in the environment, to color and
surface structure of objects, etc., to date the proof of a robot control
program is still in physical experiments. To know what robot behavior will
result from a specific robot control program, one actually has to run the
program on a real robot. Numerical models of the complex interaction between
robot and environment interaction are still imprecise approximations, due to
the sensitivity of robot sensors to variations in environmental conditions.
However, chapter 6 looks at one approach to construct a more faithful model of
robot-environment interaction, and at the conditions under which such modeling
is achievable.
The purpose of this book is not only to give an introduction to the
construction of mobile robots and the design of intelligent controllers, but
also to demonstrate methods of evaluation of autonomous mobile robots - the
science of mobile robotics. Scientific method involves the analysis of
existing knowledge, identification of open questions, the design of an
appropriate experimental procedure to investigate the question, and the
analysis of the results.
In established natural sciences this procedure has been refined over decades
and is now well understood, but in the relatively young science of robotics
this is not the case. There are no universally agreed procedures yet, neither
for conducting experiments, nor for the interpretation of results.
Environments, robots and their tasks cannot yet be described in unambiguous
ways that allow independent replication of experiments and independent
verification of results. Instead, qualitative descriptions of experiments and
results have to be used. Widely accepted standard benchmark tests in the area
of mobile robotics do not exist, and existence proofs, i.e. the implementation
of one particular algorithm on one particular robot, operating in one
particular environment, are the norm.
To develop a science of autonomous mobile robotics, quantitative descriptions
of robots, tasks and environments are needed, and independent replication and
verification of experiments has to become the standard procedure within the
scientific community. Existence proofs alone will not suffice to investigate
mobile robots systematically. They serve a purpose in the early stages of the
emergence of a scientific field, but have to be supplemented later by rigorous
and quantitatively defined experimentation. Chapter 7 therefore discusses
mathematical tools that allow such quantitative assessment of robot
performance, and gives three case studies of quantitative analysis of mobile
robot behavior.
The book concludes with an analysis of the reasons for successes in mobile
robotics research, and identifies technological, control and methodological
challenges that lie ahead.
Mobile robotics is a vast research area, with many more facets than this
introductory textbook can cover. The purpose of this book is to whet your
appetite for mobile robotics research. Each chapter of this book includes
pointers to further reading, and world-wide web links, in addition to the
references given in the text. Using these, you will hopefully agree that
mobile robotics is indeed a fascinating research topic that throws some light
on the age-old question:
"What are the fundamental building blocks of intelligent behavior?"
================================
τΏτ
Stay hungry,
--J. R.
Useless hypotheses:
consciousness, phlogiston, philosophy, vitalism, mind, free will, qualia,
analog computing, cultural relativism
Everything that can happen has already happened, not just once,
but an infinite number of times, and will continue to do so forever.
(Everything that can happen = more than anyone can imagine.)
http://www.kartoo.com/cgi-bin/k.cgi?q=virtropy&l=0&m=1
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