Embedded Robotics - robots robotics

454 Pages·2006·5.52 MB·English

Embedded Robotics
Thomas Bräunl
E R
MBEDDED OBOTICS
Mobile Robot Design
and Applications
with Embedded Systems
Second Edition
With 233 Figures and 24 Tables
123
Thomas Bräunl
School of Electrical, Electronic
and Computer Engineering
The University of Western Australia
35 Stirling Highway
Crawley, Perth, WA 6009
Australia
Library of Congress Control Number: 2006925479
ACM Computing Classification (1998): I.2.9, C.3
ISBN-10 3-540-34318-0 Springer Berlin Heidelberg New York
ISBN-13 978-3-540-34318-9 Springer Berlin Heidelberg New York
ISBN-10 3-540-03436-6 1. Edition Springer Berlin Heidelberg New York
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P
REFACE
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I
t all started with a new robot lab course I had developed to accompany my
robotics lectures. We already had three large, heavy, and expensive
mobile robots for research projects, but nothing simple and safe, which we
could give to students to practice on for an introductory course.
We selected a mobile robot kit based on an 8-bit controller, and used it for
the first couple of years of this course. This gave students not only the enjoy-
ment of working with real robots but, more importantly, hands-on experience
with control systems, real-time systems, concurrency, fault tolerance, sensor
and motor technology, etc. It was a very successful lab and was greatly
enjoyed by the students. Typical tasks were, for example, driving straight,
finding a light source, or following a leading vehicle. Since the robots were
rather inexpensive, it was possible to furnish a whole lab with them and to con-
duct multi-robot experiments as well.
Simplicity, however, had its drawbacks. The robot mechanics were unreli-
able, the sensors were quite poor, and extendability and processing power were
very limited. What we wanted to use was a similar robot at an advanced level.
The processing power had to be reasonably fast, it should use precision motors
and sensors, and – most challenging – the robot had to be able to do on-board
image processing. This had never been accomplished before on a robot of such
a small size (about 12cm (cid:117)(cid:3)9cm(cid:117)(cid:3)14cm). Appropriately, the robot project was
called “EyeBot”. It consisted of a full 32-bit controller (“EyeCon”), interfacing
directly to a digital camera (“EyeCam”) and a large graphics display for visual
feedback. A row of user buttons below the LCD was included as “soft keys” to
allow a simple user interface, which most other mobile robots lack. The
processing power of the controller is about 1,000 times faster than for robots
based on most 8-bit controllers (25MHz processor speed versus 1MHz, 32-bit
data width versus 8-bit, compiled C code versus interpretation) and this does
not even take into account special CPU features like the “time processor unit”
(TPU).
The EyeBot family includes several driving robots with differential steer-
ing, tracked vehicles, omni-directional vehicles, balancing robots, six-legged
walkers, biped android walkers, autonomous flying and underwater robots, as
VV
Preface
well as simulation systems for driving robots (“EyeSim”) and underwater
robots (“SubSim”). EyeCon controllers are used in several other projects, with
and without mobile robots. Numerous universities use EyeCons to drive their
own mobile robot creations. We use boxed EyeCons for experiments in a sec-
ond-year course in Embedded Systems as part of the Electrical Engineering,
Information Technology, and Mechatronics curriculums. And one lonely Eye-
Con controller sits on a pole on Rottnest Island off the coast of Western Aus-
tralia, taking care of a local weather station.
Acknowledgements
While the controller hardware and robot mechanics were developed commer-
cially, several universities and numerous students contributed to the EyeBot
software collection. The universities involved in the EyeBot project are:
• University of Stuttgart, Germany
• University of Kaiserslautern, Germany
• Rochester Institute of Technology, USA
• The University of Auckland, New Zealand
• The University of Manitoba, Winnipeg, Canada
• The University of Western Australia (UWA), Perth, Australia
The author would like to thank the following students, technicians, and
colleagues: Gerrit Heitsch, Thomas Lampart, Jörg Henne, Frank Sautter, Elliot
Nicholls, Joon Ng, Jesse Pepper, Richard Meager, Gordon Menck, Andrew
McCandless, Nathan Scott, Ivan Neubronner, Waldemar Spädt, Petter
Reinholdtsen, Birgit Graf, Michael Kasper, Jacky Baltes, Peter Lawrence, Nan
Schaller, Walter Bankes, Barb Linn, Jason Foo, Alistair Sutherland, Joshua
Petitt, Axel Waggershauser, Alexandra Unkelbach, Martin Wicke, Tee Yee
Ng, Tong An, Adrian Boeing, Courtney Smith, Nicholas Stamatiou, Jonathan
Purdie, Jippy Jungpakdee, Daniel Venkitachalam, Tommy Cristobal, Sean
Ong, and Klaus Schmitt.
Thanks for proofreading the manuscript and numerous suggestions go to
Marion Baer, Linda Barbour, Adrian Boeing, Michael Kasper, Joshua Petitt,
Klaus Schmitt, Sandra Snook, Anthony Zaknich, and everyone at Springer-
Verlag.
Contributions
A number of colleagues and former students contributed to this book. The
author would like to thank everyone for their effort in putting the material
together.
JACKY BALTES The University of Manitoba, Winnipeg, contributed to the
section on PID control,
VI
Preface
ADRIAN BOEING UWA, coauthored the chapters on the evolution of walk-
ing gaits and genetic algorithms, and contributed to the
section on SubSim,
CHRISTOPH BRAUNSCHÄDEL FH Koblenz, contributed data plots to the sec-
tions on PID control and on/off control,
MICHAEL DRTIL FH Koblenz, contributed to the chapter on AUVs,
LOUIS GONZALEZ UWA, contributed to the chapter on AUVs,
BIRGIT GRAF Fraunhofer IPA, Stuttgart, coauthored the chapter on robot
soccer,
HIROYUKI HARADA Hokkaido University, Sapporo, contributed the visualiza-
tion diagrams to the section on biped robot design,
YVES HWANG UWA, coauthored the chapter on genetic programming,
PHILIPPE LECLERCQUWA, contributed to the section on color segmentation,
JAMES NG UWA, coauthored the sections on probabilistic localiza-
tion and the DistBug navigation algorithm.
JOSHUA PETITT UWA, contributed to the section on DC motors,
KLAUS SCHMITT Univ. Kaiserslautern, coauthored the section on the RoBI-
OS operating system,
ALISTAIR SUTHERLAND UWA, coauthored the chapter on balancing robots,
NICHOLAS TAY DSTO, Canberra, coauthored the chapter on map genera-
tion,
DANIEL VENKITACHALAM UWA, coauthored the chapters on genetic algo-
rithms and behavior-based systems and contributed to the
chapter on neural networks,
EYESIM was implemented by Axel Waggershauser (V5) and Andreas Koestler
(V6), UWA, Univ. Kaiserslautern, and FH Giessen.
SUBSIM was implemented by Adrian Boeing, Andreas Koestler, and Joshua
Petitt (V1), and Thorsten Rühl and Tobias Bielohlawek
(V2), UWA, FH Giessen, and Univ. Kaiserslautern.
Additional Material
Hardware and mechanics of the “EyeCon” controller and various robots of the
EyeBot family are available from INROSOFT and various distributors:
http://inrosoft.com
All system software discussed in this book, the RoBIOS operating system,
C/C++ compilers for Linux and Windows, system tools, image processing
tools, simulation system, and a large collection of example programs are avail-
able free from:
http://robotics.ee.uwa.edu.au/eyebot/
VII
Preface
Lecturers who adopt this book for a course can receive a full set of the
author’s course notes (PowerPoint slides), tutorials, and labs from this website.
And finally, if you have developed some robot application programs you
would like to share, please feel free to submit them to our website.
Second Edition
Less than three years have passed since this book was first published and I
have since used this book successfully in courses on Embedded Systems and
on Mobile Robots / Intelligent Systems. Both courses are accompanied by
hands-on lab sessions using the EyeBot controllers and robot systems, which
the students found most interesting and which I believe contribute significantly
to the learning process.
What started as a few minor changes and corrections to the text, turned into
a major rework and additional material has been added in several areas. A new
chapter on autonomous vessels and underwater vehicles and a new section on
AUV simulation have been added, the material on localization and navigation
has been extended and moved to a separate chapter, and the kinematics sec-
tions for driving and omni-directional robots have been updated, while a cou-
ple of chapters have been shifted to the Appendix.
Again, I would like to thank all students and visitors who conducted
research and development work in my lab and contributed to this book in one
form or another.
All software presented in this book, especially the EyeSim and SubSim
simulation systems can be freely downloaded from:
http://robotics.ee.uwa.edu.au
Perth, Australia, June 2006 Thomas Bräunl
VIII
C
ONTENTS
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PART I: EMBEDDED SYSTEMS
1 Robots and Controllers 3
1.1 Mobile Robots. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Embedded Controllers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.4 Operating System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2 Sensors 17
2.1 Sensor Categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.2 Binary Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.3 Analog versus Digital Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4 Shaft Encoder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.5 A/D Converter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.6 Position Sensitive Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.7 Compass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.8 Gyroscope, Accelerometer, Inclinometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.9 Digital Camera. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3 Actuators 41
3.1 DC Motors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.2 H-Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.3 Pulse Width Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.4 Stepper Motors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.5 Servos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4 Control 51
4.1 On-Off Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.2 PID Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.3 Velocity Control and Position Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.4 Multiple Motors – Driving Straight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.5 V-Omega Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
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Contents
5 Multitasking 69
5.1 Cooperative Multitasking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
5.2 Preemptive Multitasking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.3 Synchronization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.4 Scheduling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.5 Interrupts and Timer-Activated Tasks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6 Wireless Communication 83
6.1 Communication Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6.2 Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.3 Fault-Tolerant Self-Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6.4 User Interface and Remote Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
6.5 Sample Application Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
PART II: MOBILE ROBOT DESIGN
7 Driving Robots 97
7.1 Single Wheel Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
7.2 Differential Drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.3 Tracked Robots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
7.4 Synchro-Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
7.5 Ackermann Steering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7.6 Drive Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
7.7 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
8 Omni-Directional Robots 113
8.1 Mecanum Wheels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
8.2 Omni-Directional Drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
8.3 Kinematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
8.4 Omni-Directional Robot Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
8.5 Driving Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
8.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
9 Balancing Robots 123
9.1 Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
9.2 Inverted Pendulum Robot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
9.3 Double Inverted Pendulum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
9.4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
10 Walking Robots 131
10.1 Six-Legged Robot Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
10.2 Biped Robot Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
10.3 Sensors for Walking Robots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
10.4 Static Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
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10.5 Dynamic Balance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
10.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
11 Autonomous Planes 151
11.1 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
11.2 Control System and Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
11.3 Flight Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
11.4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
12 Autonomous Vessels and UnderwaterVehicles 161
12.1 Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
12.2 Dynamic Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
12.3 AUV Design Mako . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
12.4 AUV Design USAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
12.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
13 Simulation Systems 171
13.1 Mobile Robot Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
13.2 EyeSim Simulation System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
13.3 Multiple Robot Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
13.4 EyeSim Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
13.5 EyeSim Environment and Parameter Files . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
13.6 SubSim Simulation System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
13.7 Actuator and Sensor Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
13.8 SubSim Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
13.9 SubSim Environment and Parameter Files . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
13.10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
PART III: MOBILE ROBOT APPLICATIONS
14 Localization and Navigation 197
14.1 Localization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
14.2 Probabilistic Localization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
14.3 Coordinate Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
14.4 Dijkstra’s Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
14.5 A* Algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
14.6 Potential Field Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
14.7 Wandering Standpoint Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
14.8 DistBug Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
14.9 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
15 Maze Exploration 217
15.1 Micro Mouse Contest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
15.2 Maze Exploration Algorithms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
15.3 Simulated versus Real Maze Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
15.4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
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