Parallax Boe-Bot, QuadCrawler, Toddler, SumoBot, HexCrawler Assembly Manual
SumoBot® – Mini-Sumo Robotics
Assembly Documentation and Programming
VERSION 2.1
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This documentation is copyright 2002- 2005 by Parallax Inc. By downloading or obtaining a printed copy of this
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BASIC Stamp, Stamps in Class, Boe-Bot, SumoBot, SX-Key and Toddler are registered trademarks of Parallax, Inc.
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ISBN 1-928982-26-3
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Preface · Page iii
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We maintain active web-based discussion forums for people interested in Parallax products. These lists are accessible
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• SX Microcontrollers and SX-Key
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Javelin Stamp
that is programmed using a subset of Sun Microsystems’ Java
– This list is widely utilized by engineers, hobbyists and students who share their
®
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–Exclusively for educators and those who contribute to the development of
– The purpose of this list is to provide a conduit between Parallax and those who
®
, Toddler®, SumoBot®, HexCrawler and QuadCrawler robots are discussed here.
– Discussion of application and design using the Javelin Stamp, a Parallax module
– Discussion of programming the SX microcontroller with
®
tools and 3rd party BASIC and C compilers.
®
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ERRATA
While great effort is made to assure the accuracy of our texts, errors may still exist. If you find an error, please let us
know by sending an email to editor@parallax.com. We continually strive to improve all of our educational materials
and documentation, and frequently revise our texts. Occasionally, an errata sheet with a list of known errors and
corrections for a given text will be posted to our web site, www.parallax.com. Please check the individual product
page’s free downloads for an errata file.
Table of Contents · Page v
Table of Contents
Preface.........................................................................................................vii
Recognitions..............................................................................................vii
Audience...................................................................................................viii
Educational Concepts from the SumoBot.................................................viii
Copyright and Reproduction.......................................................................ix
Chapter 1: Assemble the SumoBot............................................................. 1
Let’s Build the SumoBot ..............................................................................2
Tools Required ............................................................................................2
About the Parts in the SumoBot Kit............................................................. 2
Chapter 2: SumoBot Locomotion.............................................................. 11
How a Servo Works...................................................................................11
Time Measurement and Voltage Levels .................................................... 11
SumoBot Motion Test................................................................................ 16
Challenge Yourself ....................................................................................21
Chapter 3: SumoBot Sensors and Border Detection............................... 23
Line Sensor Theory ...................................................................................23
Our First Operational Sumo Program........................................................29
Challenge Yourself ....................................................................................34
Chapter 4: Infrared Object Detection ........................................................35
Infrared Headlights ....................................................................................35
The FREQOUT Trick................................................................................. 36
Installing and Testing the IR Emitters/Detectors........................................ 37
Testing the IR Pairs................................................................................... 39
SumoBot Motion Control............................................................................ 41
Chapter 5: Basic Competition Code.......................................................... 45
Final Competition Notes ............................................................................52
Appendix A: SumoBot Parts List............................................................... 53
Page vi · SumoBot – Mini Sumo Robotics
Appendix B: Standard Mini-Sumo Competition Rules............................ 55
Appendix C: Mini-Sumo Ring .................................................................... 65
Appendix D: SumoBot PCB Schematic .................................................... 67
Preface · Page vii
PREFACE
Like its human counterpart, robot Sumo was born and thrives in Japan. It was
introduced to the United States in the early 1990's by Dr. Mato Hattori. One of the early
American adopters of robot Sumo was noted Seattle Robotics Society member, Bill
Harrison, who organized some of the first U.S. robot Sumo tournaments.
While things started out very slowly, robot Sumo eventually caught on. Bill created a
"lightweight" class that matched the Japanese physical dimensions of 20 cm by 20 cm,
but reduced the mass from three kilograms (6.6 pounds) to one kilogram (2.2 pounds).
The intention was to reduce the sophistication of the components required to construct a
working Sumo robot. Those early contests didn't have much in the way of corporate
support with prizes, so Bill resorted to offering 30 hours of his own machine-shop
services to the winner.
As luck would have it, Bill's friend Robert Jorgensen won that first contest prize. Since
Robert already had a winning Sumo robot, he suggested that they build a smaller version,
about half the size and weight of the lightweight class to be used as a robot Sumo
demonstrator. The result of their work was a very small Sumo robot that measured just 8
cm by 8 cm and mass about 240 grams. Bill took that first small Sumo to a contest in
San Francisco and actually won the lightweight competition – against bigger and heavier
robots. The Mini-Sumo robot class was born.
The Mini-Sumo dimensions (10 cm x 10 cm) and mass (500 grams) were formalized and
Bill published adapted Japanese robot Sumo rules on his Sine Robotics web site
(mirrored on many other sites, and reprinted with permission in this document). Through
Bill's tireless efforts and nearly ten years of travel – often toting more than 20 robots in
his bags – Mini-Sumo robotics has grown to a favorite activity among robot clubs all
across the United States.
RECOGNITIONS
Many Mini-Sumo designs – especially the dual-wheel-and-scoop concept – can be traced
back to Bill Harrison's early efforts to promote Mini-Sumo robotics competition.
Parallax also recognizes Bill Boyer of the Dallas Personal Robotics Group for his version
of the dual-wheel-and-scoop design that was refined and developed into the Parallax
SumoBot robot described in this text.
Page viii · SumoBot – Mini Sumo Robotics
This text was authored by Jon Williams of Parallax, and contains additional material by
several contributors, including Andy Lindsay and Ken Gracey of Parallax, as well as Bill
Wong of Pennsylvania. Bill is an editor with Electronic Design magazine and a serious
BASIC Stamp
® robotics enthusiast. Bill enjoys creating BASIC Stamp powered robots
with his daughter, who has gone on to win several county and state awards with her maze
solving robotics projects.
AUDIENCE
SumoBot was written for ages 12+ as a complimentary text to Parallax’s Robotics with
the Boe-Bot and Advanced Robotics with the Toddler student guides. Like all Parallax
texts, this series of experiments teaches new techniques and circuits with minimal overlap
between the other publications. The general topics introduced in this series are: basic
SumoBot locomotion under program control, edge avoidance, and opponent detection
based on a variety of sensor inputs, as well as navigation opponent hunting using
programmed artificial intelligence. Each topic is addressed in an introductory format
designed to impart a conceptual understanding along with some hands-on experience.
Those who intend to delve further into industrial technology, electronics or robotics are
likely to benefit significantly from initial experiences with these topics.
If your experience with the SumoBot
® robot differs from our expectations, please let us
know at support@parallax.com.
EDUCATIONAL CONCEPTS FROM THE SUMOBOT
Educators frequently ask us at Parallax what can be learned from our different texts and
application notes. The SumoBot is considered an intermediate robotic project and
generally will instruct the following concepts:
• Interaction between mechanical and electrical systems, and the ability to tune
hardware or adjust software to obtain desired results.
• Intermediate programming skills with the BASIC Stamp 2 microcontroller. An
efficient SumoBot program makes use of efficient BASIC Stamp programming
techniques with BRANCH and LOOKDOWN, variable aliasing, general sound
programming practices (constant/variable definitions that allow for program
customization in just a few places rather than throughout an entire program).
• A step-wise process which starts with the basics and builds to something more
complex and ultimately more useful.
Preface · Page ix
Chapter 1: Assemble the SumoBot · Page 1
Chapter 1: Assemble the SumoBot
There's an old axiom among robot enthusiasts that states, "It's harder than it looks...."
Speaking from experience, we know this to be true. That said, the purpose of this
statement is not to alarm or dissuade the new robot builder, but simply to remind him or
her that robotics – even on a small scale – is a serious endeavor and shouldn't be taken
lightly. Patience is indeed a virtue. Follow the construction steps carefully and you'll
have your SumoBot running and ready to compete in about an hour or so.
The SumoBot is capable of doing any of the things other rolling robots can do. As you
learn to program the SumoBot for competition, you’ll become a more proficient – and
efficient – programmer and will learn to exploit the BASIC Stamp microcontroller’s
capabilities. The SumoBot demonstrates the importance of a PBASIC program that uses
constants and variables, as well state-oriented design. A well-designed program means
you can easily tune the software for the right mechanical control in just a few places
rather than rewriting your entire program.
A surface-mounted BASIC Stamp 2 microcontroller provides the intelligence for the
SumoBot. The BASIC Stamp is used throughout the Stamps in Class educational series,
and provides plenty of program space, speed and memory for use with a SumoBot.
The SumoBot is a purpose-built rolling robot, much like its general-purpose cousin the
Parallax Boe-Bot. While they share the same differential drive mechanism and the use of
sensors, the SumoBot design meets the specific criteria defined by Mini-Sumo
competition rules:
• Maximum [width and depth] dimensions of 10 cm by 10 cm
• Maximum mass of 500 grams
The standard SumoBot comes with two sets of sensors: two QTI line sensors to keep the
SumoBot on the playing surface and two sets of infrared emitters/detectors used to locate
its opponent. Advanced users may expand on the standard SumoBot design by adding
ultrasonic or IR distance measuring, tilt sensing and motor current sensing.
Page 2 · SumoBot – Mini Sumo Robotics
LET’S BUILD THE SUMOBOT
The SumoBot chassis design leaves little room for mechanical alteration; a requirement
to stay within standard Mini-Sumo competition rules. Where the student is encouraged to
explore changes is in the types of sensors used to detect the Sumo ring border and the
opponent and the software algorithms used to control the SumoBot robot’s behaviors.
The demonstration code provided with this text will focus on the standard sensors
provided in the SumoBot kit. Future supplements may be published that deal with
advanced sensors and techniques for incorporating them into the SumoBot robot’s control
logic.
TOOLS REQUIRED
A Parallax screwdriver is included in your kit. You may find a pair of needle-nose pliers
and a wire stripper to be useful (not included).
ABOUT PARTS IN THE SUMOBOT KIT
Appendix A includes a parts listing for the SumoBot robot kit. These instructions refer to
different pieces of hardware. If your SumoBot kit is missing a piece, Parallax will replace
it free of charge. Replacement Parallax Continuous Rotation servos and infrared emitters
and detectors are available to purchase online from the Parallax Component Shop
(www.parallax.com → Component Shop). If you need other parts replaced, please
contact sales@parallax.com or call toll free in the United States: 1-800-512-1024.
If you have trouble identifying the type of part referred to in these instructions, see the
color back cover of this text that shows each part with a colored picture and Parallax
stock code.
Chapter 1: Assemble the SumoBot · Page 3
Step #1
Install the Battery Box
Parts Required:
• Battery Box
• (2) 4/40 3/8" long
flat-head countersunk
machine screws
• (2) 4/40 nuts
• SumoBot chassis
Stand the SumoBot on its PCB mounting ears. Install the plastic battery pack using two
4/40 3/8” flat-head screws and nuts. The screws will be countersunk into the battery
pack when tightened and should be out of the way of the batteries.
Step #2
Install the Servo Motors
Parts Required:
• (2) Parallax
Continuous Rotation
Servos
• (8) 4/40 3/8" long
pan-head machine
screws
• (8) 4/40 nuts
• SumoBot chassis
Using four 4/40 3/8” pan-head machine screws and 4/40 nuts, attach each servo motor
to the chassis. The easiest way to do this is to hold the nut with one finger while
turning the screwdriver with the other hand.
Page 4 · SumoBot – Mini Sumo Robotics
Step #3
Install the Rear SumoBot
PCB Stand-offs
Parts Required:
• (2) 5/8" round
standoffs
• (2) 4/40 3/8" long pan-
head machine screws
• SumoBot chassis
Using a 4/40 3/8" pan-head machine screw, attach each stand-off to the rear of the
SumoBot chassis.
Step #4
Install the Front SumoBot
PCB Stand-offs
Parts Required:
• (2) 5/8" round
standoffs
• (2) 4/40 1" long pan-
head machine screws
• SumoBot PCB
Using a 4/40 1" pan-head machine screw, attach each standoff to the front mounting
holes of the SumoBot PCB.
Chapter 1: Assemble the SumoBot · Page 5
Step #5
Mounting the PCB
Parts Required:
• SumoBot PCB
• (2) 4/40 3/8" long
pan-head machine
screws
• (2) 1-1/4" round
stand-offs
• (2) Nylon washers
• SumoBot chassis
Feed the ends of the 1" long pan-head machine screws through the front mounting
holes on the SumoBot chassis. Secure the rear side of the SumoBot PCB to the 5/8"
standoffs with two 3/8" pan-head machine screws. Holding the chassis upside-down,
place a nylon washer onto the end of each 1" long pan-head machine screw, then
secure by threading on the 1-1/4" round standoff.
Nylon Washer
Step #6
Prepare the Wheels
Parts Required:
• (2) SumoBot wheels
• (2) SumoBot rubber
tires
Stretch a "tire" of each wheel and adjust so that the "tire" is centered across the wheel.
Page 6 · SumoBot – Mini Sumo Robotics
Step #7
Mount the Wheels
Parts Required:
• (2) Prepared
wheels/tires
• (2) Black servo-horn
screws
• SumoBot chassis
Carefully press each prepared wheel onto the servo splines. Secure each wheel with
the small black Phillips head screw.
Step #8
Mount the Scoop
Parts Required:
• SumoBot scoop
• (2) 4/40 1/4" long pan-
head machine screws
• (2) 4/40 nuts
• SumoBot chassis
Using two 4/40 1/4” pan-head machine screws and 4/40 nuts, attach the scoop to the
SumoBot chassis. Carefully center the scoop before tightening the screws and nuts.
Step #9
Install Line Sensor
Wires
Parts Required:
• (2) 10" 3-pin
extension cables
• SumoBot chassis
Chapter 1: Assemble the SumoBot · Page 7
Carefully feed each 10" 3-pin extension cable through the center chassis slot.
Step #10
Install the QTI Line
Sensors
Parts Required:
• (2) QTI line sensors
• (2) 4/40 1/4" long
pan-head machine
screws
• SumoBot chassis
Using two 4/40 1/4” pan-head machine screws, attach the QTI line sensors to the 11/4" round stand-offs. Connect the ends of the 10" 3-pin extension cables to the QTI
line sensors, noting the polarity markings B[lack]-R[ed]-W[hite] on the QTI sensors.
Page 8 · SumoBot – Mini Sumo Robotics
Step #11
Make the Connections
Plug the servo motors and QTI
sensors into the SumoBot PCB
connectors as indicated below.
Note that the "B" pin on each
connector is for the black wire.
X7 = Left Servo Motor
X6 = Right Servo Motor
X5 = Left QTI Line Sensor
X4 = Right QTI Line Sensor
Connect the battery pack wires to
SumoBot PCB connector X1.
The battery pack's white-striped
lead connects to the
+ terminal.
Note: Previous versions of the SumoBot PCB
were labeled "SumoBoard" instead of
"SumoBot." These boards are electrically
identical to the SumoBot PCB illustrated.
When using SumoBot PCBs with a revision
code of C or earlier, the Vs1 and Vs2 (servo
ground) connections must be jumpered to
Vss for proper servo operation.
Step #12
Powering the SumoBot
Chapter 1: Assemble the SumoBot · Page 9
The SumoBot PCB has a three-position power switch. The state of each position is
shown below. The three-position switch has a middle position that powers the entire
circuit except the servos. A complete schematic of the SumoBot PCB is included in
Appendix D.
Position 0 – No Power
Position 1 – Power PCB
Position 2 – Power PCB & Servos
Chapter 2: SumoBot Locomotion · Page 11
Chapter 2: SumoBot Locomotion
The first task of any Mini-Sumo robot is to move – most competition rules do not allow
the robot to stop (without competitor contact) for more than a few seconds. In this
experiment you will learn how to get the SumoBot moving and learn to take control over
its motion.
HOW A SERVO WORKS
Normal (un-modified) hobby servos are very popular for controlling the steering systems
in radio-controlled cars, boats and planes. These servos are designed to control the
position of something such as a steering flap on a radio-controlled airplane. Their range
of motion is typically 90° to 270°, and they are great for applications where inexpensive,
accurate high-torque positioning motion is required. The position of these servos is
controlled by an electronic signal called a pulse train, which you’ll get some first hand
experience with shortly. An un-modified hobby servo has built-in mechanical stoppers to
prevent it from turning beyond its 90° or 270° range of motion. It also has internal
mechanical linkages for position feedback so that the electronic circuit that controls the
DC motor inside the servo knows where to turn to in response to a pulse train.
SumoBot motion is controlled using two pre-modified Parallax Continuous Rotation
servo motors using a process called differential drive. The modification "tricks" the
feedback circuitry so that the servo will stop only when it receives a centering command;
it also allows the servo to continuously rotate in either direction. When both motors are
turning in the same direction, the SumoBot will move in that direction. When the
SumoBot servo motors turn in different directions, the chassis will rotate. The rate of
movement or rotation is determined by motor speeds.
TIME MEASUREMENTS AND VOLTAGE LEVELS
Throughout this text, amounts of time will be referred to in units of seconds (s),
milliseconds (ms), and microseconds (µs). Seconds are abbreviated with the lower-case
letter “s”. So, one second is written as 1 s. Milliseconds are abbreviated as ms, and it
means one one-thousandth of a second. One microsecond is one one-millionth of a
second. Figure 2.1 shows how Milliseconds and Microseconds equate in terms of both
fractions and scientific notation.
Page 12 · SumoBot – Mini Sumo Robotics
Figure 2.1: Milliseconds and Microseconds Details
ms1 ×==
1
1000
µ
s1 ×==
1
1,000,000
A voltage level is measured in volts, which is abbreviated with an upper case V. The
SumoBot PCB has sockets labeled Vss, Vdd, and Vin. Vss is called the system ground or
reference voltage. When the battery pack is plugged in, Vss is connected to its negative
terminal. Vin is unregulated 6 volts (from four AA batteries) and it is connected to the
positive terminal of the battery pack. Vdd is regulated to 5 volts by the SumoBot PCB’s
onboard voltage regulator, and it will be used with Vss to supply power to circuits built
on the SumoBot PCB’s breadboard.
3-
s
101s
6-
s
101s
Figure 2.2: SumoBot PCB Voltage Labels
Vss = 0V (ground)
Vdd = 5V (regulated)
Vin = 6V (unregulated)
The control signal the BASIC Stamp sends to the servo’s control line is called a “pulse
train,” and an example of one is shown in Figure 2.3. The BASIC Stamp can be
Only use the Vdd sockets above the SumoBot PCB's breadboard for the
activities in this workbook. Do not use the Vdd on the 20-pin App-Mod
header.
Chapter 2: SumoBot Locomotion · Page 13
programmed to produce this waveform using any of its I/O pins. In this example, the
BASIC Stamp sends a 1500 µs pulse to P13 (left servo) and P12 (right servo). When the
pulse is done being executed the signal pin is low. Then, the BASIC Stamp creates a 20
ms pause.
Figure 2.3: Servo Pulse Train Analysis
This pulse train has a 1500 µs high time and a 20 ms low time. The high time is the main
ingredient for controlling a servo’s motion, and it is most commonly referred to as the
pulse width. Since these pulses go from low to high (0V to 5V) for a certain amount of
time, they are called positive pulses. Negative pulses would involve a resting state that’s
high with pulses that drop low.
The ideal pause between servo pulses is 20 milliseconds, but can be anything between 10
and 40 milliseconds without adversely affecting the servo’s performance.
The BASIC Stamp 2’s PULSOUT instruction works in increments of 2 microseconds. For example, the following snippet of code creates a 1500 µs pulse:
PULSOUT P13, 750 ' 1500 us pulse on pin 13
A pulse width of 1500 µs (normally, the centering command) will cause the modified
servo to stop. To make the servo turn we must give change the pulse width toward either
end of the standard control range of 1000 to 2000 µs. Since the right side servo motor is
physically mirrored from the left, its control signals are as well. Figure 2.3 shows the
control signaling for the SumoBot servos.
Page 14 · SumoBot – Mini Sumo Robotics
Figure 2.4: SumoBot Servo Control Pulses
For pulses between the 1500 µs stop point and the extremes on either end of the control
range, there is a degree of speed control. This range is not linear, however, and at pulse
widths just outside the stop band, servo current increases dramatically. At some points in
the control range, the servo current can go high enough to cause an excessive load on the
BASIC Stamp's regulator circuitry, causing it to reset or behave erratically. For MiniSumo competition, precise speed control is not a requirement. The goal is to find the
opponent and move quickly toward him.
Open the BASIC Stamp Windows Editor.
to align the SumoBot motors.
2
1
Load the following program that will be used
1
The Parallax BASIC Stamp Manual 2.x includes a “Quick Start” section that details how to open and
launch the BASIC Stamp Windows Editor.
2
Source code for this text is available in a zipped file for download from www.parallax.com.
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