Servo magazine 08 2007

Tạp chí Servo

35 The Day That Robots

Took Over the Park

by Camp Peavy

Crowds gathered in San Francisco, CA

to watch the 2007 RoboMagellan contest portion of RoboGames.

by Bryan Bergeron

Learn a simple, inexpensive, and power ful localization approach based on RFID technology.

Say hello to a dif ferential

Remote Control on Your Bot

Features & Projects

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VOL 5 NO 8

ENTER WITH CAUTION!

Introducing SERVE’

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Columns

08 Robytes by Jeff Eckert

Stimulating Robot Tidbits

10 GeerHeadby David Geer

TeRK

14 Ask Mr Roboto by Pete Miles

Your Problems Solved Here

74 Appetizer by Vern Graner

Recovering Our Technical Literacy

79 Then and Now by Tom Carroll

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Ubiquitous Robotics

If — like me — you follow

the RSS feeds from engadget,

medgadget, newlaunches, and

similar websites, it’s easy to get the

false impression that robots are

freely running around Japan,

Korea, and much of Europe, leaving

the commercial US robotics

industry in the dust Granted,

academicians in Asia and Europe

frequently announce impressive

anthropomorphic robot prototypes,

but few have become commercially

viable However, as with the

Terminator, iRobot, and Star Wars

movies, these announcements are

influential in raising the public’s

expectation of what robotics is

and what real robots can and

should do Unfortunately, one

side-effect of this phenomenon is the

tendency to ignore the contribution

of robotics to everyday life in

the US

Consider the modern elevator

as one example of ubiquitous

robotics The average person that

presses a call button on the first

floor of a high rise serviced by a

bank of elevators doesn’t think

about the embedded systems or the

computer network that determine

which elevator to move to the

ground floor and which ones to

direct elsewhere

Similarly, most people don’t give

much thought to the sensors that

detect an excessive load or that

sense someone or something is

blocking the elevator doors, or

the safety brake system that

prevents catastrophic falls should

the cable fail

Not too long ago, elevatorswere controlled manually by adedicated elevator operator Today,even the greeting and floorannouncement have been replacedwith a speech synthesizer keyed

to the door-opening sequence and floor

Robotics technology has alsobecome an indispensable, ubiquitouscomponent of healthcare Although

US healthcare lags behind that ofmany other developed countries,robotics have been embraced byclinicians, nurses, and administratorsbecause of increased time pressure

on clinicians, a focus on errorreduction, and a national nursinglabor shortage Nurses are too busy and in short supply to waste their time babysitting IVdrips, and instead rely on roboticinfusion pumps to deliver precisequantities of fluid and drugs

to patients

Similarly, time-strapped patients

no longer travel to clinics to havetheir blood pressure or blood glucosemeasured, but they rely instead onreadily available and affordableautomatic sphygmomanometers and glucometers In the case ofautomatic sphygmomanometers,medical technicians and nurses havebeen replaced by microcontroller-directed pneumatics and digitalsignal processing algorithms basedsolidly on robotic principles

Aside from the obviousapplication of robotics in militaryweapons systems, robotics is alsointegral to the operation of virtuallyevery modern vehicle, frommotorcycles and automobiles toships and planes There are high-

Mind / Iron

by Bryan Bergeron, Editor Œ

profile examples of robotics in the consumer automobile

industry, such as the self-parking Lexus LS 460L

However, even a lowly utility vehicle with a fuel injection

engine, anti-lock brakes, and air bag is dependent on

robotic technology

Even the personal trainers in my health club are

being replaced by KoKo robotic weight training

equipment (www.kokofitness.com), which are

outfitted with motors, sensors, and touch screens The

system dynamically adapts to my strengths and

weaknesses, and keeps a personal log of my progress

on a removable USB Flash memory stick Back in my

office, a Logitech Orbit web camera automatically tracks

my face with robotic pan and tilt so that I’m never out

of frame during a video teleconferencing session

Once you realize the extent of our immersion in

robotics technology, it’s tempting to proclaim that all of

the good inventions have been made, and that there’s

no room for innovation Rubbish! Every time I see a

of an airplane, I wonder why someone hasn’t convertedthe carts to autonomous robots that tirelessly servicepassengers I suspect that the answer lies in humanbehavior, and not with technological limitations or lack

of innovation on the part of US roboticists

As the auto workers demonstrated in the 1980s, theprospect of being replaced by a robot — even for a dulltask such as collecting waste at the end of a flight —isn’t regarded highly by the likely operators of such arobotic system Perhaps one day soon semiautonomouscarts, controlled wirelessly by highly-skilled workers inIndia who are versed in airline safety, will deliver softdrinks and remove trash from the economy classsection, leaving the human touch to the price-insensitivefirst class cabin

Take a look around Aside from your projects,where does robotics interface with your life? Moreimportantly, where could you apply your knowledge ofrobotics to address a challenge just begging for a

SV

Bot Mates and Remates with

Satellite

Late in June, Boeing (www.boe

ing.com) posted an announcement

that its Orbital Express system had

performed its first fully autonomous

“fly-around and capture” of a NextSat

client spacecraft in a five-hour

test, thus achieving a milestone in

performance and vaguely following

the plot of an erotic film According

to Boeing, the Autonomous Space

Transport Robotic Operations

(ASTRO) service craft “used onboard

cameras and a video guidance system

to separate from, circle, and remate

with the Ball Aerospace NextSat

client spacecraft.”

After completing the fly-around,

ASTRO maintained its relative position

with NextSat at 120m for 17 min,

then “maneuvered above NextSat to

perform a corridor approach to

within centimeters of the client

spacecraft The capture mechanism

grappled NextSat and performed a

soft berth, drawing NextSat and

ASTRO together.” Presumably, they

then had a cigarette

Closer to home and somewhat

less romantic, the Canadian

Department of National Defense

recently announced that it will be testing an aquatic robot for locatingand protecting whales In operation,the 1.5m Slocum Glider AUV willmaneuver about listening for whalecalls and relay avoidance information

to Canadian warships and other largewater craft

An early test in the Bahamasproved that the Glider can pick up thesounds produced by beaked whales,which is difficult both because of their high frequencies and the shynature of the animals The Glider — a

$50,000 product of Webb Research

(www.webbresearch.com) — seems

perfect for the job, as it is very quiet and unintrusive and does not use a propeller to generate movement

Rather, it moves up and down in the water by changing buoyancy, and its wings provide

steerable gliding,

there-by achieving horizontalpropulsion

Powered by alkalinebatteries, it can bedeployed for up to 30days, at depths to200m, and over a range

of up to 1,500 km

There is also a thermallypowered version thatcan be deployed for up

to five years with arange of 40,000 km Incase you’re curious, it’s

named after Joshua Slocum, whobecame the first man to sail soloaround the world in 1895-1898

Development

Since 2003, the California Citrus

Research Board (CRB, www.citrus

research.com) and Vision Robotics

Corp (VR, www.visionrobotics.

com) have been collaborating in the

development of a robotic citrus harvester It’s not even in the prototype stage as of this writing, but

VR was issued a patent for a newangled-axis machine vision system earlier this year; the company demon-strated a robotic grape vine pruningsystem at this year’s World Ag Expo,and it had a tree fruit harvester display

of sorts at an apple and pear tradeshow in the Netherlands

Apparently, things are movingalong The harvesting process willactually involve two multi-armedrobots The first — called the Scout —will use arrays of stereo vision, scanning heads to create a virtual 3D image of a tree Using that information, it will devise a pickingstrategy and relay it to the Pickerrobot, which is towed behind it

According to estimates by the

Orbital Express ASTRO and NextSat

autonomously perform operations

CRB, the picker will be more

economi-cal than its human counterparts, even

at today’s wages For example, a

system costing $350,000, working

39 weeks, six days per week, and

12 hours per day could perform its

job for $17 per bin — $1 less than it

costs now

The system should work equally

well for things like apples, pears, and

even cherries This could put a whole

new wrinkle into the immigration

debate

The Negotiator Tactical

Surveillance Robot, from Robotic FX

(www.roboticfx.com) is already

used by various law enforcement

agencies for search and rescue, SWAT

duty, HAZMAT handling, and other

applications, but the company

recently announced that it is now

available with a six-axis robotic arm

The arm extends its capabilities by

allowing it to perform tasks such as

opening doors; lifting, carrying, and

delivering small objects; undertaking

explosive ordnance disposal; and

performing detailed inspections

According to company president and

chief designer Jameel Ahed, the new

arm was inspired by the da Vinci surgical system, which mimics thehuman hand “As a result, we havedeveloped a system that allows theoperator to focus on the dangeroustask at hand rather than worryingabout flipping the wrong switch orpushing the wrong button,” he said

According to Ahed, theNegotiator costs only about one third

as much as its nearest competitor

Even if you aren’t in the market forone, check out the website The videosand Hollywood-style sound effects are entertaining

Tot Bot for Man-Machine Interaction Study

Every cute little robot deserves

a cute name, hence KASPAR, forKinesics And Synchronisation inPersonal Assistant Robotics KASPARhas eight degrees of freedom (DOF)

in his head and neck and six in his arms and hands, two DOF eyes fitted with video cameras, and amouth that can open, close, andsmile Developed by the AdaptiveSystems Research Group at the

University of Hertfordshire (adapsys.

feis.herts.ac.uk), he was formerly

used in the Aurora project, which looked into using robots as

therapeutic and educational tools

to help autistic children, and is currently part of the IROMEC project,

a pan-European study looking to provide playmates for children withdisabilities

The news is that he has now beenadopted by the European RobotCub

project (www.robotcub.org) to

study human-robot interaction Theproject is a five-year undertakingaimed at developing an open-sourcerobot platform for cognitive develop-ment research Its version — the iCub

— will be able to crawl on all fours andsit up; its head and eyes will be fullyarticulated; and it will have visual,vestibular, auditory, and haptic sensorycapabilities

Now if they can just program it towhine and climb the curtains, it couldreplace the real thing SV

R o b y t e s

The Negotiator tactical surveillance

robot now can be fitted with a

six-axis arm Photo courtesy

of Robotic FX, Inc.

Artist’s conception of iCub.

Photo courtesy of RobotCub.

KASPAR is a child-size humanoid being used to study human-robot interaction.

Photo courtesy of the University of Hertfordshire.

More Than an

Expansion on the

Personal Rover Project

Until recently, the Personal Rover

Project (PRP, 2001-2005) was a means

by which Carnegie-Mellon University

(CMU) brought robotics education to

children and the world

Now, the Telepresence Robot Kit

(TeRK) is the curriculum’s tool to enable

robotic learning and construction at all

levels — grade school to college andinformal settings like the Smithsonian

Hundreds of thousands have used andlearned from the two projects

The CMU Community Robotics,Education, and TechnologyEmpowerment (CREATE) Lab engineered TeRK to keep robotics funand interesting while maintaining aneducational bent

TeRK robot projects are also relatively cheap (in the hundreds of dollars instead of the thousands), whileoffering very capable robots as results

TeRK is available to the generalpublic and educational institutions andenvironments

What’s New With TeRK?

With TeRK, students and asts can more easily learn robotics

enthusi-and build enthusi-and control their ownrobots By using “recipes” instead ofinstructions and a framework forrobot building that is much more userfriendly than the previous program,teachers can get kids and adults intorobotics faster, piquing their interestwith the ease that robot building can possess

TeRK — actually a series of robotsand robot recipes — is easy enough foranyone to build with readily availableparts At the same time, new roboti-cists can use these advanced robots astools for many lessons at all levels.Perhaps one of the most interest-ing factors, roboticists can controlthese robots via wireless technologyfrom anywhere using an Internet computer

TeRK robot types include a fun,flower piece and a tri-wheeled movingrobot with a camera eye

The Key to TeRK

In addition to the recipes — whichare very thorough and user-friendly —there is a single piece of hardware (theQwerk controller board) that simplifiesmuch of the process

TeRK is a more compact kit as itcomes only with the key elements thatare necessary for each robot recipe.Each kit comes with a Qwerk con-

Contact the author at geercom@alltel.net

by David Geer

TeRK

Carnegie-Mellon Telepresence Robot Kit (TeRK) Helps Students CREATE Their Own Robots!

This Qwerkbot, shown with Emily

Hamner, a senior research associate in

the CREATE Lab, is a tri-wheeled mobile

bot with a camera eye and Internet link.

This robot can be built with parts from

one of the recipes and a TeRK kit.

Grad student Tom Lauwers, together with Hamner, adds some finishing touches to his Qwerkbot.

control on the robot’s devices such

as motors and moving parts, and a

camera CMU and Charmed Labs

developed the controller

The Qwerk controller contains the

processor that makes the variety of

TeRK robots and kits both simple and

possible Capabilities include control of

up to four motors, 16 servos, sensor

interfaces, eight analog ports, 16

digital I/O ports, and an I2C bus

The robots can transmit what they

see in the form of both video and

photos They can even do Internet

searches for their operators

The robots have practical

applica-tions for starting roboticists who want

to keep their projects after

construc-tion The tri-wheeled robot can

become an automated sentry to

monitor activity in the home, in case

its owner needs to determine who

broke in — or simply which pet broke

the vase

There are other robot recipes not

ready for prime time yet, like one for

a bot equipped with environmental

sensors to test for air and even noise

pollution Another robot is simply a

child’s teddy bear

The kits are also reusable Once a

budding roboticist has learned a few

tricks with their first project, they can

customize or create ideas for new

robots, based on Charmed’s Qwerk

controller

The Qwerk controller is actually a

Linux computer itself, adaptable to

other computing languages Qwerk

comes with a Field Programmable Gate

Array (FPGA; an integrated circuit that

can be programmed in the field,

post-manufacturing) for motor, servo,

and camera control, as well as control

of other devices like amplifiers

Qwerk is USB compatible and

extendable with GPS technology and

web cameras

The Internet Makes

All the Dif ference

With the Internet in place as an

established information utility with

where to control and make practicaluse of these robots

Speaking of the Internet, some bigInternet companies like Google, Intel,and Microsoft played important roles

in supporting the TeRK R&D over thepast two years

Recipes

Simple instructions for simplerobots appear in each TeRK robotrecipe Once completed, the bots seekout wireless Internet connections uponactivation

From there, the operator can control the robot from any computer

on the Internet, using a web browser

This doesn’t require the operator to be

at a computer near the robot; theInternet connects the operator androbot together

The additional software neededfor TeRK robots is available free fromtheir website The roboticist can modify software and write additionalprograms

According to Professor IllahNourbakhsh, TeRK project head, CMU, the Qwerkbot Classic is the easiest Qwerkbot to assemble, usingthe Qwerk controller (processor) Bymounting two motors on the Qwerkprocessor and adding a caster for mobility, the Qwerk controllerquickly becomes a robot There is noprogramming or software compilationrequired

Both the Qwerkbot Classic and theQwerkbot+ (harder to assemble, addspan/tilt features) require a teleoperat-ing interface for command and control

of the bots This is a software interfaceused through a web browser (Internet

Without much robotics experience or know-how, the average new robotics enthusiast or student can get up to speed on building this Flower bot from a TeRK kit The TeRK bots use a controller from Charmed Labs.

Hamner and programmer Christopher Bartley adjust the Flower robot, which

is the product of another TeRK kit This bot is as aesthetically pleasing as it is

interesting and fun.

Thanks to a three-year grant fromIntel, the TeRK project is researching

“community robotics” under theheading NeighborhoodNets TheNeightborhoodNets research will uniteart, design, engineering, and other sciences to find out how human communities (that’s us, folks) could

Qwerk controller-based robots

The research will join people andtechnology in “qualitative research” and

“informal learning” and gauge ies using interviews and observation.Eventual robot applications includeneighborhood block watches (robotwatchers), community gardens (robot

discover-NEIGHBORHOOD NETS — A BIG TeRK PROJECT, NEIGHBOR!

Explorer, Firefox,Opera — any webbrowser is compati-ble) The interface offers on-screen and keyboard control of

the bots

The operator can compel/propel the robot around and

see what it sees through its camera with this program With

Qwerkbot+, new roboticists can also manipulate the pan/tilt

action of the camera Start/stop and operation of the robot

via the software is very intuitive, taking only one or a few

steps per operation

The Flower robot recipe helps roboticistscreate a flower, which isn’t mobile (belowthe “stem”) The seven-degree-of-freedom-robot mimics a flower’s actions like blooming, wilting, and adds petal motion forpersonality

The Flower can track motion via three

of its sensor-equipped petals and even catch a light ball or comparable object, making it a great addition to a living room,office, or den

The Flower requires the Robot UniversalRemote (RUR) and Flower Power softwarefor command and control

Flower Power is a simple, graphical scripting language(no coding needed; kind-of the software programming version of a web host that lets a new web builder build a sitewith a few keystrokes or clicks of the mouse) This language

is in the family of what is called “iconic programming” or

“graphical programming,” according to Nourbakhsh

Additional Software

The Robot Dance Studio program enables the roboticist

to create and save a “dance” or series of movements Theuser moves the robot through certain actions and steps andthe software saves and repeats the series of motions Therobot can also follow the recorded series in reverse

The Express-O-Matic software enables the roboticist toprogram the rest of the TeRK robot line similar to how FlowerPower enables programming the flower

The Fake Qwerk program is a testing environment forQwerk and TeRK software, which the roboticist can create.The program displays the software’s commands on-screen sothe roboticist can see what the robot receives; this is usefulfor a variety of software testing applications

The Prototyping Playground software helps moreadvanced robot programmers with Java programming forQwerk controllers

Roboticists can freely download all the software sourcecode following the GNU license, which is a form of free public use license It contains a framework for creating newTeRK projects SV

GEERHEAD

Carnegie-Mellon University — www.cmu.edu

Computer science at Carnegie-Mellon

“herd” non-robotic chairs aroundtables and around the room

Three motors, including one toadjust the drive wheels for the convenience of a human occupant,enable the chair

THE TeRK ROBOT CHAIR

A Qwerkbot can transmit what it sees

over the Internet as it travels through

a given setting or environment.

Perform proportional speed, direction, and steering with

only two Radio/Control channels for vehicles using two

separate brush-type electric motors mounted right and left

with our mixing RDFR dual speed control Used in many

successful competitive robots Single joystick operation: up

goes straight ahead, down is reverse Pure right or left twirls

vehicle as motors turn opposite directions In between stick

positions completely proportional Plugs in like a servo to

your Futaba, JR, Hitec, or similar radio Compatible with gyro

steering stabilization Various volt and amp sizes available

The RDFR47E 55V 75A per motor unit pictured above

www.vantec.com

STEER WINNING ROBOTS

WITHOUT SERVOS!

Order at

Q. Maybe you can answer this

question of mine Why are

there so many different types

of Sumo contests? I used to think that

mini Sumo was all there was, then I

found out that it was based on a

Japanese contest with bigger sized

robots Then the February issue of this

magazine talked about bigger Sumo

robots in the Combat Zone column

Then, I find on the Internet that a

con-test called RoboGames in San Francisco,

CA has eight different Sumo events —

even a couple different humanoid

contests Wouldn’t it be better if

everyone used the same set of rules?

— Bill G.

A.A short history on robot Sumo is

that it was invented in Japan and

was loosely based on one of their

most popular sports — Sumo wrestling

In 1989, the first official robot Sumo

contest was held with 33 robots, and

since then it has grown to having

several thousand robots competing

each year throughout Japan

Fortunately, good things migrate

to the rest of the world Bill Harrison,

using the Japanese rules, invented themini Sumo and 1 kg classes, andinvented the micro and nano Sumoweight classes These rules are stronglybased on the Japanese rules, and manycontests throughout the world followthe same set of rules that Bill Harrisonderived His rules have basicallybecome the “Unified Robot SumoRules.” Table 1 shows the differentrobot sizes and the associated Dohyo(Sumo ring) diameter the robots compete on For the most part, therules are identical for all these differentclasses Most contests throughout theworld follow the same set of rules asshown at the RoboGames andRobothon websites (see Links)

In the ideal world, everyone would

be following the same set of rules,right? The only real driving reason tofollow a common set of rules is so that

a robot will be able to compete in different contests without having to bemodified or completely rebuilt But inreality, rules are made/altered based

on what the local builders want to do

Some contest organizers are very stiffand will say to follow this particular

set of rules or you can’tplay, whereas other contestorganizers are more inter-ested in having fun andwant to maximize the num-ber of people competing sothey allow rules to evolvebased on competitor input

This is why there are so

In Japan, they used to only have a

3 kg weight class running remote controlled robots and autonomousrobots Then in 2002, they added anew weight class, the 10 kg weightclass They allow magnetic and vacuumsystems so the robots can get moretraction The crowd likes the brutalforce these robots have

Other contests don’t allow ums or magnets Some say it violatesthe “spirit” of the rules (Funny though,the creators of the event allow them.)Other contests only allow autonomousrobots, while other events allow tethered robots Some clubs only runone weight class As you may havenoticed, the Ontario group — whichhas a very long-time running event —has a completely different set of rules.RoboGames is making robot Sumoeven more exciting by hosting ahumanoid robot Sumo event Sumostarted with humans on their feet, thenwent downhill to robots on wheels, butnow has returned to its origins oflegged humanoid competitors If wewant to talk about the “spirit” of therules, then robot Sumo should only

vacu-be with humanoid robots on a sandy Dohyo

The main goal is to get people tohave fun building and competing withrobots Most robot builders don’t travel around the country competing incontests, so the local rules are the only real rules that they need to be concerned about This is why it is very

Tap into the sum of all human knowledge and get your questions answered here!

From software algorithms to material selection, Mr Roboto strives to meet you where you are — and what more would you expect from a complex service droid?

by Pete Miles

Our resident expert on all things robotic is merely an Email away

to compete Though a contest may

have the same name that you are

familiar with, the execution of the rules

can be very different Table 2 shows

a list of other weight and size classes

in other contests, including the OCAD

Sumo event

As you can see, there is quite a

range of different sizes for Sumo

robots, and new ones come along

from time to time Take, for example,

the PicoBot (Figure 1) built by Zac

Wheeler (www.poor-robot.com).

This little robot Sumo is half the size of

the Nano Sumo division At 1.25 cm on

a side, this little guy has proven that a

Pico Sumo weight division is actually

possible Way to go, Zac!

When people ask me about

set-ting up Sumo rules, I highly encourage

them to follow the standard set of rules

that most clubs follow, so that robots

can travel from contest to contest But

if they want to use their own version, I

say go for it It’s all about having fun

while learning

Q. I have an old Toshiba laptop

and I am thinking about

getting a USB oscilloscope for

it The oscilloscopes I am looking at

require USB 2.0, but my laptop only

has a pair of USB 1.1 ports Are there

any inexpensive converter/adapters

available?

— Bill Berry

A.Well, you may be in a bind here

There are no direct USB 1.1 to

USB 2.0 converters The main

difference between the two is that theUSB 2.0 ports are about 40 timesfaster than the USB 1.1 ports You canplug in the USB 2.0 devices into a USB1.1 port and you may still be able touse it, but you will be limited by thethroughput speed of the USB 1.1

Depending on how fast the USB oscilloscope outputs it data, you may

or may not be able to use it, or youwon’t be able to use it for capturingdata at higher rates One of the problems that you may encounter isthe classic “Blue Screen of Death”

when Microsoft Windows XP (or whatever OS version you are running)receives too much data Believe me, Ihave done this many times You reallyonly have four options here:

1) Get a USB 1.1 compliant USB oscilloscope

2) Be willing to accept system crasheswhen using a USB 2.0 oscilloscope on

a USB 1.1 port

3) Get a PC card to USB 2.0 adapter ifyour laptop has a PCMCIA port.4) Get a newer laptop that has USB 2.0 ports

Class Size (W x L x H), cm Weight Dohyo Diameter

Humanoid 20 x 20 x 50 3 kg 154 cm Lightweight 20 x 20 x Unlimited 1 kg 154 cm Japanese 10 kg 30 x 30 x Unlimited 10 kg 254 cm Lightweight

Autonomous 20 x 20 x Unlimited 3 kg 76 cmStandard

Autonomous 32 x 32 x 32 cube 10 kg 122 cmLightweight 30 x 30 x 30 cube 4.5 kg 183 cm Sumo Clever None 68.2 kg 244 cm octagon Sumo Classic 46 x 46 x 46 cube 90 kg 183 cm

Table 2 Small selection of other robot Sumo size/weight classes.

Figure 2 Parallax USB 1.1 compliant oscilloscope.

Photo courtesy of Parallax, Inc.

Figure 1 PicoBot, the world’s smallest

Sumo robot.Photo courtesy of Zac Wheeler.

• Official Japanese Rules:

on these rules): www.fsi.co.jp/sumo-e

Here are a couple solutions for addressing options 1 and

3 For option 1, Parallax (www.parallax.com) sells a nice,

inexpensive USB oscilloscope that is USB 1.1 compliant; see

Figure 2 Its maximum sampling rate is 1 Ms/s, which

has been working well for most of my needs If you need

something faster, however, then you are probably going to

need to get one of the faster USB 2.0 oscilloscopes

The other inexpensive option — if your laptop has a

PCMCIA card slot — is to obtain a USB 2.0 port adapter

I recently did this to an old laptop I take to contests for robot re-programming Figure 3 shows a budget USB 2.0PCMCIA card I purchased for $40 from Circuit City

(www.circuitcity.com) With this card, I was able to add

two USB 2.0 ports to my computer These cards can beobtained at just about any computer store or on the Internet

A keyword search of “USB 2.0 PCMCIA Cardbus” will yieldthousands of places to buy them

Q.Do you know if those big balloon type wheels that

you see at the hobby shops for the really big modelairplanes will make good robot wheels?

— Nick Hertz

A.Your wheel selection really depends on the size of

the robot, and what you intend to have the robotdrive over I personally haven’t seen very many robotsusing these types of wheels There is nothing wrong with them; they are perfectly fine wheels Some are solidrubber, and some have a rubber tread and a foam core,while others are pneumatic and require air pressure toinflate them

Probably the most famous robot that I know of thatuses these types of wheels, is nBot, built by David P.Anderson Figure 4 shows this two-wheeled balancingrobot This amazing robot can travel over just about any terrain There are several videos of nBot on

Mr Anderson’s website,

www.geology.smu.edu/~dpa-www/robo/nbot/index.html His balancing robot has

been the inspiration for many robot builders who are building self-balancing robots Mr Anderson told me that

he likes these wheelsbecause they have goodtraction and have anoval cross section Theoval cross section allowsthe very center of thewheel to touch theground, which is wellsuited for obtaininggood odometry results.The wheels he uses onhis robots are from C.B Associates (www

Figure 3 Budget USB 2.0 PCMCIA card adapter for

Know of any robot competitions I’ve missed? Is your

local school or robot group planning a contest? Send an

email to steve@ncc.com and tell me about it Be sure to

include the date and location of your contest If you have a

website with contest info, send along the URL, as well, so

we can tell everyone else about it

For last-minute updates and changes, you can always

find the most recent version of the Robot Competition FAQ

at Robots.net: http://robots.net/rcfaq.html

— R Steven Rainwater

19 RoboCountry

Takamtsu City, Kagawa, Japan

Remote-control humanoid robots combat

15 BotTrot 4Bottle Race

This is a robot contest that you can enter fromhome Build the course, record a video of yourrobot completing it, and submit the video by thecontest date The rules are minimal so almost anyrobot can enter whether it has wheels, legs, ortracks; whether it’s autonomous or remote-control

www.botmag.com/articles/06-10-07_4bottle_ robot_race.shtml

18-21 US-European Micro Air Vehicle Competition

Toulouse, France

Tiny autonomous flying robots compete againsteach other indoors and outdoors The indoor mission consists of flying into a 3.6 meter squareroom though a window and identifying two targetswhile avoiding randomly placed coat hangers Theoutdoor mission requires the robots to fly throughobstacles and over two 1.2 x 1.5 meter placardswithin a 1 km radius

www.mav07.org

21-23 Robothon

Seattle Center, Seattle, WA

Lots of events including Robo-Magellan,Micromouse, line-following, line maze solving, the Walking Robot Contest, Mini Sumo, and

3 kg Sumo

www.robothon.org

26-28 Critter Crunch

Hyatt Regency Tech Center, Denver, CO

Held in conjunction with MileHiCon See robotcombat by the folks who invented robot combatcompetitions

www.milehicon.org

26-28 Korea Intelligent Robot Contest

Pohang Indoor Gymnasium, Pohang City, Korea

Several events are planned for autonomous robotsincluding Micromouse, MIROzSOT games, andintelligent robot demonstrations

http://irc.piro.re.kr

Send updates, new listings, corrections, complaints, and suggestions to: steve@ncc.com or FAX 972-404-0269

The HUB-12

Lynxmotion introduces

the latest addition to

its extensive aluminum

hub lineup The HUB-12

is an adapter used to

mount RC truck tires

and rims to a standard 6 mm motor shaft The other end

of the hub has the popular 12 mm hex pattern found on

most 2.2” rims for R/C monster trucks The hubs are made

from 6061 T6 aluminum and are extremely rugged and

durable They can be used with a large variety of rims from

several different manufacturers They can also be used

with foam tires made for 10th scale, on-road “touring”

cars Price is $8/pair

For further information, please contact:

four-legged intelligent life

form with extraordinary

multi-directional movement

capabilities and advanced sensory awareness

This intergalactic arthropod features a sleek outer

shell and large rounded eyes Roboquad uses his rotating

legs, agile head, and articulated neck to explore and

navigate around his environment Featuring multicolored

flashing lights and funky sound effects, Roboquad

maneu-vers in all directions with unique, spider-like movement

Roboquad’s mobility allows him to move in any

direction Using his rolling crabwalk, Roboquad will travel

in a futuristic crawling motion surveying the world around

him When a foreign object enters Roboquad’s path, he

may scan for an escape route or simply back away to avoid

a possible collision

independent control of each motor By using the way directional pad on the remote control, you can moveRoboquad’s legs together in pairs or simply move each legindividually — in, out, or have it roll under his body Set Roboquad to get up on his toes or cycle through hisdifferent gaits Have Roboquad check his legs and he willlook at each foot to make sure everything is okay.Roboquad is equipped with both dance and movementdemos that showcase his range of motion

eight-Equipped with a high quality vision system,Roboquad’s sophisticated eyes project a focused IR(infrared) beam that reflects against his environment so hecan make smart decisions on where things are and where

he can go Roboquad has the ability to spot movements at

up to six feet and easily navigate around obstacles

Roboquad’s deep IR scanner and fast scanning headenable him to see shapes of all sizes including people, fur-niture, and doorways, and will flinch if suddenly startled.Able to detect the difference between dark and light,Roboquad will turn on his head-mounted LEDs when facedwith darkness When the lights go out, Roboquad keepsgoing and may even start dancing

Using advanced sound sensor technology, Roboquadreacts quickly to sounds and will scan his environment forany possible intruder Roboquad can respond aggressively,scared, or nervously as he reacts to sight, sound, or both.Roboquad has three controllable personality settings.Whether you want Roboquad to spend his time scanninghis environment or traveling a great distance at a fasterspeed, it’s up to you You have the ability to manage hisawareness, activity, or aggression levels which directlyaffect the way he reacts to your presence and objects Just by switching his aggression level to high, Roboquadwill change from a shy robot into one feisty character Turn his activity level to high and he will become quick and responsive

Roboquad can be controlled by remote or be left in anautonomous mode to explore his environment, scanningand avoiding obstacles on his own There are 72 functionsthrough the remote Control sensors, movement, and personality settings Roboquad is also completely programmable You can program specific walking ormotion routines with a sequence of up to 40 commandsfor a complete interactive experience Each time you giveRoboquad a program command, Roboquad will perform alittle bit of the move and make an affirmative sound.With guard mode, Roboquad can act as a securitylookout When Roboquad enters into guard mode, he willmove into his aware stance to look and listen for any dis-

Once he enters this mode, you willhave approximately 5-7 seconds toclear the area Roboquad will thenrespond differently depending on hisaggression level to any sound orobject within his scanning range.Roboquad features volume control and extended battery life for prolonged missions After fiveminutes of no signal from his remotecontrol, Roboquad will enter sleepmode Roboquad will automaticallypower down after 24 hours of being

in sleep mode

With four C batteries (notincluded) for Roboquad and threeAAA batteries (not included) for theremote control, Roboquad is easy

to use and fully functional right out

of the box

Roboquad (ages 8 and up) will

be available nationwide this fall for

an approximate retail price of $99.For further information, pleasecontact:

Servo Erector Set

Lynxmotion announces another

new addition to their ServoErector Set, a robust, all-aluminumround hexapod chassis The top andbottom panels are made from lasercut 0.06” aluminum They are available in either a clear or blackanodized finish, with black anodizedstandoffs The chassis is lightweight

at only 11 oz assembled The pleted chassis has a height of 2.00”and an outside diameter of 11.75”

WALL TRANSFORMERS, ALARMS,

FUSES, CABLE TIES, RELAYS, OPTO

ELECTRONICS, KNOBS, VIDEO

ACCESSORIES, SIRENS, SOLDER

ACCESSORIES, MOTORS, DIODES,

HEAT SINKS, CAPACITORS, CHOKES,

TOOLS, FASTENERS, TERMINAL

STRIPS, CRIMP CONNECTORS,

L.E.D.S., DISPLAYS, FANS,

BREAD-BOARDS, RESISTORS, SOLAR CELLS,

BUZZERS, BATTERIES, MAGNETS,

CAMERAS, DC-DC CONVERTERS,

HEADPHONES, LAMPS, PANEL

METERS, SWITCHES, SPEAKERS,

PELTIER DEVICES, and much more

3DOF leg kits are compatible with this chassis, and are

simple to install The AH3-R robot kit now includes

the new chassis, but current owners can upgrade by

purchasing the chassis by itself Nothing says “robot” like

aluminum Watch the website as we grow the aluminum

parts selection The price is $39.95

For further information, please contact:

CMU 01 Robot Vision Cam

The CMUcam developed at Carnegie Mellon University

provides a real-time, object tracking vision system

that is easy to interface

to microcontrollers and

personal computers The

CMUcam performs

onboard real-time image

processing for object and

Features of the CMUcam include:

• Track user-defined color objects at 17 frames per second

• Find the center of the object

The CMUcam program allows simple, high-level data

to be extracted from the camera’s streaming video Theboard communicates via an RS-232 or a TTL serial port andhas the following functionality:

• Find the centroid of any tracking data

• Gather mean color and variance data

• Adjust the camera’s image properties

• Dump a raw image (single or multiple channels)

• Control five servo outputs

• Automatically uses servos to do two axis color tracking.For further information, please contact:

Featured This Month

Features

22 Heavy Power Batteries

by Brian Benson

24 Heavy Power Spinning

Weapons by Jay Johnson

27 High Power Switching

by Ray Billings

30 Heavy Safety by Kevin Berry

31 Tips for High Power Wiring

by Paul Ventimiglia & Colleen Shaver

32 Club Corner: Northeast

Robotics Club by Alan Young

Events

27 Results — May 13 - Jun 10

33 Upcoming — August & Sept

Heavy duty robots requireheavy duty power supplies

That’s why when you designyour high kinetic energyweapon or overpowered drivetrain you must ensure thatyou have the batteries toback it up Battery failure is

a common issue in highpower systems; so don’t let

it happen to you! Batteriesfor heavy power setupsoften need to meet fourrequirements: they need tosource a large amount of

current quickly; they need to beable to source that current for asustained duration; they must notsuffer greatly from voltage sag;and they must dissipate heat well

so they don’t melt down Voltagesag is when a battery pack’s voltage drops (or sags) down,when it is sourcing a high level ofamps Some 24 volt batteries candrop down as low as 11 voltsunder heavy loads This can wreakhavoc with your electronics, espe-cially if you are using a receiverBEC (battery elimination circuit) or

Combat Zone belongs to the builders and fans of the sport If there is

a topic you think would make a good dedicated edition, like our November

2006 Welding Special or this month’s Heavy Power theme, let SERVO know.

— Kevin Berry

voltage regulator It also results in

your motors not delivering the power

they are capable of so that when you

need that extra burst of power in a

match, it isn’t there

You can buy or assemble

batter-ies in nearly any capacity, amp

output, weight, and size However,

as with any engineering problem,

you must pick and choose which

characteristics are most important;

you cannot get the best of all worlds

There are four types of batteries that

are typically used in combat robots:

NiCad, NiMH, SLA, and LiPoly Each

has its own characteristics that make

it useful for different types of

applica-tions The following explanations

should help you to decide what type

of battery is best for your high power

application

NiCad

Nicad (nickel cadmium) batteries

are often the best for situations

where you need to source a

sustained high amp output They are

heavier than NiMH but are far more

robust in terms of being reliable in

abusive, high draw applications

Good battery packs can source up to

80 amps continuously for a few

minutes and put out up to 200 amps

in bursts Four 2,400 mAh cells can

be seen in Figure 1 These batteries

are good in bots ranging from 150

grams up to 340 lbs

NiMH

NiMH (nickel metal hydride)

batteries are similar to NiCad except

for a few key differences They are

lighter than NiCad and will

gener-ally run longer, but cannot source

the number of amps that NiCads

will They are more fragile in

terms of long-term effects from

abuse Trying to pull more amps

than they can handle repeatedly

will reduce their future output

capacity However, the NiMH

technology has been improvingrapidly to the point they are starting to match the ratings

of NiCads These batteries are suitable for all weight classes

SLA

SLA (sealed lead acid) ies are capable of sourcing thegreatest number of amps for veryshort bursts However, they cannotoutput a sustained high amp drawvery well They are the heaviest ofthe types of batteries covered in thisarticle These batteries are generallythe cheapest and can usually bebought in 12 volt packages Due tothe size and weight, these batteriesare only useful for the upper weightclasses, generally 120 lbs and above

batter-LiPoly

LiPoly (lithium polymer) batteriesare a newer technology that hasmade its way into the sublightweight classes These batteries offerthe lightest solution and can outputthe least number of amps They areoften the most fragile and expensive

If used beyond their specified ratings,they will suffer from irreparable damage As mentioned, this type ofbattery is generally only useful for 30

lb robots and below Because of theirsmall size and ratings, they are mosteffective in small robots

Implementation

After choosing your battery technology, it is important how thearray is assembled The way a pack is

built will have a large effect on how

it performs event after event SLAand LiPoly batteries are often purchased as-is, and so you are limited in the number of ways to bat-tle-harden them For these batteries,shock-mount them to avoid damageand make sure they are held in well.For NiCad and NiMH packs, you have

a few more options

The two biggest enemies of tery packs in robot combat are shockand heat Heat is especially a problemfor applications that stress the packs

bat-To help solve this problem, “ringed”packs were created Ringed packsconsist of two small cardboard rings(see Figure 2) that go around eachcell When the pack is then assem-bled, it leaves an air gap between thecells as shown in Figure 3

This offers a big difference thermally to building the pack so thatthe cells are tight together but stillallowing a path for heat to escape Italso allows you to cool the packquickly after a match by placing thepack on a fan to blow the heat away.The more surface area open to theair that a pack has, the greater

FIGURE 1 Four 2,400 mAh Nicad cells, ready to be built into a pack.

FIGURE 2 Cardboard spacer rings

and heat shrink covered cells, ready

to be put together.

FIGURE 3 The air gap between the cells is apparent in this pack.

Spinning weapons are a popular

part of robotic combat — blades,

and disks, and drums, oh my! These

high-powered, kinetic energyweapons can dish out devastatingdamage in the blink of an eye andleave your opponent’s bot a smokingruin on the arena floor To dominatethe battlefield, a spinning weaponneeds power and plenty of it!

In this article, we’ll look at how

to handle the high power ments for a vertical bar spinnerweapon in a typical middleweightrobot BrainStorm (Figure 1) tookfirst place in the middleweight class(120 lbs) at BattleBeach 2006 and alarge part of the victory was because

require-its weapon system could deliver hitafter hit without self-destructing

All Hail the MagMotor!

Depending on the weight classyou intend to fight in, there are anumber of very good motor choices

to power a spinning weapon — Eteks,D-packs, chainsaw motors, etc — butveteran robot fighters know one ofthe workhorse motors for spinningweapons is the MagMotor or “Mag.”Nearly every component in these no-nonsense powerhouses has been

ability it has to cool down

Shock is a problem for all batterypacks and can be fixed with a few

simple tricks When building a pack, I

prefer to use solder braid to connect

the cells Solid bars might pop off the

cells and cause an incomplete circuit

I have had this happen, and now only

use braid on my packs When building

the pack, add glue between each cell;

goop, shoe-goo, or any similar flexible

glue will work This will strengthen

the pack to resist flexing during large

shocks A ringed and glued 24 volt

pack can be seen in Figure 4

The last important factor in the

battle-worthiness of your pack is theshrink wrap When packs get hot, youdon’t want the shrink wrap to melt offand cause a short circuit To protectagainst this, first don’t ever mountyour packs directly against somethingconductive such as metal Second, use

a high temperature and abrasionresistant shrink wrap Commonly usedwraps include multiple layers of standard shrink wrap, Teflon shrinkwrap, or a standard soda bottle

I prefer the soda bottle trickbecause they are cheap, the plastic isstiff and thick so as to provide a rigidframe for the pack, and it’s clear soyou can see what’s going on underthe covers It is also very simple Just

cut the ends off of a plastic bottle, slide over the pack, and apply heat It will quicklyshrink down around the pack Abattery pack showing both theplastic bottle and standardshrink wrap methods can beseen in Figure 5

Conclusion

When building a heavypower system, remember thatthe batteries are the heart of themachine They provide the energy toall of your other high power compo-nents So when they fail, your robotfails Remember that heat and shockare your greatest enemies, so design

to account for them Also

periodical-ly check your batteries to make surethey are working as you expect It isnot uncommon for batteries toweaken after years of use

Finally, remember to be safearound high current and voltage systems, they pose many hazards;from battery fires to electrocution.Make sure that you know what youare doing It could be much morecostly than you anticipate SV

FIGURE 1 BrainStorm,

a basic wedge with a 12-pound solid titanium spinning bar.

HEAVY POWER SPINNING

● by Jay Johnson

FIGURE 4 A pack ringed and glued All that

is left is to solder the wire braid on and

shrink wrap the pack.

FIGURE 5 A 24 volt Nicad pack with both standard shrink wrap and protection from a soda bottle shrunk down.

optimized for robotic applications

and the result is a rock-solid

perma-nent magnet DC (PMDC) motor that

can really dish out the hurt!

These motors are available from

www.robotbooks.com and the

“Robot Motors” section of the

website has loads of technical details

All three of the MagMotor models

are highly efficient; under typical

operating conditions, over 80% of

the electrical power supplied to the

motor is delivered to the weapon

system as mechanical power The flip

side is that a bit less than 20% of the

power moving through the Mag is

converted to other forms of energy —

mainly heat!

If You Can’t Stand the

Heat

Heat is the #1 enemy of high

amperage electrical systems and

nowhere is this more true than in a

spinner’s weapon system The

differ-ence between success and failure is

understanding the magnitude of the

electrical current flowing through the

robot under variable conditions and

designing the system to withstand the

massive flux of electrons and the

resultant heat build-up Most

impor-tantly, the system components have to

be able to survive the “worst case

sce-nario” — because in robotic combat,

the worst case is bound to happen!

Uncontrolled heating can cause

the windings inside the motor to

burn through their insulation, create

electrical shorts, and quickly reduce

your motor to an expensive pile of

smoldering metal The motor brushes

can also take a lot of abuse in

high-current applications, so make sure

you have some spares on hand and

inspect the brushes for wear before

every event

PMDC motors are least efficient

when the motor is turning slowly —

either during weapon spin-up or in a

stall condition According to the

Tentacle Combat Robotics Torque/AH

Calculator (see “Tools” at http:

//architeuthis-dux.org/tcr-home.

asp), the C40-300 Mag has a

blister-ing 480 stall amperage at 24 volts

There is NO WAY you want thatmuch amperage pouring into themotor and being converted to heat!

Quit Stalling!

A C40-300 Mag directly drivesthe weapon shaft in BrainStorm —there is no clutch or slippage mecha-nism (Figure 3) It is possible, in factlikely, that at some point during afight the weapon will becomestalled The C40-300 is a bruiser of amotor, weighing in at nearly 12pounds! The S28-400 — its smaller,yet comparably powerful sibling —uses rare-earth magnets to slimdown to a mere seven pounds Manybuilders have succumbed to thetemptation to use the smaller motor,but due to its greater mass, the C40can survive a higher heat load — atleast for a while (It is also $150cheaper.) Of course, I wouldn’t recommend running any motor atstall for more than a moment!

So what can we do to prevent astall from cascading into a total thermal meltdown? We need to limitthe amperage available to the motor

One great way to do this is to use acurrent-limiting speed controller, such

as the AmpFlow This is an excellentsolution that also gives you propor-tional control, reversing capability,and a host of advanced features, but

it comes with a hefty price tag (seethe sidebar for costs and sources onall parts mentioned in this article)

In BrainStorm, we are using amuch more basic (and vastly cheap-er) system to control the motor Ourweapon motor is switched on andoff via a Team Delta R/C switch thatcontrols a White-Rodgers 586 seriessolenoid (Figure 4) This is an “all ornothing” control solution; theweapon is either full on or full off

Using a solenoid also allows themotor to draw as much current as itwants from the batteries

Don’t Get Torqued Off!

In most of our other weaponized

robot designs, we have used a V-belt

to drive the weapon, rather than adirect connection The advantage of

a properly tensioned V-belt setup isthat slippage of the belt can preventthe motor from experiencing stallconditions and thus will keep theamperage surges to a minimum It

is still possible to overheat into the motor — if the belt is slipping

on the motor-side pulley, the frictionwill quickly heat the pulley and then transfer undesirable heat intothe motor

Another option to control motorstalling is a “torque limiter.” Daltonmakes the torque limiters most commonly used in robot combat —their OSD model can be used with achain drive or directly on the weapon (some modification may benecessary) These devices act as friction clutches — they are able totransmit only a set amount of torque (an adjustable limit) Beyondthis torque threshold, the deviceslips Just set the torque limiter to disengage at less than the stalltorque of your motor

Assault and Batteries!

We use two 24 volt, 3.0 hour Nicad BattlePacks in parallel to

amp-FIGURE 2 MagMotor C40-300 (right) and S28-400 (left).

FIGURE 3 BrainStorm’s weapon setup.

power the weapon motor When

freshly charged, each BattlePack can

deliver roughly 80 amps continuous

and higher amps for short peaks

This gives us a total of 160 amps

available to the weapon motor We

know from its technical specs that

the C40-300 Mag can handle 160

amps for three minutes, so our

available battery amps are pretty well

matched to the maximum amperage

we want the motors to be able

to draw

It would take some serious effort to overcook our motor with

this battery setup However, if we

doubled the number of batteries in

parallel in BrainStorm, we would

have twice the run time (cool!), but

we would also have enough amps

readily available to do serious harm

to the motor much more quickly

(seriously un-cool!)

The Mag will try to pull everyamp it can out of the batteries

during a stall A rapid drain under

heavy load will cause the

tempera-ture in the batteries to shoot

through the roof — and if one cell

experiences thermal failure, it is

likely the whole pack will go into

catastrophic melt-down What can

we do to protect our batteries fromthis expensive failure? Because weunderstand the consequences ofrunning the motor in stall, we rely

on the R/C operator (yours truly) toimmediately switch the weaponmotor off if a stall condition occurs

In this way, the motor and batteriesnever experience more than one ortwo seconds of stall Because itrelies on human intervention (and

we humans are notoriously prone toerr!), this is a riskier solution thanthose that rely strictly on hardware

or software to prevent or minimizestalls

We’re Going to Need Bigger Wire

Weapon system design is allabout optimization The motor, batteries, speed controller, wiring,and connectors must all be part ofthe solution or the weakest link willundoubtedly fail An important component of a high current systemthat is often overlooked is the wiringand connectors Improperly sizedwiring or connectors can easily overheat during large amperagedraws, melt through their insulation,

and cause a crippling electrical short

or even a fire

Figure 5 shows a typical selection of wire and connectors ForBrainStorm, we chose to use doublestrands of 12 AWG wet noodle wire.I’d like to tell you I used some complex equation to correctly sizethis wiring, but honestly wire sizing is

an art in itself Be sure to check outthe wiring article in this month’sCombat Zone for more info

Because robot combat has such

a short duty cycle — generally onlythree minutes at a time – the standard wiring load charts can’t easily be applied I looked at thewiring setups other builders wereusing on similar motors and used myown previous experience Back atBattleBots 5.0, we operated an S28-400 powered, belt-driven spin-ning weapon against a target almostnon-stop for three minutes, using asingle strand of 12 AWG wet noodle.The weapon was continually spin-ning up, hitting, and spinning upagain The heat overwhelmed thewire and we learned a lesson: If indoubt, use bigger wire!

Build Big or Go Home!

Let’s recap:

1) Select your weapon motor

2) Determine the maximum ampload the motor will tolerate

3) Size the batteries to supply a reasonable amperage

4) Provide stall protection of somesort

5) Use adequate wiring (bigger isbetter!)

There is an ever-present tion to shave weight from a combatrobot in order to pack on thickerarmor or more batteries If you want

tempta-to build the next legendary spinningweapon, my advice is don’t skimp onthe weapon components Now let’sbring on the power! SV

Jay and Valerie Johnson are Big Bang Robotics and have been designing, building, and fighting combat robots since 2001.

FIGURE 4 White-Rodgers

586 solenoid — a solid choice for controlling big current.

FIGURE 5 Wiring and connectors,

assorted sizes.

Parts List

• C40-300 MagMotor $299 www.robotbooks.com

• RCE210 R/C Relay Switch $33.50 www.teamdelta.com

• White-Rodgers 586 Series $70 www.teamdelta.com

SPNO Solenoid

• Ampflow Speed Controller $645 www.robotbooks.com

• Dean’s Wet Noodle Wire, 12 AWG $1.50/linear ft www.teamdelta.com

• 3.0 AH Nicad BattlePacks $162 www.battlepack.com

• Torque Limiters www.daltongear.com

• Tentacle Robotics Torque/AH Calculator http://architeuthis-dux.

org/tcr-home.asp

ComBots Cup 2007/Maker Faire

was presented by ComBots in

San Mateo, CA on 5/19/2007 and

5/20/2007 Results are as follows

(purse shown where applicable):

● Heavyweights — 1st: Brutality,

$6,500, spinner, Demolition; 2nd:

Sewer Snake, $2,500, lifter,

PlumbCrazy; 3rd: Original Sin,

$1,000, wedge, Piranha

● Middleweights — 1st: Piranha 3,

$1,625, flipper, Piranha; 2nd: Vicious

Verdict, $625, spinner, Basher Of

Bots; 3rd: Angry Asp, $250, drum,

PlumbCrazy

● Lightweights — 1st: BigB, wedge,

Late Night Racing; 2nd: Texas Heat,

spinner, CM Robotics; 3rd: Homer,

plow, Ice

● Beetles — 1st: Fear Factor Sr 2,

spinner, Probotics; 2nd: Lil Bit

Wackey, spinner, Hawg; 3rd:

Unknown Avenger, flipper, Ice

● Ants — 1st: Stumpy, pusher, DMV;

2nd: Instruct A Bot, saw, Composite

Labs; 3rd: Unblinking Eye, spinner,

Hammer Bros

Mechwar 10 was presented by

Mechwars Robot Combat in

Eagan, MN on 5/19/2007 and5/20/2007 Results are as follows:

● 390 lb class, four entries — 1st:

MidEvil, pusher, Foaming Rampage,Ray Willett and Jesse Willett; 2nd:

Bug Bite, pusher, Falcon, RandWhillock; 3rd: Jay, pusher, TheDestroyers, Sheldon Itscovich

● 340 lb class, four entries — 1st:

Vladiator, flipper, Moon Robotics,Billy Moon; 2nd: Psychotic Reaction,spinner, Kontrolled Kaos, FrankCrabtree; 3rd: Stump Grinder, spin-ner, FUBAR, Paul Erickson

● 220 lb class, seven entries — 1st:

Ty, pusher, Bobbing for French Fries,Tim Schmitt; 2nd: Eugene, spinner,Moon Robotics, Billy Moon; 3rd:

T-bolt, pusher, Thunder, Ray Lau

● 120 lb class, four entries — 1st:

Wedge Warrior, wedge, Wedgie, RoyWard; 2nd: Bot Named Sue, scoopw/saw, Robocommand, Pierre Smith;

3rd: Norbert, pusher, Tin CanRobotics, Jeff Iverson

● 60 lb class, three entries — 1st:

Sawdust, pusher, FUBAR, Ken Erickson;

2nd: Bob, flame thrower, Bobbing forFrench Fries, Jon Schmitt; 3rd: Disruptor,fodder, 564 Robotics, Chris Fischer

● 30 lb class, four entries — 1st:

Pyromancer, flame thrower,Killerbotics, Richard Stuplich; 2nd:Death by Snu-Snu, taunter, KontrolledKaos, Ken Olson; 3rd: Chain Mail,flail, Love Bots, Sean Hoyt

● 3 lb class, six entries — 1st:

Thanatos, full body spinner, Python,Brian Schwartz; 2nd: Firefly, pusher,Booyah, Adam Carlson; 3rd: TossedSalad, pusher, KAT Robotics, JohnThompson

● 1 lb class, six entries — 1st:

Underwhere?!, spinner, HazardousRobotics, Eric Mueller; 2nd:Microvice, clamp, Night Owl, MartyLawson; 3rd: Anti, taunter, 564Robotics, Chris Fisher

UK Events

XFM Featherweights Championshipswas held in Ipswich on June 2ndand 3rd, 2007 at the New Woolsey

Theatre Go to www.extremefight

ingmachines.com for more

informa-tion Results are as follows:

● 1st: Skink, Full Pressure flipper,Team Wind Power; 2nd: Hannibalito

2, Full Pressure flipper, Team RCC;3rd: Little Flipper 2, Full PressureFlipper, Team Big Nipper SV

There has been a resurgence ofinterest and many new activerobots in the larger weight categorieslately The larger class machines garner the most media attention, and

the fans in the stands always look ward to the “big guys.” Maybe you’vebuilt combat robots in the smallercategories and are considering moving up to a larger class Maybe

you want to jump right in with one

of these high power machines So,

how do we control a really high

power system? How do you define

what “high power” really means?

Let’s look at some of the setups used

by top builders today

First, we need to define a highpower system I once built a 30

pound combat robot that could

briefly pull around 100 amps at 24

volts during initial spin up; one of the

higher output machines of its weight

class If you only built smaller weight

class robots, this might seem to

define high power, yet to larger

weight category robots this is

relatively small

Okay, so what does it take tomove around heavyweight and super

heavyweight class machines, and

operate the high power weapons

that these machines employ in

combat? For purposes of control,

let’s call high power anything that

can draw over 250 amps (at 24V or

above) at any point in a combat

match This describes pretty much all

Heavyweight and Super Heavyweight

class machines, and many

Middleweights, as well

Per the RFL rules, all combatrobots require a mechanical mainpower switch to deactivate therobot Okay, so how do we reliablyturn on and off a bot that uses thiskind of power level? All manners ofswitches, and even removable links,have been used with some success

Various automotive and marine applications require control over highamperage, and have been tried atone time or another For many years,one of the standards used for higherpowered bots was a Hella brandswitch These are an automotiveproduct, and were originally used toturn on arrays of driving lights

They had several advantages

They were fairly cheap, could easilyhandle high power loads (100 ampscontinuous up to 1000 amps surge!),and were fairly lightweight at aroundfive ounces So, why aren’t we all stillusing them? They also had a couple

of disadvantages

The key was removable in the off position, but remained in thehousing in the on position Many amatch was lost due to the key beingdislodged and coming out of thehousing, turning the bot off duringcombat! This was cleverly solved byreplacing the plastic key with a smallmachined metal key that stayed in

the switch, and adding a retaininghousing to keep this metal key inplace, which also provided a bettermounting arrangement

These modified versions of theHella switch are still used in combattoday, and are available from

Team Delta (www.teamdelta.com).

However, there is still a major issuewith them, and you will find most ofthe top teams no longer use them forthis reason The switch was neverdesigned to withstand the harshshock loads that combat robots routinely see Under high impacts, theback of the switch has been known toseparate from the housing, which notonly kills the robot but also providesfor some interesting spark displays asthe live exposed power leads bouncearound the inside of the bot! Somebuilders have modified the back of theswitch to keep them together, withsome measure of success However,there are better options available now.The standard for use in combattoday is the Whyachi switch Theseare specifically designed for use incombat robots and are — in my opin-ion — clearly superior to other avail-able options They come in severalsizes, with the largest being the MS-2.With an impressive 500 amp rating for three minutes, and up to1,000 amps surge, these are capable

of handling the highest of loads seen

in combat today The construction isvery solid, and I have never seen onefail from shock loads They are alsolightweight at five ounces, and at

$65, I consider them a bargain.Okay, so we now have a reliablemeans of turning on and off therobot with a high power system.What about control of this powerduring a match? For drive systems,some form of proportional control ismandatory, but what are you going

to use to control these kinds ofpower levels?

There are many commerciallyavailable electronic speed controllersavailable that are designed aroundsuch power levels You can find sev-eral of these at the Robot Combat

Marketplace website (www.robot

The Hella brand power switch,

with the removable key.

Here is a Team Delta Hella switch modified

with a Lexan brace across the back of the

switch housing This setup increases the

weight of the switch to nine ounces.

The Team Whyachi power switches are the new standard for high power switching, and are available at www.teamwhyachi.com.

The modified Team Delta version of the Hella switch uses an allen wrench to activate.

controllers.html) Match the

maxi-mum current and operating voltage

of your particular motor with a speed

controller than can handle it, and you

should be set

A very useful tool in determining

what your maximum current will be

is the Team Tentacle torque

calcula-tor (www.architeuthis-dux.org/

torquecalc.asp) Pretty much all of

the motors used in combat today are

listed there, and you can plug in your

particular configuration to determine

how much current you will be pulling

to spin your tires If you take this

figure and double it, you will now

have the current it would take to spin

your tires with your opponent sitting

on top of you, which should be the

maximum current you can pull in a

match In reality, if your drive train

becomes jammed due to battle

damage, it is possible to pull as much

current as the stall amperage (also

listed in this tool)

But what about REALLY high

power — something like what’s

needed in any of the nastier kinetic

energy weapons that get used?

Some builders like to also use

elec-tronic speed controllers for weapons

This does give an extra measure of

control, as they can vary the speed of

the weapon Should the weapon

become unbalanced due to combat

damage, sometimes running it at a

lower speed allows you to continue

fighting Sounds good — so why

wouldn’t everyone want proportional

control over the weapon?

Electronic speed controllers that

handle high current are heavy,

expensive, and may not truly handle

the current your motor can use The

Sevcon controller and the Ampflow

controller are both high quality units,

capable of over 300 amps

propor-tional control, at up to 40V for the

Ampflow and 58V for the Sevcon

But, at 3.4 pounds for the Ampflow

and over six for the Sevcon, these

things are heavy Plus, they both fall

short of delivering the surge amps

that really high power weapons

need For these reasons, I prefer

sim-ple contactors for weapon control

Solenoid contactors have beenused for switching high power loads inindustry for longer than any of us hasbeen alive This is a simple, effective,and economical method of switchingelectric loads on and off Commercialcontactors are literally available for justabout any voltage/amperage combina-tion that you can imagine But forcombat applications, we have a fewspecific criteria

They need to be lightweight,extremely rugged and dependable,and capable of handling the maximum surge current your specificsetup can use Remember, a contactor goes from completely off

to completely on instantly, so the initial surge current is likely to be veryclose to the stall current of the motoryou are using

Commonly used contactors inthe larger weight categories are listed on the Robot Combat

The phenolic housing can crackunder high shock loads, requiringsome form of shock isolation mount-ing if you expect them to holdtogether (not a bad idea for any electronic component in a combatrobot!) The bigger problem though,and one that you need to keep inmind for any brand of contactor,comes when you exceed the inrush

current capability of the unit It ispossible for really high current levels

to weld the contacts together in theclosed condition, thereby keepingthe motor permanently on This is areal problem, both from a controland a safety point-of-view

If you have a weapon that drawsthat much current, and then have noway to turn it off, all manner of safe-

ty issues arise At the very least, it caninconvenience an event while every-one sits around watching your highpower weapon spin in the arena untilyour batteries are completely drained

I personally have welded the contactsclosed before, and have seen it happen several times to others.Obviously, a new option was needed.With a little research, I found amarine contactor that was specificallydesigned for high inrush amps Also,due to the relatively harsh environ-ment that marine equipment is facedwith, the physical construction istougher than any automotive unit Ihave found To top it all off, they arelighter than the White-Rodgers units,

as well These are the “E” seriesswitches, available from West Marine.With a capability of 2,000 inrush

The Ampflow and Sevcon speed controllers are both high quality units capable

of over 300 amps of proportional control.

The standard White-Rodgers 586 solenoid These are rated for 200 amps continuous, and 600 amps surge.

amps and a five minute rating of 275

amps, these are capable of handling

the highest of loads seen in combat

today Through my personal use of

these in combat, I honestly feel those

ratings are on the conservative

side The unit itself is very solidly

constructed, although the “feet” canbreak off if the top isn’t supported

They are more expensive than theWhite-Rodgers units, but if yourinrush amperage can exceed the

600 amp maximum of the Rodgers, for both safety and reliabili-

White-ty, I feel they are a better choice

Reliably dealing with high amperage and/or high voltage systems requires an attention to detail

that lower power systems might notneed You should isolation-mounteverything important with padding orrubber standoffs Properly support thewires in the bot with zip ties or p-clamps, and make sure they are rout-

ed safely Make sure to use wire that

is gauged heavy enough to handle thecurrent and voltage you plan on using

Be extra careful when ing any work on a high power system An errant placement of

perform-a screwdriver or wrench cperform-an be disastrous when there is enoughpower available to violently melt thatparticular tool! If you pay attention

to all the details and plan your components according to yourneeds, you too can safely control ahigh power combat robot SV

Many robot builders are used

to working with electricity andcircuits “Heavy power” to most

involves a Ni-Cad battery with an

amp-hour or two, at 12 volts When

dealing with the kind of power

sources featured in this issue of

Combat Zone, builders may be

mov-ing into a new and potentially (pun

alert — sorry!) very dangerous world

The first rule of safety in any situation — especially one like this

— is THINK! The kind of current

available is hundreds of amps, not to

mention the possibility of a sized explosion! Before you make aconnection, before a tool goes nearthe bot, before a battery terminal isuncapped, THINK!

medium-The next rule — common toworking with electricity and machinetools — is no jewelry Rings, necklaces, even dangling earringscan lead to disaster, in one of twoways Hooking yourself into a circuitvia a ring or necklace is a bad idea

Dropping metal items onto live nals is only slightly less dangerous

termi-It’s best to have tool handles covered with an insulating material When thisisn’t possible (i.e., wrenches),consider wearing electrician’sgloves In any case, referring

to Rule One, before you applypressure to a tool handle, orapply it to the bolt or screw,ask the question: “WHEN itslips, where will it go?” Youwill find yourself putting in a

blocking guard (like a piece ofwood), or holding the tool at a different angle

Before making the connections

to the batteries, stop and visuallytrace all wiring Look for inadvertentshorts due to design, stray wirestrands, solder blobs, or lugs toonear structure Where you can, apply

an ohmmeter to verify isolation fromthe frame and between + and - (Thismay not work well through motorsand speed controllers, relays, etc.,but it’s worth trying where you can).NEATNESS COUNTS when wiring

— the heavier the power, the more

it matters See the photo for a vivid illustration of some “interest-ing” bot wiring

Finally, make sure you have aneasy way to disconnect power! Weall know the RFL rules require it, butsometimes in the shop, we get the

“we’ll just hook it up for now, andput in that Whyachi switch I forgot toorder later” mentality Don’t do it!

The “E” series switch, available from West

Marine (www.westmarine.com).

This is the author’s Heavyweight class robot Last Rites The Perm PMG132 motor spinning the massive weapon bar has an impressive

960 amp stall current at 48V.

HEAVY SAFETY

● by Kevin Berry

Photo courtesy of

Masanori Ikeda.

No matter how well you think

your robot is designed to

perform, if your wiring is not up to

par, your chance of seeing the magic

smoke is going to drastically increase

Planning and practice are needed to

wire a robot properly and efficiently,

or your 15-horsepower Etek with 12

gauge solid wire will be the perfect

addition to your Antweight instead

of your Heavyweight

Planning Your Wiring

For robots in general, if you do not

design in and leave room to route your

wiring you can quickly run into major

problems You may think wire routing

does not matter, but when there is

nowhere for your high current wires to

run except right by your receiver —

causing interference — you will start

singing another tune Particularly with

robots in the 60 lb class or higher, the

wire you need to correctly support

electrical loads can be cumbersome,

unwieldy, and weighty

Wire designed for 200-500 amps

can be up to a half inch in diameter

and not at all flexible Since these

larger wires can be stiff, make sure

you also design in space for your

fingers and the necessary tools to

attach the wires to motors When it

comes time for quick repairs in the

heat of battle, you will be thankful

for designing in that space

Do not forget about how heavylarge wire can get Six and fourgauge wire is huge, and so are theconnectors, making weight a majorconcern With the routing designedinto the robot from the start, you canfind the shortest path for the wires, decreasing resistance, savingrobot weight, reducing costs, andminimizing frustration when thewires just cannot fit where youthought they would go

Choosing the Right (Size) Stuff

Using undersized wire for yourapplication is going to lead toincreased resistance This translatesinto more heat, wasted power, andpotential for dangerous situationslike fire in your robot The same

is true if the ring terminals or removable connectors you use aretoo small for the wire and load Sincecombat robots tend to have shortduty cycles, you can often push thestandard current ratings somewhat,but it is recommended you choose

a wire size appropriate for the

expected performance of your robotand its components

When selecting wire for batteries, 12 gauge works great forsub-C nickel-cadmium (NiCad) andnickel metal-hydride (NiMH) packs;anything more is just a waste ofspace However, for the full-C NiCadpacks which deliver more current, 10gauge is the way to go For robotsusing sealed lead acid (SLA) batterieslike the Hawker Odyssey — which can

Sometimes I’ll even wire in a fuse or

breaker just for testing purposes,

which I’ll remove later before

button-ing up for combat

Sooner or later, you’ll need to dothe infamous “smoke test.” It’s calledthat for a reason! (Rats, now wheredid I put that fire extinguisher?)

You may find yourself asking why

oh why, did I power it up on the workbench in the garage? I guess Iforgot Rule One SV

POWER WIRING

● by Paul Ventimiglia and Colleen Shaver

Heavyweight Brutality has a second power switch, saving over 40 inches of 4 awg wire Also shown are the eight battery leads and

4 awg wire for the DPacks.

An example of an Exide SLA used in FIRST

robots and batteries from Brutality The FIRST

battery has 4 awg wire going into a 50 amp

Anderson connector while Brutality has 12

awg going to small Anderson powerpoles.

Most of Anderson’s products are designed for

continuous applications, but robots running

for two to three minutes can push them far

past their ratings safely for short periods.

Use the power switch as the central connection for all positive leads Positives from the battery go on one side and positive out to the robot on the other Connect the negative leads from the battery to the rest of the robot via ring terminals and a floating bolt wrapped in

electrical tape.

source up to 600 amps — six or four

gauge wire is the norm

For connections to large motors,like Eteks, LEMs, DPacks, and Black

Maxes, four gauge wire is a good

choice When shopping, look for

“welding” ground cable wire, which

has higher flexibility and is cheaper

Car audio wire is also a high quality

option with good flexibility, but it will

take more from your wallet

Joining Your Wires

In robot combat, attention todetail can make a huge difference in

your win/loss record You should

always crimp and solder each

connec-tion Doing just one or another leaves

your entire power system to chance;

the crimp mechanically holds the wire

while the solder allows the current to

transfer more easily For an iron, I use

a Weller bought from Home Depot

for around $15 It works perfectly if

you use the provided large chisel tip

The type of connectors you usewill be determined by your battery

SLA batteries will leave you with just

two large terminals, but using

sever-al NiCad/NiMH packs in parsever-allel canreally open up your possibilities Anexample is my heavyweight Brutalitywhich runs eight NiCad packs in parallel Each battery has a short 12gauge wet noodle wire going to a 45amp Anderson connector Althoughthe connectors are small, they handle

a sub-C pack well Using eight smaller battery connections allowsflexibility in design and layout

Anderson PowerPoles, availablefrom a wide variety of places, areuseful on all parts of the robot Acheap crimper can roll the sides ofthe 45 amp contact into a circle andthen you can carefully flow a smallamount of solder into the joint

The contact is then simply insertedinto the housing

However, a good amount of theconnections on your robot will usering terminals Choosing a stud sizewill be based on your resources andyour robot I use a quarter inch studsize whenever possible because ourshop is littered with a variety of quarter inch bolts and many motorshave the same size studs However,the contactors for my weapon motorrequire a 5/16th ring terminal

Choose the size that works best for

you and always select the correct sizefor the wire you are using

When you purchase ring nals, go for “heavy duty” or gold-plated as they are noticeably thickerand can handle higher currents Toinstall them, strip back your wire casing and crimp on the terminalfirst A standard crimping tool worksfor small wires, but eight gauge andlarger will typically require a vise tosquish the connector For four gaugeconnectors, I often use a ball peen hammer After crimping,always solder the connection

termi-As you prepare your wiring,remember to use heat shrink andelectrical tape to protect your robotand electrical components This willhelp to prevent shorting out in theevent something comes loose duringthe match or pieces start to fly Thiswill also help to secure your connec-tions while you are making thosehard hits on your opposition

The Whole Shebang

Proper wiring — especially inheavier combat robots — can be afrustrating and daunting task.However, if you take the time in yourinitial design to account for the spaceand weight needed for the appropri-ately sized wire, the final stages ofyour robot will come together moreeasily, you will have better access forspeedy repairs, and your systemshould be ready to handle the rigors

of the combat robot arena SV

The Northeast Robotics Club

(NERC) is a nonprofit organization

devoted to supporting the hobby of

combat robotics Since its inception in

2001, NERC has hosted more than 15combat tournaments Their first event

consisted of a dozen competitors, aneight-foot-square combat arena, and astanding crowd of spectators Today,

Sample wire and connectors for effective

wire design Dean’s 12 gauge wet-noodle

wire is the most useful wire for combat

robots in my experience It handles 50-100

amps continuously and surges much higher

in a match I use it without issue to run the

S28-150 MagMotors in my heavyweight.

Must-have tools for proper wiring of your combat robot: soldering iron, small wire crimper, crimper for Anderson powerpoles (red handle), ball peen hammer, electrical tape, and heat shrink.

Northeast Robotics Club

● by Alan Young

the events have grown to include

more than 100 bots, a 16-foot-square

arena, and a 1,000-seat stadium

During NERC’s seven-year

histo-ry, the bots have evolved, as well

Early ’bots were often built from

common household items such as

powered screwdrivers, salad bowls,

and PVC pipes Today’s advanced

bots are constructed from aluminum,

titanium, and composite materials

with high-powered brushless motors

and lithium polymer batteries

The types of machine tools used

and skills have also progressed It is

possible to build a competitive bot

with a pencil and paper, a drill press,

and a hack saw, but more and more

builders are using computer aided

design (CAD), metal lathes and mills,

and abrasive waterjet cutting The

result of this progress is an amazing

new breed of combat robots that

can dish out and withstand

stagger-ing amounts of destruction

Despite the advancement in bot

technology, the majority of builders

are still garage tinkerers Young and

old alike are constantly improving their

designs and their building skills The

diversity of builders and their machines

is a great aspect of this hobby In thisarena, a 10-year-old middle school student can take on and defeat a 50-year-old mechanical engineer

The weight classes that NERCsupports at their events include 150-gram, one-pound, three-pound,12-pound, and 30-pound full combatclasses A given event may run a subset of these classes For anyoneinterested in a slightly less violentmatch, NERC has recently created the30-pound Sportman’s Class This classlimits the power of spinning weapons,which are the most frequent cause oftotal robot destruction

While spinning weapons are ited in the Sportsman’s Class, at leastone active weapon is required Sofar, the most popular Sportsman’sweapons have been electric-poweredhammers and pneumatically-actuated flippers This class is justgetting started, and club memberslook forward to the new and innova-tive designs that will be built

lim-NERC’s next event will beOctober 20th at the Franklin InstituteScience Museum in Philadelphia, PA

The Franklin Institute RoboticsChallenge will feature a full day ofrobot fighting in the 12-pound, 30-pound, and 30-pound Sportsman’sclasses Competitors and spectatorsare welcome In addition to the tour-nament, NERC is also assisting theFranklin Institute’s PACTS (Partners inAchieving Careers in Technology andScience) members in building theirfirst combat robots PACTS is a youthprogram devoted to science enrich-ment, career development, and leadership for students in thePhiladelphia area After designingand building their ‘bot, they will par-ticipate in the October tournament.February 15 will mark NERC’ssixth annual event at the MotoramaMotorsports Expo in Harrisburg, PA.This draws over 100 robots every yearfor one of the largest combat events

in the world All six weight classes will

be represented at this three-day event For more information about NERCand their upcoming events, check out

their website at www.nerc.us SV

Classes will be three-poundand 12-pound bots, using aDouble Elimination orRound Robin format using

RFL Rules No ICE or open flames.Entry Fee: $40 for the first 12-poundrobot; $25 for the first three-poundrobot Additional robots are halfprice Entry fee discounts for helpingwith arena setup and take-down

Solaris, built by Pete Covert, has a close

encounter with Justin Matthews’ Darkblade.

Photo by Brian Benson.

Upheaval, from builder Alan Young, and PITR, built by Greg Ferree, show that

“air time” isn’t a one-way street

Photo by Brian Benson.

NERC members Jonathon Durand, James Iocca, Sam Hanson, Brandon Nichols, Dan Provenzano, Joe Provenzano, and Sam Harrington display some of their bots.

Photo by Alan Young.

EVENTS

UPCOMING — August and September

Special entry fee considerations forbuilders who are under 18 Arena:

12 x 12 with 18” x 18” pit surrounded by 2” high wall, making

it very difficult to accidentally

drive into it Go to www.

westernalliedrobotics.com formore information

UK Events

Championships will be held on8/28/2007 through 8/31/2007 Itwill be hosted by Roaming Robots.Thirty-six Heavyweights and 20Featherweights have signed up Theevent will take place at Hafan y MôrHoliday Park, Pwllheli, Gwynedd,North Wales

Robots Live! Hemel Hempsteadwill be held on 9/1/2007 and9/2/2007 This event will take place

at Sportspace Hemel Hempstead,Park Road, Hemel Hempstead Go

to www.robotslive.co.uk formore information

UK Antweight Championshipswill be held on 9/8/2007 inLuton Bedfordshire Event will hostcompetitions in the flea (25-75g)division, Ant (75-150g), andSuperAnt (150-250g) division.Competition will be DoubleElimination

Roaming Robots Winter TourRound 1 — Doncaster will beheld on 9/15/2007 at The Dome,Doncaster Leisure Park, BawtryRoad, Doncaster, South Yorkshire

Go to www.roamingrobots.co.uk

for more information SV

June 17, 2007 perched high above

the Pacific Ocean with the Golden

Gate Bridge clearly in sight,

RoboGames “RoboMagellan” proved

beautiful, competitive, and fun

Four out of the five robots starting

managed to touch the orange goal

cone and the fifth got within 18 feet

Two did not start: dead PC/104 board

and grass too tall (i.e., wrong scale)

RoboMagellan is a navigational

challenge covering approximately 300

feet or the length of a football field An

18” orange cone is placed on a given

GPS coordinate and designated the

“goal.” Robots are timed until they

reach the goal Optional bonus cones

are offered which yield a fractional

multiplier (.5x, 3x, etc.), decreasing

the total judged travel time Robots are

failsafed with dead-man switches and

must not cause damage to theenvironment The RoboMagellanrules are owned and maintained bythe Seattle Robotics Association

The map was distributed athigh noon Competitors were

b y C a m p P e a v y

Photos by Tim Craig

Robots Took Over the Park

T H E D A Y T H A T

A map of the course is distributed

30 minutes before the event and contestants are allowed to walk the

course, but not the robots!

allowed to walk the course, take measurements, and carry

parts of their robots (GPS, etc.), but not whole robots At

12:30, the contest began with Bob Allen and Ted Larson of

Ologic, Inc with their entry “Odyssey,” which garnished a

three minute, 17 second run

RoboMagellan events take on the persona of golf

com-petitions as large groups of people follow the robot like apopular golfer More than one sunbather or picnicker had towonder why all these people were walking around this waybefore noticing the cute little contraption leading the parade

On Odyssey’s second run, it got caught up a twistedtree (I don’t know what type of tree this was, but I can tellyou that it has lived a tortured life.) It seemed to take delight

in swallowing robots The huge statue of Senator Burtonnear the goal offered a visual Easter egg, as well as differentterrain (bricks) for the electromechanical creatures to roam

“Connan” by Robert Scheer and Jim Remington was thesecond robot up They didn’t really have enough groundclearance to get through some of the turf, but this robot hadsome cool slip detection that helped it get out of numerousincidences of high centeredness Its best run was the firstwhich got within 18’ of the goal

“Intrepid” by Mark Curry was probably the best robot onthe course On its first run, this animated autonomous R/C carlived up to its name touching both bonus cones and reachingthe goal After the fractional multiplier, the event time wastwo minutes and 21 seconds Intrepid’s second run was slower as Mark decided to try touching just one bonus cone(three minutes, 11 seconds) He got caught by the twistedtree on the third run but still managed to make it to the goal

At this point, a wedding had set up on the left side ofthe course and I just knew Intrepid was going to march rightdown that nice white silk aisle fortunately the robot turnedright and went around the chairs (whew!)

Next up was Jim McGuffin and Doug Coral with “A3” (Iremember A1 from a few years back) A3 looked a bit like achoo-choo train with an odometer wheel on the back whichcame in useful as a wheelie-bar A3 managed to touch cone

#1 with a total time of six minutes, 44 seconds, whichreduced to three minutes, 22 The second run finished 36’from the goal, and the third run well, let’s just say the codechange did not work out as planned The robot went back

and forth, round and round not

real-ly going anywhere near the goal butentertaining the crowds nonetheless.The last contestants were the boysfrom Cal Poly: Scott Barlow and TysonMessori Using just an odometer andcamera, “SpyBot” is a beautiful example

of simplicity It got very close to the goalbefore catching glimpse of someone’sorange shirt and veering left around therim of the crater about 96’ from thegoal The second run was better 27’from the goal On the third run, theynailed it with a straight shot; oneminute, 30 seconds

the cone in two minutes, 12 seconds time It was run out-of-the-box from the Seattle Robothon in October.

Jim McGuffin and Doug Coral’s “A3” successfully touched the

goal after touching Bonus cone #1 (.5) for an event time of

three minutes, 22 seconds.

Mark Curry’s “Intrepid” was the class

of the field touching both bonus cones and the goal with an event time of

At the end of the day Cal Poly’s SpyBot took Gold, Bob

and Ted’s Odyssey took Silver, and Mark Curry’s Intrepid took

Bronze It was a beautiful day for robots and spectators alike

In the future, electromechanical Frisbee chasers, robotic

football catchers/throwers, and all manner of robotic

recreational devices will become commonplace We are on

the edge of something enormous — and on this day, we

caught a glimpse of it We not only saw the future, we made

it It was the day robots ruled the park! SV

The boys from Cal Poly took Gold with this one minute,

31 second straight shot using just odometry and a camera.

“SpyBot” was a model of simplicity and sophistication.

Connan is clearance-challenged, but managed to make his way

through the rough with some slick slip-detection technology.

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$//63(&,),&$7,216$792/76

Localization — determining the

posi-tion of a robot relative to

landmarks or to absolute global

geometry — is a fundamental challenge

in mobile robotics Wall-followers useultrasonic and IR sensors to track theirposition relative to a wall or other barrier

GPS-equipped outdoor robots determinetheir absolute position by triangulatingsatellite signals Other robots use com-plex visual pattern recognition of theirsurroundings to determine their location

as part of an overall navigation system

This article introduces a simple, sive, and powerful localization approachbased on RFID technology, using the pop-ular Boe-Bot as a development platform

inexpen-Localization

Most simple mobile robots are holonomic, meaning that even though thewheels may turn 20 revolutions forwardand then 20 revolutions backwards, therobot will not return to its original posi-

non-tion Slippage between the wheels andthe surface, imperfections in the surface,and other environmental factors — unlessdetected and compensated for — createlocalization errors that accrue over time.Now, suppose there is a way todivide the surface of a room into a grid,with each grid labeled with a unique iden-tifier that can be read by a robot, as inFigure 2 As long as our robot has aninternal representation of the grid inmemory, it can move from any point onthe grid, using any physically possiblepath The path shown in Figure 2 starts atgrid 45, continues straight ahead to grid

21, veers right to grid 16, and so on Thegrid is also useful in calculating the bestmulti-point path, which would be useful

in delivering multiple parcels to multiplerecipients in the shortest period of time.The robot needn’t have the entiregrid in memory The desired sequence

robot in Figure 2 can be programmed

such that if it moves from grid 39 to

grid 34, it will veer left until it connects

with one of the grids shown in blue

Imagine the possibilities if the grid

itself could contain memory of the

robot’s path and time With this

capabil-ity, a robot could leave a path for other

robots to follow, as in collaborative

robots If a human were to go first and

leave a digital trail, then the robots could

follow the human without direct

obser-vation or other complicated technology

It turns out that the enabling

technology for these possible scenarios

— RFID — is readily available and

relatively inexpensive It’s been used in

robotics for real-world applications For

example, in 2006, NTT Communications

Corporation tested a pair of RFID-guided

shopper assistant robots at a large mall

in Japan [1] Shoppers first identified

themselves with RFID tags and then

selected a store they wished to visit using

a touch screen interface The robots led

the shoppers to their desired destination

The shopping robots relied on

thousands of RFID chips embedded

under the carpet in the mall for

position information RFID data were

wirelessly communicated to a central

computer that issued motion

commands to the relatively simple

robots Offloading the heavy

process-ing to a central computer significantly

lowered the cost of individual robots

RFID

Radio Frequency Identification or

RFID technology consists of a wireless

reader and compatible transponders or

tags that emit unique identifiers when

polled Inexpensive tags are available in

a wide variety of physical and electrical

configurations for applications in

manu-facturing, asset and data management,

and event control There are RFID cable

ties, security cards, sew-on buttons for

laundry control, key fobs for access

control, rings for poultry management,

and implantable glass cylinders for pet

identification See the Synometrix

website (www.synometrix.com) for

an extensive listing of RFID tag shapes,

sizes, and applications

Passive tags are activated by RFenergy from a reader Activetags — which have a greateroperating range — are batterypowered Both active and pas-sive RFID tags may be read-only

or read-write, with up to about2K of non-volatile memory Theother major electrical variable isoperating frequency, whichdefines the bandwidth availablefor data transfer and, in general, themaximum operating distance

Typically, the higher the operating frequency, the greater the maximum readand read-write distance For example,Synometrix offers long-range RFID systems, capable of ranges from two toabout 80 meters, using active tags operat-ing at 2.4 GHz Their 919 MHz long-rangesystem operates at up to 10 meters, whiletheir medium-range systems cover up toabout one meter and operate at 13.56MHz The Synometrix 125 kHz systemsoperate at up to about 60 centimeters,depending on the reader Other manufac-turers, such as Texas Instruments, offersimilar systems with comparable ranges

It’s important to note that, as withany other wireless system, range is a function of transmitter power, receiversensitivity, and directional attributes ofthe transmit and receive antennas Theoptimum configuration is deter-

mined by the application Forexample, a charge card systemwith a range of over a few cen-timeters could be problematicbecause of security issues

However, a 10 meter rangewould be appropriate for vehicletracking, and a system with aone meter range would be goodfor access control to an event or

to track runners as they crossdesignated points in a road race

The RFID system used inour project is a 125 kHz, pas-sive, read-only system available

from Parallax (www.parallax.

com) Parallax offers a reader

and a variety of tag tions, including the plastic round

configura-and glass cylindrical tags shown in Figure

3 Figure 4 shows a close-up of the glassRFID tag, with an iron core and coil wind-ings visible in the top third of the tag.The Parallax RFID system is a short-range system capable of reading up toabout four centimeters, depending onthe type and relative orientation of thetag The plastic round tags can be readfrom about four centimeters when thereader and tag antennas are in thesame plane — that is, face to face.However, if you turn the tag or reader

on end, then the range is less than acentimeter Similarly, the glass RFID tag

is best read with the windings in thesame plane of the reader As you cansee in Figure 4, the windings are alongthe long axis of the tag, meaning thatthe greatest operating range occurswhen the tag axis is perpendicular tothe reader — standing on end

Line-Modifying the

Boe-Bot Line-Follower

To illustrate the utility of RFID

local-ization, let’s modify a Boe-Bot

equipped with the standard

line-ollowing kit from Parallax The goal is

to create a line-following robot that

uses RFID to make small course changes

to move from one line to the next

Consider the track defined in

Figure 5 A robot starting at the

bottom of the line moves forward until

it senses RFID tag A At this junction,the robot veers right and follows thenew line When the robot senses RFIDtag B, it follows the associated program instruction, such as changingspeed or turning around With moretags and more alternative paths, acomplex navigation system is possible

Operating Environment

For a test track, take a white posterboard and create a path with 3/4 inchelectrical tape Following Figure 5, create

an alternate path that branches off at anangle If you leave a white space betweenthe two tracks, you can avoid possibleconfusion of the line-following program

Next, mount an RFID disc under theposter board along the main track a fewcentimeters before the branch Use asmall piece of tape to affix the disc so

that it can be repositioned later

Hardware

I mounted the ParallaxRFID reader card on the bottom of my Boe-Bot usingslotted plastic standoffs, asshown in Figure 6 Drill twoholes in either side of the Boe-Bot chassis about 1 cmfrom the bottom edge I used

a Dremel to create slots in twoplastic standoffs that were leftover from the tractor tread kit

However, any non-conductingstandoff will work It’s also

possible to tape the reader in place,but this will limit access to the batterypack — a potential problem if you usenon-rechargeable batteries Regardless

of the mounting method, the readershould be horizontal and about a cen-timeter above the supporting surface

Software

The software used for this project is

a combination of the QtiLineFollow.bs2and RFID.bs2 programs that may bedownloaded from the Parallax website.Program flow, illustrated in Figure 7,involves first checking for the presence

of an RFID tag If one is found, the ciated subroutine is called Otherwise,the line-following program is executed.The core line-following subroutine

asso-is of the following form:

Follow_Line:

Select IRPattern Case %010 Gosub Forward Case %001 Gosub Rotate Right Case %100

Gosub Rotate Left EndSelect

ReturnThe infrared (IR) pattern from thethree line following sensors is used todirect the servos on the Boe-Bot If bothleft and right sensors show no absorp-tion and the center sensor shows absorp-tion (pattern 010), the robot is followingthe line, and the appropriate response is

to move forward If the right sensorshows absorption, while the other twosensors do not (pattern 001), then therobot is too far left, and it should rotateright to correct for the deviation.The tag handling subroutine,which is called before the line-followingsubroutine, takes the following form:

Tag_Found:

Select TagNum Case A Gosub Pivot_Right Case B

Gosub Pivot_Left EndSelect

Return

[1] NTT CSR Report 2006 NTT

Communications Group, 2006 [cited

2007 June 8]; Available from: