Tạp chí Servo
Trang 4This Month In
THE COMBAT ZONE
Features
28 The Holy Grail of Combat Robotics
Usable Melty Brain (Par t 2)
31 Manufacturing: Win With
Bulletproof Planetary Gearboxes
Events
34 Results and Upcoming Competitions
35 Rumble at the Rock:
BotsIQ Gone Varsity
Robot Profile
36 Dark Pounder
SERVO Magazine (ISSN 1546-0592/CDN Pub Agree#40702530)
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08 Robytes by Jeff Eckert
Stimulating Robot Tidbits
Pace Robotics Lab — Activevision Robot Technology Captures Sights in 3D
by Bryce and Evan Woolley
Back to Basics: Why Turning RC Cars into Robots Makes All the Difference
Your Problems Solved Here
by Heather Dewey-Hagborg
Artificial Life — Part 1:
Introduction to Genetic Algorithms
by Gordon McComb
Robot Kits for Easier Robotics
by Allison F Walton and Filomena Serpa
When Art and Servos Mix
Women of Robotics
PAGE 79
Trang 5by Robert Doerr
This time, BOB gets lots of cool stuf f added to him, including a Handy Board controller, H-bridge, power distribution, and sonar boards.
Controller: Part 2
by Fred Eady
The preflight work from last month will now be applied to create controlled rotational movement
of a stepper motor shaft.
Controller Using RobotBASIC
by John Blankenship and Samuel Mishal
RobotBASIC is a free programming language known for its integrated robot simulator However, it also can be used for nearly any control application.
Robot From Scratch
by Brian Benson
This new series of articles will take you through the entire process of designing and building a custom robot.
PAGE 38
PAGE 10
PAGE 14
Features & Projects
Trang 6Published Monthly By
T & L Publications, Inc.
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As highlighted by the Consumer
Electronics Show (CES), 2008 is
shaping up to be a good year for
robotics innovators who rely on
inexpensive, capable platforms for
their experiments The most impressive
platform in the traditional D3 (dull,
dirty, and dangerous) camp was the
$99 iRobot Looj (www.iRobot.com).
The treaded, weather resistant, remote
controlled vehicle (see Figure 1) is
intended to facilitate the D3 job of
cleaning gutters of leaves, pine cones,
twigs, and other light debris Although
the robot’s movement is limited to
linear forward and reverse and access
to the NiCad battery pack is somewhat
awkward, the robot seems like the
perfect platform for an amphibious
vehicle I’ll be featuring the Looj in an
upcoming teardown article
As in previous years, consumer
robots is less about sweeping floors,
clearing gutters, or performing equallydistasteful D3 tasks, and more about
entertainment WowWee (www.wow
wee.com) promises to be a ready
source of development platforms,following the popularity of theRobosapien among the robotics modcommunity Highest on my want list isthe Bladestar indoor flying machinewith onboard obstacle avoidance Thethree-channel digital IR controller isespecially intriguing, in that it impliescontrol is possible through a wirelesslaptop link that can be used to providepath planning in addition to simpleobject avoidance Other members ofthe WowWee lineup — including thefour-legged Roboquad, emotiveRobopanda, and series of Alive pets —also seem promising
If you’ve ever developed a WiFiinterface to your robots, then you’llappreciate the Meccano Spykee ‘spy
Mind / Iron
by Bryan Bergeron, Editor
Mind/Iron Continued
FIGURE 1
Trang 7robot’ with built-in Skype VoIP phone, webcam, and
software suite (www.meccano.com) The French robot,
sold under the Erector brand in the US, seems equally
valuable as a source of parts and as a development platform
At $300, the treaded robot is about the price of a WiFi
webcam without audio capabilities, battery pack, or mobility
I’m undecided about the viability of the long-awaited
Pleo (www.pleoworld.com) as a repurposable robotics
platform Given the hype, I was expecting something with
the capabilities of the discontinued Sony Aibo However, I
don’t envision squads of autonomous, bucolic Pleos
playing robosoccer That may change with the efforts of an
innovative modder, however
One of the more interesting robotics products
featured at the 2008 CES that spans the D3 and
entertainment categories is the Gibson Robot Guitar
(www.Gibson.com) Thanks to robotics and electronics
developed by Tronical (www.Tronical.com), the guitar
frees the guitarist from the dull and time-consuming task
of retuning the guitar It’s difficult to rationalize the added
$700 expense for simply keeping six strings in tune, but
where the German Tronical technology shines is in
alternative tuning and intonation adjustments
Many traditional and modern songs use alternatives to
the standard EBGDAE tuning (i.e., the first or thinnest
string is tuned to E, the next string to B, and so on)
Retuning a guitar to common alternatives such as Dropped
D (DADGBE) or Delta Blues (DGDGBD) takes time So much
time that performers typically switch guitars between
songs to accommodate alternative tuning With the Robot
Guitar, alternative tuning is as simple as turning a selector
switch The six motors in the head and piezo audio
detectors in the bridge adjust individual strings to the
appropriate tension within four seconds
The other big headache the Tronical technology
addresses is adjusting intonation, which typically involves a
trip to the guitar shop for adjusting the bridge Instead of
simply pressing a button, correcting intonation involves
manually adjusting the distance between points holding
the strings (the nut at the far end and the bridge at the
near end) While this is a manual operation, the circuitry in
the guitar signals the operator how far to turn the
adjustment screws to achieve proper intonation
There have been other automatic, motorized tuners on
the market, but the Tronical-Gibson is the first to pull it off
in a clean, fully integrated way Because the Tronical
components are the same size and actually lighter than
traditional components, the system is available for Fender
Strats and a variety of Gibson guitars The system can be
quickly installed and removed tracelessly without extra
drilling, holes, or screws
While the market for all stringed instruments is
threatened by all electronic instruments, the Robot Guitar
is a good example of how robotics can be integrated
seamlessly and almost invisibly into an existing product to
provide enhanced value I leave you with the challenge of
identifying application areas where the same approach can
be applied to activities of daily living, from driving and
cooking to simply moving from one place to another SV
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Trang 8Climbing the Walls
In the common tradition of
borrow-ing robotic concepts from nature is
Waalbot, which needs no magnets or
vacuum devices to attach itself to
vertical planes Like a common gecko,
this Carnegie Mellon (www.cmu.edu)
invention uses tiny fibers on its feet to
adhere to just about any surface The
lit-tle guy isn’t much bigger than a quarter,
but he sports two sets of three-footed
wheels, each with its own motor The
spring-loaded tail keeps the critter
pushing against the wall’s surface
Motion control, including
steer-ing, is provided by a PIC
microcon-troller and power by lithium-ion
batteries Projected applications
include inspection, surveillance, and
possibly spacecraft repair Coming
soon to a Waal-mart near you
Dinosaurs to Roam Again
Dubai, to put things in
perspec-tive, is the second largest nation within
the United Arab Emirates, even though
it occupies only 4,114 sq km (about 16
sq mi) This puts it on a par with
Headland, AL But its population is
1,422,000, as opposed to Headland’s
3,523, so a lot of people must be
standing up most of the time On thepositive side, Dubai’s gross domesticproduct in 2006 was $46 billion, whichmeans they have a lot of extra moneyfor fun projects And these folks, whohave already created a private islandarchipelago shaped like the Earth’scontinents, and the world’s first underwater hotel, don’t think small
The current hot project there isRestless Planet, a “unique, world-classnatural history phenomenon” that willrecreate 11 acres of the Earth as it was
100 million years ago The park —projected to cost $1.1 billion — will feature 109 robots housed in a 75 mdome, constituting the world’s largestcollection of animatronic dinosaurs
The bots are being created by Japan’sKokoro Co under the direction offamed paleontologist Jack Horner
The first one out of the gate is T
Rex (the lizard, not Marc Bolan), which
is capable of ing you with hungryeyes, breathing, andcurling its lips, but itwill probably stopshort of eating you
follow-A series of rides willtake visitors through
a collection of high-tech effects thatillustrate the birth ofthe planet and the
creation of its topographical featuresand oceans The finale is a visit to theage of dinosaurs Restless Planet isscheduled to open late this year, sobook your flight to the City of Arabia
(www.cityofarabiame.com) early (The
current price is $1152, round trip KLM.)
Baby Seals Boost
Mental/Physical Health
Most of the bots you see these daysare aimed at some sort of mundane application, be it industrial or service ButJapanese developers seem to be wrapped
up in what has been called the “cult ofcute,” and one of the most adorable isParo, the baby harp seal from Intelligent
System Co (www.intelligent-system.
jp) It is classified as a “mental
commit-ment robot,” defined as one
devel-The CMU Waalbot climbs walls using
dry adhesion Photo courtesy of
Carnegie Mellon Nanorobotics Lab.
Left: Paro, the robotic baby harp seal, photo courtesy
of Intelligent System Co., Ltd Right:The real thing, photo by Rei Ohara, courtesy of harpseals.org.
The Restless Planet theme park will feature 100+ mechatronic
dinosaurs Photo courtesy of City of Arabia.
by Jeff Eckert
Trang 9oped to interact with human beings
(often the sick and elderly) and make
them feel emotionally attached to it
According to the company, such
devices provide three basic therapeutic
effects: psychological (e.g., relaxation
and motivation), physiological
(improved vital signs), and social
(stimulating communication between
patients and caregivers) Going beyond
a common stuffed animal, Paro
incorporates tactile, light, audio,
tem-perature, and posture sensors to
com-prehend people and its environment
It recognizes light and dark and
gets sleepy at night It blinks its eyes
and makes seal noises It likes to be
pet-ted and tries to avoid you if you smack
it Paro can even recognize words and
where your voice is coming from, and
you can tickle it by touching its whiskers
Pretty clever But with Paro’s
$3,200 price tag, a cat might be a
more cost-effective solution
Don’t Eat the Yellow Ice
Also more huggable than it needs
to be is Yuki-taro, from Research &
Development, Inc (RDI,
www.rdi-japan.com), which has been described
as “a supercute robot that eats up
snow and poops ice blocks.” Developed
by a consortium in Japan’s snowy
Niigata Prefecture, it is self-guided via a
GPS system and cameras mounted in
his “eyes.” He measures 63 x 37 x 30 in(160 x 95 x 75 cm), weighs in at 880 lb(400 kg), and his droppings are 24 x 12
x 6 in (~60 x 30 x 15 cm) ice bricks
Given the nature of his diet, youprobably won’t want to crush up thebricks for your evening cocktail, butthe ice could be stored for refrigera-tion or air conditioning in summermonths Yuki-taro isn’t ready for massproduction yet, but its inventors hope
to be selling them within five years
The estimated price will be $9,000
Report on Future Military Systems
In its infinite wisdom, the US
Department of Defense (www.
defenselink.mil) has released a report
titled, “Unmanned Systems Roadmap2007—2032,” which outlines how the military intends to proceed in developing, acquiring, and integratingunmanned technology over the next
25 years This should prove helpful toinventors, defense contractors, hostilegovernments, terrorists, and anyoneelse who has an interest in such things
The Roadmap covers not onlyUAVs but land- and maritime-operatedsystems, as well The report is available
at a somewhat out-of-the-way corner
of the DoD website, or you can
download it at www.jkeckert.com/
unmannedsystems.pdf.
Do-It-Yourself Earth Defense
Strangely, the DoD’s Roadmapcompletely ignores the threat of aliensfrom outer space, but Daniel H Wilson,Ph.D., has it covered in his latest book,
How to Build a Robot Army Regardless
of whether you find yourself attacked
by aliens, ninjas, or zombies (or mies or great white sharks or Godzilla),you can get the better of your blood-thirsty adversaries using the techniquesoutlined within You can pick up the
mum-paperback edition from amazon.com
for a paltry $11.16 as of this writing.And may the farce be with you SV
R o b y t e s
Yuki-taro, the snow-eating robot.
Photo courtesy of RDI.
New report from the DoD outlines its plans for future unmanned systems.
Photo courtesy of
US Department of Defense.
Daniel Wilson’s latest book, How to Build a Robot Army Photo courtesy of Bloomsbury USA.
Trang 10Pace University Labs produced the
“activevision” technology (per a
Pace University academic paper)
in conjunction with research into a
much larger robot cognition project
With activevision, the robot models
itself and its environment in a 3D world
using graphics rendering engine
technology from Ogre3D, just like that
used in gaming software
The robot sees the world around it,
then assembles it in 3D It saves and
works within that reservoir of graphical
data in order to develop changing and
improving perceptions of its surroundings
ADAPT-ing
The robot vision project, called
Adaptive Dynamics and Active
Perception for Thought (ADAPT), fallsunder the work of three Universityresearch groups: one from PaceUniversity (computer science), one fromBrigham Young, and one from Fordham
The research has produced severalrobots, which are available fromActivMedia today along with some others These robots are capable of
a variety of responses in largely unpredictable environments usingrobotic cognition and activevision
There were obstacles to ing this level of perception with earlierrobots Developers had to pre-programthose robots to work in their environ-ments So, while the pre-programminghad a lot to do with how they couldrespond, it didn’t help them learn fromthe environment or produce their ownperceptions before they responded
accomplish-By developing robotic cognitive ities, researchers hope to be able to giverobots the tools they need to learn fromtheir environments and adapt according-
abil-ly Some of the pieces to that puzzleinclude the abilities for the robot to solveproblems and improve navigation
Seeing is Predicting
The mobile robot in the ADAPTresearch sees by first predicting what itwill see It does this using a virtualmodel of the world around it throughits multimedia This exists in the SOARsoftware and algorithms (SOAR is acognitive software architecture andframework for developing intelligentrobotics systems), and in memory.The virtual, multimedia aspect ofthe model exists in a 3D game Ogre3D is an open-source programming platform, virtual-world-based game withadvanced graphics It uses state-of-the-art game physics (the physics make virtu-
al objects in the game respond to eachother in the same way that the sameobjects would respond in the real world).The robot uses its machine visionand software tools to create a copy of itsenvironment with itself included It storesand interacts with 3D data in the virtualgame world, learning from the process.This forces the robot to use its intelli-gence so it can make decisions based onits perceptions of the world around it andnot on feedback (based on machinevision techniques) from that world alone.The robot learns to adapt andrespond to the world around it as a part
of a complex problem-solving process.The robot’s software uses the virtual
Contact the author at geercom@alltel.net
by David Geer
PACE ROBOTICS LAB
Activevision Robot Technology Captures Sights in 3D
Pace Robotics Lab has developed a real looker — a robot with
machine vision that remembers the world in 3D.
ActivMedia Activrobot, Pioneer 2 rear angle view This early experimental version is the granddaddy to ActivRobots’ Pioneer 3 models, including the P3-DX The P3-DX comes with battery, two wheels, caster, motors, encoders, and a front ring of sonars.
side-The robot must have its microcontroller, as well as a sonar board, power board, ARCOS microcontroller server software, on the hardware I/O bus with ARIA software and ARIA Robotics API for software developers (to add to the robot’s skills), and an operator’s manual.
Trang 11world to model everything the robot
per-ceives and responds to in the real world
This way, the robot’s intelligence
can attempt to sort of reason out what
happens in the real world by use of the
stored “working memory elements” of
the virtual world, according to a Pace
Lab Obstacle Avoidance paper, by Dr
D Paul Benjamin, et al
Machine Vision
The cognitive, machine vision robot
— Pioneer 2 — sees through a pair of
FireWire (IEEE 1394) Canon VC-C4
cam-eras and “framegrabbers.” The camcam-eras
are mobile via a pan/tilt hardware device
from Directed Perceptions The computer
uses an onboard Linux OS for command
and control, which interfaces wirelessly
with a single PC-based computer
The software brains of the Pioneer
2 consist of two parts: one that
process-es the “bottom-up” or simple view of
the world; and, one that processes the
“top down” or closer look view
The bottom up view is quick and
dirty, giving the background and the
general lay of the land This image
simply provides a view with objects the
robot may want to examine more
closely This software runs on Intel’s
Open Vision software library
The top down vision system is
much more complex and elaborate The
robot’s system activates this element of
the robot’s vision when the robot wants
to take a closer look at something in the
environment that the first vision system
has only vaguely mapped out This is for
specific object recognition
This “ERVision” software will look
at an object to recognize its distinctaspects It will then model the image inthe virtual world and store that so theobject won’t have to be recognizedagain This saves time and effort
As the virtual world becomes morecompletely detailed, the robot’s memo-
ry and perception of its world becomesmore clear and accurate This way, therobot’s obstacle avoidance proficiencyincreases in its surroundings
In case any of the obstacles should
be mobile objects (say a house cat, forexample, that might have been sleeping
in one spot when it was originally nized), the robot is able to determinewhether any objects it has recognizedbefore are now where they are sup-posed to be (whether they have moved)
recog-by use of the virtual world model
SOAR
SOAR, an architecture for developing intelligent robot systems,has been in use for 25 years It is
an integral part of the project that hasproduced the Pioneer 2 robot (shown
in the images) with activevision
The current version of the software
is SOAR v8.6, for those who would like
to investigate its use on their next project SOAR developers hope to bringSOAR to the point where it can enable allthe tasks of the kinds of intelligentrobots the world envisions for the future.The goal is for SOAR to solve open-
Camera and sonar view of Pioneer 2.
Pioneer 2 with camera mount and cabling, top view The P2 is the predecessor to the P3-AT from ActivMedia This model has four wheels and motors with encoders The AT model has optional sensing software to make utilize the new sensing hardware and turn that into intelligible commands the robot can follow.
The robot comes with upgrades including inertial correction that counters “skid steer dead reckoning errors.” The bot can be accessorized with laser range finders, both front and rear sonars, pan/tilt/zoom color cameras, stereo range finder cameras, and day/night vision cameras Finally, GPS, color-tracking, compasses, and tilt position sensing hardware round out some of the most desireable add-ons Internet operation is also available with this model.
Another angle view of the Pioneer 2.
Pioneer 2 with a view of serial cable.
Trang 12ended problems where, for example, there may not be a
single right answer The developers want the architecture to
learn and use a variety of knowledge bases and problem ing skills They want it to enable robots to interact intelligent-
solv-ly with the world around them They want to enable robots tolearn more about their own activities, tasks, and behaviors.SOAR bases perception and action on all existing knowledge including the latest interpretation of inputs fromthe outside world SOAR follows a robot AI model thatappears to closely resemble how human beings process information for the purposes of perception and response.Working forward from version 8, developers are seeking tostore multiple representations and interpretations of acquiredknowledge, as well as to acquire that knowledge in differentways SOAR brings all this knowledge to bear on every perception, decision, and reaction at the software’s runtime.Developers are turning SOAR into a suite of cognitive capa-bilities matching those of the human brain SOAR can retrieveknowledge and memories of previous perceptions and reactionsand model those to determine how to react in the current state
Fine Tuning
In order to make sure the virtual world as perceived andmodeled by the robot and the real world match up, therobot’s rules test for differences between the two If there is
a new object, if an object has moved or changed, there arerules to deal with these differences
To do this, SOAR and the vision system work to collectthe more vague bottom up information about segments ofvisual data, stereo information (there are two cameras), andmotion information
The SOAR system applies rules to the robot to force it toexamine the object from the top down by turning its stereovision
to focus on the object more exactly System rules process the top
down vision data by examining portions
of the object via the object recognitionsoftware The results of those examina-tions are stored in SOAR SV
Pace robot clip
http://csis.pace.edu/robotlab/ clips/RobotWorldModel.mpg
Large Pace robot clip (save file before viewing)
http://csis.pace.edu/robotlab/
clips/puma.avi
RESOURCES
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
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Trang 13The International Business Development Event for the
Personal, Service and Mobile Robotics Industry
April 8-10, 2008 Pittsburgh, PA
David L Lawrence Convention Center
BUILDING AN INDUSTRY
Now in its fifth year RoboBusiness Conference & Exposition is the must-attend event for those
interested in the business and technical issues related to the development of the personal, service and
mobile robotics industry
WORLD CLASS SPEAKERS
RoboBusiness 2008 features two days of keynotes & general sessions delivered by internationally
recognized leaders from business, government and academia RoboBusiness tracks include:
Q Business Development and Partnership
Q Applications and Products
Q Achieving Autonomy New!
Q Workforce Development New!
Q RoboMedicus/Healthcare Robotics New!
Q Security and Defense
Q Intelligent Transportation and Field Robotics New!
Q First Responder Robotics New!
Q Consumer Robotics
EXPOSITION AND SPECIAL EVENTS
Q Expo floor featuring over 75 companies from around
the world
Q Opening night Networking Reception
Q ‘Open Door’ Keynote New for 2008
iRobot CEO Colin Angle’s keynote open to all attendees
Q Robot Hall of Fame reception and induction
ceremony New for 2008
Q Site visits to Carnegie Mellon Robotics Institute and
National Robotics Engineering Center New for 2008
For more information or to register, visit
Register by March 14th and Save $200 on a Full Conference Pass
Trang 14As a mechanical engineering
student, Evan has been learning
about things like how Bessel
functions are the eigenfunctions of the
Sturm-Liouville Equations that can be
used to describe heat conduction in
nonrectangular geometries, and how
computational methods like the
Newton-Raphson method can be used
to find the solution to large nonlinear
systems Such highbrow concepts in
engineering — however interesting they
might sound — can only be mastered
with a firm grasp on the fundamentals
of engineering and physics
In our last article with the V-Bot,
we alluded to the simple R/C cars that
we outfitted with aluminum armor and
weapons for “rumbles.” While these
simple emulations of the action we had
seen on Battlebots might have seemed
like nothing but wholesome fun, we
were actually learning the
fundamen-tals of engineering that would be the
foundation of our success in big bot
competitions like FIRST and beyond
Keeping the Team
Together
Our first foray into robotics came
when we were in middle school, and
with the help of our dad and scavenged parts from CosworthRacing, we competed in Botbash 2001with our 60 lb entry Troublemaker Thethrill of competition inspired us tospread the joy of robotics to our peers,and when we got to high school weformed a robotics club, Club CREATE(Chaparral Robotic Engineers andTechno Explorers)
Our original ambition with ClubCREATE was to enter a combat roboticscompetition, but the design andfundraising process was daunting andslower than the lowest setting on acrock pot Brainstorming sessionsbegan to lose their luster when we didn’t have much to actually work on,
so we had to think of something else
to do; something fun, yet productiveand instructive
To keep the team interested and tohone our skills in combat driving, weorganized a series of rumbles withsouped-up R/C cars The extent of ourmodifications was basically to outfitour cheap R/C cars with aluminumweapons, but that was already a goodlesson in some shop skills We learned
to use aviation shears, hacksaws, andjigsaws, and while these skills may betaken for granted by many folks that
have been hobbyists or professionalsfor a long time, you have to learnsometime
The R/C car rumbles were a greatproject to practice our shop skills on,because it was just for fun and conserv-ing time and material was not an issuelike it would be in a competition likeFIRST So we were able to build ourconfidence with tools in a relaxed setting, and with all the metalworking
we did, we even became acquaintedwith the properties of materials
The Burning Means It’s Working
Our most sophisticated endeavor
in crafting our weapons was a rudimentary foray into heat treatment
of materials We employed usedengine oil as our heat treatment fluid,and the objects of our treatment werenails that we thought lacked the bite to
be truly fearsome We used an acetylene torch to heat up the futureinstruments of destruction, and then
we quenched them to seal the deal.While we might not have known thesubtleties of the effects of heat treatment and quenching on grain size,simply becoming familiar with the
THIS MONTH:
Back to Basics
Trang 15process was still a valuable lesson.
Our tutelage in materials science
included a number of other topics that
may have been somewhat less exciting,
but also undeniably useful Working
with our makeshift aluminum weapons
was a good introduction to the
different alloys of aluminum We
learned useful tidbits about how 7075
aluminum is unweldable and will tend
to fracture instead of bend, and
that 6061 aluminum is much
more amenable to being bent and cut
by aviation shears
We picked up other useful tidbits
like how the number at the end of the
alloy designation (like T6) referred to
the heat temper And again, even
without knowing the subtleties of the
International Alloy Designation System,
simply being able to identify the
different alloys was a great first step
Our endeavors to create the most
fearsome weapons also introduced us
to a variety of materials, most notably
titanium, which loomed imperiously in
our untrained minds as something
particularly formidable Like all
materials, titanium has its uses and its
drawbacks, but we simply saw our
titanium valves as the perfect way to
give our combatants a sophisticated
bite They may not have been
particularly sharp, but they were
titanium, so the valves were cool
And in our situation where
scavenged materials were plentiful,
discussions about where they came
from (in this case, racecar engines)
were natural and informative
Not all of our lessons in
materials came with the cold luster
of assorted metals — we were
also introduced to the world of
reinforcing materials like carbon
fiber We appreciated the carbon fiber for its cool factor and its goodstrength-to-weight ratio, and eventhough we weren’t referring to things like ultimate tensile strength,resilience, and compressive strength,the project was still helping us todevelop that intuitive sense of whatmaterial is effective for a certain application Such an intuitive sense iscertainly useful for many projects during the initial brainstorming stage,and it certainly buoys confidence inone’s problem — solving abilities
And, of course, we became wellversed with that most indispensable ofall the engineer’s favorite materials —duct tape Competitors like the DuctTape Avenger can attest to the univer-sal applicability of the stuff, even if it isnot the most elegant of solutions(though not for lack of trying)
Other simple lessons were alsoinstilled in our budding scientificminds during the building phase, like everything from the virtues of conserving material (try cutting thatpiece from the edge instead of thecenter so you can get another spikeout of it) to the benefits of puttingbevels in plates to improve strength
Just learning the little tricks that experience teaches was a great benefit of the project
Are You Ready to Rumble?
To turn our cheap R/C cars intofearsome competitors, we had to consider more than just weapons — thescariest weapons would be useless ifthey were on a robot that couldn’t stayupright One of the important lessons
we learned in the rumbles that applies
to everything from R/C cars to FIRSTrobots was the importance of keepingtrack of the center of gravity
Tall robots might look intimidatingwhile upright in their full glory, butthey become much less terrifying oncethey have inevitably tipped over.Bryce’s low profile Quagulis was nearlyimpossible to flip over and, as a result,was one of the top competitors in therumbles Evan’s Duct Tape Avenger
Trang 16Twin T Tweaks
was a higher profile robot that often
found itself on its side after sustaining
a well placed hit at the hand of one of
its rivals
Center of gravity may seem like
another one of those intuitive
con-cepts, but crashing R/C cars are much
more exciting display of physics than,
say, the equation for center of mass:
R =∫ ρ(r) r dV
∫ ρ(r) dV
which basically integrates a position
weighted mass density and divides that
by the total mass This formula is muchless intuitive to the untrained mind,and this points to another benefit ofthe rumbles — all of the lessons wewere learning would eventually be for-malized by formulas and theories insidethe classroom and lecture hall, but ouradventures with Quagulis and Nidhogggave us a personal context thatallowed us to visualize and learn all ofthese lessons more easily
Keeping Our Momentum
The rumbles were also very instructive on the subject of momentum While smaller competitorslike Miscreant and the Masking TapeAvenger might look fierce, they weretragically outmatched by the sheer size of bots like Slag The essence ofthis disadvantageous match-up was in the difference in momentum betweenthe competitors Momentum is given
by the equation:
p = m*v
where p is momentum, m is mass, and
v is velocity Some of the smaller carsdid have comparable speeds with thebigger competitors, but they were sore-
ly outmatched in the mass department
This points out the benefit of ing robots into different weight classes,which we did in our rumbles In therealm of combat robots in particular,change in momentum can be related
separat-to force by the impulse equation:
F*Δt = m*Δv
where F is force, Δt is the time interval over which the force isapplied, m is the mass of the movingobject, and Δv is the change in velocity due to the impact Manyprospective engineers have an intuitive sense of this phenomenon,but seeing it put into practice as onearmored R/C car runs into anotherwith spikes clashing and tires squealing is enough to spark the curiosity to ask the question as to why
it actually happens in the first place.Once again, this is a time when wewere developing a context for our laterformal training, and all the talk aboutelastic and inelastic collisions and conservation of momentum could beassociated with exciting images andmemories in addition to the equationsand pictures in the textbooks
Sporque — Not Just
a Freakish Utensil Anymore
Occasionally, the rumbles couldinvolve some pushing matches andother displays of brute force, and suchincidents were very enlightening in thearea of speed and torque Quicker bots like the Duct Tape Avenger mightlook intimidating when they reached ramming speed, but slower, torquierbots like Slag would inevitably win in ashoving match
Of course, these comparisons arenot completely fair because the R/Ccars may have been graced with differ-ent motors, but it was still certainlyillustrative of the unavoidable tradeoffbetween torque and speed In
an ideal world, it would be wonderful to have both hightorque and high speed, but therumbles did us the service ofopening our eyes to the harshreality that you can’t always getwhat you want
A tentative foray intomotorized weapons was able todemonstrate an extreme case
of the torque/speed tradeoff
We were able to get our hands
on some nondescript highspeed motors, and they seemed
SLAG.
MISCREANT.
Trang 17to be the perfect way to create some
menacing spinning weapons After
outfitting the shafts with some cut
aluminum, attaching an extra power
source of a couple AA batteries, and
fastening the whole thing together
with generous amounts of duct tape,
we couldn’t deny that the spinners
looked positively ferocious on little
bots like Nidhogg The aluminum
blades spun at such speed that they
became a blur, and to look at them
one would likely think that they
were capable of inflicting some
serious damage
As those acquainted with the laws
of physics might have already guessed,
the spinning weapons were, to say the
least, disappointing They would come
to a screaming halt after what seemed
like a simple love tap on its rival, and
the worst damage they could do was
purely cosmetic And on top of all that,
they even had a slightly noticeable
effect on the movement of the R/C car
that was sporting it — turning became
more difficult We may not have
built an effective weapon, but we did
unintentionally create a passable
gyroscope
Despite the ineffectiveness of the
spinning weapons, the whole scenario
was the perfect segue into a discussion
about gear ratios Many times,
discussions that make ample use of the
terms “ratio,” “radius,” and “angular
velocity” might cause an uncooperative
student’s eyes to glaze over in a bored
stupor, but the rumbles once again
gave an exciting context to the
discussion Talks like these weren’t just
about geometry and enigmatic Greek
letters, they were about improving the
weapons on your bot so that next time
you might just be able to give
Miscreant what’s coming to it
C F E.
The rumbles also began our
life-long education in the subject of Cool
Factor Engineering Making
some-thing functional may be paramount,
but we think the penultimate goal of
any project should be to make
something that you are proud of In
general, we find that we are proud of
a project when it is interesting, eyecatching, and simply exudes an air ofcoolness In the case of our R/C cars,that might mean adding plates of carbon fiber, or using titanium valesfor weapons instead of cut aluminum
The tiny competitor Bucephalus was
a perfect example of how to achieve cool factor through a careful combination of sculpted aluminumand Greek mythology
In later projects like FIRST robots,cool factor might be achieved withclean wiring, smooth bottom panels byvirtue of countersunk screws, or colorful stickers that gave credit to ourgenerous sponsors Whatever form itmight take, cool factor is one way that
we and our teammates have been able
to establish that all important ownership of our projects Personaltouches and details meant to add just alittle bit of flair are important, becausethey can be the deciding factorbetween pointing to a project and saying “I made that and it completes atask” versus “I made that, it completes
a task, and it’s awesome.”
Cool factor also plays a role in thelarger world of robotics, and especially
in the arena of public opinion Case inpoint: The Neiman Marcus 2007 holiday windows promised robots decorating a Christmas tree, and whenthe curtains were pulled back to revealautomotive assembly line robots dutifully placing ornaments, someexpectant onlookers asked themselves
“where are the robots?” But when ple see Honda’s Asimo on televisionseemingly leading the march to thefuture, they are hard pressed to identify it as anything other than arobot Automotive assembly robots,though undeniably functional, lack thecool factor required to make them universally recognizable as robots
peo-Folks inside the technology tries may have no problem identifyingthe indefatigable arms as fine specimens of the robotic species, butmany people are looking for somethingthat looks like Rosie from the Jetsons
indus-or a Transfindus-ormer to fit their definition
of a robot Critics of this perception ofrobots may argue that designs thatlook like Optimus Prime are not nearly
as effective at vacuuming floors as
a Roomba, but they probably also wouldn’t deny that it would be totallyawesome to have Megatron doing your dishes
Some research scientists mighteschew public opinion as inconsequen-tial for robots that are firmly rooted inR&D laboratories, but commercialrobotics companies need to appeal totheir consumers through sleek designsthat are undeniably benefited by theaddition of a bit of cool factor
Cool Factor Engineering fosters asense of pride in one’s work, andshows that functionality and aestheticvalue are not mutually exclusive It’senough to challenge Oscar Wilde’sadage that “all art is quite useless.”
Fun: Part of a Balanced Intellectual Diet
What we’re trying to say is thateven a really simple project that seemsmore concerned with fun than withhard scientific principles can still reinforce a solid foundation in engineering Even if the participantsdon’t know the exact terminology forcenter of gravity or tank style drivetrain, they are still learning the principles, and they are developingthat all important intuitive sense ofwhat works and what doesn’t
Simple projects like these are also
Back to Basics
BUCEPHALUS.
Trang 18a great way for parents to mentor their
kids, even if they don’t have the
technical background of the mentors
on FIRST teams that know the ins and
outs of C programming and control
theory All an effective mentor needs
to do is start asking the right questions
— “why do you think the Duct Tape
Avenger flipped over?” or “how do you
think you can make that
flamberge-esque spike stronger?”
Kids can learn to celebrate thesearch for answers, and according toDean Kamen, we get what we celebrate Our R/C car rumbles — liketheir larger combat robot inspirations
— don’t celebrate violence or tion; they celebrate the competitivetesting of ideas, and the prospect ofcustomizing an R/C car for battle likebigger bots on TV might be justenough to pull Junior away from the
destruc-Guitar Hero for an afternoon Justinstilling that positive association withproblem solving and science is thefirst step to helping them becomesuccessful engineers, and that’ssomething any mentor can do nomatter what their level of technicalexpertise
Little fun projects like our R/C carrumbles can also instill that sense offun and excitement that kids don’tlearn to associate with engineeringfrom doing free body diagrams andrepetitive calculus problems It canexpose them to the exhilaration ofproblem solving, even if the problem isfinding the way to best inflict mortaldamage upon your mechanical opponents And our R/C car rumblesreally did that, by keeping the robotclub together and giving us the foundation we needed to succeed incompetitions like FIRST and beyond.The thrill of competition and theexcitement of duels between rivals likeQuagulis and the Duct Tape Avengerkept the imaginations of the team upand running — many times the smallscale tussles would inspire ideas that
we planned to put into practice on abigger robot
At first, our target big bot was theproposed combat robot, but upon discovering FIRST and the KleinerPerkins Caufield and Byers grant, wedecided to change course and followthe path of least financial resistance.And, in truth, if you look at our robot
MO, built for the 2003 FIRST Season(Stack Attack), you can see that many
of the lessons and inspirations of therumbles finally found their form MOhad a low center of gravity, slantedsides reminiscent of combat robotwedges, and it was decked out with the very same aluminum alloysthat we used when fashioning ourpint-sized weapons
After a successful run in tions ranging from FIRST to PAReX(Phoenix Area Robotics Experimenters)
competi-to the Solar Cup, the team membersthat participated in those rumbles arenow sprinkled throughout the country
as engineering students at top notchuniversities, and they’re living proofthat fun does a brain good SV
Twin T Tweaks
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Trang 19Know 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
7-8 AMD Jerry Sanders Creative Design Contest
University of Illinois at Urbana-Champaign, IL
Check the website for the details of this year’s contest
or — the most interesting — build robots that cancreate graphic works of art
www.nationalroboticschallenge.org
8 Fort Collins Robot Fire Fighting Challenge
Discovery Science Center, Fort Collins, CO
This is a regional for the Trinity College Fire FightingRobot contest Autonomous robots must locateand extinguish a flame in a scale model of a home
www.strout.net/fcr f fc
15-16 Manitoba Robot Games
Tec Voc High School, Winnipeg, Manitoba, Canada
Included in this competition are a mix of events for autonomous and remote-controlled robotsincluding Japanese style mini-Sumo, Western styleSumo, a robot Mini-Tractor Pull, Super Scramble,line-following, and the Robo-Critters contest for kids
www.scmb.mb.ca
15-16 Roboticon
University of Guelph, Ontario, Canada
The robot contest is part of a larger UniversityOpen House day which includes contests in every-thing from flower arranging to pancake flipping
www.collegeroyal.uoguelph.ca
29 CIRC Central Illinois Bot Brawl
Lakeview Museum, Peoria, IL
This event includes RC combat, autonomous Sumo, line-following, line maze Autonomous andremote-control robots
http://circ.mtco.com
30 Boonshoft Museum Robot Rumble
Boonshoft Museum, Dayton, OH
This event includes robot building and competition
www.boonshoftmuseum.org
TBA Penn State Abington Mini Grand Challenge
Penn State Abington, Abington, PA
Includes outdoor autonomous mobile robot navigation
www.dprg.org/competitions
Apri
26 RoboFest
Lawrence Technological University, Southfield, MI
Includes game competition — two autonomous robotswork together Also robot exhibition, RoboSumo,RoboFashion show, and mini urban robot challenge
http://robofest.net
12-13 Trinity College Fire Fighting Home Robot contest
Trinity College, Hartford, CT
The well-known championship event for fire fighting robots
www.trincoll.edu/events/robot
Send updates, new listings, corrections, complaints, and suggestions to: steve@ncc.com or FAX 972-404-0269
Trang 20Q. I would like to know your opinion on performing
some simple modifications to my SumoBot from
Parallax so that it can be used to solve line mazes It
is my understanding that I would need some encoders on the
wheels so that it can keep track of how far it has moved so
that it can repeat its previous paths I am not an electronics
expert, so I am hoping that you can point me to something
that is more plug-and-play than build from scratch Any help
would be greatly appreciated
— Lynn Brown
A.This sounds like a fun project! I think I have the ideal
set of plug-and-play products for you Yes, encoderscan be a big help in solving a line maze, but they arenot required Many people do this without encoders
As for simple off-the-shelf, plug-and-play encoders thatwill work great with the SumoBot, take a look at the
WheelWatcher encoders from Nubotics (www.nubot
ics.com) These encoders are designed to mount directly
to regular servo motors (that have been modified for continuous rotation) like those used with the SumoBot.These encoders will keep track of how many degrees eachwheel rotates and the direction of each rotation Theseencoders also come with a self-adhesive encoder disk that ismounted to the inside of the wheel With the SumoBot’s 2.6inch diameter wheels, these encoders — by themselves — cankeep track of positional accuracy of at least 0.25 inches oftravel (π * 2.6 inches/32 counts per revolution = 0.25 inchesper count) Technically, all the BASIC Stamp has to do is keeptrack of the encoder counts for each wheel as the robotmoves through the maze
But, having the BASIC Stamp keep track of all of
the encoder counting, direction control, turning, updating theservo motion commands every 20
ms, and monitoring the line sensors while trying to solve themaze is going to be a bit of a programming challenge That’s not
to say it can’t be done since manypeople have been very successful
in doing this, but there is anotherplug-and-play device that will greatly simplify all this
The WheelCommander fromNubotics (Figure 1) is a closed loopdifferential servo motor controller.With this controller, all you have to
do is tell the robot how far youwant it to go, how fast you want it
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?
Figure 1 The WheelCommander closed loop
differential servo drive motor controller Figure 2 Original Parallax SumoBot
before modifications.
Line Maze is typically a contest where a line is placed down
the center of a maze puzzle There is no wall in this type of a
maze and the robot must use the line to solve the maze Many
contests allow the robot to run through the maze several times,
and the fastest run time is used for the final score Remembering
the maze path helps to greatly reduce the amount of time
required to solve the maze on subsequent attempts One
source for a complete set of rules for this type of a contest can
be found at the Robothon website (www.robothon.org).
LINE MAZE
Trang 21to move, or what angles
you want it to turn (there
are many other
parame-ters that you can control)
You no longer have to
worry about controlling
and monitoring each
individual wheel to do all
of this The robot’s motion
is now controlled by a
small set of RS-232 serial
commands or I2C
com-mands, and best of all, the
BASIC Stamp no longer
needs to update the servo
positions every 20 ms This
frees up the BASIC Stamp
to focus on monitoring the line sensors and solving the maze
When the robot reaches an intersection, it can query the
WheelCommander to see how far it has moved and can
record this value for later analysis
Figures 2 through 13 show some assembly steps in
upgrading the Parallax SumoBot with WheelWatcher
encoders and the WheelWatcher Commander for motion
control Figure 2 shows the original Parallax SumoBot (before
modifications) with the opponent infrared sensors removed
Figure 3 shows the jumbled mess of wires after the BASIC
Stamp embedded in the SumoBoard has been removed
Figure 4 shows the servo removed from the SumoBot
next to all of the parts that come with a WheelWatcher kit
All of the nylon spacers and washers shown here are not
used in the assembly process Depending on the geometry of
the servo motor, different combinations of washers and
spacers are used to ensure that the WheelWatcher board is
properly spaced on the servo
The manual that comes with the WheelWatcher lists
several spacer and washer combinations to use with several
different types of servos The Parallax servo shown here was
not included in the list in the manual, but it uses the same set
of spacers as the Futaba S3001; so use the short spacers and
the thick washers in the assembly process
Figure 5 shows the WheelWatcher mounted on theservo The clear plastic disk on the servo’s output spline is thealignment tool that comes with each WheelWatcher kit Thistool ensures that the encoders are mounted with the properorientation with respect to the servo shaft Figure 6 shows the servo and WheelWatcher mounted back on theParallax SumoBot
The existing Sumo ring edge sensor cannot remainmounted in its original position using the existing 1-1/4 inchlong aluminum spacer This will interfere with the connector
on the WheelWatcher It will have to be removed Since linesensors on line following robots are located more towardsthe centerline of the robot, I turned the sensors around andused the two existing holes at the base of the robot frame asnew mounting locations
To conserve parts, I used two of the long spacers fromthe WheelWatcher kit and the small nylon spacers that were
on the original sensor post with a new 4-40 x 5/8” longscrew to remount the sensors Figure 7 illustrates these components and Figure 8 shows the bottom of the robotwith the new sensor orientation Note that the distancebetween the sensors is now about one inch
Figure 5 WheelWatcher mounted on the servo Figure 6 WheelWatcher and servo mounted
back on the Parallax SumoBot.
Figure 4 Servo, wheel, and WheelWatcher components Figure 3 SumoBoard removed
from the SumoBot.
Trang 22The best place to mount the WheelCommander is right
on top of the servos (directly under the SumoBoard) Due to
vibrations in the robot and flexure between the two servos, I
decided that I was going to place a small board between the
WheelCommander and the servos Figure 9 shows some
double sided foam tape added to the servos for mounting
the intermediate board, and Figure 10 shows a 1/4” thick
piece of scrap Sintra (expanded PVC) You can use different
types and sizes of material here This was just something I
had lying around I then used two more pieces of double
sided foam tape to attach the WheelCommander to this
board (see Figure 11)
Figure 12 shows all the wiring attached to the WheelCommander Youshould notice that there is anew battery attached tothe front of the robot TheWheelCommander requires
a minimum of 6.2 volts tooperate properly Since theregular SumoBot usesonly four AA batteries(6.0V), they were insuffi-cient to power theWheelCommander along with the BASIC Stamp and drivethe servo So, I added a 9V battery to the front of the ParallaxSumoBot This battery fitted nicely in front of the servos andWheelCommander A rubber band was used to hold the battery to the screws that hold the servos in position
Figure 13 shows the completed robot The servo power
to the WheelCommander is plugged into the B and R pinsused to power the servos on the original SumoBoard I chose
to do it this way so that I can take advantage of the three-way power switch on the SumoBoard to make sure that the servos are not accidentally powered during
rogramming efforts The rest
of the wiring is pretty much the same as outlined in theWheelCommander manual.Ideally, you would add apower switch to turn the power
on to the WheelCommander Ichose to use simple connectors.There are two things youare going to want to downloadfrom the Nubotics website.The WC Wizard programand the example program(wc116_bs2_demo.bs2) for theBASIC Stamp The WC Wizard is
a great utility for testing andconfiguring the WheelCommanderfor your specific robot’s geometry Also with the WCWizard, you can tune the PID(Proportional, Integral andDerivative) constants for theclosed loop position and velocitycontrol of your robot
In addition, you can changethe serial communication baudrate for the WheelCommander.The default baud rate is 38400.Now all of these configurationparameters can be transmitted
to the WheelCommander via the BASIC Stamp The WCWizard has some nice visual
Figure 7 Reusing parts for sensor relocation Figure 8 New edge/line sensor orientation.
Figure 11 WheelCommander mounted
on the servos Figure 12 All wiring attached to
the WheelCommander.
Figure 9 Double sided foam tape for
mounting the WheelCommander to the servos Figure 10 Intermediate board between the
servos and the WheelCommander.
Trang 23feedback to help with the PID tuning.
To avoid a huge problem I had with using the WC
Wizard, make sure that the RS-232 adapter between your
computer and the WheelCommander converts the signal to
standard TTL voltage levels (0-5V) and that it inverts the l
ogic levels, or the two devices won’t communicate with
each other Also, make sure that the CTS and RTS lines
are jumpered together The WheelCommander manual
recommends several adapters from Acroname (www.
acroname.com) who is also a distributor of the Nubotics
products
It is highly recommended that the baud rate be changed
from 38400 to 9600 for the BASIC Stamp that is embedded
on the SumoBoard This is because at higher baud rates, they
don’t synchronize together properly
In the example program, there is a subroutine called
“initfw” (see below) The call to this routine is normally
commented out since it only needs to be called once The
first command “F0302” changes the baud rate to 9600 If
the baud rate was changed by the WC Wizard, this line can
be commented out The command “F0289” MUST be
execut-ed one time successfully after the baud rate has been
changed to 9600 Otherwise, the BASIC Stamp won’t be able
to effectively communicate with the WheelCommander
(actually setting bit 0 to high for the Mode Constant is
needed) This command adds a critical time delay in the
seri-al communication strings that is needed for the BASIC Stamp
to properly synchronize and transmit all bytes back and forth
At this point, you should be ready to start programming
your robot to solve line mazes Like I said before, this sounds
like a fun project When you get your robot up and running,
write a short article about what you did and submit it to
SERVO Magazine I am sure many readers would love to
learn and see what you did
Q. I have noticed over the years that you use the
BASIC Stamps and the SX microcontrollers in most
of your examples Why is that, and why haven’t you
talked about the new Propeller microcontroller from Parallax?
This looks like a very interesting microcontroller, especially
with its multitasking capabilities
— Shawn Kidwell Montgomery, CA
A. I suppose that some people may think I am biased
towards Parallax (www.parallax.com) products Well,
to tell you the truth, I am biased towards them
Especially in the context for this magazine and the way I write
my articles The way I look at all of this is that most of the
people that read this magazine want to learn how to do
something I have chosen a writing style that tries to explainhow you would go about solving various challenges with realworking examples, along with explanations of how thingswork and also showing some pitfalls
This teaching style is one of the main reasons I like ing with Parallax products They have the best documenta-tion in the world on how to use their products (along withmany other topics such as basic electronics) with many prac-tical examples Their documentation style is about teachingpeople how to do things from scratch, taking you from little
work-to no experience work-to making you a competent embeddedmicrocontroller applications designer/robot builder If yourun into a problem, give them a call or go to their onlineforums, and they will bend over backwards to help you
If after building one of my example products, you want
to learn more about what you can do with a BASIC Stamp orwith the SX microcontroller — or even with the Propeller —you can find the answers on the Parallax website or on their
forum pages (http://forums.parallax.com).
I am not saying that other microcontrollers and documentation is bad They have their places, and they havesome very devoted supporters/developers In most applica-tions, just about any microcontroller will work just as well asany other microcontroller Some just do certain things betterthan others That is why there are so many to choose from
In most applications, Parallax products will do a fine job
As for the Propeller chips from Parallax, to tell you thetruth, I haven’t really had the chance to dive into them untilrecently And now that I have, I wish they were aroundmany years ago when I first got involved with robotics Forrobotics applications, the Propeller chips are probably thebest microcontroller out there The reason I say this isbecause it can do multiple things at the same time Withother microcontrollers, we spend a lot of time trying to figure out how to write code that can continuously monitorits environment, make decisions on what the sensors aretelling it, and controlling all the functions of the robot.Trying to get the right timing of all of these different things
Figure 13 Completed reconfiguration of the Parallax SumoBot.
Trang 24often becomes very difficult, and in many cases, desired
capabilities are scrapped because proper timing cannot
be executed
Here is a different way to think about robotic
programming: Habits Yes, habits Let’s use an interesting
illustration — driving a car When you first drove a car (for
those of you that are not old enough to drive, you will
expe-rience all of this), it was a very complex endeavor Working
the gas pedal, brakes, clutch pedal, working the stick shift,
the steering wheel, turn signal, looking at and reading road
signs, watching out for all the cars in front of you, to the
sides, the rear, and planning your route to your destination
These are many different things that are done at the same
time But after driving the car for a while, you no longer had
to think about all of these things Instead, you get in the car,
turn it on, and proceed to your destination Now the only
thing on your mind is the next robot project you are
working on All of the early trials in learning how to drive are
now habits that are automatically happening without any
conscious thought
But when we program our robots, these basic little
habits are still a main part of the thought process Thus, the
main microcontroller is spending all its time working on all
the tiny little details Can you imagine how tough it will be to
drive, if every time you got behind the wheel it was like the
first time, and you have to actively process every little detail?
Traffic would definitely be lighter since most people would
give up and take the bus
Now if we can off-load many of these little “habits” to
parallel processors, they can then spend all their time focused
on dedicated activities — such as: infrared sor arrays with ultrasonic sensors for obstacledetection; a video camera for tracking a redcolored object; PID motor speed controller; RFdata uploading and downloading; etc All ofthese tasks then talk to the main processor todetermine what to do next based on the datafrom the various inputs Each one would runindependently without having to deal with thetiming of the other processes You could usemultiple microcontrollers that are dedicated to each task to
sen-do the same thing But every processor can share databetween each other on an as-needed basis without a mainprocessor having to coordinate the efforts between them This can open up a bunch of new programming/robotbehavior capabilities
Take, for example, a remote control humanoid robotusing an off-the-shelf Playstation 2 wireless controller I havewritten several articles on how to simplify the communicationbetween devices using these types of controllers since theactual data transmitted wirelessly is rather complex, and ittakes a certain amount of time to process Now when ahumanoid robot is moving 17 different servos at one time,there is a lot of control algorithms running to synchronize theservos If the human operator decided to tell the robot toturn to the right while the robot is walking forward, the mainmicrocontroller will finish the current set of motions thenlook for the remote control It will send out a command, “I
am ready,” and the controller will respond with its currentstate Then the robot will respond to it In many cases, by thetime the robot is ready to make that right turn, it is too late, especially in a ROBO-ONE style of competition
(www.robo-one.com).
Now if a Propeller was being used to control the robot,
it could be monitoring the Playstation 2 controller continuously, and when a new motion command is executed,the robot will have continuous information about controllerstatus and can immediately respond without any lag times between motion sequences Believe me, the lag time israther annoying
The Propeller can run up to eight different 32 bit tasks atthe same time This is a ground up design from Parallax that
no other company has done — a true multitasking troller With a clock speed up to 80 MHz and a total of 64kbytes of memory, some very amazing things can be donethrough the 32 I/O pins which can sink/source up to 40 mAeach The Propeller has two different programming languages One is called SPIN and the other is assembly,where SPIN is Parallax’s higher level programming language.Figure 14 shows a photo of the Parallax Propeller demoboard with the H48C three-axis accelerometer module with
microcon-a NTSC LCD video monitor grmicrocon-aphicmicrocon-ally displmicrocon-aying the orientation of the accelerometer All of these componentsare available at Parallax and the source code can be downloaded from their website The Propeller is directly controlling the video display
One of the coolest features about this microcontroller
is that its programming environment is an object oriented
LCD Drivers Xbee Transceiver CMU Camera Tracking
TV Terminal Gamecube Controller GPS Drivers
VGA Drivers Playstation 2 Controller HM55B Compass
Four Servo Driver NES Controller Kalman Filter IMU
32 Servo Driver IR Remotes Memsic 2125 Accelerometer
PID Motor Control H48C 3-Axis Accelerometer Quadrature Encoders
Table 1 Propeller objects that may be of interest to robotics applications.
Figure 14 Propeller displaying accelerometer
orientation on a video display.
Trang 25programming language This makes life really easy in writing
programs for the Propeller Instead of having to develop
code for yourself for every little task, you can use objects
that have already been developed — either by yourself or
someone else — to perform several functions Table 1 shows
a short list of objects that are available for robotic
applications (downloadable from the Parallax Object
Exchange; http://obex.parallax.com) There are many
more types of objects that can be downloaded and new
ones are constantly being added The reason I bring this up
is that it won’t take you long to get some fairly advanced
robotic controls up and running
When I started reading about all the things the Propeller
can do and looking at the source code for some of these
objects, it was pretty intimidating at first since it didn’t look
like anything I was really used to seeing So I broke down and
read the first three chapters of the Propeller manual and
typed in and ran all 12 examples in Chapter 3 This took a
couple evenings to go through After all of this, I was quite
comfortable in reading, understanding, and writing code for
the Propeller Remember what I said before — Parallax has
some excellent documentation
The H48C three-axis accelerometer demo setup shown in
Figure 14 is one of the coolest things I have seen in a really
long time The ability to display information — especially
animated graphics — on a TV display without any special
hardware really makes visualizing where the sensor is going
intuitive The Propeller is going to make the Nintendo WIIcontroller look like child’s play in my opinion
I believe the Propeller microcontroller is going to be thebig breakthrough for many of our robotic projects because
we will now have a better way to continually sense our environment and process the various robot controls all at thesame time without any time sharing constraints that havebeen holding us back I believe this will give our robots thoselifelike responses that we have been dreaming about SV
I hate to say this, but this is my last column as Mr.Roboto I have enjoyed all of your great questions and comments over the years It is amazing that I started thiswhen the magazine first came out in 2003 With our newdaughter and other time commitments at home and church,
I have decided to slow down on my writing efforts I am notgoing away completely since I will be submitting some full-featured articles in the near future on topics that includebalancing robots, humanoid robots, and CNC controllers,
to name a few, all using and demonstrating the power of the Propeller microcontroller In the meantime, a highlyrespected and experienced robot builder and writer,Dennis Clark, will be taking over the Ask Mr Roboto helmwith next month’s issue Thank you for all of your support,and keep those great questions coming in!
SIGNING OFF
Trang 26module types The board
provides the antenna, power
supply regulation and RS232
/ USB interfaces to the Micro
RWD module itself
Features include 24-pin
DIP socket for Micro RWD Modules, LEDS for visual status
indication, selectable PCB and coil based antenna for 13.56
MHz and 125 kHz operation (Antennas are etched into
the circuit board External antennas are not necessary.),
voltage regulation allowing 9-12V DC power supplies to
be used Additional connectors have all the Micro RWD
module electrical signals available
The Universal Base Board data sheet details the link
settings, circuit diagram and interface connections Gerber
files for the PCB layout (useful for the antenna dimensions)
are available on request Please note that the Universal Base
Board does not have the USB module or a Micro RWD
mod-ule fitted as standard These items are supplied separately
For further information, please contact:
DC Motor Driver
The H-Bridge DC Motor Driver is designed to allow
TTL output to control the speed and direction of a
DC Motor Input Voltage is 12 VDC and Rated Motor
Voltage is 4V, 6V, and 9V
Application Note:
1) Connect Motor Pin to DC Motor (Pin 1 & 2)2) Connect Pin 4 to Ground and Pin 3 to 12 VDC.3) Connect Pin 5 through 8 to any microcontroller
Pin Assignment:
Pin1 – Motor Pin (+); Pin2 – Motor Pin (-); Pin3 – 12 VDCPin4 – GND; Pin5 – Speed Control 1; Pin6 – Speed Control2; Pin7 – Motor Enable; Pin8 – Motor Direction
For further information, please contact:
Racing Robot Learn
to Solder Kit
The Racing Robot Learn toSolder Kit features a threewheel motorized chassis and acolorful robot face that flashes on and off
as the robot races out of control Race this robotagainst others to see which robot is the fastest Kitfeatures 18 components that you install first to learn goodsoldering techniques Once you have mastered solderingyou then install the one IC circuitry, Face circuit, motor andmechanical assembly Operates from one 9V battery (notincluded) Size of Face PC board about 1.5” x 2” Size ofmain chassis PC board 2” x 4” Complete with all parts, PCboards, motor and instructions Skill Level 1
For further information, please contact:
Far EastNoble Sdn Bhd
Tel: 877•898•1005 Website: www.trossenrobotics.com
Trossen
Robotics
Tel: 800•227•7312 Website: www.chaneyelectronics.com
ChaneyElectronics
Is your product innovative, less expensive, more functional, or just plain cool? If you have a new product that you would like us to
run in our New Products section, please email a short description
(300-500 words) and a photo of your product to:
newproducts@servomagazine.com
Show Us What You’ve Got!
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Trang 27PP:KLWH ZDWHUFOHDU
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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
SchmartBoard — the developer of a
new technology that has
significant-ly simplified the creation of electronic
circuits for hobbyists, education, and
industry — has announced the winners
of its second annual Schmartie Awards
Schmartie Award participants, as a
part of the SchmartDeveloper program,
posted electronic circuit designs with a
bill of materials that included the correct
SchmartBoards (prototype boards) to the
company’s “SchmartDeveloper” website
The grand prize winner receives a $1,000
cash prize, and SchmartBoard will
manu-facture and market a SchmartModule
product with the winner’s name on it In
addition, the winner will receive a
com-mission on each of these product sold
The circuits and information about
the winners and other applicants can
be found at www.schmartdevelop
er.org The winners of the contest are:
• Grand Prize — Giannis Kedros of
Thessaloniki, Greece — wins the grand
prize for his Serial to USB Module
• 2nd Prize — Charles Wenzel of Austin,
TX — wins a DSO8502 500 MHz Digital
Oscilloscope from Link Instruments for
his Low Jitter Quadrature Clock
• 3rd Prize — John Day of Toronto, ON
Canada — wins a Weller WD1002
Soldering Station from Cooper Tools
for his USB to Serial and I2C Module
• Honorable Mention — Daniel F Ramirez
of Amherst, NH — wins a Parallax
Boe-Bot for his Schmart DC Motor
Controller
• Honorable Mention — Russell Pead of
Littleton, MA — wins a Parallax
Boe-Bot for his TTL Test Board
• Honorable Mention — Robert Gatt of
Port Fairy VIC, Australia — wins a
Parallax Boe-Bot for his IR Proximity
Detector
The criteria used to choose the
win-ners were originality, how well Schmart
Board technology was used in the design,
how useful the design is in the real world,
and marketability of the design
Co-sponsors of the contest were Nuts
& Volts Magazine, SERVO Magazine,
Cooper Tools, Link Instruments, Jameco
Electronics, Mouser Electronics, Fry’s
Electronics, Circuit Specialists, Intellect
Announces Six Winners
in Schmartie Awards
Trang 28Featured This Month:
Features
28 The Holy Grail of Combat
Robotics — Usable Melty
34 Dec 2007/Jan 2008 Results
and Mar/Apr 2008 Upcoming
Events
35 Rumble at the Rock: BotsIQ
Gone Varsity
by Michael Bastoni
ROBOT PROFILE – Top
Ranked Robot This Month:
36 Dark Pounder by Kevin Berry
In Part 1, we looked at four botsthat tackled the difficult task ofmaking the whole bot a kineticenergy weapon using a phenome-non of rotating bodies called
“Translational Drift,” or in thecombat vernacular, “Melty Brain.”
In a traditional “Full Body Spinner”
(FBS), contrary to the name, theouter shell spins, but the baseplatform is a traditional “tankdrive” vehicle In a Melty, thewhole bot spins, and by varyingthe drive speed of each wheel asthe bot spins, a translationalmovement results
● by Kevin Berry
Usable Melty Brain Part 2:
Looking Under the Hood — The Technology of Melty Brain
THE HOLY GRAIL
OF COMBAT ROB TICS
FIGURE 1
Trang 29Ilya Polyakov of Team Carnivore
is generally credited with the first
attempts at putting this technology
in the box He says; “At the time, I
was taking Dynamics as part of my
M.E course work and the vector
math behind combined translational
and rotational motion really hit the
spot The identical but opposite
rota-tional velocity vectors combined with
a single translational vector made
sense in the tank-drive perfectly.”
Figure 1 attempts to translate
(sorry, pun alert) this jargon into
language the mere mortal can
under-stand without having the dreaded
(and aptly named) brain meltdown
Ilya also provided a concise
sum-mary of the system’s requirements:
1) The system needs to know how
fast the robot is spinning — this is
fundamental for knowing how often
to output commands
2) The system needs to know where
the robot is pointing or where it
is within one rotation cycle, in
order to control the direction of the
translation
3) The system must be able to make
wheel speed changes at fast rates of
20-30 Hz (once every revolution of
the robot)
4) The mechanical system must be
powerful enough to influence the
robot’s mass enough to make it
translate in the short time the
translational force is being applied
Blade Runner
Polyakov’s first build of Blade
Runner used a BS2SX microcontroller
and a digital compass for directional
and rotational speed sensing
Unfortunately, the hundreds of amps
flowing through the power wires
created some very flawed compass
readings
Version 2 was as basic as
possible with xenon strobes on the
robot illuminated once every
revolution, and Ilya acting as the
tachometer He would sync upthe program speed in the BS2
to the robot’s speed manuallywith a separate R/C channel,then steer the virtual front ofthe disk by advancing orretarding the timing Thiswould align the stationarystrobe light with his opponent
Two other channels controlled the magnitude ofthe translational fwd/rev andleft/right vectors He relates:
“The system worked great in testing,once I got the program rate somewhat synced up to the robotspin rate, I could controllably translate the robot As always, several issues arose in the ring — witharena lighting set up for TV filming,the strobes were barely visible, letalone visible enough for proper persistence of vision
Between the difficulty of seeingthe strobe and the pressures of combat driving, I was never able tomanually sync up the strobe Even if Ihad, I probably would not haveknown it due to the lighting condi-tions I attribute the failure of thatversion to poor planning and lack ofpreparation Had I tested the strobes
in bright sunlight, I would have foreseen the lighting issue and puredriving practice could have takencare of the combat driving issues.”
(Point to remember: LTFD — “Learn
To Flippin’ Drive!”)For Blade Runner 2, the Meltysystem was upgraded to run on aRabbit microcontroller and multiplesolutions for the poor visibility weretried Among the more wacky oneswere strobe goggles made out of 3Dshutter goggle LCD elements, aBS2SX, and a Linx RF serial link to thebot, none of which were successful
As the BattleBots TV serieswound down, so did Ilya’s attempts
at creating a translational drift bot
His path finding efforts led to other,more successful bots
Melty B
Rich Olson of Team SpamButcher
built a successful antweight bot using melty brain technology “To determine its relative position in each spin,” Rich says, “Melty B uses
an accelerometer to measure the centrifugal force created by the rotation of the bot The level of Gforce detected is then run through a formula that accurately determineshow fast the robot is spinning Oncethe exact spin rate is known, it’s possible to determine where it is inthe current spin based on timing.”The robot flashes an LED eachtime it hits a point in the spin it thinks
is “forward.” When spinning, the LEDappears as a streak indicating to thedriver which direction the robot willmove when the stick on the remote
is pushed forward To adjust whichdirection the LED is facing, the drivermoves the remote left or right If atracking error is causing the robot’sheading to drift, the driver can compensate by steering the oppositedirection — just as they would for acar that’s out of alignment
“After working the bugs out,using just an accelerometer for heading tracking works surprisingly
FIGURE 2 Blade Runner 1 guts.
FIGURE 3 Melty B guts.
Trang 30well in both testing and combat I had
originally planned on using an
infrared beacon to improve tracking
accuracy, but that doesn’t seem
need-ed now.” To move forward, Melty B
powers down the motor that’s facing
towards the direction it wants to
travel for a portion of the spin This, in
effect, repeatedly moves the center of
rotation slightly each spin — causing
the robot to travel across the arena
The robot controls its motorsusing inexpensive Darlington drivers
(transistors) Since these only allow
for on/off control, Melty B isn’t
capable of “normal” driving, and can
only move in a melty-brain style The
bot has a top speed of 1,400 RPM
and can “translate” at about 1.5 feet
per second At top speed, forces inside
the robot can reach over 100 Gs
Rich coded his software — over
500 line’s worth — in Bascom AVR
The source code is available on his
website at www.spambutcher.
com, and is extremely well
comment-ed He also has video of the bot in
test and combat
The microcontroller is anATMEGA168 with a 20 MHz crystal
He used the Bascom’s commercial
compiler (due to program size)
Motor control is via STMicroelectronicsBU941ZT Darlington drivers from
Mouser.com, the accelerometer is a
Freescale 200G MMA2301EG, alsofrom Mouser His MCU board is aPololu Baby Orangutan Mega168
To monitor the directional indicator, he built a 13 inch high sensor tower at the center of rotation, which has two functions
The tower had two requirements
First, it needed to receive infraredcontrol data from the handheld con-troller transmitter (same technology
as TV remote controls), with a 360field of view and a range of at least
20 feet To meet this, the IR receiver ispointed straight up into a 1/2 inchthreaded hole in a one inch OD Lexanrod IR light from any direction is scattered by the threads (they act likeprisms) down towards the receiver,giving it 360-degree coverage
Second, it must provide a directional reference pulse each timethe sensor under the side facing lens
is pointing at the control operator
Without this reference pulse on each revolution, controlleddirectional movement is notpossible
Of the two functions, Dalefound the second to be themost challenging IR light fromthe control transmitter reflected off nearby objects(opponent, stage floor, andwalls) and appeared to becoming from more than onedirection Fortunately, lightcoming directly from the
transmitter appears as a small pointsource while reflections are weakerand spread over a much larger area
He used two sensors spacedabout 0.3 inches apart Light directlyfrom the transmitter (point source)can only focus on one at a time.Diffused reflected light will strikeboth sensors, not just one A shortsection of program code in themicrocontroller senses the conditionwhere one sensor is illuminated andthe other dark, times the length ofthis condition, and sets a sync flagwhen all conditions are true Thispretty much eliminated falsing due toreflections off floors and walls Healso held off reading the sensoragain for about 270 degrees for evenmore robustness
The directional beacon receiver’shomemade Lexan lens was cut from
a one inch diameter rod and thenpolished It’s a cylinder lens andfocuses light only in one dimension,converting a point image into a line.Focal length is about 0.4 inches Theresult is very sharp focus in the horizontal plane and no focus in thevertical plane, so the vertical location
of the IR transmitter can vary without affecting the performance
As the sensor tower rotates, asharp vertical line of IR light sweepsacross the photo sensors Since thecontroller sends IR control signals tothe bot, it must be pointed at it at alltimes To help aim the controller, hebolted a laser pointer on it
Due to problems unrelated tothe melty system, Scary-Go-Rounddidn’t perform well If it had, Daleplanned to add an autonomousmode This would consist of twobasic sensor systems, similar to those
in Sumo bots One would sense theedge of the stage and move away,the other would sense the other botand move towards it A complete
build report for Scary is at www.wa
4dsy.net/robot/scary-go-round.CycloneBot
CM Robotic’s CycloneBot hassome of the most sophisticated
FIGURE 4 Go-Round guts.
Scary-FIGURE 5.
CycloneBot guts.
Trang 31Most combat bot builders in the
smaller weight classes start out
using drill motors or small custom
planetary gearbox boxes such as
those marketed by BaneBots Many
of those builders have found, as I
have, that the stress of combat will
break the gearboxes at the most
inconvenient times
The failure is usually a broken pin
in the second stage, which leads to
stripped gears, motor burnout, andcrushing defeat Fortunately, thischeap and easy upgrade will fix the problem, win battles, and saveyou money
Parts and Resources List
You will need only a few consumable parts, some scrap
aluminium, and a few small toolsthat you may need to buy You willalso need some gearmotors; I chosethe BaneBots 42 mm model for thisproject For major tools, a drill press,grinder, and either a good bench vice
or an arbor press is essential
electronics in the sport The brain is a
Nios soft processor, running inside a
Cyclone FPGA, made by Altera The
processor runs a Web server that is
hooked back through an 802.11
wireless link with user commands
coming from a USB joystick hooked
to a laptop The laptop runs a
custom application which allows a
copilot to tweak various parameters
during combat
The toughest challenge the team
hit with Cyclone Drive was
maintain-ing directional information inside the
machine In order for the robot to
process a command to go “North,” it
needs to know where North is, in the
driver’s reference frame Quadrature
encoders are used on the wheels,
and this is pretty reliable for relative
direction However, the wheels slip,
change diameter based on speed,
and when the bots go flying on
impact, all bets are off! Thus,
some system is needed for absolute
correction of heading, locking
the robot’s reference frame to the
driver’s reference frame
Their first approach was to use a
two axis magnetometer to measure
the Earth’s magnetic field Measuring
that magnetic field in an environment
with 18 HP of brushed DC motorsthat see peak currents over 1,000Awas extremely difficult and requiredextensive lab testing They had
to test a variety of different shielding, grounding, physical locations, wiring architectures, andalgorithm parameters for the magnetometer to best insulate itfrom the motor, motor controller, andpower line noise
They found that on the secondversion of the bot (with its lowerchassis), the magnetometer was only2” from the arena floor, whichswamped the ability of the magnetometer to read to Earth’smagnetic field So, they changedover to a dual laser transmitter One(a visible laser) is used for sighting,and the other (an infrared laser) fordirectional information
After prototype testing using asimple eight bit microprocessor, theybuilt their “beta” version using a DSP-based control system The fairly advanced 16-bit DSP processorhad all the usual motor controlperipherals: quadrature encodersand pulse width modulation generators, in particular This setupworked for them from the start They
got some basic communications andcontrols running, but the system was-n’t flexible enough for all their needs
So, they moved to the tion of the Nios processor and AlteraCyclone FPGA The communicationssystem uses a dual approach:802.11b for the primary system and
combina-a robot-specific 900 MHz system forthe backup system
Operation at the laptop is itive CycloneBot can be commandedwith simple joystick input to movenorth, south, east, and west.Telemetry is passed back to the laptop through the data stream forreal-time status checking and laterdiagnosis and evaluation
intu-The heavy computational lifting
is handled by the onboardCyclone/Nios combo, freeing thedriver from the usual demanding relative-path-based control require-ments This intent-based controlallows the pilot to focus his attentioncompletely on the strategy of thematch SV
Material and photos were contributed by Ilya Polyakov, Team Carnivore; Rich Olson, Team Spambutcher; Michael Worry,
CM Robotics; and Dale Heatherington, Dale’s Homemade Robots.
Trang 32to provide accuracy Start with the
output plate holder; it is nothing
more than a 3” x 3” piece of 1/2” to
3/4” MDF and a 1/4” countersink
screw as shown in Figure 1 Drill ahole 3/4” in from each corner andcountersink the holes to fully recessthe screw head Make sure that both
sides of the jig are completelysmooth so that the output plate will lie flat
The next jig holds the planetarygears for drilling and is a little morecomplicated (see Figure 2) One corner has a 4 mm hole to help youalign the pins, while another cornerhas the gear holder When you drillthe 10 mm hole for the gear, sneak
up to the correct depth using a gear
as a depth gauge The gear shouldsit just proud of the jig surface,which makes it easy to check that thegear is sitting flat in the holder Iused a slitting saw to cut the slot, however, a hacksaw will do thesame job
Disassemble Gearbox
Remove the long case screwsfrom the front of the motor and separate the parts You only needthe output plate for this project,
so put the remaining parts safely toone side
Before drilling and reaming theoutput plate, remove the originalpins You can do this with a press,however, I just use the 3 mm screwsthat hold the gearbox together aspunches and press the pins out in thevice — it is all the original screws arereally good for
Modify the Drills
The drills double as locationdevices to align the parts in thedrill press Taper the ends of the9/64” and 4 mm drills to abouthalf the original width by holdingthem reversed in a cordless drillchuck and spinning them against
FIGURE 1 The output plate jig.
FIGURE 2 The gear holder and pin aligner.
Planetary gear motor n/a
5/32” x 3/8” steel pins 98381A486 Three to four needed per gearbox
4 mm drill 28255A33 For drilling the gears 9/64” drill 8947A116 Drilling the output plate Reamer 0.1557” 2777A22 Reaming the output plate Circlip pliers 57805A42 or similar Optional for some motors Scrap aluminum n/a 2” x 3” x 3/8” thick for jigs
PARTS LIST
FIGURE 3 The major components
of the gearmotor.
Trang 33the side of a fine grinding
wheel
Modify the Output
Plate
Attach the output plate
to the MDF jig and screw it
down hard
Insert the 9/64” drill in
your drill press with the
tapered end down Position
the output plate jig and lower the
drill bit so the drill lines up with one
of the plate holes, then clamp the jig
in place Reverse the drill bit and drill
out the hole, then change to the
reamer and ream out the hole to its
finished size Repeat this sequence
for the remaining holes Once
you have drilled an output plate,
use a fresh corner of the jig for the
next plate
Insert a pin into the hole of the
holder jig; using an arbor press or a
sturdy bench vice, align the pin with
a hole in the output plate and press
it all the way into the plate I find that
sticking the output plate to the vice
with a small magnet saves growing a
third hand Make certain the pin is
exactly square to the plate before
pressing it in Repeat for the
remain-ing holes
Drill Out the Gears
Insert each gear into the holder
and push it down while tightening
the clamping screw, then check that
the gear is sitting flat Align the
gear in the drill press the same way
as the output plate and drill it out to
4 mm
After drilling out the gears,countersink them very lightly and polish the bores using the 4 mm drill
as shown here
Test that the gears spin freely ontheir pins; if not, then polish thebores again The ends of the 4 mmpins will be sticking out from thegears a little; grind them down carefully until they are flush with thetops of the gears
Assemble the Gearbox
Clean out all traces of swarffrom the gears; it is a prime source ofjamming Clamp the front mountingblock vertically in a vice, then dropthe output plate back over the end ofthe shaft Place the ring gear on thefront block and start inserting thesecond stage gears, spinning the output shaft to test for sticking Ifthe shaft becomes harder to turn,take out a gear and reinsert it Oncethe second stage spins freely, apply
some light grease
Next, insert the first stage carrier plate; I find that positioning itabove the second stage gears andturning it until it drops downbetween them works best Test for smooth running again beforeinserting the first stage gears one byone Finally, close the gearbox upwith the back plate and motor andinsert all the screws — another threehanded operation
This gearbox modification willscale up and down to different sizedgearboxes, although drilling largerbores in small brass gears may berisky The next mod for a BaneBotsstyle gearbox should be replacing allthe stock 3 mm screws with high tensile cap head screws and Locktite,which will hold the parts togetherreliably and will not break understress SV
Nick can be contacted via his build thread at
www.robowars.org/forum/viewtopic.php
?t=74&start=0.
FIGURE 4 Pressing out the pins.
FIGURE 5 Pressing in the pins with the pin holder jig.
FIGURE 6 Aligning a gear for drilling.
FIGURE 7 Polishing the gear bores Several sets will give you some manly calluses!
Trang 34Dec 17, 2007 –
Jan 11, 2008
Roaming Robots presented a
corporate show on December8th at the Williams F1 HQ and
Conference Centre Christmas party,
and an educational workshop on
December 10th at St Albans School
Wreck-The-Halls was presented
by Carolina Combat Robots inGreensboro, NC on December 29,
2007 Results are as follows:
● Antweights — 1st: “Big Buzz,”
Team Kelly PA
● Beetleweights — 1st: “Pure Dead
Brilliant,” Team Rolling Thunder
● Hobbyweight — 1st: Apollyon,”
Team Near Choas Robotics; 2nd: “Cheep
Shot 3.0,” Team Rolling Thunder
RoboChallenge presented their
Thinktank Christmas SpecialDecember 28th and 29th in
Birmingham, England Results are
as follows:
● Featherweight Tag Team
Competition — 1st: “Beauty” (FP
flipper), “Rip” (LP flipper); 2nd: “Little
Hitter” (CO2 powered Axe), “G3”
(FP Flipper)
Upcoming Events for
March – April 2008
Roaming Robots will present
Easter Robot Rumble on 23/2008 at Colchester Leisure World
3/22-in Colchester, UK Go to www.roam
ingrobots.co.uk for more details.
Central Illinois Bot Brawl 2008 will be presented by CentralIllinois Robotics Club in Peoria, IL
on 3/29/2008 Go to http://circ.
mtco.com for more details.
Categories will be: RC Combat (1
lb Ants only), Autonomous Sumo (3
kg, 500 g, LEGO), Line Following, LineMaze Entry fee is $7 per entry if youpre-register, $10 per entry for walk-ins Free admission for spectators
BotsIQ will hold a RegionalCompetition on 3/28-29/2008 in
Pittsburg, PA Go to www.bots
iq.org for more details.
Roaming Robots will hold anevent on 4/6/2008 at theFenton Manor Sports Complex, CityRoad, Fenton, Stoke on Trent, ST4
2RR, UK Go to www.roaming
robots.co.uk for more details.
Robots Live will hold an event4/12-13/2008 at OlymposBurgess Hill, The Triangle, TriangleWay, Burgess Hill, West Sussex, RH15
8WA UK Go to www.robots
live.co.uk for more details.
Seattle Bot Battles 2008 will be sented by Western Allied Robotics
pre-in Seattle, WA on 4/12/2008 at theSeattle Center’s “Center House.” Go
to www.westernalliedrobotics.com
for more details
Event Time: 12:00 noon - 6:00
pm, Safety Inspection: 10:00 am to11:30 am One and Three poundbots Format: Double Elimination or
Round Robin (RFL Rules) No ICE oropen flames Entry Fee: $25 for first
3 lb or 1 lb robot Additional robotsare half price Special entry fee considerations for builders who areunder 18 Arena: 8 x 8
Rotunda Rumble will be presented
by Synergy Robotics Entertainment
of America, Synergy RoboticsEntertainment, and the CRCA areproud to announce “Rotunda Rumble.”Rotunda Rumble will feature multipleweight classes in both the STUDENTand PROFESSIONAL leagues The mainevent will run 150 gram, Ant (1 lb),Beetle (3 lb), Hobbyweight (12 lb),15lb, and Featherweight (30 lb) classes.Prizes: Student 15 lb Class;
$2,500 in merchandise for 1st Place,Trophies to 1st, 2nd, and 3rd Place.Professional 12 lb and 30 lb Class;
$500 to 1st Place, Trophies to 1st,2nd, and 3rd Place
BotsIQ: The Competition 2008 will
be presented by BotsIQ in MiamiBeach, FL on 4/30/2008-5/4/2008 Go
to www.botsiq.org for more details.
All teams are welcome to compete in the following categories:Table Top (Task oriented — samegame as last year); 15 pound competition — Middle Schools, HighSchools, and Post SecondaryInstitutions; 120 Pound Competition
— High School and Post SecondaryInstitutions SV
EVENTS
Results and Upcoming Events
Trang 35The Plymouth North High and
Plymouth South High School
Robotics Teams sponsored a BOTSIQ
15 lb competition The Plymouth
North High school engineering class,
under the direction of teacher
Michael Bastoni and welder James
Stevens, designed and constructed a
12’ Octagonal battlebox The 1/8”
steel floor is supported by eight
sec-tions of welded 3” structural channel
aluminum frames The walls are 5’x5’
x 3/8” polycarbonate framed by
1-1/4” aluminum square tube frames
The roof is 3/8’ poly and aluminum
set on an approximately 1:6 slope
This is the first BOTSIQ arena of this
design in the country and it was
shipped to Florida and used at the
2007 National BOTSIQ championship
The Event
Following the 2007 BOTSIQ
championship, we announced the
desire to host a combat robot event
in Plymouth, MA We were not sure
how many robots would come since
we made the announcement in the
early weeks of October 2007, listing
December 1, 2007 as the event date
We had hoped for 6-10 robots and
expected that we could grow the
event from there We were amazed
that 25 15 lb combat robots from 18
schools showed up ready to fight!
We had only one forfeit throughout
the whole day of combat
The event went off without a
hitch The arena
was set up in the
center of the
manu-facturing shop
sur-rounded by lathes,
mills, and welding
equipment, a
per-fect place for a
combat robot event
and an homage to the earlydays of Marc Thorpe and theWest Coast crazies whobirthed the sport We set up
a 14’ TV screen in the auditorium and pumped inlive video and sound frominside the arena so folkscould sit in movie theatercomfort and hear and watch
15 lb fighting robot action,which looked and soundedlike 300 lb combat robots on the bigscreen The live and video visualexperience was enhanced since weshut down the room lights and litonly the BattleBox, and pumpedamplified sound into the arena room,
as well as the auditorium Little botsgot real big!
We had both high school andcollege teams from as far away asFlorida and New Jersey
Results
● First Place (Undefeated): “GoodKnight” from Bergen CountyTechnical School, NJ
● Second Place: “The Hook” fromWI
● Third Place: “Juggernaut” fromWorcester Polytechnic Institute, MA
I think the story here is the grassroots start up Students designingand building the arena AND the
robots, and making the venue available to surrounding teams Inthis way, engineering in general, androbotics in particular, can become intime varsity level competitive sportsthat will rival the status of other var-sity sports programs We didn’t nail apeach basket to an auditorium balcony we built a combat robotarena! This event will be held on asemiannual basis, made possiblethrough the sponsorship of Entergy
Corporation (www.entergy.com), SolidWorks Corporation (www.solid
works.com), and GEARS Educational
of the Bergen County Academy robotics team.
The 12’ Octagonal arena was designed and built by the organizers, sponsors and students at Plymouth North High School Engineering Program Copies of these plans made by Mahuta Tool Corp (www.mahuta tool.com) are available from BOTSIQ by contacting Nola Garcia at nola@botsiq.org
Trang 36Dark Pounder has competed in
RobOlymics/RoboGames 2007,
Smackdown in Sactown III, Texas
Cup, Robot Shoot-Out, Most Extreme
Robot Challenge, Robot Rebellion
5.4, Robot Rebellion 5.3, Robot
Rebellion 5.2, Robot Rebellion 5.1,
2004 RFL Nationals, Rocket City
Robot Assault, Robot Rebellion 7.0,
Robot Rebellion 6.0, and Robot
Rebellion 4.0 Details are listed
below:
● Frame: 3/16” 7075 aluminum
vertical supports, 0.03 titanium belly;
horizontal carbon rod stiffener, 0.03
titanium formed shell
● Drive: Two BaneBots 11:1 ratio 16
mm drive motors to 3/4” wheels
● Wheels: Two 1” Dubro wheels
turned down to 3/4”
● Configuration: Vertical asymmetricbar spinner with rounded form wedge(front or rear, depending on opponent)
● Drive ESC: Barrello Ant 150 dual5A controller
● Drive batteries: Two 2S1P 400mAh 20C Hyperion LiPoly
● Weapon: 3” asymmetric cleaverblade of 1/8” hardened chromoly steel;
drive pulley mounted to blade on liveaxle (3/8” grade 8 bolt), 27,000 RPM
● Weapon power: 16A start-up and8A cruise at 14.8V
● Weapon motor: GWS inrunnerbrushless motor GWBLM005A(3,900 Kv)
● Weapon ESC: GWS 25A brushless
● Armor: 0.03” 6Al-4V titanuimshell form wedge, 0.06” Ti verticalarmor near the blade
● Future: Design works, but will tune asnecessary, 1.5 ounces under weight, sosome future armor additions possible
● Design philosophy: Rounded formshell maximizes armor strength, protected wheels, blade rotation, andbot orientation direction dependent
on exploitation of opponent’s nesses; assymetric blade for greaterbite on opponent Reliable, pre-dictable vertical spinner weapon, lowcenter of gravity with high velocityweapon of smaller diameter SV
weak-Photos and information are courtesy of Russ Barrow All fight statistics are courtesy of
BotRank (www.botrank.com) as of January 12,
2008 Event attendance data is courtesy of The
Builder’s Database (www.buildersdb.com) as of
1 lb PounderDark 44/5 1 lb PounderDark 28/3
Hunter 9/1 (sport) 30 lb Bounty Hunter 9/1
60 lb Wedge of Doom 43/5 60 lb Agent 7 5/0
120 lb PlungerDevil's 53/15 120 lb Touro 5/0
220 lb Sewer Snake 35/9 220 lb Brutality 4/0
340 lb Shovelhead 39/15 340 lb PsychoticReaction 4/1
390 lb MidEvil 28/9 390 lb MidEvil 3/0
Top Ranked Combat Bots
Rankings as of January 14, 2008
Historical Ranking is calculated by
perfomance at all events known to
BotRank
Current Ranking is calculated by performance at all known events, using data from the last 18 months
History Score Ranking
(sport)
Historical Ranking: #1 Weight Class: 1 lb Antweight Team: Dark Forces
Builder: Russ Barrow Location: Richardson, TX
BotRank Data Total Fights Wins Losses
Lifetime History 49 44 5 Current Record 31 28 3
Dark Pounder – Currently Ranked #1
Trang 37June 12-15th, 2008 San Francisco, CA
Events:
Compete at RoboGames 2008!
Last year, over 1000 builders from around the world brought over 800
robots to San Francisco, in the 4th annual international event This year,
we expect even more robots and engineers to compete Be one! With 80
different events, there’s a competition for everyone - combat, androids,
sumo, soccer, Lego, art, micromouse, BEAM, or Tetsujin! More than half
the events are autonomous Even if you just come to watch, you’ll be
overwhelmed with the diversity
Last year, RoboGames hosted teams with over 800 robots from Argentina,
Australia, Austria, Brazil, Canada, China, Colombia, Czech Republic,
Denmark, Germany, India, Indonesia, Iran, Japan, Korea, Mexico,
Nether-lands, Peru, Singapore, Slovenia, Sweden, Taiwan, UK, and the USA
Be a RoboGames Sponsor!
RoboGames is the world’s largest open robot competition - letting people
of any age, gender, nationality, or affiliation compete Sponsoring
Robo-Games not only helps more people to compete, but also gets your
company unrivaled press coverage and visibility The event has been
covered by CNN, ESPN, Fox, CBS, ABC, NBC (live), EBS Korea, NHK
Japan, BBC, and countless print and web companies Your logo can be
everywhere the cameras turn!
Rent a Booth!
Booth spaces are at the front of the venue, ensuring lots of traffic With
3000-5000 people each day, you’re company will get amazing traffic!
-SERVO Magazine
Trang 38It is important that a power-assist exoskeleton robot
automatically assists the user’s motion according tothat motion intention in real time Electromyographic(EMG) signals — which are generated when muscles areactivated — are one of the most important biological signals to determine the user’s motion The amount ofthe EMG signal indicates the muscle activity level (i.e.,the amount of generating force) and it can be easilymeasured using simple electrodes
If the amount of generating force by certain muscles is estimated, the amount of user’s joint torquecan also be estimated (see Figure 1) Therefore, it can beused to activate the power-assist exoskeleton robot automatically, since it directly reflects the intention ofthe user Consequently, human motion can be estimated
if the amount of muscle force of certain muscles is estimated If the user’s motion is estimated in real-time,the motion can be easily assisted by the exoskeleton.The EMG-based control is not very easy to be realized,however, because of several reasons
In this article, EMG-based control methods forpower-assist exoskeleton robots will be introduced Softcomputing technologies such as fuzzy reasoning, neuralnetworks, or genetic algorithms are powerful tools tomake the robot system intelligent They can be applied
to develop an effective EMG-based controller for assist exoskeleton robots We will discuss, two kinds ofEMG-based control methods in which soft computingtechnologies are introduced and applied
power-The Geometry of Power-Assist
Because the power-assist exoskeleton robot is supposed to be directly attached to the user’s body, thedesign condition of the robot architecture is restricted incomparison with that of ordinal robots The actuators,sensors, links, and frames of the exoskeleton must all belocated outside of the user’s body and not disturb theuser’s motion under any configuration Moreover, theweight of the exoskeleton should not be directly supported by the user’s body
Therefore, the hardware design is harder to come
up with than that of ordinary robots Development ofsmall-size, light-weight, and high-power actuators such
Control of Power-Assist
With Biological Signals
A viable power-assist exoskeleton
robot — sometimes called a power
suit, man amplifier, or man
magnifier — is something that
many people in industry, military,
and medicine, have been anxiously
waiting for Recent progress in
robotics technology has increased
the number of power-assist
exoskeleton robots that have come
onto the scene.
Biceps (agonist muscle) Triceps
by Kazuo Kiguchi
FIGURE 1 Joint torque
and muscle force.
Trang 39as artificial muscles are required to be
practically wearable for daily living
Upper-limb motion is involved in
many important activities in daily living,
so assistance here is important for
physically weak persons Figure 2
shows an example of 4 DOF (degrees
of freedom) upper-limb motion (i.e.,
shoulder vertical flexion/extension,
shoulder horizontal flexion/extension,
elbow flexion/extension, and forearm
pronation/supination) [1]
In this case, the exoskeleton robot is
attached to the mobile wheelchair
Therefore, the user does not carry any of
the weight at all The exoskeleton
main-ly consists of a shoulder motion support
part, an elbow motion support part, and
a forearm motion support part
The shoulder motion support part
is composed of an upper arm link,
driv-er and driven pulleys (one for shoulddriv-er
horizontal flexion/extension motion,
another one for shoulder vertical
flex-ion/extension motion), two DC motors,
two potentiometers, an arm holder, and
the mechanism for the center of
rotation (CR) of the shoulder joint The
1 DOF elbow motion part consists of a
forearm link, pulleys, a DC motor, and a
potentiometer The forearm motion
sup-port consists of a wrist frame, an inner
and outer wrist holder, a wrist cover, a
wrist force sensor, and potentiometers
Usually, the movable range of the
human shoulder is 180° in flexion, 60° in
extension, 180° in abduction, 75° in
adduction, 100-110° in internal rotation,
and 80-90° in external rotation The
lim-itation of the movable range of the
fore-arm motion is 50-80° in pronation and
80-90° in supination, and elbow motion
is 145° in flexion and -5° in extension
Considering the minimal amount of
motion required in everyday life and the
safety of the user, shoulder motion of the
4 DOF exoskeleton is limited to 0° in
extension and adduction, 90° in flexion,
and 90° in abduction Limitation of the
forearm motion is 50° in pronation and
80° in supination, and 120° in flexion and
0° in extension for the elbow motion
In order to activate the
exoskele-ton in accordance with the user’s
intended motion, the EMG-based
con-trol can be applied as explained next
In order to control the 4 DOF limb motion, 12 kinds of EMG signalsshould be used, as shown in Figure 3
upper-Control with Biological Signals
In order to assist the motion of theuser, the exoskeleton robot must deter-mine the generating motion in realtime
The user’s motion can be estimated inreal time by monitoring the EMG signals
of the certain muscles Since the
amount of EMG signal indicates theactivity level of the muscles, the amount
of generating force by the user can beestimated by monitoring these signals.However, this EMG-based con-troller is not very easy to be realized,because: 1) obtaining the same EMGsignal for the same motion is difficulteven with the same person since thesignal is biologically generated; 2) theactivity level of each muscle and theway they’re used for certain motion isdifferent among individuals; 3) activity
Control of Power-Assist Exoskeleton Robots with Biological Signals
FIGURE 2 4DOF assist exoskeleton.
power-FIGURE 3 Location of electrodes.
Trang 40of antagonist muscles affects the joint
torque (see Figure 1); 4) many muscles
are involved in a joint motion; 5) a
muscle is used for more than one kind
of motion; 6) the role of each muscle
for a certain motion varies with joint
angles; and 7) the activity level of some
muscles (such as bi-articular) are
affect-ed by the movement of the other joints
There are basically two kinds of
methods to carry out power-assistance
based on the user’s EMG signals Oneway is a fuzzy-neuro control method(the combination of flexible fuzzy control and an adaptive neural network) [1]-[4] and the other is a muscle-model based control method
In the first method, the user’s motion
is estimated based on the EMG activationpatterns of the related muscles, and thenthe power-assist is performed to accom-plish the estimated motion The fuzzy IF-THEN rules are designed based on therelationship between the human motionand the EMG activation patterns of therelated muscles The designed fuzzy IF-THEN rules are transferred into theform of neural networks so they canadapt to an arbitrary user As the number of assisting DOF is increased, therequired fuzzy IF-THEN rules becomemore complicated to cope with this
In the second EMG-based method,the user’s motion is estimated on theamount of EMG activity levels of the related muscles A muscle-model (i.e., amatrix) that relates human joint torqueand the amount of EMG activity levels isbased on the knowledge of human anato-
my However, each component of thematrix must be modified according to theposture of the user, since the relationship
between the human joint torque and theamount of EMG activity levels varies
A fuzzy-neural network can beapplied to modify the muscle-model inreal time according to the posture ofthe arbitrary user The control systemfor the power-assist exoskeleton robotfor 5 DOF upper-limb motion (i.e., shoulder flexion/extension, shoul-der adduction/abduction, shoulderinternal/external rotation, elbow flexion/extension, and forearm prona-tion/supination) is shown in Figure 4.The relationship between the EMGsignals and the generated joint torquesare written as the following equation ifthe posture of the user’s upper-limbdoes not change
EQUATION 1:
where τsv is torque for shoulder ion/extension motion, τshis torque forshoulder adduction/abduction motion,
flex-τsr is torque for shoulder rotational
Control of Power-Assist Exoskeleton Robots with Biological Signals
16 15 2
1
16 15 2
1
16 15 2
1
16 15 2
1
16 15 2
1
Ch Ch Ch Ch
w w w
w
w w w
w
w w w
w
w w w
w
w w w
w
f f f
f
e e e
e
sr sr sr
sr
sh sh sh
sh
sv sv sv
sv
f e sr sh sv
Μ Λ
Λ Λ Λ Λ
τ τ τ τ τ
Abduction — Moving a limb away from
the midline Think B for bird (aBduction)
– raising your arms like a bird preparing
for flight.
Adduction — Moving a limb toward
midline Think D for down (aDduction)
— pushing your arms down in a resting
position.
Pronation — Rotating the forearm and
hand so that the palm is down Think P
for pouring water out of an imaginary
bowl in the palm of your hand.
Supination — Rotating the forearm and
hand so that the palm is up Think S for
holding a bowl of soup in the palm of
your hand.
Anatomy Lesson
... of the designCo-sponsors of the contest were Nuts
& Volts Magazine, SERVO Magazine,
Cooper Tools, Link Instruments, Jameco
Electronics, Mouser Electronics,... and 3rd Place
BotsIQ: The Competition 2008 will
be presented by BotsIQ in MiamiBeach, FL on 4/30 /2008- 5/4 /2008 Go
to www.botsiq.org for more details.... Events for
March – April 2008< /b>
Roaming Robots will present
Easter Robot Rumble on 23 /2008 at Colchester Leisure World
3/22-in