10 SERVO 12.2013
The rules of the competition
disallow any weapons that would hurl
nasty pieces of critters into the
unprotected audience since the Critter
Crunch does not use an armored
protective arena. It is simply an eight
foot by eight foot OSB (Oriented
Strand Board) surface held off the
ground by a simple 2x4 frame sitting
on the floor (Figure 1). The
competition is similar to the familiar
Sumo events since you win by forcing
your opponent off the combat surface
or causing your opponent to be
immobile. For the complete rules,
look at www.milehicon.org/Files/
Critter%20Crunch%20rules.docx.
A few years ago, I challenged
these “proto” makers to create
genuine robots to compete against
the humans. Subsequent years have
seen an assortment ranging from
LEGO RCX-based robots, to
microcontroller powered, to an
imitation of Grey Walter’s Tortoise on
the field. I have fielded Silver Surfer
for the last three years — each year
with slightly improved programming
and sensor packages (see Figure 2).
It has gotten better over time, but I’m
no doubt hampered by my tradition of
starting work on it a week before the
competition. (I am a professional
procrastinator.)
A custom robot board whose
processor is an Atmel ATMEGA8535
controls Silver Surfer. It is
programmed using avr-gcc. It is
connected to a laptop via a Bluetooth
virtual com port using a SparkFun
Bluesmirf board. It has an IR range
finder facing forward, and IR
proximity detectors on each side and
the rear. Finally, the robot uses two
downfacing IR proximity detectors to
see the edge of the board.
This year, sadly, it went too fast
without enough traction and had
some issues staying on the board.
(Sigh, maybe next year ...) This critter
is fully autonomous. I use the terminal
connection to calibrate the board
edge detectors, as well as start and
stop the beast.
I am, of course, happy with the
turnout of a new generation of
“critterers” — especially since my son,
Brendan has designed (with a little
help from Mr. Roboto senior) his own
bot which he has competed with the
last three years. This year, he just
missed a trophy; he battled and lost a
tie for third place. His critter’s name is
Munch shown in Figure 3.
The only other fully autonomous
critter that always attends is Otto
whose owner — John of Sussex of
England — sends each year to
by Dennis Clark
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december2013_MrRoboto.
Ask Mr. roboto
As I write this, I have just returned from MileHiCon 45. This is an annual Fantasy, Science Fiction, writers, illustrators, and everything else convention held in Denver, CO. Lots of stuff happens there, but
that which is of most interest to me is the Critter Crunch. The Critter
Crunch is the brainchild of Bill Llewellin of the Denver Mad Scientists Club (of
which yours truly is also a member). I'm sure that you've all heard of Robot Wars
and BattleBots from TV, and their respective competitions. Critter Crunch is older
by far than all of them. In fact, 2013 marks the 24th year of the Critter Crunch.
This competition is broken (now) into two brackets: the 2 lb and 20 lb classes. Of
these two, the 2 lb is the most competitive; this year, we had 12 entries. In the
early years, the classes were dominated by 20/30/40 somethings that were mild
mannered (or not) engineers and scientists in their regular lives. Something about
mechanical mayhem appealed to these mad scientists. (Perhaps because many of
them worked in the defense industry? Dunno ...) Regardless, it is great fun and
inexpensive to enter. I have seen everything from cheap RC trucks with custom
metal shells to custom-machined works of art compete and win. This year, we
saw that this crunchy fun isn't just for the adult engineers and scientists. We had
an assortment of adults as usual, but the field was dominated by kids from the
age of nine on up to high school students. It's working! Something is pulling the
younger generation into engineering remote-controlled battling critters!
