Playing the “Who Can Beat Who” game
is an integral part of the design process.
the weight of a multibot
must be incapacitated to win
a round, often three bots are
used. This means three 120
pound middleweights (with
one losing 20 pounds on a
diet) would fight a 340
The odds of a 120 pound
weapon inflicting damage on
super-heavyweight armor are
slim. Another technique
using one “90%” bot and
two smaller “door stops”
hasn’t worked well in
• 60 pound Lightweight
• 120 pound Middleweight
• 220 pound Heavyweight
• 340 pound Super-heavyweight
Imagine how many shafts
have been broken in combat
to arrive at this optimized
sizing. Using these calculations, the optimum design
can be done up front.
this. This is backed up by steel
wheel shaft data from successful
combat bots (see Table 2).
Comparing heavyweights and
super-heavyweights with similar
aspects, the theoretical scale factor
would be (340 lb/220 lb)1/3 =
1.16, and the ratio between the
shaft diameters is 1.25”/1” = 1.25
— a value reasonably close to
1.161.5 = 1.249.
The bottom line is that theory
combined with common sense is a
very powerful design tool in practice.
There are basically 16 types of
combots: rammers, wedges, lifters,
launchers, thwackbots, overhead
thwackbots, spearbots, horizontal
spinners, sawbots, vertical spinners,
drumbots, hammerbots, clampers,
crushers, flamethrowers, and
multibots. While there are infinite
subtle differences, they can always
be categorized into one of these 16
types. There are also bots with interchangeable weapons (chameleons).
Bots known as “Swiss Army Knives”
with two or more weapons
are usually not very efficient
or effective, with the exception of using a wedge as a
secondary weapon. This is
so common as to be almost a
standard design technique.
There are also defensive
items like bumpers or hold
don’t do well. To get
around the rule that 50% of
Cost is variable, depending on
creativity, resourcefulness, and
design. However, a survey of typical
costs for bots built with high quality
parts reveals these numbers
(including R/C equipment and spare
batteries). See Table 3.
Bots can certainly be built for
more or less than these numbers.
But, it’s best to remember, this is
not a cheap sport. For the interested
new builder, smaller bots like
featherweights or insects (less than
12 pounds) are a good option.
The stunning craftsmanship of Buster, a
Super-heavyweight milled from titanium.
Photo courtesy of Hal Rucker.
The Robot MarketPlace has
some great tips about sponsorship.
tips.html). Basically, it’s not easy to
get a sponsor if you haven’t built a
bot before. The only exceptions are
companies whose owners or directors already know you well. Most
big companies don’t sponsor robots.
It’s better to look at smaller local
shops that might benefit from the
exposure. Also, you have to call or
visit in person. Email isn’t likely to
bring you sponsorships.
Bring or mail business cards
with your team’s information and
logo. Prepare a presentation folder
with lots of nice photos. Show the
26 SERVO 06.2009