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| The Robot (AsianSensation V0.2 or AsianGlow) |
Our robot is an exercise in symmetry. It is
perfectly square, has four wheels driven by two
motors each, and can, from a stand-still, move in
any direction. We used up the majority of our
Lego bricks, exhausted our supply of support
pegs, and thus ended up with a very heavy
robot. Partially because of the design and
partially because of Kip's obsession with
bracing, our bot was mean looking. When standing
on the board, our bot resembled a futuristic Lego
tank ready to kill rather than some of the
competition's cutesy Lego creations adorned with little flags.
So how can our bot move in any direction, from a
stand-still no less? To accomplish this feat we
employed a unique drive train and control setup
called 'synchro' drive. A synchro-drive robot is
able to individually (or in unison) articulate
its wheels with 180º of freedom, and also have
each independently powered. This eases mobility
constraints, allows for very precise motion, and,
almost above all else, looks really cool. With
this, we are afforded the ability to keep the
'front' of our bot trained on a target while the
wheel assemblies (the heart of the synchro drive)
turn and power the robot in any direction.
Three sides of our robot (East, West, and South)
are impassable for balls and create a semi-cage
underneath the super-structure of the robot. The
North side of our robot has a one-way ball gate
to allow ball entrance without exit--once they
are in, they are there to stay. With this
design, we are able to protect and keep balls we
want to protect by driving over them with the
one-way ball gate, and then push others like a
bulldozer into or out of scoring zones.
Within each of the four wheel assemblies are two
motors hooked up to a 75:1 gear train, one shaft
encoder to keep track of our distance, and an
Infrared Sensor to orient our bot at the
beginning of each round. All of these sensors
and motors are hooked into our HappyBoard (the
robotics control board) and are monitored and
controlled through our code. Batteries and
Happyboard were mounted as central as possible to
evenly distribute weight, and also to protect them the best from any collision.
While the theory and some application of the bot
sound promising, there were issues that proved to
be continual headaches. First of which was the
bot's inability to constantly drive
straight. Because of the symmetry of the bot, it
only takes one component off (say, a wheel put on
backwards--sorry team) to produce severe
drift. In addition, moving over surfaces that
were not perfectly flat threw the bot off course
without proper correction. Our code did have the
ability to detect and combat these issues, but
given time constraints and several operating
system issues, we were unable to really get a
good crack at rigorously testing it. In
hindsight, given the complexity of the bot
compared to the task, we probably would have
decided to change to a simpler design. But if we
did, we'd be just like the others, and our team
is *definitely* not like the others.
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