Swarm Robots and
Sensor Virtualization
By Mike Keesling
What started out as a
blurb about Zhu Zhu
pets™ in SERVO
Magazine has turned
into a disturbingly
large pile of Zhu Zhu
pets. Some boxed,
hopeful of a friendly
home, others hacked
apart, pelts laid
aside like carcasses
in some hideous
abattoir. Fear not for
them though, they
are destined for
greatness.
FIGURE 1. Modified Zhu Zhu pet
with Arduino, Xbee, battery, and
H-bridge all decked out.
It started with one labeled “Mr. Squiggles.” I bought him, hoping to find a simple differential drive platform that could be easily hacked. For $10, I thought why not. I figured I would get two nice wheels at the very least. The sad truth is that Mr. Squiggles did not deliver my expected treasures. There was but a single motor,
plus the wheels are deliberately cast off kilter to make the
little artificial hamster wobble as he scuttles about.
So, how does a mock gerbil survive in a modern world
with only one motor betwixt its two wobbly wheels? The
same way cheap toys have been doing it for years: a turn
on reverse mechanism. There is a clever little kick-stand
which induces rotation when the motor runs in reverse.
Certainly clever for a toy, and I suppose that a clever
roboticist might cut their losses and move on, but I saw this
as a challenge.
So, now — seven Zuh Zhu pets later — I have a $70
challenge that I won’t be backing away from any time
soon.
Anatomy of a Gerbil
The anatomy of this pesky plastic pest is at first a
challenge, but there is a lot to be salvaged, right? Well, yes
and no. The well-sighted and budget conscious among you
can certainly make a lot out of all the artificial gerbil guts.
There is a discreet H-bridge on the circuit board, some nice
bump switches, and a speaker. I won’t be throwing these
tiny treasures away, but I won’t be using them right now
either. I am more interested in reliability and repeatability,
and when hacking toy hamsters, you can’t count on either.
I am also not terribly interested in cutting traces and
injecting signals on a board that is small, optimized, and
may be different if they source to different vendors. I have
a lot of other things to accomplish first if this fleet is to
grow in numbers (as hamsters are known to do).
So, new brains are most certainly a must-have, and a
new motor drive is of great utility too. Throw in wireless
communications and a microcontroller, and you have a lot
of potential. I shopped around and noticed that the fine
folks at SparkFun ( www.sparkfun.com) had all that I
needed, so I put together a big shopping list. They have a
SERVO 04.2010 73
