Build Your Own Combat Robot

Chapter 6: Power Transmission: Getting Power to Your Wheels 105
Early in the robot design process, you usually decide that you want your robot
to move at a certain speed and have the ability to push a certain amount of weight.
These specifications can help you select an appropriately sized motor.
Ideally, you will be able to find a prepackaged gearmotor that will meet your
specifications. If you cannot find the perfect gearmotor, you will have to settle for
whatever you can find and live with a different robot speed and strength—or you
can build your own speed reducer.
The type of power transmission you’ll need for your robot is a simple speed-reduction
setup, not the type of power transmission commonly found in automobiles
or motorcycles. In some cases, you may want to increase the speed of a gearmotor;
but in most cases, you will be reducing the speed of the motor. This type of power
transmission usually consists of a set of chains and sprockets, timing belts,
V-belts, gears, or even a secondary gear box.
The power transmission is also often used to transmit the power of the motor to
two or more robot wheels. In most cases, two separate axles are driven at the same
time through chains and sprockets, timing belts, and V-belts.
True Story: Grant Imahara and Deadblow
“The most spectacular failure I had was in Las Vegas, during season 2.0,” says
Grant Imahara, the renowned builder behind Deadblow. “I was waiting to fight
a robot named Kegger built by a team called ‘Poor College Kids.’ It was probably
going to be a prettyeasymatch, but BattleBots teaches you not to be overconfident,
because anything can happen.”
Indeed, Grant has seen just about everything. He was there at the birth of
the sport, since Marc Thorpe, an Industrial Light and Magic co-worker, created
Robot Wars in 1995 and gave Grant tickets to attend. “I was captivated, and
knew that I had to build a robot of my own.”
Deadblow was the result of that obsession; and at this particular event, Grant
found himself charging the onboard air tanks—essential to power the weapons—
in preparation for competition. “I was filling my two onboard air tanks from an
external SCUBA tank, which was a pretty standard thing for me to do. I had
done it a million times. But this time I heard a loud ‘pop,’ followed by a rush
of high pressure air coming out of the robot.”
Grant describes how the nearby mass of people backed away uneasily at the
ominous sound of rushing air. “That pop meant that I had ruptured one of my
air lines and the weapon— Deadblow’s onlyweapon—couldn’t work without air. I
knew that if the robot couldn’t fight at its designated time, I would have to forfeit
my match.”