Thomas Tilley
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One of my colleagues had asked me if I had any ideas for a
fun and geeky project that we could do with the students
from our
department at a BBQ. As I pondered a suitable project I happened
to be passing a junkyard that had a few old motorbikes prominently
displayed out the front. I thought "wouldn't it be fun to extend
the PVC water pipe Tron controller
and use the handlebars from a real motorbike to
play GL-Tron" and then it dawned
on me - why use just the handlebars, why not use the whole motorbike!
Most of the university students here in Thailand ride motorbikes so
we would have a ready supply of machines to use. However, we needed a
way of connecting the bikes to the computer with minimal modification
- so the students wouldn't mind their bikes being used. I decided to
add turn buttons to the bikes using tact switches mounted on small
sections of PVC pipe. These could be easily attached to the front of
the handlebars using cable ties (and easily removed later on). On the
right hand pipe sections I also mounted
a mercury switch so that
the bike's accelerator could be used within the game. On most
motorbikes it is possible to turn off the fuel line so that this
wouldn't flood the engine. The first two images below show the PVC sections mounted on the
handlebars. The orientation may seem a little counter-intuitive but
the handlebars are shown as if you are facing the front of the bike
(imagine a headlight between the two images or
see the video below for a
cheap, Blade
Runner-style overview
by Rick
Deckard). The would-be lightcyclist turns by squeezing the
buttons, which are attached to the front of the handgrips, with their
index fingers. The bike's center stands are used to keep them upright
and a 1/2 round of bamboo jammed beneath the back wheel stops them
from rocking backwards and forwards. The turn buttons and the accelerator switch are connected to the
computer via a "breakout box" which is plugged into a hacked USB
joystick (my
original Thrustmaster USB
joypad which is now housed in a project case - in the picture
below right it is the black box closest to the tire on the red
bike). The joypad has 4 direction inputs plus 8 buttons which gives a
total of 12 available inputs. Each bike requires 3 inputs (left,
right, and accelerate) so in theory it should be
possible to connect a total of 12/3 = 4 bikes.
The breakout box simply consists of 6 sprung stereo speaker
terminals mounted on a project box which are wired to a male 25-pin
D-sub miniature connector. The buttons on the joypad all share a
common connection so only 13 of the 25 pins are used and all of the
black terminals are wired together. While it would have been possible
to solder connections from each bike directly to a 25-pin D-sub
connector this set-up allows to easily swap wires on the fly and
doesn't require any soldering.
You can see the bikes in action here:
Up to four lightcycles can race in GL-Tron with any combination of
human or computer players. We set-up the bikes outdoors and used a
data projector with a bedsheet for a screen. The picture below left
shows the first bike we wired playing against the computer. Games are
usually more fun with a human opponent so we also wired up a second
bike for head-to-head battles and of course women can
be "Tronnies"
too.
On another occasion we also set the bikes up indoors and while the
hacked USB joypad has enough inputs for 4 bikes to be connected at the
same time GL-Tron doesn't seem to like using the "up" and "down" keys
in-game. This leaves enough inputs for 3 bikes to play using their
accelerators but with 4 players we could only use the left and
right controls. This could easily be overcome by handing control for
some of the bikes over to a second hacked joystick.
A number of people have asked why I didn't wire up the bikes so
that you could turn the handlebars to steer rather than pressing
buttons. While I think this would be possible I don't think it would
be as easy to hook up (or later remove from) the bikes. In addition I
think the inertia involved in turning the handlebars would make it
difficult to turn quickly enough at times. For example, imagine trying to
do this.
You may also be interested in reading about some of my other projects, many of which use hacked controllers, PVC water pipe, GL-Tron, and/or mercury switches: