Peter Moore and his mates from Cenqua in
Australia were the second contestants in the T-Shirt contest. Their entry
was a contraption (I don't know a better word: Rube Goldberg would have
been thrilled) that used centrifugal force to propel the shirts, and a
pile of electronics to figure out when to let go. If you'd like to get a
better look, they have a large
collection of photos up on the web. The release mechanism involved
infrared sensors on the spinning wheel that operated the solinoids that
released the shirts. The sensors were used to receive trigger information
from the computer and a funky wire-wrapped board.
The early prototypes were pretty straightforward. No electronics. Real
reliable. What they ended up with was a total victory for creeping
featurism.
They managed to launch a reasonable number of shirts, and got great range,
but the vast majority of the shirts were randomly spewed all over the
stage and backdrop. The infrared sensors were their undoing, and an
interesting case study in just how hard testing is.
They had done a lot of testing, in lots of circumstances. They had had
problems the night before with the stage lights having enough IR to
trigger the device prematurely. They had tuned and corrected for that.
But it was the large, professional-grade photographic flashes that did
it. No one had fired off one of those in the vicinity of the launcher
during any test runs.
Just as in every branch of engineering, "shit happens", and it's
incredibly hard to predict.
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