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[DPRG] Contests at the Science Place

Subject: [DPRG] Contests at the Science Place
From: Randy M. Dumse rmd at newmicros.com
Date: Tue Feb 5 14:05:27 CST 2002

> I definitely don't think we need to be making modifications to
> the course the day of the contest.

Let me second that opinion. Let's NOT be trying this for the first time on
the day of the contest.

Some other points:

If you drill two 1/4" holes in the sides, how do you plan to align the beam
with the far hole? It won't "just happen" because you're good with a drill.
If someone bumps one side board or the other, you will loose alignment. (The
body of our laser has alignment screws for fine tuning the angle of the
beam, but even that won't help if the sides get bumped or skewed during a

If you use a laser beams without any encoding, how are you going to protect
them from swamping from sunlight, the strobing from flourescent lamps,
camera flashes, people walking infront of the open glass and casting a
shadow on the course? or clouds passing over for that matter? There's
nothing magical about the laser light compared to any other light source,
unless you use colored bandpass filters, or long collumating tubes (which
increases the alignment problem) to select just the laser from all other
sources. If you do use encoding, will it interfere with the 40kHz typ.
sensors on the robots?

Do you really need a directional sense on which way the robot is going? That
doubles (quadruples really) the alignment problems. (Our timers do not have
direction sense in them. I've often thought about such a system, but it is
usually unwarranted compared to the complications it adds.)

Do you need a Reset or Continue button to cancel false starts or continue
accidental stops, like the robot goes across the line multiple times before
getting on down the course.

Do you need an RS232 output so the numbers can transfer to a laptop with any
transcription errors?

There's a whole bunch of engineering put into our Equestrian Timers. It's
not as easy as it appears at first blush. The beams are fine enough to pick
up a fly at 40mph, so we can catch the robots as are. The settings are all
adjustable, so we can choose as small a beam break as we wish (down to a
millisecond) and the debounce times are programmable as well (default is 2
seconds, just like Ed's automotive app.). By programmable, I mean you can
change them from the console key pad.

I'm back in the office most of this week, and probably next, if someone
wants to take this for a project and spear head it, I can certainly give
some of the benefit of my experience. We can start with what I've got and
modify it, but I may not have too much time to devote. I'm busy now just
getting ready for a presentation on the 9th.


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