Subject:
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Re: how does a bar code reader work?
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 30 Dec 1999 21:46:56 GMT
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Original-From:
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The WordMeister <dwilcox@wordsmithdigital+antispam+.com>
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Viewed:
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923 times
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Actually, this may be easier than you think. If you look at the MindStorms
site somewhere, an ATM machine was built by an MIT student (the same guy who
built the photocopier pictured on the RIS box) that scanned a 1x2 flat plate
that had several horizontal lines on it. The ATM would count the lines, and
dispense that many pieces of candy.
A similar arrangement would work for the trains. I'd start with a white band
for initial detection, and then alternate several black and white bands. The
RCX could count the bands by measure reflected light values, and determine
which train was which.
For more accuracy, you might want to have, say, 3 alternating bands on one
train, and six on the other--that way if the reader "misses" a line or two,
you could still account for this. For example, the code might see if the
counter was between 1 and 3 for one train, and 4 to 6 for the other.
Hope this makes sense.
--Doug Wilcox
WordSmith Digital Document Services
403 VFW Drive
Rockland, MA 02370
781-871-6162
fax 781-871-6264
http://www.wordsmithdigital.com
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-----Original Message-----
From: Guido Heunen <heunen@crys.chem.uva.nl>
To: lego-robotics@crynwr.com <lego-robotics@crynwr.com>
Date: Thursday, December 30, 1999 7:13 AM
Subject: how does a bar code reader work?
> Hi,
>
> Can someone explain me how the bar code reader of the codepilot works.
> I figured out the basics, but I can not get to the clocking stuff. You can • move
> either slow or fast over the bar codes to program the codepilot.
>
> I want to use the rcx to detect different trains by fixing a bar code under
> the engine and wagon chasis. With this, I hope to redirect trains to • another
> track, stopping at stations, changing train composition etc...
>
>
> Guido
>
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