Subject:
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Mindstorms at the Minnesota State Fair
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Newsgroups:
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lugnet.loc.us.mn
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Date:
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Tue, 29 Aug 2000 16:36:02 GMT
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Viewed:
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2423 times
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Hey folks,
I've had the pleasure of building a Mindstorms Champsosaur, a prehistoric
crocodile type creature, as part of an interactive exhibit for the Minnesota
FIRST LEGO League and the Science Museum of Minnesota. The exhibit is in the
Wonders of Technology building at the Minnesota State Fair which runs through
September 4.
It has the basic shape of a crocodile with the RCX built into the body.
The motion platform is a narrow tracked design with two extra idler wheels
inside the track. This moves the track-to-floor contact points closer together
which enables the bot to turn very sharp corners.
Each track is driven separately and a third motor is used to operate the jaw
so it can 'eat'.
There are three light sensors. Two face down for line following (a river) and
there is one in the mouth for detecting 'food' (foam balls).
There are also five touch sensors. Each leg has one touch sensor and the fifth
is configured as a limit switch for detecting when the jaw is open all the way.
The closing strength of the jaw is limited by a 24T clutch gear.
It is currently programmed to find and follow the 'river',
a five inch wide and 7 foot long blue line on a white background,
when innitially pointed towards it. When it reaches the end of the 'river',
it opens it's mouth and expects to be fed. After being fed it turns around 180
degrees and heads off to the other end of the 'river'. It then opens it's
mouth and expects the 'food' to be removed. It turns around and repeats this
fetch cycle until switched off.
While following the river, bumping either of the front legs will trigger the
same feeding response as the end of the river.
Bumping either of the rear legs will cause the bot to turn around to 'see' what
was bothering it, then it will continue on it's way again.
It's great fun watching kids feed it and the most common comment by adults is
that it must be following something magnetic in the table. :-)
There is a web cam for viewing the booth (when it's not overloaded)at either of
the following URL's :
http://www.hightechkids.org/mnstate.htm
http://www.smm.org/museum/temporary/pages/StateFair.html
and a very quickly made set of building instructions at :
http://www.visi.com/~dc/cbot/
I'll add more info and pictures soon.
-- Doug
dc@visi.com
http://www.visi.com/~dc
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