Subject:
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Re: Worm Drive Question
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 25 Nov 1998 23:49:44 GMT
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Original-From:
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stephen p spackman <{stephen@}stopspam{acm.org}>
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Viewed:
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2385 times
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CERRINA, Benoit wrote:
>
> This is exactly what he was proposing without the bottom floor sensor, his
> problem however was how to tell the elevator where to go, with only two
> sensor slot left he can only input a 2bit number ie from 0 to 3 hence four
> floors.
> However here is another way to do the floor number you could use the light
> sensor and a paper band with shades of grey you slide it in front of the
> sensor and push a button when its at the right place
>
> IIIII
> IIII
> III
> [===] II
> I
>
> III = shades of grey on the Paper
> [===] light sensor
You can do WAY better than that, and without *cheating* by using a
(non-LEGO!) paper strip.
The light sensor can reliably distinguish the *colours* of smooth
plates. One of the standard exercises for the Dacta control lab is to
make a barcode reader. So any kind of system that needs to determine its
current location (another nice example being a train... hmm...) can work
by having a sequence like <x><y><black><y><x> of smooth plates, all
separated by white. So a location (approached from either end) is
"named" by the colour sequence <x><y> (for which you should be able to
get at least 9 values and probably 16 or more), with the set point at
the black stripe. So all your location needs are taken care of by one
sensor. Note that it can also do end-of-run detection (<black> will do
just fine).
A bit of mechanical cleverness will let the car location sensor do the
door positioning too - let the sensor travel laterally with the doors.
So we still have two inputs to do floor selection and call buttons.
Floor selection could be handled with a second light sensor: give your
denizens code cards for the floors they want to go to and build a second
card reader. (You could build buttons from this idea too, but it's more
work).
I don't have a solution for the call buttons yet. Perhaps the crucial
insight is that the car only needs to know about calls above and calls
below, not *which* floor is calling. Something slightly mechanical with
sliding rods, or something more electrical with lots of switches in
series/parallel should work....
stephen (who suddenly wants to make advanced two-axis elevators...)
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Message is in Reply To:
 | | RE: Worm Drive Question
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| This is exactly what he was proposing without the bottom floor sensor, his problem however was how to tell the elevator where to go, with only two sensor slot left he can only input a 2bit number ie from 0 to 3 hence four floors. However here is (...) (26 years ago, 25-Nov-98, to lugnet.robotics)
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