Subject:
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Re: A robot who knows his position (fwd)
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 30 Apr 1999 14:49:57 GMT
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Viewed:
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1004 times
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In lugnet.robotics, lego-robotics@crynwr.com writes:
> <cut>
>
> > > I think a magnetic or gyro compass would work better. Is there anybody • around
> > > who did interface a compass to the RCX?
> >
> > I did consider trying to rig up a crude light-sensor looking at a cheap
> > compass, but thought against it. Just detecting the, usually red and blue,
> > arrow sounds pointless, whilst taking one apart and attaching a patterned • disk
> > to it seems infeasible as the card of the disk would probably be too heavy • for
> > the compass needle to move around. Is this the only way to do this without
> > building some sort of little bit of electronics gadgetry?
>
> I have not tried this yet as I have not figured it all out yet but....
> The dive compass I have (which is relativly large) has a window
> visible from the side this has degree markings and lines for every
> degree. The lines are reasonably large 2mm or so and have a very
> distinct white on black marking. It should be possible to detect the
> lines with the light sensor, but detecting the direction of rotation
> may be more difficult. There is also a large white arrow on the top.
> How were you going to detect the arrow if the sensor could pick it up.
Well, I was just going to place the light sensor statically relative to the
case of the compass, and overhead. It would simple note whenever the head of
the arrow went past. This is pretty useless, which is why I didn't do it.
Now I come to think of it, if you allowed the light sensor to move such that
it could follow the head of the arrow, then we could arrange it so that the
light sensor starts off above the bright arrow. However, when the arrow moves
as a result of movement then the light sensor assembly starts "seeking" right
and left until it encounters the bright arrow again. Since the assembly knows
how far it has travelled, and in what direction, it can give a reading on
bearing. Unfortunately this would require use of a motor and some fidgeting
around with some code to drive the thing. However, it sounds like it may be
do-able and useful. Can anyone see any problems with this?
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Message has 2 Replies:
 | | Re: A robot who knows his position (fwd)
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| For people that don't mind non-lego solutions, how about the Dinsmore compass: (URL) haven't personally used one yet, but it seems like with a bit of processing, you could get it to return a value like a light sensor. Also, the price is pretty good (...) (26 years ago, 30-Apr-99, to lugnet.robotics)
| | | Re: A robot who knows his position (fwd)
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| On Fri, 30 Apr 1999, Mike Moran wrote: . . . (...) Yes. It is unnecessarily clumsy and heavy and would require considerable computer attention to track rotation successfully. I believe digital encoding would be better. Anyone know how one determines (...) (26 years ago, 30-Apr-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: A robot who knows his position (fwd)
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| <cut> (...) I have not tried this yet as I have not figured it all out yet but.... The dive compass I have (which is relativly large) has a window visible from the side this has degree markings and lines for every degree. The lines are reasonably (...) (26 years ago, 30-Apr-99, to lugnet.robotics)
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