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In lugnet.robotics.nxt, Brian Davis wrote:
> In lugnet.robotics.nxt, Philippe Hurbain wrote:
>
> > Your fiber optic cable idea is interesting... and it works well!
>
> I've also used this the other way around, using a fiber optic cable to route
> light to the phototransistor itself. Do this with more than one light sensor,
> and you can have much better spatial resolution (the ends of two fiber optic
> cables can be right next to each other; not so the light sensors themselves).
Hi Brian,
What kind of application needed this precision? Line follower?
Did you need to shield the fiber to avoid stray coupling of light to the
phototransistor?
Philo
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In lugnet.robotics.nxt, Philippe Hurbain wrote:
> What kind of application needed this precision? Line follower?
Yes. I didn't end up using it because speed ended up being more critical than
precision, but for narrow lines I may go back to it. I suspect I might be able
to use it to follow lines drawn by a black marker.
> Did you need to shield the fiber to avoid stray coupling of
> light to the phototransistor?
No. Well, kind of. I used a 1x2 Technic beam with a "stud pin" in the hole to
securely hold the fiber, and placed this right over the front face of the
olod-style light sensor. The first time I did this, it didn't work at all...
because there was almost no ambient illumination to get a reflected signal from.
When I tried it, I can't remember but I think I used a LEGO lamp as a light
sensor for surface illumination. You should be able to do this with the LED
light as well I'd guess.
--
Brian Davis
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