Subject:
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Re: Autonomous Robot
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 9 Aug 2000 01:08:55 GMT
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Viewed:
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597 times
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How exactly do the retroreflectors work? I was under the impression that you
couldn't selectively reflect light unless you had a parabolic dish - and then
it would all focus on one point. Do your reflectors have a convex mirror, or
some other arrangement?
--Ian
In lugnet.robotics, sjbaker1@airmail.net writes:
> Another idea might be to put patches of retro-reflective tape on the robot.
> That stuff is *supposed* to reflect all light back to its source - no matter
> where it comes from. Now the tower can scan the floor until it gets a strong
> reflection from the laser in the tape and the tower can continually track the
> tape as the robot moves around the room.
>
> [...]
>
> However, experiments I did last night with a laser pointer showed that for
> at least one kind of bicycle reflector, it only retro-reflects when the
> incident light beam is within about 45 degrees of the primary axis of the
> reflector.
>
> Beyond that angle there is a pretty sharp cutoff when no light is reflected
> back to the laser at all. That might be good enough for the scanning tower
> position finder idea - providing the robot never drives much further from the
> base of the tower than the tower is high. If you put the spinning laser on
> the ceiling - you could probably get the entire room.
>
> [...]
>
> Also, at close ranges, the retro-reflection was a bit TOO good - and the laser
> light was reflected back so accurately into the transmitter that you wouldn't
> be able to get a Lego light detector close enough to pick it up! I suppose
> you could fix that with a 'beam-splitter' (a semi-silvered mirror) - or once
> again, ensure the tower is tall enough that the beam has enough room to
> diverge some more after it bounces back off the robot.
>
> I have to admit that I was suprised at just how good a 25 cent retroreflector
> could be.
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Message has 1 Reply:
 | | Re: Autonomous Robot
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| (...) you (...) then (...) or (...) No, there are no convex mirror, just triangular prisms, like small pyramids. Their angles are designed to reflect the light back to the direction it came from (thru' two reflections). I can provide an example in (...) (24 years ago, 9-Aug-00, to lugnet.robotics)
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Message is in Reply To:
| | Re: Autonomous Robot
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| (...) Yes - but that wouldn't be a funnel shape - it would need to be a 'retro-reflector' that reflects all light back to it's source - no matter the direction. That's why I was babbling on about the retroreflective tape they have on kids clothes (...) (24 years ago, 9-Aug-00, to lugnet.robotics)
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