Subject:
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Re: (long) Rotation Sensor from "Extreme Creatures" Fiber Optics
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 29 Dec 1998 18:41:23 GMT
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Original-From:
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Ben Kimball <ben@fusiondev.com%AvoidSpam%>
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Viewed:
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1090 times
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> -Now, if i could just tell which direction it was rotating...that would be
> somthing.
Here are some ideas Maurice Hilarius sent me on the subject. I hope he
doesn't mind my reposting them.
"1) You attach a smaller wheel on a shaft which is part of the drivetrain.
This wheel rotates on the shaft, but with a small amount of friction. The
wheel has a small piece, or "stop-driver" attached to it. When the wheel
turns in one direction the friction causes it to push the "stop-driver"
towards the touch sensor. When it turns the other way it pulls it away
from
the touch sensor. By monitoring the state of the touch sensor we can tell
direction of travel.
2) Again with a friction wheel we mount a light source on a driven shaft.
It is mounted so as to pivot. Again a small amount of friction is
required.
Motion in one direction causes it to be rotated so as to point at a light
sensor. Motion in the other direction causes it to pivot so that it it is
pointing away from the light sensor. With a bit of ingenuity it would be
possible for it to "release" from the driver wheel after a quarter turn in
either direction, so that the friction is not continuous."
Of course, I haven't actually /built/ one... ;) The clutch wheel probably
has way too much friction, but I bet a belt would work if you found the
right combination of belt tension and driveshaft torque. The only
disadvantage I see to this method, apart from the power loss from
friction (hopefully negligible) is the delay: you won't know that the
direction has changed until the cam (or whatever) travels its full
course, tripping or releasing the sensor. This can probably be minimized
by a very short "throw" distance. Depending on tolerance, you might even
be able to eliminate it by "riding" the break point on the touch sensor.
Somebody stop me, I'm rambling helplessly...
Cheers!
Ben
Cheers!
Ben
--
Ben Kimball <mailto:ben@fusiondev.com>
Fusion Development <http://www.fusiondev.com/>
Custom Intranet Solutions P.O. Box 204325, Austin TX 78720-4325
Visit the siphonFAQ! <http://siphon.scripting.org/siphonFAQ/>
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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