Subject:
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Adder-Subtractor w/Clutch?
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 23 Jul 1999 17:14:31 GMT
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Original-From:
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Jonathan Woodward <WOODWARD@GUESSWORK.spamcakeCOM>
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Viewed:
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1017 times
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-So, my Lego Ogre project is proceeding.
(http://www.io.com/~woodward/lego/) The current assembly I'm having
problems with consists of two motors, one powering the left tread, one
powering the right tread. The output from these motors is also being
piped through an adder-subtractor, and the "A-B" output of the subtractor
is being used to rotate the articulation point of the tank.
-However, I forgot to put a clutch on the A-B output. The tank can
only articulate a certain distance, and I don't want to put strain on the
drivetrain, so there _should_ be a clutch in there.
-A sketch of the important parts of the layout is at...
http://www.io.com/~woodward/temp/diff2.gif
-This sketch is modified from Leo's sketch of an adder-subtractor,
found at...
http://carol.wins.uva.nl/~leo/lego/
-All praise be unto him for introducing me to this device and its
applications. As you can see, I placed an 8-tooth gear between the two
16-tooth gears (instead of putting a 24-tooth gear one level up, as Leo
does). That isn't a major change. The arrow going off to the left is the
A-B output. It's an axle that runs through the lower 16-tooth gear, into
the lower differential, and ends in the bevel gear inside the diff. The
diffs are being turned by the motors from below. There's no place to add
a clutch on the A-B output without major re-design. (The clutch part, for
those of you unfamiliar with it, is a 24-tooth gear where the hub and the
rim can turn separately under enough force.)
-But, I was thinking, maybe the clutch doesn't need to be on the A-B
output. The whole adder-subtractor is a single assembly whose parts
interrelate. If I replace one of the 24-tooth gears on the _A+B_ side of
the adder-subtractor, if the A-B output stalls, the stoppage will feed
back through the assembly, and be absorbed by the clutch, without strongly
affecting the rotation of the differentials, and thus not affecting the
motors and the treads.
-This looks right to me; does it look right to y'all?
-JW
Jonathan Woodward woodward@guesswork.com http://www.io.com/~woodward/
"If you have any trouble sounding condescending,
find a Unix user to show you how it's done." -Scott Adams
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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