Subject:
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Re: Synchro drive in Lego
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 16 Jan 1999 16:17:53 GMT
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Original-From:
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S. Crawshaw <sc10003@eng.cam.!avoidspam!ac.uk>
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Viewed:
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1626 times
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Assuming I have got the design spec right (ie, a wheel which can turn 360+
degrees and drive independently), I have managed to build one from just
the Mindstorms bits. But it needs two motors at the moment, since I
haven't got a differential left to make a ratchet device. Unfortunately I
can't show it as I haven't got camera/scanner/web page.
The basic idea is to fix the diff. onto the "wheel assembly" using two
medium (12 tooth) gears locked into those green bits with the axle-shaped
hole. The wheel drive axle goes straight through the diff, while the
turning is achieved by a 16 tooth gear which turns the diff. This gear is
ratcheted.
To drive the wheel, use the drive axle. If you're going the right way then
the entire thing can't turn due to the ratchet.
To turn, you need to rotate *both* axles - if you don't rotate the drive
axle then the wheel turns as the entire thing turns.
eg. if the drive axle is attached to motor A, and the turning axle to
motor B
drive: A>
turn: A< B<
With a second diff. you could operate this device with only one motor.
Hope that helps ... maybe I'll get a picture somehow.
Right, now I've made one. What am I supposed to use it for?! Oh, forgot to
say, it's (including the wheel) about 10cm tall, which makes it rather
difficult for eg. a "dodgem car" type vehicle... Also, you can't put too
much load on it as you're relying on the differential (and the single axle
going through it) to supply the necessary torque to keep it vertical.
Stuart
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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