Subject:
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Re: "synchro drive"
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 5 Feb 1999 06:31:09 GMT
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Original-From:
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Doug Carlson <dcarlson@NOSPAMnet-info.com>
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Viewed:
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3112 times
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> Gord Goebel wrote:
> > Here's my two cents worth:
> >
> > Doug Carlson wrote:
> >
> > > I'm not sure I follow the problem in the design I used.
> > > One feature which isn't spelled out on my page is that each wheel
> > > is offset from the center of its turntable by a distance equal to the wheels
> > > radius.
> >
> > Excellent idea! :)
Wish it was mine. :-)
> >
> >
> > > When the turntable turns (while the vertical drive shaft is static) the wheel just • runs
> > > in circles equal to its diameter and the vehicle doesn't move at all.
> >
> > It seems to me that you must have accidentally hit on the right ratios between the
> > size of the wheel and the sizes of the bevel gears since the problem is caused by the
> > wheel's bevel gear turning as it rotates around the bevel gear on the stationary
> > vertical drive shaft...
I just used the 12T miter gears. 1:1 with the wheel offset equal to the wheel radius.I was
just lucky that it fit the turntable so well.
> >
> >
> > > If you drive both the steering and main drive systems at the same time the whole
> > > vehicle
> > > runs in a circle (while still 'facing' the same direction) the diameter of which
> >
> > What if you WANT to change the direction it's facing? I guess a turret is the only
> > feasible answer. hmmm?
I think the point of this platform is that it's handy to always have a directional
reference.Kind of a built in compass. At least until the errors creep in.
It would be pretty easy for the turret to track the direction of travel and maybe even
use the Adder/Subtracter to deviate left or right when useful.
> >
> > >
> > > can be changed
> > > by the the ratio of main drive speed to turning drive speed. So you can 'turn' on
> > > a point or any radius you might choose.
>
> > Or a parabola.
>
> > >
> > > One other benefit of this offset design is that the wheel contact point is not
> > > 'scrubbed'
>
> > That's why it's an excellent idea. ;)
:-)
> > >
> > > as would be the case with a center mounted wheel when the turntable rotates.
> > > I have also read of a design using a differential between two wheels per
> > > 'turntable' to
> > > equalize the load on the wheels.
>
> > Excuse me for being a nit picker but the idea is to equalize the load on the turntable
Actually not, I think it was wheel deformation caused by non-uniform loading that wasthe
issue. This caused some extra tracking errors. But I agree that with a LEGO platform
it may be more important to equalize the load on the turntable. Especially if the wheel is
offset more from the center.
> >
>
> > > -- Doug
> >
> > ------------------------------------------------------------------------
> > Gord Goebel <gggii@passport.ca>
> > DataJack Consulting
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message is in Reply To:
 | | Re: "synchro drive"
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| I'm not sure I follow the problem in the design I used. One feature which isn't spelled out on my page is that each wheel is offset from the center of its turntable by a distance equal to the wheels radius. When the turntable turns (while the (...) (28 years ago, 4-Feb-99, to lugnet.robotics)
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