Subject:
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Re: an idea, can someone tell me if this is possible/been done before/etc?
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 2 Dec 2003 21:36:34 GMT
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Original-From:
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Kevin Clague <kevin_clague@yahoo.com^ihatespam^>
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Viewed:
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1340 times
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--- Jim Choate <ravage@einstein.ssz.com> wrote:
>
> On Tue, 2 Dec 2003, Kevin L. Clague wrote:
>
> > What if we assume that each output drives a motor,
>
> Bad assumption but it would work, the RCX is too
> limited on I/O to be
> doing that sort of stuff except in the case of
> simple rollers/walker.
> Since legs have symmetry it's silly not to take
> advantage of it here,
> you've got to use it to keep the thing in some sort
> of static/dynamic
> balance. If you're going to use
> differential/planetary/co-axial/pullies/etc.
> then -use- them [1].
I guess we're talking different things here.
You were telling me to use all three motor/sensors. I
claim I only need two for my Quad242.
I have to see WWW to know what you are talking about I
guess, or else you lost me.
Static balance requires no special hardware typically.
Dynamic balance is much harder. I've tried to do it
with accelerometers, but it doesn't work well by
themselves. I have a rate gryo that I'd like to
interface to RCX, but have not had time yet.
>
> Basic engineering efficiency. My approach is
> Occham's Razor and the
> concept of 'elegence'. If there is -anything- that
> isn't demonstrably a
> requirement for the goal(s) then it's 'outta here!'.
I understand this concept, although I prefer not to
put anything in in the first place. I don't
understand your point here. What proposal are you
making?
>
> With regard to the discussion of walkers and leg
> blockage. Let's assume
> for a moment that instead of using switches or
> something we decide to do
> something mechanical. For example a triangular cam
> attached to the end of
> the leg segment. It would allow the end of the leg,
> assuming sufficiently
> low compliance [2], to move up over an object due to
> the rotational
> translation of forces the cam would provide. It
> takes the horizontal
> energy and transforms it into vertical energy.
OK.
>
> You can also move the cam farther up the leg, say a
> gear with a pin
> sticking out of it. It would normaly be positioned
> such that the pin was
> at the bottom of the rotation at all times during
> normal operation.
> However, when the leg stalled the extra torque would
> be sufficient to trip
> some sort of 'switch' (eg a rubber band providing
> counter tension) once
> the torque got over a specific amount. The rotation
> of the gear would move
> the pin to the top, thus providing a tad extra leg
> clearance for the bot.
> It would need a bang/bang stop at this point just to
> make sure nothing got
> too torqued out of shape if the leg is still
> blocked.
Not done much concerning blocked legs. I've not
creted anything that advanced.
>
> [1] It reminds me of an article SciAm many years ago
> about using pullies
> and springs to do basic
> addition/subtraction/and/or/not. Pretty
> powerful, don't know if it's universal as in
> UTM.
UTM?
Kevin
>
> -- --
>
> Open Forge, LLC 24/365 Onsite Support for PCs,
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>
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>
> James Choate 512-451-7087 ravage@ssz.com
> jchoate@open-forge.com
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