Subject:
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Re: Pneumatics and the RCX -how?
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 26 Oct 1999 16:20:18 GMT
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Viewed:
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453 times
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In lugnet.robotics, lego-robotics@crynwr.com (Doug Carlson) writes:
> I'd love to get a hold of some small RCX controllable valves also.
> I just finnished building a six legged pneumatic walker that would
> benefit from these for different walking motions.
> Presently, it just walks forward with the tripod gate type motion.
> It uses 20 of the small pneumatic cylinders (three per leg) with two inside
> the body to
> flip the air switches and has the Cybermaster rubber tipped thingies for
> feet.
> There are a few pictures and a short MPG movie at :
>
> http://www.net-info.com/~dcarlson/pnwalker.htm
> (just a temporary location for now, I'll add this to my main page listed in
> my sig soon)
Very nice construction!!! Could you post some pictures of your hand-held
controller too? (Whatever is on the off-screen end of the tether seen in the
video clip.) Is that just a battery box, or is there more to it?
> I hooked it up to a different compressed air source (@ 30 psi) for the
> movie so i could capture more gate cycles.
> With a LEGO compressor and three air tanks it just takes a couple steps
> (quickly) and then waits for the pressure
> to build up again. It takes almost 30 psi to flip the switches when using
> the small cylinders to actuate them. This is actually a benefit because it
> enables the pneumatic cylinders driving the legs to move before the gate
> switches flip to the next state.
>
>
> Doug
>
>
> At 11:53 AM 10/21/99 +0000, you wrote:
> >
> > I have been searching for the answer to this one for a while. My intent is
> > to find a supplier who has small electrically operated (solenoid) valves • which
> > can be driven by the RCX output(s).
> >
> > I have found one so far, but the valves are very pricy. But I haven't given
> > up!
> >
> > I do intend to find an alternative to driving the lego valves using a motor.
> > That is simply a waste of energy. I have built lead screws around 10/32 nylon
> > studding which convert motor output into linear motion, much like the drive
> > from a pneumatic cylinder. They are hugely powerful and demolish designs • which
> > fail to provide adequate limit switches! But there is something very
> > charismatic
> > about robot designs which use pneumatic parts, and thus my quest!
> >
> > If I am successful, I assure you, I will publish!
I had some thoughts about this that I posted a few weeks back... Basically I
noticed that it is easy to pinch the pneumatic hoses closed with your fingers,
so it should be possible to construct your own valves by pinching hoses with
cams on an axle. This would require very little torque, and it should be
possible to run multiple cams from a single axle/motor.
Another design would be to run the hose through the holes in a pair of Technic
beams, then slide one beam relative to the other to pinch the hose closed.
I'm sure there are hundreds of other ways to build pneumatic valves out of the
pieces that we already have.
In a design like the six-legged walker, I would imagine that you could use a
single shaft with synchronized cams that can run the entire walker off one
motor. It would require some clever mechanics, but it's basically the same
way that the valves in an automobile engine work together, driven off a single
cam shaft.
And based on your pictures, it looks like you're up to the challenge of
designing "some clever mechanics" to make it work. Keep us posted!
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Message is in Reply To:
 | | Re: Pneumatics and the RCX -how?
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| I'd love to get a hold of some small RCX controllable valves also. I just finnished building a six legged pneumatic walker that would benefit from these for different walking motions. Presently, it just walks forward with the tripod gate type (...) (25 years ago, 21-Oct-99, to lugnet.robotics)
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