Subject:
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Re: MERLIN valves & sensors
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 5 Sep 2004 23:33:43 GMT
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Viewed:
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1069 times
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In lugnet.robotics, Steve Baker <sjbaker1@airmail.net> wrote:
> Joe Strout wrote:
> > Did you catch that these are *proportional* air valves? A LEGO mechanical air
> > switch is not proportional, is it? (Genuine question -- I haven't gotten my
> > hands on one yet, so I could be mistaken about that.)
>
> LEGO switches certainly aren't proportional - but I question the value of
> proportional pneumatic controls. The pressure either side of the valve
> will equalize very rapidly even if the control is opened only a small
> amount. Proportional valves can control the air speed - but not the
> pressure.
>
> So you could maybe control the rate at which a Lego cylinder would expand
> or compress - but not the force it could apply or how far it would extend.
But if you have a feedback system, the speed at which it activates is very
important to avoid overshoot. Unfortunately the LEGO pneumatic switches do not
make it easy to create feedback circuits, as they require a lot of force and
have a relatively large "dead" area.
(Please, oh please, LEGO, make a sliding pneumatic valve!!!)
As to proportionality, they do open slowly, but over a fairly small percentage
of the travel. So no, they aren't proportional.
ROSCO
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Message has 1 Reply:
Message is in Reply To:
 | | Re: MERLIN valves & sensors
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| (...) LEGO switches certainly aren't proportional - but I question the value of proportional pneumatic controls. The pressure either side of the valve will equalize very rapidly even if the control is opened only a small amount. Proportional valves (...) (20 years ago, 5-Sep-04, to lugnet.robotics)
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