Subject:
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Re: Pneumatic switching circuits
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Newsgroups:
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lugnet.technic
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Date:
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Fri, 28 Jan 2005 22:39:18 GMT
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Viewed:
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2720 times
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In lugnet.technic, Joseph Greene wrote:
> <SNIP>
> > > So I think I have a way to do this..but I'm running into walls...
> >
> > I understand the above very well, but I do not understand the stuff below.
>
> OOPS.. I changed diagramming method to a physical ascii art diagram without
> clarifying it..
> Below is 2 switches actuated by a slider which pushes first one switch handle
> (left switch) from far left to far right then when pushed past the far left
> switch begins to push the right hand switch from left to right.. at it'f full
> travel the slider with the 0 (Think Technic Ball from the ball and socket
> stuff)would move past the right hand switch so that on the retracting cycle it
> would flip the right then left switches.. thus reversing the order of
> operation...
> Think of it as an ASCII anitmation...
I thought that might be what it was.
> > >
> > >
> > > ->---0----
> > > \ \
> > > SW SW
> > >
> > > ->---0---
> > > | \
> > > SW SW
> > >
> > > ->---0---
> > > / \
> > > SW SW
> > > ->---0---
> > > / |
> > > SW SW
> > >
> > > ->---0---
> > > / /
> > > SW SW
> > >
> > > and the revers would flip the switches in reverse order!
> > >
> > > Cool.. Anyone done this? Any ideas The mechanics of it are killing me.. and some
> > > of my LEGO.. I already busted 1 axle pin...
> > >
> > > there are alternatives.. but this one would look the smoothest.. in my opinion..
> > > There is of course the old - Break out the RCX and code it answer.. which is a
> > > possibility.. but I'm trying to do it all Pneumatic/Mechanical...
> >
> > I admire you doing it all pneumatically.
> >
> > I ended up having to have two pistons that were purely timing switches. There
> > were races in the circuit where things didn't stay pressured when needed, so the
> > two extra pistons/switches were race killers. I've used this circuit for
> > quad242, its succesor, and hex363, and phd.
> >
> > Kevin
>
> hmm.. I'm working hard on fully groking the pneumatic sequencing page..
> although with my moshed net connection, It never finished downloading all of the
> images (I gave it 4 hours)... I'd get better performance from a 56k modem..
It all started when JP Brown (famous for his Rubik Cube Solver out of LEGO),
made the bold statement that you could not do boolean logic using LEGO
pneumatics, because of the switches. Inutitively I knew this had to be wrong.
His bias was because he knew how it was done in the industry.
I created a couple of versions of dual piston, dual switch dual polarity
pneumatic gates (both AND and OR), and made a few pneumatic adding machines.
Then Mark Terrabain came along and told us about his single piston single switch
single polarity AND gate. It is very cool. You can think of the pressure hoses
that drive the piston as one input, and then the other input goes into the input
port of the switch. The switch port closest to the piston is the A AND B output
port.... the other port is the NOT A AND B (where A is the input that drives the
piston).
In my walkers, I use two switches per piston. One tells you when the piston is
expanded, and the other tells you when the piston contracts.
Your legs are going to work in pairs right?
So lets say pair 1 has two pistons A and B for vertical lift. Each piston has
two swtiches. Let's use two switches to tell when piston A and piston B are
both expanded.
/ /
+----/--+ +----/--+
|O1 O2| |O1 O2|
| | I | | I |
+-|-----+ +---A---+
A | B |
+---------------+
We hook pressure into switch A's input I. We hook switch A's O1 output to
swtich B's input I. Now we will get pressure out switch B's O1 output only when
switch A and switch B are flipped to the right..... I'm assuming here that
piston A and piston B flip their switches to the right when they are expanded.
We never use either switches' outputs O2, so we have to plug them (think short
hose segment and light sabre blade).
\ \
+--\----+ +--\----+
|O1 O2| |O1 O2|
| I | | | I |
+-----|-+ +---A---+
A | B |
+-----------+
The above diagram gives you pressure out O2 when both pistons are contracted.
So the above gives you the ability to synchronize when the two legs in pair 1
are both lifted or dropped. You can use the exact same thing for pair 2.
The other leg movement (horizontal) can happen on all four legs at a time. You
can use the technique above only with four pistons and eight switches to tell
when all the legs have swept to either extreme.
Now for the sequence.....
When pair 1 is up, you want to sweep the legs.
When all the legs have swept, lower pair 1.
When pair 1 is down, raise pair 2.
When pair 2 is up, sweep the legs.
When all the legs had swept, lower pair 2.
When pair 2 is down, raise pair 1.
And the cycle repeats.
So...... the "pair 1 up" can be used to pressurize the legs to sweep one
direction.
The "legs swept the first direction" output can be used to pressurize pair 1 to
lower its legs.
The "pair 1 down" output can be used to force pair 2 up.
The "pair 2 up" output can be used to pressurize the legs sweep the opposite
direction.
The "legs swept opposite direction" output can be used to force pair 2 down.
The "pair 2 down" output can be used to force pair 1 up.....
Does this help?
Kevin
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Message has 1 Reply:
 | | Re: Pneumatic switching circuits
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| (...) <SNIP> (...) I was wondering what the mthod of choice for this was... (...) That helps a lot.. looks like I'm gonna need to find around 30 more switches... Best source I found Technic Wreckers has a bunch.. but I fear shipping from Australia (...) (20 years ago, 29-Jan-05, to lugnet.technic)
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Message is in Reply To:
| | Re: Pneumatic switching circuits
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| <SNIP> (...) OOPS.. I changed diagramming method to a physical ascii art diagram without clarifying it.. Below is 2 switches actuated by a slider which pushes first one switch handle (left switch) from far left to far right then when pushed past the (...) (20 years ago, 28-Jan-05, to lugnet.technic)
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