Pneumatics

Josiah Wood

Hey,

What do I need in order to control say 20-30 pneumatic pistons with·a microcontroller?· They don't need to be extremely powerful, but each piston does need to move about 6 inches.· The system only needs to be powerful enough to lift itself using about 3 or 4 of the pistons, but all the pistons need to be the same.

Also, any recomendations as to where I can find cheap pneumatic parts (specifically the pistons since I need about 20-30 of them) would be appreciated.

Thanks,

Joey

LoopyByteloose

If you want to control all 30 pneumatic pistons at the same time, you need 30 bits minimum of output pins or approximately 4 bytes (4x8=32).

Of course if you do that all with·one or more·shift registers and 4 8-bit latches, pumping out 4 byte groups to a separate pin on each latch, it only occupys a few pins on a BasicStamp for information and for enabling which latch is read. Using one of the faster Stamps will make it all happen so fast that you won't know a serial output and shift register is involved.

Take a look at the 74HC595 or TPI6595 demultiplexers -- each one can handle 8 bits.· Search for them on this web site and forum.

Of course you need a selenoid pneumatic valve on each of the piston lines and then you need to use a driver (say the Darlington Driver UNL3803A [noparse][[/noparse]accually four of these]) to turn on and off each of the selenoids.

And, you will need a power supply for all of this above the selenoid voltage (because the drivers have a voltage drop caused by their insertion).

You could power the test run with a CO2 tank and regulator (to avoid the noisy compressor). CO2 in small tanks is available at your local Coca-cola distributor or a welding supply.

Pneumatic pistons with 6 inches of movement are readily available, pneumatic selenoids are readily available. And you have the serial port and several input pins left over for control on the BasicStamp.

I am living abroad so I have no idea where you might want to look for ordering the stuff. I was into pneumatics some 15 years ago and all these parts were available through various surplus suppliers.

With 30 pistons, I just wonder if the software isn't your biggest challange. Take a look at Parallax's Toddler documents for concepts of using DATA tables and transitions for reducing the program size.

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G. Herzog in Taiwan

Post Edited (Herzog) : 8/29/2004 5:56:06 AM GMT

Lee Harker

Joey,
Here are a couple of places you could look for pneumatic cylinders and valves. www.herbach.com & www.surpluscenter.com.
For 20-30 I think you're going to run into quite a few bucks.

Lee Harker