[ngreen]

yes, this is very possible. We used a pneumatic lift last year that could stop in multiple positions.

I drew a fast diagram in paint of how we did it last year.

Basically it involves routing all exhaust from the double solenoid through a single solenoid and putting a stop or loop on the NOT ON state of the solenoid. Make sure you stop the exhaust of the single solenoid too. Then you can program the single and double solenoids to work together. When you push one button on the joystick the single solenoid kicks on to allow the exhaust to escape to atmosphere, and when it is released the solenoid will switch to the pressured side and stop. We used two buttons, extending and retracting but made so they would trigger on side of the double solenoid and put the single solenoid into the ON state. With a little more programming you could probably be pretty exact as to when you stop.

I'll include the diagram. Any questions just ask.

I added a picture of last years robot in a halfway position. The cylinders are behind the yellow fiberglass poles.