[kwotremb]

Sounds like you have something similar to what we did this year on our robot. We had our entire mast and arm asembly rotate at a pivot point at the base that was controlled by a pnuematic cylinder. We used the flow control valves without any issues at all (basically the simple screw ones that replaced the straight or 90s that you screw onto the festo valvues). We had them pass inspection at 3 different events so I believe there should not be any issues with you using them. I thought it worked great for us.We only had the 'up' part of the piston hooked up to the air. Then for down all we did is have a flow control valve on the output that we controlled to make sure the fee fall of the arm was at a rate we needed.

Now for you, I would think for 'up' you guys should be able to use a flow control valve on the output just as you are thinking with the down. The flow control will make sure the rate at which the air can escape is limited, or more controlled. That way when the arm is moving slowly at first, the speed is not limited at all because the air can escape as fast as air is going in the other side of the cylinder. Then when you start to get to the top the air pressure will start to build up due to the fact that it will not be able to escape fast enough and slow down the rate of the arm. Hopefully that should be enough to prevent some of the slam you are experiencing on the top. Another simple way to melp out some of the slam is to put a bumper on the arm or frame where they hit, that way the slam is less violent. We were going to do this until we designed it so our cylinder maed out before we hit a hard stop. Hopefully this helps.