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Unread 17-01-2004, 03:03
ngreen ngreen is offline
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AKA: Nelson Green
FRC #1108 (Panther Robotics)
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Re: Mulit-postioning with pnuematics this year?

Quote:
Originally Posted by pras870
I've actually been looking for a way to do this for the past 2 years. I have a pretty firm grasp on pnuematics from the past 2 years, but I still fail to see how this could be done

I've also found, that amazingly, pneumatics actually weigh less then a motor driven assembly. Our team has always seemed to have a weight problem, and I'm always looking for a way to incorporate pneumatics instead of motor driven for the fact that they weigh less and are actually more reliable, but I've always been under the assumption, with the materials first gives us, you can only open and close a cylinder in 2 positions (full and closed).
If is very possible. I will give you the most complete explanation as to why. I'm currently working on a chemical engineering degree and one of my professor said something that applies here while speaking on diversity. Differences cause change. In pneumatics the difference in pressure cause the cylinder to extend or retract. It relies on this pressure to move. Since the pressure before the double solenoid is set and won't keep increasing past 60psi you don't have to worry about it to continously compressing. Air flowing from the 60psi side against an open exhaust at 1 atm causes the stroke to be pushes towards the one atmosphere side and the air leave the cylinder through the exhaust. If instead you route all exhaust from the cyclinder to a closed air system the cyclinder will not work or move because it is pushing against the non-atmospheric pressurized air in the tubing. Draw out a vector. When a 60psi force pushes against a 60psi force the resulting force is 0. There is no change. So we have have both choice possible. Movement and No Movement so how do we get these to work together without me walking along and doing it manually. First gave us these wonderful Festo single solenoid to use. First step is to route all exhaust through the single solenoid. Use a tee to connect the two exhaust and use a single piece of tubing to connect to the solenoid. Next plug the exhaust of the single solenoid. It is easier this way and stops it from leaking that way. Next add a loop or a stop to one of the holes on the two holed side. Note: Single solenoid work in NOt on and on and the state will revert back to not on when the power is cut. Lastly find a good programmer that will make both solenoids work together. Think that using this system, to move you must have the exhaust go through the non plugged side of the single solenoid(the one open to the atmosphere). Also, using the double solenoid you trigger just one side to switch. THere are many more things you can do with a good programmer with this system. Like pushing a button that is set to extend the cylinder for a certain time (or possibly distance).

It works. Believe me. Look at my sloppy diagram for more reference. My team wouldn't have dared built a lifting mechanism like that if we couldn't control where we stopped it. Manipulating the boxes with accuracy was a key last year. Any questions just ask. I really want to see the capabilities with a rotary actuator. Think 45 degrees.