Ok, Here's My $0.02:
Alright, First off, Our Team is Using Pneumatics All the way. ONE Piston for our uber-cool arm.
To give you an idea of the range we can accomplish:
-The Arm Fits within starting size (duh)
-The Arm
will utilize
Mid-Stroke Positioning (This is "Stopping the piston in between fully out and in") The Mid-Stroke Positioning allows us to stop our arm at any point between retracted and extended. We developed a system in 2003 which also allowed us to do this with our staged forklift, and for those who shun mid-stroke positioning to be "inaccurate", I will try to have some pics or video for you to see how "inaccurate" it is
But anyway, for those interested, the "basic" way to stop the piston mid-way is to block the Exhaust output from the solenoid controlling your piston.
Do a search and you'll quickly find more info on the subject.
Back to our Arm!
-It's capable of "grabbing" a tetra on the ground and capping it onto the center goal, up to 2-3 tetras on Center
-It stacks one at a time (Which I know many of you out there are stacking before hand
)
-It can stack 5-6 Tetras on the "Standard" goals
-Our arm will weigh approx. < 20lbs, Including the Four ~4.5 - 5' Counter-Support beams spreading across the chassis.
-The "grabber" section of the arm extends from 8" to 10'4" from ground level.
Now, to be fair, here are a few issues we may see developing with our arm:
-Lack of Air (I'm not too Worried about this one, by the looks of our Pneumatics Board, but always something to look out for! Especially with our Pistons...)
-Tipping (Once again, we've put alot of work into maintaining our CG in our Design, plus its simple and small (surprisingly, yes), so I'm not at worried about this yet either. We also do not extend our arm out very far outside of our robots x,z axis size (38x28)
I hope to have more Info up soon, but for those interested, here's a GIF of a (much) older model of the arm in motion:
http://www.raptar.net/ArmAnim.gif
(This was made a while back, much changes since then
)
Hope the info helps!