All,
Here is a design that we chose not to use, but may give you some ideas.
http://pejaver.com/FRC2011/Proposal-1-13-11.pdf or
http://pejaver.com/FRC2011/Proposal-1-13-11.htm (7 pages, best viewed in IE)
CHERRY is a simple solution inspired by the Cherry Picker device.
The components are like a human arm. The Support arm (upper arm) hinges around the “shoulder” joint. The picker arm (fore arm) hinges around the “elbow” joint. There is a “hand” at the other end of the picker arm which hinges on a “wrist” joint.
As designed, all joints swivel in the vertical plane along the center of the robot. All joints have rotary position sensors and use worm drives.
It can hang up to 9’ 5” high and allows autonomous mode & minibots. It uses just 3 motors & 3 worm drives, no pneumatics. It uses software to move the hand intelligently and minimize driver workload.
It picks up pieces off the floor like a fork lift. The hand swivels to cradle the game piece more securely so that it doesn’t fall off during motion. The robot’s maximum horizontal dimension during the game is limited to 60" (original requirement).
Have fun...
--solo