This is an improved version of a previous design, http://www.chiefdelphi.com/forums/showthread.php?t=147276
Most changes involve trying to solve the problems stated by this extremely helpful post by SoftwareBug2.0, http://www.chiefdelphi.com/forums/showpost.php?p=1574346&postcount=14
The design uses ball caster wheels a couple inches from the center of the top of the basketball. This wedges the ball into the 6" wheels in the center of the robot. Also, ball wheels designed to hold the basketballs in the robot have been added.