Team RUSH dual-pathed ball possession mechanisms this year during prototyping.
We were working on a single-roller design, as well as a setup consisting of 2 powered rollers.
After testing both prototypes, we realized that the "pinch" was working much more effectively than the single roller design.
After a little more testing we discovered that having only one roller powered and a bottom bar gave the same effect as both rollers powered, so for simplicity's sake we powered only the top. We also had a flat hard stop to prevent the ball from going > 3" inside our frame perimeter.
We spring loaded the bottom bar down to ensure ball contact with the floor at all times but still received several carrying penalties (most courtesy of Richard
), but with a bit of tweaking mechanically and of driver actions we managed to avoid them entirely after our first 2 events.