We designed our robot to do "drive by scoring." Meaning, we were able to score a ringer while still moving, thereby elimating a lot of the defense that would be played against us. The inspiration for this design came from two teams, Wildstang in 2005, and Rhodewarriors in 2006. Both teams scored off the side of their robots, and were able to use their drivetrains to ward off most defensive attacks.
We accomplished the same effect by allowing our grabber to rotate 90 degree to the left and right after picking up a ringer. The picture below shows the extra degree of freedom we have with our manipulator. As I said, in theory this mechanism works great. However, we found it very difficult to actually have any room to drive around in, nevermind a clear shot at any side of the rack. Fighting your way to/from the rack seems to be about the only way to score this year. (Unfortunately...)
Here's the picture of us in
"drive-by" mode.
We powered this "wrist" mechanism with a window motor, geared down about 6:1. We tried two different codes to operate it. The first had the arm mimic the joystick position, so the co-driver had to hold the joystick in the position he wanted the arm to be in, with position feedback controlled with a gyro. The 2nd mode of operation allowed the co-drive to only use the joystick to move it to position, just like an elevator or arm. We then used a "home position" button to return the arm to it's vertical position, again controlled by the gyro.
Feel free to ask more questions. Hope it opens up some ideas for other teams.
BEN