paper: 4 wheel independent drive & independent steering ("swerve")

[artdutra04]

Nice, simple explanations of the inverse kinematics* of an independent swerve. We derived the same end result for the independent swerve for our 2010 robot, but wrote all the control code in Java.

Because we had to use the ~20W Denso motors for turning the wheel pods, the max omega of the individual wheel pods was rather slow. While translating was rather zippy with a max speed of around 10 ft/sec, complex motion was somewhat sluggish due to slow wheel pod rotation. It was an unfortunate situation, but we were able to combat this by increasing the maximum range of motion of the pod rotation to 400°-450° (I don't remember the exact value off the top of my head), to decrease the number of times the pod would have to pivot 180° and reverse the wheel direction.

* I remember back when implementing PID control was considered something of a dark art on FRC robots, much like inverse kinematics is now. I'd love to see more teams utilize inverse kinematics for various arms/elevators on their robots, especially since the inverse kinematics for a 2 or 3DOF open-kinematic-loop mechanism isn't particularly difficult and can be solved with only high-school geometry.