[Dave McLaughlin]

With a crab drive all of the wheels are oriented in the same direction relative to the field, and all wheels are powered so that the robot moves in that direction. With a pure crab drive there is no way to change the orientation of the robot relative to the field, so most teams implement a turreted manipulator (Team 118 in 2007 and 2008 are good examples). A pure swerve is where all wheels are powered independently AND steered independently so that each wheel can be facing a different direction relative to the field. Our "half swerve" has the front and rear wheels steered together, and the left and right wheels powered together.