[Al Skierkiewicz]

Chris wrote a very good description of the problem but there is at least one more option and that is to have the drive wheels turn in the direction you want to go. We have used this on two robots and call it "crab steering". This year, all four wheels were driven and all four turned. The effect on robot movement is to make it look like a crab running down the beach to avoid waves. The robot moves in any direction without having to point in that direction. There are down sides to this approach though...Software must get feedback for position info, turning driven wheels is more mechanically complex and driver practice is essential to know the reaction of the steering during competition. That last one is the most important because there no longer is a "front" side although the robot is still capable of backing up or moving forward in any direction. Think of it as the queen on a chess board, any direction same power and same speed in all directions, extreme manueverability.