[RyanN]

Originally Posted by KenWittlief

Since you only care about the end positions, all you need is a piston and a lever. The piston does not need to go to its stops, put mechanical stops on the lever that can be adjusted to set the alignment for each wheel.

if fact, it could be spring loaded in one direction, so the robot will default to one direction if your pnuematics fail (or simplify your pnuematics so they are only driven in one direction.

I agree, a simple lever and pneumatic piston is all you would need, a mechanical stop will certainly work. Remember, simplicity is your friend. More complicated things tend to break more, and are harder to fix. All you need to have is a piston on a hinge and a lever attached to the wheel base.