[Al Skierkiewicz]

EH,
To respond to your original question, the simplest solution is to tie all four modules together for steering. You are going to have to provide some method of getting all the wheels aligned but then you should be good. We have made independent steering when we wanted to achieve something special. For instance, strafing in an arc for Rack and Roll. When discussing power, most teams will use some form of transmission built into the wheel module as external drives can be less efficient. The downside of crab steering designs is the weight and space needed for the system and the complexity of programming and feedback. Above all else, the best crab is only as good as it's drivers so practice is essential. Lot's and lot's of practice.