Haven't given it a lot of thought but if I were to design this unit I would have used two independent systems. Meaning two wheelchair controllers. That way you get the same control as a tank or professional grade mower. Push one stick forward and pull one back and you spin in place as one motor would be trying to go forward while the other was trying to go reverse. Also if something broke you still have a redundant system. Could be really neat! Are the controllers really expensive.