So I built a r2d2, I was originally going to make it into a custom case mod. Now I want to make it mobile. I can't seem to find information on what motors to use. I would like it to move at about 4 - 4.5 fps, it can have a Max wheel diamater of 6 inches, and he weighs aprox 30lbs with all equipment in him. I will be using a arduino board with a ro-bot-x shield used in to either a labtop or a motor xoom to control him via pc-pc connection. Any advice would be very helpful. Thank you