Here is a picture of the underside of the bot:
Please excuse the sub par wiring job. We're still working on cleaning that up.
When twisting the joystick to the left, the front and back wheels turn away from each other. The front go forward and the back go backward. When twisting the joystick right, that is reversed, with the front going back and the back going forward.
As for the joystick, we are using a Logitech extreme 3D pro.