[Jogo]

Really like the idea of that use of throttle.

Out of curiosity, is there anything special about the function x^3+x?

Recently we've used an exponential graph:
Let min = lowest desired value (min>0, usually the highest value at which the robot doesn't move)
Let max = highest desired value (usually, max = 1.0)
Then, output = min(max/min)^joystick value.

This also enables us to vary the max value for the turning axes based on the robot's forward speed.