Nonholonomic metrics gives rise to potential functions allowing
real-time obstacle avoidance
See: M. Khatib, H. Jaouni, R. Chatila, J.P. Laumond, "Dynamic path modification for
car-like nonholonomic mobile robots", in IEEE Int. Conf. on Robotics
and Automation, Albuquerque, April 97
The small white square is an unexpected obstacle; the nonholonomic path is
updated in real-time and maneuvers are automatically computed to avoid it.
Potential are derived from an efficient function computing the
to an obstacle .