This paper deals with the complete characterization of the shortest pa
ths for a car-like robot, Previous works have shown that the search fo
r a shortest path may be limited to a simple family of trajectories. O
ur work completes this study by providing a way to select inside this
family an optimal path to link any two configurations, We combine the
necessary conditions given by Pontryagin's Maximum Principle with a ge
ometric reasoning, This approach enables us to complete the local info
rmation with a global analysis of different wave fronts. We construct
a partition of the configuration space in regions where the same kind
of path is optimal to reach the origin, In other terms, we determine a
shortest path synthesis by providing, at each point, an optimal contr
ol law to steer the robot to the origin.