Abstract:The motion planning problem of unmanned autonomous vehicle (UAV) is reviewed. UAV operates in both structured road and unstructured field with differential constraints. The problem of trajectory generation can be simplified with the differential flatness of Ackerman steering vehicle. Compared to direct trajectory generation method, pathvelocity decomposition method is more popular. Clothoids, splines and polynomial spirals are used for path generation. The two major planning algorithms of great practical significance are rapidly random tree(RRT) in the name of samplingbased and A* in the name of searchbased methods.