Optimal path planning based on spline-RRT* for fixed-wing UAVs operating in three-dimensional environments

This paper proposes a spline-RRT* algorithm and describes its application to path planning for fixed-wing UAVs operating in three-dimensional environments. The tree structure of the proposed spline-RRT* algorithm is extended by using a spline method based on a cubic Bézier curve. Through the use of this spline method, the algorithm can produce a smooth path without any post-processing and can also handle the initial approach direction, that is, the heading and flight path angle for the target UAV. A dynamic feasibility check, incorporating a geometric collision check, is also run as part of the tree extension, allowing the algorithm to generate a smooth three-dimensional path that is both geometrically and dynamically feasible while also being cost-optimal. Several simulation results show the validity of the proposed spline-RRT* algorithm, implying that it can be effectively applied to path planning for fixed-wing UAVs operating in three-dimensional environments.