Low-altitude Trajectory Planning Method for Fixed-wing VTOL Aircraft Based on Adaptive Airspace Structure Topology

In current air traffic management systems, aircraft trajectory planning methods based on uniform gridsare widely adopted but exhibit inherent limitations. The uniform grid partitioning of airspace fails to adaptivelymatch variable-scale obstacle distributions, resulting in reduced planning efficiency, higher computational costs inspecific airspace sectors, and diminished responsiveness to dynamic trajectory adjustments. To address these challenges, an adaptive airspace mesh-scaling topology algorithm is studied in this paper. This approach applies adaptive Delaunay triangulation to match the spatial distribution of obstacles and enables rapid local reconstruction ofthe airspace structure in response to the updates from dynamic obstacles. Subsequently, a trajectory-searching network is constructed using this adaptive topology. The A* algorithm generates the initial trajectories on this network.To mitigate excessive length and sharp turns in initial paths, a trajectory refinement algorithm is de-signed. This optimization method replaces sharp turns with circular arcs through local detection. Non-conforming arcs are optimized by adjusting the safety boundary radius to comply with the operational characteristics of fixed-wing VTOL aircraft.Simulation results from the specific test examples show that the adaptive airspace mesh-scaling topology algorithmreduces the number of airspace grid cells by 69.33%, significantly compressing the search space. The trajectory refinement algorithm can reduce trajectory length by 8%-15% while markedly enhancing smoothness of the trajectory, there-by decreasing the complexity and energy consumption of flight control. In summary, this study provides an efficient and practical solution for low-altitude trajectory planning of fixed-wing VTOL aircraft.