Path Planning of Multiple UAVs for the Early Detection of Wildfires in the National Park of Kotychi and Strofylia Wetlands

The surveillance of the National Park Kotychi and Strofylia Wetlands in southwest Greece with Unmanned Aerial Vehicles (UAVs) is studied in this work. As comprehensive coverage of the region cannot be attained with just stationary ground cameras, multiple parallel moving UAVs are utilized. The region is divided into squares, which are further subdivided into regular grids with nodes whose weights are calculated based on the fire risk of the corresponding region. Heuristic methods are proposed for selecting the UAVs’ start and goal graph nodes. The graph with the start and goal nodes serves as input to the A* algorithm, which computes offline short paths that direct the UAVs to cross areas with the highest fire risk. The number of UAVs is progressively increased as the coverage of the previous detections proves insufficient. The authors determine the number of UAVs needed for each section of the divided area. They also demonstrate that the UAVs can scan simultaneously without collisions, as each UAV follows a unique path inaccessible to the others. Finally, the presented computations and results show that the proposed method can effectively contribute to fire scanning in the area.