Helicopter trajectory planning method based on improved IRRT*-D* algorithm in forest fire rescue scenarios

Helicopters are widely employed in forest fire rescue operations due to their strong manoeuvrability, rapid response capabilities, and fewer terrain constraints. However, because of the dynamic and unpredictable nature of forest fire environments, helicopters may inadvertently enter high-risk areas—such as zones with extreme temperatures and dense smoke—when following pre-planned routes, thereby compromising flight safety. To address the challenges associated with helicopter firefighting and rescue operations in dynamic fire scenarios, this paper firstly constructs a multi-threat environment model tailored to forest fire conditions. Considering the performance constraints of various rescue helicopters, an improved IRRT*-D* trajectory planning algorithm is proposed that accounts for both helicopter heterogeneity and environmental dynamics. This integrated trajectory planning algorithm combines the rapid search capability of the Informed-RRT* algorithm with the path optimization strength of the D* Lite algorithm, ensuring that safe and effective flight paths are generated in real time for helicopters operating in dynamic fire environments. Finally, the effectiveness of the proposed method is evaluated through simulation experiments conducted in different forest fire scenarios, with results compared to those of other trajectory planning algorithms. The simulation outcomes demonstrate that the improved IRRT*-D* algorithm exhibits fast convergence, optimal path quality, and algorithmic stability when addressing helicopter trajectory planning in complex fire environments, thereby ensuring the safe operation of helicopters in high-risk forest fire scenarios.