UAV 3D Trajectory Planning and Optimization Using A* Algorithm Based on Free Space Method

Due to the complexity of three-dimensional (3D) map modeling, the A* algorithm is inefficient in planning 3D trajectories for unmanned aerial vehicles (UAVs). This paper designs a method for planning 3D trajectories using A* algorithm based on free space method to address this issue. The method translates the 3D trajectory planning problem into a two-dimensional (2D) trajectory planning problem through flight surface extraction, thereby enhancing the efficiency of trajectory planning. In addition, a trajectory optimization method considering safety parameters and offset costs is designed for the waypoints that fail to meet UAV restrictions. The optimization method consists of longitudinal trajectory altitude adjustment and horizontal trajectory smoothing to ensure the trajectory aligns with the UAV climb rate constraint, normal overload constraint and minimum turning radius constraint. Simulation results show that the designed method delivers higher efficiency in 3D trajectory planning and optimization than the conventional method, and the optimized trajectory adheres to the above constraints.