Three-dimensional path planning for unmanned aerial vehicles based on principles of stream avoiding obstacles

Using the principles of fluid computation, a three-dimensional (3D) path planning method for unmanned aerial vehicles (UAVs) is studied by imitating the natural phenomenon of a flowing stream avoiding obstacles. First, an analytical solution of the steady 3D ideal flow acting on a single spherical obstacle is used to imitate the movement of a UAV. Then, a rotation-translation matrix in combination with the stream data are designed to generate streamlines when there are multiple obstacles in arbitrary positions. To verify the effectiveness of the method and introduce the method of numerical simulation, the fluid model and numerical solution suitable for 3D path planning are analyzed. Finally, the streamlines that satisfy the maneuverability constraints of the UAV are selected as the flight paths. Length of the path and times of motion in longitudinal and latitudinal directions are chosen as sub-objective functions to make a comprehensive evaluation. Simulation results demonstrate that in analytical paths, the model of spherical obstacles will reduce computation, and paths distribute in a ribbon from the starting to the finishing area; the numerical paths can deal with complex terrain, and paths distribute in a planned space. Both methods based on fluid flow can avoid local minima of a potential field, satisfy UAV constraints and provide multiple alternative paths. In addition, the paths are smooth and have the optimal characteristic of flow around obstacles.