UAV Path Planning in the Presence of Unknown Environments

Real-time path planning under the unknown environment such asdynamic obstacles and unknown terrain is one of the key problems for uninhabited aerial vehicle (UAV) guidance and control. UAVs should be able to cope with unknown environments since the environment information given prior to actual action may not be complete. Therefore, the pre-planned flight trajectory should be modified using the real time information of various sensors. The re-planning of the flight trajectory has to be performed in real time, and the feasible trajectory should be generated. In this study, D* lite algorithm and RRT (Rapidly-exploring Random Tree) are used for the problem of path planning of UAV in the presence of unknown environments. Those algorithms are re-formulated to generate a smooth trajectory that can avoid collision with unknown terrain and/or dynamic obstacles. D* lite algorithm generates a trajectory for collision avoidance, and RRT smoothes the trajectory in order to enhance the feasibility. Numerical simulation is performed for the problem having unknown terrain. Simulation result shows the effectiveness and usefulness of the proposed method. The performance of the proposed method is compared with that of conventional D* lite algorithm and RRT.