Abstract: In the application of wireless charging for large-scale ground sensor nodes by multi-UAVs,route planning schemes have a great influence on the coverage probability and the lifetime of WSN.However,the limited flight duration and collision avoidance constraints increase the difficulty of flight route planning.Firstly,this paper proposed a centra-lized Sequential Greedy Route Planning Scheme (SGRP).In SGRP,with the position information of ground nodes,UAVs add nodes sequentially to the task sets and put them to the most appropriate order of the routes.Theoretical analysis proves that even in the worst case,SGRP can guarantee at least 50% performance compared with optimal route planning scheme.Secondly,based on SGRP,with the modified CPA collision detection model,this paper designed a Sequential Greedy Anti-collision Route Planning Scheme(SGACRP).In SGACRP,an optimal matched combination of node,UAV and ordered path is selected at each iteration,maximizing the utility and meeting the requirements of the limited UAVs’ resource and collision avoidance.Finally,by taking the time-discounted reward function as the utility function,simulation proves the effectiveness of the anti-collision measure,and verifies that though an increased charging completion time of WSN is caused by the proposed anti-collision measure,no loss is made to the monitoring probability of WSN.On the other hand,simulation proves that setting the static scores of nodes as different values according to their distance to objects can effectively improve the monitoring probability of ground WSN.

Key words: Closest point of approach, Collision avoidance, Route planning, Wireless charging