Cooperative utilization of Unmanned Aerial Vehicles (UAVs) in public and military surveillance applications has attracted significant attention in recent years. Most UAVs are equipped with sensors that have bounded coverage and wireless communication equipment with limited range. Such limitations pose challenging problems to monitor mobile targets. This paper examines fulfilling surveillance objectives to achieve better coverage while building a resilient network between UAVs with an extended lifetime. The multiple target tracking problem is studied by including a relay UAV within the fleet whose trajectory is autonomously calculated in order to achieve a reliable connected network among all UAVs. Optimization problems are formulated for single-hop and multi-hop communications among UAVs. Three heuristic algorithms are proposed for multi-hop communications and their performances are evaluated. A hybrid algorithm, which dynamically switches between single-hop and multi-hop communications is also proposed. The effect of the time horizon considered in the optimization problem is studied. Performance evaluation results show that the trajectories generated for the relay UAV by the hybrid algorithm can achieve network lifetimes that are within 5% of the maximum possible network lifetime which can be obtained if the entire trajectories of all targets were known a priori.

翻译：近年来，无人机在公共和军事监视应用中的协同利用引起了广泛关注。大多数无人机装备的传感器覆盖范围有限，且无线通信设备作用距离受限。这些限制对移动目标的监控带来了挑战性问题。本文研究如何在构建具有延长寿命的弹性无人机网络的同时实现监视目标以获得更优覆盖。通过将中继无人机纳入编队并自主计算其轨迹以在所有无人机间建立可靠连接网络，研究了多目标跟踪问题。针对无人机间的单跳与多跳通信建立了优化问题模型。提出了三种用于多跳通信的启发式算法并评估其性能，同时提出了一种在单跳与多跳通信间动态切换的混合算法。研究了优化问题中考虑的时间范围的影响。性能评估结果表明，混合算法生成的中继无人机轨迹可实现网络寿命，该寿命与假设预先已知所有目标完整轨迹时能获得的最大网络寿命相差不超过5%。