In this paper, we investigate the problem of controlling multiple unmanned aerial vehicles (UAVs) to enclose a moving target in a distributed fashion based on a relative distance and self-displacement measurements. A relative localization technique is developed based on the recursive least square estimation (RLSE) technique with a forgetting factor to estimates both the ``UAV-UAV'' and ``UAV-target'' relative positions. The formation enclosing motion is planned using a coupled oscillator model, which generates desired motion for UAVs to distribute evenly on a circle. The coupled-oscillator-based motion can also facilitate the exponential convergence of relative localization due to its persistent excitation nature. Based on the generation strategy of desired formation pattern and relative localization estimates, a cooperative formation tracking control scheme is proposed, which enables the formation geometric center to asymptotically converge to the moving target. The asymptotic convergence performance is analyzed theoretically for both the relative localization technique and the formation control algorithm. Numerical simulations are provided to show the efficiency of the proposed algorithm. Experiments with three quadrotors tracking one target are conducted to evaluate the proposed target enclosing method in real platforms.

翻译：本文研究了基于相对距离与自位移测量的多无人机对运动目标进行分布式包围控制问题。提出了一种基于带遗忘因子的递推最小二乘估计技术的相对定位方法，可同时估计“无人机-无人机”与“无人机-目标”的相对位置。采用耦合振荡器模型规划编队包围运动，该模型能使无人机均匀分布在圆周上。由于耦合振荡器运动的持续激励特性，该模型还能促进相对定位的指数收敛。基于期望编队模式生成策略与相对定位估计值，提出了一种协同编队跟踪控制方案，使编队几何中心渐近收敛至运动目标。从理论上分析了相对定位技术与编队控制算法的渐近收敛性能。数值仿真验证了所提算法的有效性。为评估所提目标包围方法在实际平台上的性能，开展了三架四旋翼无人机跟踪单个目标的实验。