Distributed Multicircular Circumnavigation Control for UAVs with Desired Angular Spacing

This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary target. By defining a coordinated error relative to neighboring angular spacing, under the premise that target information is perfectly accessible by all nodes, a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving target. Besides, to avoid the requirement of target's states being accessible for each UAV, fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense, and the upper boundary of settling time can be determined offline irrespective of initial properties, greatly releasing the burdensome communication traffic. Then, with the aid of fixed-time distributed observers, a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular spacing. It is inferred from Lyapunov stability that all errors are demonstrated to be convergent. Simulations are offered to verify the utility of proposed protocol.