Distributed Enclosing Control of Second-order Multi-Agent Systems with An Unknown Dynamic Target

In this article, we study the enclosing control problem for a group of agents of second-order dynamics with a moving target of unknown velocity. In particular, only one pathfinder has access to the relative position information of the target, and the target velocity is modeled as a dynamic signal generated by an exogenous linear system. Using the local relative position measurements, an observer of the target position is developed for each agent, based on which an estimator is designed for each agent to estimate the dynamic target velocity. Furthermore, based on the estimates of the target position and target velocity, a distributed control law is proposed for each agent consisting of distance regulation respect to the target and angle repulsion to its neighbors in conjunction with compensation of the target velocity. It is theoretically shown that the multi-agent system can globally asymptotically track the dynamic target with a circular formation of desired radius and arbitrary interval pattern. Finally, the proposed control law is shown to be effective by a simulation example.