Moving-Target Enclosing Control for Mobile Agents with Collision Avoidance

This paper studies the moving-target enclosing control problem for a group of mobile agents, under the assumption that the amplitude of the target's velocity is unknown a priori. The target's velocity is time-varying and can be viewed as a signal generated by an exogenous linear system. The neighbor topology of the agents is determined by their positions relative to the target at each time instant. Based on the relative positions, a distributed observer is proposed for the agents to cooperatively estimate the velocity of the target. Then a novel distributed control law is proposed based on the obtained estimates. It is shown that under the proposed control law the agents eventually move along a common circle of the desired radius around the moving target and also achieve any desired spaced pattern along the circle. Furthermore, conditions are derived under which the collision between each agent and the target is avoided and the inter-agent collision avoidance is also guaranteed by preserving the counterclockwise order of the agents around the target. Finally, a simulation example illustrates the effectiveness of the proposed control law.