Adaptive event-triggered observer design for uncertain target enclosing of multi-agent systems

This article investigates the cooperative target enclosing control problem of multi-agent systems under uncertain target motion using event-triggered communication. A novel event-triggered adaptive internal-model-based observer is proposed to estimate the target's position and velocity asymptotically without requiring exact knowledge of target dynamics and continuous monitoring among neighboring agents. A new event-triggering mechanism (ETM) with a strictly positive minimum inter-event time (MIET) is developed by incorporating three non-increasing resettable timer variables based on the observer states. The proposed observer design not only compensates for the sampling errors, but also associates the existence of the positive MIET with the boundedness of the system states. In addition, a new distributed formation control law that only uses the event-triggered neighboring information is designed. Simulations show that the MAS tracks the target's position and velocity asymptotically while achieving the prescribed formation pattern.