Time-varying group formation tracking for nonlinear multi-agent systems under switching topologies

In this paper, a group formation tracking controller for nonlinear multi-agent systems under switching topologies is proposed in which the group formation may have multiple time-varying subformations. Each subgroup has several active leaders with unknown but bounded control inputs and multiple followers whose dynamics are considered to consist of two parts, namely, the known linear term and the unknown nonlinear term. A distributed control protocol is then designed for the followers to realize time-varying group formation tracking, which is based on an extended state observer that estimates the state and nonlinear term of each follower. To guarantee the stability of the multi-agent system with the designed control protocol under switching topologies, a threshold for the dwell time, namely, the minimum time interval for each topology before switching, is derived. Finally, a numerical example with a group of unmanned aerial vehicles (UAVs), including three subgroups, is presented to verify the effectiveness of the proposed control protocol.