Observer-based Time-varying Formation Tracking Control for Linear Multi-agent SystemsWith External Disturbances on Directed Graphs

This work investigates the time-varying formation tracking problems for linear multi-agent systems with a leader of bounded unknown control input in the presence of external disturbances on directed graphs. To eliminate the external disturbances, an extended state observer is constructed for each agent first. Then, a distributed time-varying formation tracking protocol is designed by utilizing the estimated information, which does not require the global communication graph information. The multi-agent system is shown to asymptotically track the leader with time-varying formations and meanwhile reject the disturbance if the expected formation satisfies the feasible condition by Lyapunov stability analysis. Finally, a simulation example of switching formation is provided to verify the effectiveness of the proposed approach.