On distributed leader escort control and bipartite time-varying formation tracking of multiple ASVs

Distributed leader escort control and bipartite time-varying formation tracking (BTFT) problems are investigated respectively in this paper for a group of multiple autonomous surface vessels (ASVs) in the presence of a dynamic leader. To facilitate the analysis, it is assumed that the velocity and acceleration of the dynamic leader are bounded. By utilizing signed graphs, the following ASVs are divided into two groups to form different time-varying formation configurations. Then, two new kinds of controllers are designed respectively for completing the distributed leader escort control and BTFT tasks under the mild condition that only parts of the following ASVs can obtain the leader's information. By using tools from Lyapunov stability theory and sliding mode control theory, it is proven that the objectives of distributed leader escort control and BTFT can be respectively achieved asymptotically under the designed controllers with appropriate control gains. The results are further extended to the scenarios where the dynamics of following ASVs subject to uncertain Coriolis and centripetal matrix, and uncertain damping matrix. At last, some numerical simulations are presented to illustrate the validity of the designed controllers.