Robust Formation Control and Obstacle Avoidance for Heterogeneous Underactuated Surface Vessel Networks

This article investigates distributed robust formation control and distributed obstacle avoidance problems for networks of heterogeneous underactuated surface vessels without global position measurements. We exploit the cascaded structure of the kinematics and dynamics of generic vessel models to develop structured reduced-order error dynamics for group cooperation. By incorporating graph theory, the supertwisting control technique, and persistence of excitation concept, a distributed robust formation control scheme is developed without requiring global position measurements, where agents in the network may possess completely different dynamic models. It is shown that the stabilization of the reduced-order error dynamics guarantees the stability of the entire vessel error system subject to modeling uncertainties and bounded disturbances. Distributed obstacle avoidance is achieved by surrounding obstacles with stable elliptical limit cycles. During the obstacle avoidance stage, a part of the formation deforms to allow vessels to follow transient trajectories around static and dynamic obstacles. Simulation results are provided to demonstrate that the proposed cooperative control scheme can prevent obstacle and interagent collisions while achieving robust formation in heterogeneous underactuated vessel networks.