Distributed observer based event-triggered affine formation maneuver control for underactuated surface vessels with positive minimum inter-event times

This article investigates the distributed event-triggered affine formation maneuver control problem for multiple underactuated surface vessel (USV) systems with positive minimum inter-event times (MIET). Unlike common formation control methods that only ensure the formation system to keep a fixed geometric shape, the proposed scheme enables multiple USVs maneuver as a group in translation, shearing, rotation, or combinations of them. The proposed control strategy is composed of two parts. First, a distributed event-triggered observer (DETO) is proposed to observe the time-varying target formation under the lack of global leaders' information and govern the inter-vessel communications among the formation group. Besides, the MIET of the designed communication strategy is proved to be strictly positive and computable from formation configurations and control parameters. With these guarantees, the maximum communication frequency can be known in advance. Then, upon the DETO signals, the adaptive local tracking controller is subsequently synthesized for each vessel to realize the target formation track. Rigorous theoretical analysis and simulation results are finally conducted to verify the validness and effectiveness of the proposed algorithm.