Fixed-time event-triggered distributed formation control for underactuated USVs considering actuator saturation

This paper proposes an event-triggered fixed-time containment control strategy (FTETCCS) to address the distributed formation control (DFC) problem of multiple underactuated unmanned surface vessels (USVs). By integrating fixed-time control (FTC) with event-triggered control (ETC), this strategy achieves fixed-time stability while reducing the usage of communication resources within the system. Initially, the fixed-time containment control law is utilized to compute the desired virtual target points for the followers. Subsequently, to facilitate future real-world experiments, an event-triggered fixed-time containment control guidance law is developed. This law computes the desired heading angle and forward speed derived from the virtual target points. The resulting values are then accurately tracked using a fixed-time controller. Furthermore, this study tackles the challenges posed by lumped unknown terms and actuator saturation during USV navigation. To address these issues, a fixed-time disturbance observer and a fixed-time auxiliary saturation system are designed. The effectiveness and superiority of the proposed FTETCCS are validated through theoretical analysis and simulation studies, with an analysis of the Zeno phenomenon confirming that the event-triggered mechanism does not lead to Zeno phenomena. Additionally, an experiment demonstrate the practical applicability of the proposed event-triggered fixed-time containment control guidance law.