Global finite-time control for coordinated path following of multiple underactuated unmanned surface vehicles along one curve under directed topologies

This paper focuses on the problem of coordinated path following for underactuated unmanned surface vehicles (USVs) based on distributed control with directed topologies. First, a finite-time extended state observer is presented to estimate the velocities and model uncertainties, simultaneously. Second, a finite-time line-of-sight based guidance law is proposed for individual USV in kinematic loop to track the desired path. Specifically, a cooperative update law for the path variable is designed under one-way communication, such that all USVs maintain the same distance from each other along one curve, following a virtual leader. Then, a control subsystem is proposed by combining a novel auxiliary dynamic system and sliding mode technique for each vehicle at the kinetic level, where the auxiliary dynamic system is developed to ensure the finite-time stability of the entire system while to solve saturation problem. The closed-loop system is verified to be uniformly global finite-time stable. Finally, the numerical simulations substantiates the feasibility of the proposed coordinated path following strategy.