Path following with disturbance rejection for inhomogeneous formations with underactuated agents

This paper considers straight-line path following for inhomogeneous formations with underactuated agents. The formation can be comprised of agents with different dynamics that are each affected by a different unknown environmental disturbance. Formation path following is achieved using a twofold strategy consisting of a guidance law to steer each vessel to a predefined path and a decentralised nonlinear formation control law utilising local information only to synchronise the agents position along the path such that a desired formation is achieved. The resulting closed-loop error dynamics consisting of the path-following error dynamics and formation error dynamics is analysed using theory for feedback-interconnected systems. The origin of the closed-loop error dynamics is shown to be uniformly globally asymptotically stable. The control strategy is validated with simulation results in a case study.