GESO based robust output tracking controller for marine vessels

In this paper, a novel design for robust steering autopilot for marine surface vessels is proposed. As the uncertainties and disturbances acting on the ship due to external environmental effects, model inaccuracies, parametric variations, and nonlinearities of rudder movement are matched as well as mismatched, Generalized Extended State Observer (GESO) is used to estimate them. A composite design consisting of an output tracking state feedback controller augmented by GESO derived disturbance compensation term is formulated. Stability of the resulting closed-loop system is established and the efficacy of the controller is demonstrated through simulations by considering various practical circumstances. The results show that the controller offers highly satisfactory tracking performance in the presence of significant matched as well as mismatched uncertainties and disturbances. •A first application of GESO theory in design of robust ship autopilot.•The design explicitly accounts for rudder servo dynamics.•The GESO estimates the effects of matched and mismatched uncertainties and disturbances.•An output tracking controller is augmented by GESO estimated disturbance.•Efficacy of the controller is demonstrated through simulations.