SEMIGLOBAL EXPONENTIAL OUTPUT-FEEDBACK CONTROL OF SHIPS

This paper describes a semiglobal exponentially stable output feedback control law for automatic heading control of ships described by a non linear model, Only compass (yaw angle) feedback is used. The yaw rate signal is reconstructed by a linear observer, A wave filter is include d in the observer to reduce wear and tear on the rudder servo due to f irst-order wave-induced disturbances, Integral action is included in t he control law to compensate for wave drift (second-order wave disturb ances), low-frequency wind, and current disturbances, The performance and robustness of the controller are demonstrated in a simulation stud y of two medium-sized ships.