Tracking control of underactuated ships with uncertain actuator failures using switching control

This paper develops an actuator failure accommodation control scheme for an underactuated ship dynamic system model with uncertain actuator failures, using a switching control design. Such a design employs multiple controllers, each of which is designed for each failure pattern in the failure pattern set of interest. To stabilize the system under uncertain actuator failures, control signal selection is based on comparing the performance indices from prediction errors generated by multiple state predictors, each of which is designed for one failure pattern. Different from those problems addressed in the literature, the key feature of the underactuation problem considered in this paper is that it is unknown when and which actuator fails during system operation. Simulation results from a ship system model in the presence of uncertain actuator failures are presented to show the desired system stability and asymptotic tracking properties.