ABSTRACT
This chapter proposes both state feedback and output feedback robust adaptive controllers for an underactuated ship to make the ship follow a predefined path with guaranteed transient performance and arbitrarily small steady state position error and orientation error, despite the presences of environmental disturbances induced by wave, wind and ocean current and unknown system parameters. In the method developed for chain-form systems was adopted for an underactuated ship through a coordinate transformation to steer both the position variable and the course angle of the ship, providing exponential stability for the tracking of the reference trajectory. By introducing a first-order sliding surface in terms of surge tracking errors and a second-order surface in terms of lateral motion tracking errors, a sliding-mode control law is proposed for trajectory tracking of underactuated ships.
