ABSTRACT
This chapter addresses the stabilization control of underactuated ships in the presence of input saturation and disturbances. By introducing a virtual leader, the stabilization of an underactuated ship is transformed into a path following problem thus the error dynamic system can be divided into a cascade of two subsystems, i.e., (ϕe, re) subsystem and (x e, ye, u, v) subsystem. With proposed finite-time disturbance observer and yaw controller, the two subsystems are de-coupled within finite time. This enables the torque in surge to be designed independently by using a new backstepping technique. The chapter considers the stabilization control of underactuated ships with input saturation and external disturbances introduced by wave, wind or ocean currents. It also proposes a new finite-time saturated disturbance observer for underactuated ships to estimate the external disturbances.
