Nonlinear rudder-roll damping of non-minimum phase ships using sliding mode control

A non-minimum phase nonlinear ship model from rudder angle to roll angle is used to design a stable controller for simultaneous roll damping and course keeping. The controller is stable in presence of lst-order wave disturbances and modeling errors provided that the magnitude of the model errors and disturbances are known. Stability is proved using Lyapunov theory. The simulation results show excellent performance and robustness.