Path Following of Marine Surface Vessels Using Bow and Aft Rudders in Wave Fields

This paper investigates the feasibility of using both bow and aft rudders to achieve better maneuverability and path following performance of marine surface vessels in waves. A nonlinear maneuvering model for the S175 containership is first introduced to facilitate the evaluation of path following performance. The original aft rudder is then replaced by the new bow-aft rudder combination. Open-loop simulation result shows that the new design can make the ship more maneuverable with a smaller total rudder area. For the path following controller design, the model predictive control (MPC) approach is adopted to enforce the rudder actuation constraints. In order to achieve offset-free path following in waves, a modified MPC scheme is proposed where a linear quadratic regulator (LQR) is used to first stabilize the system so that the offset-free MPC scheme can be further applied. Simulations confirm the validity of the hybrid scheme and the path following performance using both bow and aft rudders appears to be better.