Ship Course Following and Course Keeping in Restricted Waters Based on Model Predictive Control

Ship navigation safety in restricted water areas is of great concern to crew members, because ships sailing in close proximity to banks are significantly affected by the so-called ship-bank interaction. The purpose of this paper is to apply the optimal control theory to help helmsmen adjust ships' course and maintain the target course in restricted waters. To achieve this objective, the motion of a very large crude carrier (VLCC) close to a bank is modeled with the linear equations of manoeuvring and the influence of bank effect on the ship hydrodynamic force is considered in the model. State-space framework is cast in a Multiple-Input Multiple-Output (MIMO) system, where the offset-free model predictive control (MPC) is designed for course following and the linear quadratic regulator (LQR) is used for course keeping. Simulation results show that the control methods effectively work in ship course following and course keeping with varying ship-bank distances and water depths. The advantage of adopting speed variation as the second control input is obvious.