Optimal robust control of path following and rudder roll reduction for a container ship in heavy waves

Abstract

This paper presents an optimal approach to the multi-objective synthesis of path following and rudder roll reduction for a container ship in heavy waves. An improved line of sight principle with course-keeping in track-belt is proposed to guide the ship in accordance with marine practice. Concise robust controllers for the course and roll motion based on Backstepping and closed-loop gain shaping are developed. The control parameters have obvious physical significance. The determination method is given and much effort is made to guarantee the uniform asymptotic stability of the closed-loop systems by Lyapunov synthesis. Furthermore, the multi-objective optimization method a fast and elitist multi-objective genetic algorithm (NSGA-II) is used to solve the restrictions caused by the model perturbation, external disturbance and performance trade-off. Contrasting with the existing literature, the research strategy and control performance are more in line with marine engineering practice. Simulation results illustrate the performances and effectiveness of the proposed system.