Optimal Trajectory Planning of Ship Propulsion System during Ship Speed Control

A marine propulsion system consists of an engine, a propeller and a shaft, and the hull. Its dynamic characteristics vary according to the system states. In order to design a highly developed control system and to achieve a safe navigation, it is important to understand the properties of such a complex system. In this paper, the mathematical model of a marine propulsion system is formulated and its dynamic characteristics are analyzed. An optimal trajectory planning so as to accomplish a smooth state transition and a quick system response was investigated on the basis of the previous system analysis. A performance criterion to characterize the system behavior is reasonably defined and the procedure for obtaining optimal trajectories under an engine torque limit has been formulated. An algorithm for obtaining optimal solutions was developed and simulations were conducted upon a general ship control model to evaluate the newly designed system. It was found that a marine propulsion system can be effectively operated under the optimal trajectories.