Speed Control of Large Marine Vessels

Tid: On 2019-06-19 kl 15.00 - 16.00

Plats: Seminar room (Rumsnr: A:641), Malvinas väg 10, Q-huset, våningsplan 6, KTH Campus

Respondent: Adam Jenåker

Opponent: Håkan Göransson

Handledare: Mikael Johansson

Abstract: Having a controller that is able to track a given speed reference is of high importance for ships sailing between destinations on a time schedule. Today, it is common to use a PID controller to regulate the vessel speed. However, these controllers tend to overshoot speed reference changes and have a hard time tracking a speed reference in steady state under disturbances. This thesis investigates the possibility of using Mode Predictive Control to achieve better control performance while satisfying the constraints of the propulsion system of the ship. The solution presented in this thesis is to use an MPC that based on a linearized model obtained at each sampling instance from a ship's nonlinear surge dynamics. The required thrust is then mapped to a fuel consumption setpoint for the ship's main engines. Simulation results show that the MPC can achieve offset-free tracking without overshoots. Full scale test on a ship with a length of 171 [m] shows that the controller achieves good performance at speeds over 13 [kn] and in steady state operation under modest disturbances but is unable to achieve satisfactory tracking during accelerations or deceleration at speeds lower than 13 [kn].