A method of precise control of the ship based on power and torque of propeller

This paper presents the mathematical models of propeller thrust and torque are traditionally based on steady state thrust and torque characteristics obtained in model towing tank or cavitation tunnel tests. Material from a variety of references have been used to describe the ship model, power plant, its difficulties, limitations, and possible simplifications for the purpose of automatic control design. Selected simulation results showed that these quasi steady state models do not accurately describe the transient phenomena in a thruster. A recently published dynamic model was based on the experimental observations. Describing zero advance speed conditions accurately, this model, however, does not work for a vessel at nonzero relative water speed. This paper derives a large signal dynamic model of propeller that includes the effects of transients in the flow over a wide range of operation. The results are essential for accurate thrust control in dynamic positioning and precision control of a ship.