CONTROL OF A SHIP SHAFT TORSIONAL VIBRATION VIA MODIFIED PID CONTROLLER

External disturbances and unstable working performance of main engine cause vibration to propulsion plant of a ship. The most commonly encountered vibration is torsional vibration as a result of unsteady power loads and inertia forces on the ship main engine-shaft system. Crankshaft balancing weight as a passive system and torsional damping element as an active system are used in order to prevent these types of vibration. The objective of the present paper is to use the modified Proportional-Integrative-Derivative (PID) control system to enhance the performance of the ship shaft control system and to adjust the torsional vibration for a given reference input. The conventional PID control system did not give desired results. Therefore the performance of the traditional PID controller was improved by moving derivative and proportional blocks on feedback path. All simulation results show that the proposed modified control algorithm gives a better performance than conventional PID control.