Application of Generalized Predictive Control Algorithm on Fin Stabilizer at Zero Speed

Ships roll periodically with waves when they are anchored. In order to solve this problem, the principle of fin stabilizers at zero speed is presented. Traditional fin stabilizers are controlled by analog PID controller, which is sensitive to the high frequency noises of gyroscope and ocean waves. Digital controller of fin stabilizers is analyzed in this paper to suppress these noises. Furthermore, advanced control algorithm can be easily realized with the development of digital signal processor. The power plants on ships usually can not provide enough energy for fin stabilizers at zero speed. Thus the application of discrete control algorithm, which is called generalized predictive control (GPC), on fin stabilizers at zero speed is investigated to optimize the roll reduction process. Basic generalized predictive control is extended based on the fact that the input and output signals of roll controller are constrained. Simulation results indicate that generalized predictive control is more efficient than PID control to minimize the ship roll angle in the same conditions. GPC algorithm can also enhance the efficiency of driving energy and provide a way to increase the effectiveness of fin stabilizers at zero speed.