Roll Attitude Controller Design for Ships at Zero Speed

Abstract

A longitudinal flapping zero-speed fin stabilizer system is applied to reduce the roll motion of ships at zero speed. The righting moment model of the longitudinal flapping fin stabilizer is improved by considering the eddy resistance. According to the hydrodynamic characteristics of the model, the angular velocity of the fin stabilizer is chosen as a manipulated variable to control the ship roll motion at zero speed. A master–slave control method is used to solve problems of the multi-constrained strong nonlinear relationship with fin angle, angular speed, and angular acceleration and dynamic memory function in input nonlinearity. The fuzzy sliding mode controller is conducted as the master controller to deal with parameter uncertainties and unpredictable disturbance upper bound. The output tracking feedback slave controller is used to realize the nonlinear backstepping from the roll moment to the angular velocity of the fin stabilizer, and the actual control variable is obtained. A ship with the longitudinal flapping foils is considered and the effectiveness of the proposed strategy is verified by simulations.