Robust control of the roll motion of a frigate using an adaptive sliding mode controller

One of the consequences of the wave disturbances for a surface vessel is the creation of roll motion. This, disrupts the operation of weapons, navigation equipment, personnel and missions, especially on a frigates. Therefore, roll motion and control of ship motion, especially, frigates using appropriate controllers, is very important.The nonlinear model of roll motion has a high computational complexity, so most researchers have used its linearized model. On the other hand, in many researches, for the simplicity, has not been considered, the fin actuator model and its effect on the roll model. In this paper, the fin stabilizer is used to stabilize the roll motion of a frigate and the model used in this research is a nonlinear roll motion model combined with the fin actuator model. In order to reduce of the roll motion, has been used of a robust adaptive sliding mode controller, due to the lack of sensitivity to external factors as well as estimating the disturbance band and reducing the angle of the desired roll motion. The closed-loop stability of the system has also been proved using Lyapunov theory. Then the simulation results of the closed loop system with the proposed controller are compared with the conventional PID controller and the superiority of the proposed controller performance is shown.