In this paper, a super twisting sliding mode control is proposed for the sway control of an offshore container crane system (or a mobile harbor system), which consists of a container crane mounted on a ship. The mobile harbor is used for the ship-to-ship transfers of containers in the open-sea. At shallow water ports, big container ships cannot anchor, therefore, mobile harbors are used to transport containers between the container ship, in the deep sea, and the shallow water port, thereby obviating the need for expansive and expensive new facilities. The load/unload the containers, it is necessary to suppress the sway of the load in the presence of the wave-induced movements of the mobile harbor. In this paper, a super twisting sliding mode controller is developed for suppressing the sway of the payload. The sliding surface is designed in such a way that the longitudinal sway of the load is incorporated within the trolley dynamics. Lyapunov function-based stability analysis is performed to prove the asymptotic stability of the closed-loop system. Simulation results are provided to prove the effectiveness of the proposed control law.
展开▼
