Fuzzy sliding mode control of an offshore container crane

• Published in: Ocean engineering Vol. 140; pp. 125 - 134
• Main Authors: Ngo, Quang Hieu, Nguyen, Ngo Phong, Nguyen, Chi Ngon, Tran, Thanh Hung, Ha, Quang Phuc
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2017
• Subjects: Anti-sway control; Fuzzy sliding mode control; Mobile harbor; Offshore container crane; Offshore container crane; Anti-sway control; Fuzzy sliding mode control; Mobile harbor
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2017.05.019

A fuzzy sliding mode control strategy for offshore container cranes is investigated in this study. The offshore operations of loading and unloading containers are performed between a mega container ship, called the mother ship, and a smaller ship, called the mobile harbor (MH), which is equipped with a container crane. The MH is used to transfer the containers, in the open sea, and deliver them to a conventional stevedoring port, thereby minimizing the port congestion and also eliminating the need of expanding outwards. The control objective during the loading and unloading process is to keep the payload in a desired tolerance in harsh conditions of the MH motion. The proposed control strategy combines a fuzzy sliding mode control law and a prediction algorithm based on Kalman filtering for the MH roll angle. Here, the sliding surface is designed to incorporate the desired trolley trajectory while suppressing the sway motion of the payload. To improve the control performance, the discontinuous gain of the sliding control is adjusted with fuzzy logic tuning schemes with respect to the sliding function and its rate of change. Chattering is further reduced by a saturation function. Simulation and experimental results are provided to verify the effectiveness of the proposed control system for offshore container cranes. •A fuzzy sliding mode control strategy for offshore container cranes is investigated in this study.•A trajectory of the trolley is generated to ensure the payload in a desired tolerance in harsh conditions of mobile harbor motion.•A prediction mechanism based on Kalman filtering is used to estimate the next impact of the sea motion and incorporate to the trajectory.•A sliding surface is designed to incorporate the desired trolley dynamics while suppressing the sway motion of the payload.•A discontinuous gain of the sliding control is adjusted with fuzzy logic tuning schemes with respect to the sliding function and its rate of change.