A study on the control system design for ship mooring winch system

This paper considers the control system design problem of a barge type surface vessel. The main role of a barge ship is to carry and supply cargo and materials to floating units and other marine locations. To carry out this job, the barge ship has to be positioned in a specified area. Although thrust systems are installed on the ship, in general, the mooring winch system with cable is used. Therefore, this paper proposes a single type mooring winch system and a method of designing a control system. We propose a mathematical model of the vessel winch control system, and the reliability of the control system is verified by numerical calculations and experiments. In addi- tion, a cable model is constructed from the experimental data to identify the characteristic of cable motion, which is unknown in general and considered as an uncertainty. Based on these results, a robust control system is designed, and its control performance evaluated by simulation and experiment show that the proposed approach works well. Fixed or floating units are frequently positioned at a particu- lar spot in the ocean and stationary conditions must be main- tained depending on their purpose and use. Ships either stand by inside the harbor or dock at the quay along the bank. The drill ship and its special purpose marine equipment such as rigs, FPSO, and barges maintain a steady position on the ocean's surface for a long time to extract deep sea natural resources. To move from one marine location to another ma- rine location, these fixed or floating units either use their own self-propelling apparatus or they use the passive method of being towed by tugboats. In some cases such as FPSOs and drill ships that are engaged in extracting materials and the floating units that are supporting the extraction works, their stationary position has to be limited to within the error margin of several meters. When fixed position control is required, in general, the side thruster and the mooring winch are used as the two basic position control systems. The mooring winch system installs a proper number of winches on the marine surface structures and moving units, and the winches are oper- ated to control the posture and position of the floating units by controlling the tension of the ropes. This is a topic that has been studied by many researchers throughout the world. Re- search on this topic has been limited mostly to theoretical