| Abstract | The block erection operations in the shipyards generally include block lifting, transporting, turn-over, and lowering procedure. During the operation, there are potential risks such as interferences with wire ropes, overweight, etc., which can lead to serious accidents. To check such risks in advance, the physics-based simulations are often required before the actual operation. For this, detailed modeling of the equipment and the operation is necessary to reflect the actual situation accurately, which is impossible with conventional modeling methods. Meanwhile, in the actual operation, the position and the orientation of the block should also be precisely controlled to avoid any risks. However, the actual operations are performed manually by the operator, and the cranes used for the erection of the block consist of complex equipment, which makes them difficult to control. In this study, the detailed modeling of the operation situation and the equipment are introduced for accurate simulation. Then, the control method of the crane is suggested for accurate and efficient control. Firstly, the block turn-over operation by one offshore floating crane (simply, floating crane) and two crawler cranes is simulated considering the interferences between wire ropes and the block. For this, the interaction model between wire rope and the block including contact and friction is suggested. Then, the contact forces exerted on the block are calculated. Secondly, the block lifting by the floating crane is analyzed considering the coupling motion of the floating crane and the mooring system. The interaction among the floating crane, the mooring line, and the seabed is introduced under the various sea condition. Lastly, the control of the floating crane is performed for block lifting, transporting, and turn-over operation. As the floating crane consists of complicated equipment such as booms, equalizers and wire ropes, the control theory of the underactuated mechanical system is adopted. To evaluate the effectiveness and applicability of the proposed method, it was applied to the dynamic analysis of various kinds of block erection operations by using the floating crane. As a result, the proposed method could reflect the actual operation situation properly, and the block was controlled to the desired trajectory. |
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| Publication Date | 2020-08-05 |
Hye-Won Lee, Myung-Il Roh, Seung-Ho Ham, "Method for the Accurate and Automatic Operation of Offshore Floating Cranes for the Block Erection in Shipyards", Proceedings of OMAE(International Conference on Ocean, Offshore and Arctic Engineering) 2020, Held in Virtual Conference, 2020.08.03-07