| Marine simulator plays an increasingly significant role in merchant marine officer training and channel design and some other fields. Since modern vessel is becoming larger, tug assistance operation during maneuvering is rather important. So it is neces-sary to incorporate apply mathematic model of tug assistance during maneuvering into marine simulator. In the thesis, tugboat is an individual own-ship. It is connected through line with a towed ship to carryout towing operation. In this way, mathematic model of towing operation can be used in marine simulator. The main contribution of this thesis are as follows.Firstly, mathematic model of towing operation is established, which is solved with 4th-order Runge-Kutta algorithm. Mathematic model of towed vessel is in the frame work of Abkowitz Model, based on Mariner vessel. Tugboat mathematic model is built with MMG theory. Turning circle test and Zig-zag test are conducted. The test results meet Ship Maneuverability Standards of International Maritime Organization and model accuracy is satisfactory.Secondly, mathematic model of towing line tension is built. The mathematic model for calculating towing line tension contains two cases. In the first case that towing line elongation is less than 25%, which obeys Hooke's Law, iterative algorithmis used to obtain line tension. In the second case, towing line elongation is more than 25%, which does not meet Hooke's Law. Under this hypothesis, that line tension is calculated by using the regressive polynomial obtained through line stress-strain curve. The correct-ness and practicability of the model are verified by computation example.Thirdly, test platform is established for towing operation. The test contains two cases. In the first case, tugboat and towed vessel move independently. In the second case, towing operation simulation is in process. With Visual C++6.0 programming simulation for mathematic model is tested, which proves that the towing operation model is reasonable. |
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