Publications

Sutulo, S. and Guedes Soares, C. (2015), “Offline system identification of ship manoeuvring mathematical models with a global optimization algorithm”, Proceedings of the MARSIM 2015 Conference, 8-11 September 2015, Newcastle-upon-Tyne, United Kingdom

A method for offline identification of ship manoeuvring characteristics from kinematical records obtained with full-scale trials or self-running models developed earlier by the authors has been further improved and tested. The method is based on the global search in the parameter space carried out with the classic genetic algorithm minimizing the distance between the actual (training) ship responses and the simulated responses. the numerical study was performed for a 3dof polynomial model. Only responses in velocities of sway, yaw and surge in the 30/30 zigzag were used for identification. the testing studies were performed using simulated responses also polluted with the high-level white noise. the distances were measured in three different metrics: euclidean, pseudo-hausdorff and true (two-dimensional) hausdorff. Validation of the identified models consisted in comparison of reproduced spiral curves and time histories in turning circles. besides the type of the used metrics, varied was the length of the chromosome segment in the genetic algorithm. in all cases, a substantially better performance of the hausdorff metric was confirmed. at the same time, it was discovered that the algorithm becomes less efficient when the dimension of the factor space is increased.

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