Ship hydrodynamic prediction by a novel transformer model with incremental learning

With the rapid development of maritime commerce, the complexity of ship operation environments continues to grow, so that it is crutial for ship designers to make accurate forecasting of ship performance under various sea conditions. However, there exist the following challenges in ship performance evaluation and optimization. The first challenge is the computational overhead and slow response of numerical simulations based on Computational Fluid Dynamics (CFD), and the second is the inability of traditional machine learning to achieve the computational accuracy of numerical simulations. To address these issues, this paper proposes an online surrogate model, called Increformer, for ship performance prediction. The Increformer leverages continuous self-attention mechanisms to explore the temporal dependencies between feature variables and employs continuous normalization mechanisms to handle non-stationary data issues. In addition, in order to improve prediction accuracy by the model, we employ an incremental training strategy based on elastic weight consolidation to acquire new knowledge from data streams. Experiments are conducted by using historical performance data from various types of vessels including KCS, Wigley-III, and C60. The results demonstrate that the Increformer model effectively captures the temporal information and inter-dimensional correlations in the data, with the accuracy of ship performance prediction enhanced significantly. Furthermore, ablation experiments are also carried out to assess the effectiveness and necessity of the continuous normalization mechanism, continuous attention mechanism, and incremental training strategy for the Increformer model. The findings validate the accuracy and universality of the proposed model. It is also shown that the Increformer model adeptly captures trends and fluctuations in ship sequence data and thus provides a reliable solution for ship performance prediction.