Application of Non-Stationary Ship Roll Motion Prediction and Compensation Control Based on VMD-GRU-EC

Qin Zhang, Jia-Bin Li, Ang He, Xiong Hu

Abstract: During sea-based wind turbine installation and maintenance, the ship's movement is affected by wind and waves, especially the installation accuracy and safety of the suspended wind turbine is disturbed by the non-stationary ship's roll motion. Stabilizing ship lifting platforms in complex sea conditions, a VMD-GRU-EC based prediction model for non-stationary ship roll motion is proposed. The ship movement is predicted by this model first, and then wave compensation devices are supported in the experiments to ensure safe and accurate offshore operations. To be specific, Variational Mode Decomposition (VMD) decomposes non-stationary motion into multi-modal stationary sequences, that are then input into a multidimensional Gated Recurrent Unit (GRU) for prediction. Error Correction (EC) incorporates prediction errors to further enhance accuracy. The model is applied to simulate and predict the motion of a large engineering ship under the long peak wave spectrum and Dalian sea, and the validity of the model is verified in the hardware platform. Compared to Long and Short-Term Memory (LSTM) and AutoRegressive Integrated Moving Average model (ARIMA), VMD-GRU-EC exhibits higher prediction accuracy and generalization in level 3~6 sea states and Dalian.