As the nonlinear and coupling characteristics of autonomous underwater vehicles (AUVs) are the challenges for motion modeling, the nonparametric identification method is proposed based on dung beetle optimization (DBO) and deep temporal convolutional networks (DTCNs). First, the improved wavelet threshold is utilized to select the optimal threshold and wavelet basis functions, and the raw model test data are denoising. Second, the bidirectional temporal convolutional networks, the bidirectional gated recurrent unit, and the attention mechanism are used to achieve the nonlinear nonparametric model of the AUV motion. And the hyperparameters are optimized by the DBO. Finally, the lazy-search-based path planning and the line-of-sight-based path following control are used for the proposed AUV model. The simulation shows that the prediction accuracy of the DBO-DTCN is better than other artificial intelligence methods and mechanical models, and the path following of AUV is feasible. The methods proposed in this paper can provide an effective strategy for AUV modeling, searching, and rescue cruising.
Anchor penetration is an important issue involved in the study of submarine pipeline damage accidents. To explore the penetration of a ship’s anchor under certain conditions, this study investigated the motion and force of an anchor and formulated a calculation method for the bottoming speed of an anchor. Meanwhile, the depth of anchor penetration was calculated under different conditions according to bottoming speed through programming. Finally, the reliability of the calculation method for the penetration depth was verified by comparing the actual measurement and the numerical simulation. On the basis of the findings, the calculation results were further analyzed, and conclusions were derived regarding the relationship between anchor mass, the horizontal projected area of the anchor, the anchor height on the water surface, and water depth. The conclusions provide suggestions for the application of anchor penetration in terms of seabed depth with certain reference values.
1 March 2021 in Journal of Physics: Conference Series
Based on the objectives and requirements of the pilotage service portfolio, using the design standards of HGDM organization, the nodes, activities and certification modules of ships entering and leaving the port are analysed, and the S-100 standard model of pilotage data is established. According to the characteristics and actual needs of pilotage, the technical design mode of C/S (client/server) mode of pilotage service portfolio is determined; the application example of pilotage service portfolio is verified by the service mode of tide riding opportunity in Ningbo waters for large container pilotage.