Efficient Analysis of a Deep-Seabed Integrated Mining System Using a Subsystem Synthesis Method

A deep-seabed integrated mining system for collecting manganese nodules consists of a mining vessel, a vertical lifting pipe, a lifting pump, an intermediate buffer station, a flexible pipe, and a self-propelled mining robot. Manganese nodules collected by the mining robot are transferred to the buffer and then lifted up to the vessel. Dynamic analysis of such a system is a challenging task, since large displacements due to deformation must be considered in the very long lifting pipe and the flexible pipe system. Because non-linear effects must be considered in the modeling of the lifting pipe and the flexible pipe model, nodal coordinates must be used in the flexible multibody model. This requires a large amount of computational time for the dynamic analysis. Moreover, the concept of multiple mining robots was introduced recently, increasing the complexity. An efficient method for the dynamic analysis of the integrated mining system is necessary. In this study, to improve the efficiency of analysis, a subsystem synthesis method was developed for the deep-seabed integrated mining system which can also be extended to efficiently analyze multiple mining robots. Subsystem equations of motion were separately generated for the vessel-lifting pipe subsystem and the flexible pipe-mining robot subsystem. The efficiency of the subsystem synthesis method was verified theoretically by comparing arithmetic operational counts of the developed subsystem synthesis method with those of the conventional method.