A deep-seabed integrated mining system consists of a vessel, a lifting pipe, a buffer, a flexible pipe, and a mining robot to gather resources such as manganese materials on the deep-seabed. The analysis of the dynamic behavior of such a mining system, which is serially connected from the mining vessel, lifting pipe, buffer, flexible pipe, to the mining robot, is important to develop the deep-seabed mining system.
To consider geometric non-linear effects such as large deflection with small strain in the model of the lifting pipe and the flexible pipe, the substructure method has been employed. The deformational motion of the flexible beam element can be described using Cartesian coordinates and nodal coordinates. To verify this non-linear beam model using the substructure method, a cantilever beam model was developed and these simulation results were compared with the experimental results. The substructure method requires a large amount of computational time for dynamic analysis. Thus, an efficient method of analysis is necessary.
In this study, to improve the efficiency of analysis, a subsystem synthesis method was developed for a single robot integrated mining system, and was also extended to the double robot integrated mining system. Using the subsystem synthesis method, subsystem equations of motion were generated separately. Thus, the efficiency of the subsystem synthesis method for the integrated mining system was demonstrated, and the analysis system can be extended easily.
To carry out dynamic analysis of the deep-seabed integrated mining system, the model was implemented using the MATLAB program and verified by various programs such as ANSYS and Recurdyn. In the model, 60 flexible beam elements and 80 flexible beam elements were employed for the 492m long lifting pipe and the 100m long flexible pipe, respectively. The buffer and mining robots were modeled as a rigid body. And Initial Stationary positioning and tandem position simulations were carried out.
The efficiency of the subsystem synthesis method was verified by comparing arithmetic operational counts and CPU time of the developed subsystem synthesis method with those of the conventional method.