Study On Control Methods Of Deep-sea Mining Ship Motion Simulation Platform System

A motion simulator of deep sea mining ship is an important part of a simulation system for deep sea mining with hydraulic lifting technical. At present, research activities of the simulation system for deep sea mining have been mainly focused on two aspects, namely mineral collecting subsystem and mineral lifting subsystem. Few works have been carried out on the motion simulator of the mining ship. As a supporting subsystem floating on the water, deep sea mining ship is closely related with mineral collecting subsystem and mineral lifting subsystem in terms of safety and efficiency. Therefore, it is significant to carry out relevant research on the motion simulator of deep sea mining ship.As base on the technology solution of the ocean poly-metallic mining project in our country, a research line has been proposed for developing the motion simulator of deep sea mining ship by using a six d.o,fs (degrees of freedom) parallel mechanism. In addition, a motion simulator has been built in the laboratory with the aims to simulate and to evaluate the operation characteristics of the mining ship while it operates in the deep sea mining environment. The obtained results of this thesis can be considered of providing theoretical analysis and technical references for developing deep sea mining system in our country. In details, the main contents of the thesis are organized as follows:1) Numerical computation analyses have been carried out under the condition of four and six level of waves according to the operation condition of deep sea mining ship. The responses of horizontal rolling motion and heave motion of the mining ship have been obtained under the influence of random waves.2) A nonlinear mathematical model for the valve cylinder system has been proposed, and its positive and negative movements have been unified by using S function. Simulation curves and experimental tests curves have been compared with each other, and validity of the established theoretical mathematic model has been verified.3) A conventional PID controller for a cylinder valve has been designed in Simulink(?) environment, and the control parameters have been adjusted in order to achieve a better control performance. Additionally, a fuzzy PID controller has been designed on the base of fuzzy control theory. From the obtained simulation results, it shows that the proposed fuzzy PID controller has compensated the nonlinear effect of a valve cylinder system. The whole control system has a shorter setting time, smaller overshoot, and improved control performances with respect to the conventional PID controller.4) Experimental tests have been carried out on the built motion simulator with the proposed fuzzy PID controller. Operation performances of the motion simulator have been evaluated and compared with simulation results. Experimental tests results show that the tested platform is capable of simulating single d.o.f movement and multi d.o.fs complex movement under the influence of simple harmonic wave inputs, which meets the requirements for the motion simulation of deep sea mining ship. Additionally, the validity of the established simulation model has also been verified.