Experimental study on route tracking of deep sea mining vessel

Abstract

Dynamic Positioning Systems(DPS) have been widely used for deep sea operations such as station keeping of FPSOs and semi-submersibles, and position tracking of deep sea mining vessels. Especially, since the deep sea mining vessels operate in very deep region, which is deeper than 5,000 meters, there is no alternative but DPS for position tracking purpose. Furthermore, the speed of deep-sea mining vessel is usually very slow which is lower than 2 knots. This means that steering rudder is not so effective for tracking the designated routes. In this study, the performance of DPS for course tracking of a deep sea mining vessel by means of numerical simulation and model tests. Free running model test technique is applied for experimental work, of which the system is composed of an onboard computer for thruster control and measurement, a station computer for monitoring and supervising the whole system, wireless modems for communications between system components, and a number of thrusters. Positions and heading angle are measured using a laser position tracking system. Optimal control theory(LQR with error Integral) is adopted for the design of the position controller. A series of position tracking experiments in calm water and in waves were performed for surge, sway and yaw motion of a deep sea mining vessel model. Numerical simulations were also carried out and the results were compared with those of model tests.