Design of decentralized controller for deep seabed mining system

Abstract

The deep seabed mining system is generally composed of surface vessel, lifting system, buffer, flexible pipe and miner. The mining system is regarded as a large-scale system in which each subsystem is interconnected to other ones. In order to control a large-scale system, decentralized control approaches have been proposed recently. In this paper, as a basic study on application of decentralized control, firstly, the mining system is modeled in a simplified way. Lifting system and buffer are regarded as a spherical pendulum and the flexible pipe is taken as a two-dimensional linear spring connection. Based on the derived model, the mining system can be decentralized two subsystems, the one consisting of surface vessel, lifting system and buffer, and the other, the miner. Next, this paper proposes the design of controller for each decentralized subsystem by regarding the interacting terms as disturbances. The controllers keep the distance between two subsystems constant even if the miner is moving freely. Finally, the efficiency of proposed controller is shown through the numerical simulation of the derived model. Copyright ？ 2005 by The International Society of Offshore and Polar Engineers.