심해저 망간단괴 시험집광기 제어·계측 시스템의 개발 및 실증 연구

Abstract

Commercial production of the manganese nodule deposits in 5,000m water depth confronts with technological problem in high complexity. Based on materials, structure and machinery components resisting high pressure and chloride-corrosion, the core technologies for commercial mining system, e.g. seafloor unmanned vehicle, nodule pick-up device, slurry pumping system, prediction and control of coupled dynamic behavior, real-time sensing and monitoring, total integrated operation, and so on are multi-disciplinary itself and require a high-level fusion in design stage. The collecting technology is for the gathering the nodules spread on seabed into the buffer, the intermediate storage tank at the down-end of lifting pipe. Self-propelled miner tracking the pre-determined mining paths on the seafloor is the key to accomplish the continuous mining concept. At the same time its performance can be assured only by the real-time integrated control of the total mining system because of the weakness of the seabed sediment and the strongly nonlinear dynamics of the lifting pipe. A self-propelled test miner has been developed in scale of 1/20 of the commercial capacity. It consists of tracked vehicle, hybrid nodule pick-up device, electro-hydraulic assemblage, sensors, electric-electronic unit for control and monitoring, and control station on board, etc. Each mechanical device are driven by hydraulic power. A closed-loop circuit of hydraulic system has been designed with pressure compensated reservoir. The purpose of test miner is to verify the collecting performance. The electric unit is composed of high-voltage supply system from surface and electric power supply system for test miner internal parts. The electronic unit is decomposed into sensors, hydraulic valve controllers and remote controllers, etc. The control and monitoring embedded system designed using two embedded controller. Two embedded controller configured in “Host” and “Remote”. Each controller is connected by umbilical cable using fiber-optic communication. “Remote” controller takes in some function device such as vision acquisition, data acquisition, serial communication, digital I/O and analog I/O board. We use embedded controller, NI inc. PXI platform. Remote controller, sensor signal amplifiers and various kinds of drivers are put in a pressure-resisting canister. The canister is functionally decomposed in remote control part in charge of signal transfer / process and driver part in charge of driving lamps and hydraulic valve control. The sensor unit has been designed to monitor and control of the test collector in nodule collecting operation and launching / retrieval operation. Monitoring system of the test collector consists of an embedded controller for measurement and control and a control-and-monitoring station for operation of GUI(Graphic User Interface). The monitoring GUI has been developed by using LabVIEW and consists of Host program and Monitoring program. The navigation algorithm of test miner is for the position determination approach based on Extended Kalmain Filter(EKF) using the kinematics of tracked vehicle. The miner sweeps a 2-dimensional mining area by its collecting device in a given region. And it is required that the miner path is maximized for sweeping coverage efficiency. And the control method is used by LOS(Line-of-Sight) algorithm for path tracking. The velocity of test miner driven by track is controlled by designed PI controller. The sea tests were conducted in shallow water around 100m deep in 2009 and 2010. The test site was chosen by soil weakness and morphology of seafloor. In 2009 test, Sea tests were planned for validation of the integrated performance of test miner and lifting system. Real-time remote control of the test miner was assisted by underwater navigation system. In 2010 test, only test miner, just driving, sea tests were performed for control on driving seabed and the adaptations of navigation and control algorithms. This paper describes the fundamental studies for development of the test miner, the configuration and specifications of test miner's control and monitoring system, the concept and planning of the sea tests, and some lessons from the sea trials. Some conclusions have been drawn as follow: - Performances of test miner satisfy the design requirements. It was confirmed that the remotely controlled, self-propelled miner is conceptually feasible. - Sufficient database has been acquired to be applied for design of pilot miner, which will be integrated with surface unit operation. - Learning process has finished one turn, and design experience and operational know-how were achieved.

In further work, pilot mining test is being planned for water depth of 2,000 m until 2015.