Abstract Seafloor photographs of polymetallic nodule taken by deep-sea camera are used for the estimation of the abundance. Typically, empirical equations are used to calculate abundances. However, to date, shape of the size distribution, for example, the symmetry or skewness to characterize the distribution has not been taken into account, although this effect on the estimation is expected to be significant. The effect is examined in the present paper and the errors caused by the uncertainty of the shape of size distribution are calculated. As the results, the magnitudes of these relative errors decrease with L, and are within 10%.

Abstract As the final goal of visualization of the dissociation front of methane hydrate in the sand layer, we are proceeding with a program of P-wave tomography monitoring. We describe a monitoring of the elastic wave propagation in the methane hydrate-bearing sand artificially formed in a giant pressure cell. First, we conducted a preliminary experiment to check the performance of the measurement system. In the stage of the methane hydrate generation, the P-wave velocity was estimated about 3000 m/s. In the dissociation stage, the travel time delay was not observed, but also the signal decreasing was observed with the dissociation.

ABSTRACT This paper introduces about the electric-electronic system of KIOST pilot mining robot, MineRo-II developed in 2012. The electric-electronic system for measurement and control of the robot is composed of underwater sensors, communication devices, DC power suppliers, pressure housings, etc. The robot is assembled by two unit modules, in which many sensors for oil pressure, flow-rate, temperature, velocity, heading and attitude are installed. To efficiently acquire and process a massive data from the sensors, four pressure housings - one power housing, one camera housing, and two flow-pressure housings for measuring state of hydraulic system - are set up in the unit module (Fig. 4). A vast amount of data from two modules, i.e., total eight pressure housings is sent into the main housing, and then transmitted up to on-board the control room through F/O line. LAN or serial communications through PBOF connectors are used for data transmission between pressure housings. The feasibility, reliability and stability of the electric-electronic system are verified through the pre-pilot mining test of MineRo-II in 2012.

ABSTRACT This paper concerns about subsystem synthesis method for dynamic analysis of complex multi-body tracked vehicle systems which can be divided into several subsystems. Using subsystem synthesis method, subsystems in the complex model can be independently analyzed with virtual massless reference bodies. The virtual massless reference body has information of position, velocity and acceleration for base body. In the subsystem synthesis method, analyses of position, velocity and acceleration of the subsystems are carried out in a forward recursive fashion. For overall multi-body tracked vehicle system analysis, subsystems can be synthesized to the base body with effective matrix and vector from the virtual massless reference body of each subsystem. Using these effective matrix and vector of subsystems, equations of motion with base body can be solved independently. After then equations of motion of each subsystem can be solved using results of base body. Advantages of the proposed method are investigated in terms of computational efficiency and solution accuracy. In order to show the effectiveness of the proposed method, a multi-body tracked vehicle of seafloor massive sulfide has been analyzed.

ABSTRACT The optimum design of an integrated mining system for polymetallic nodule mining is mainly dictated by the soil properties of soft seabed at 5000–6000 m depth. The entire weight distribution and traction of the mining machine depends mainly on the bearing strength and shear strength parameters of the soil. The shear strength of the soil also provides useful information for the maneuverability of the mining machine. Also, it is imperative that the mining area be delineated to eliminate vulnerable areas of low strength where the equipment may sink suddenly beyond recovery leading to anchoring of the machine. A remotely operable in-situ soil tester has been developed for 6000m operations with a cone tester and a shear vane tester and tested for operations. This paper describes the methodology used for soil property measurements and equipment's performance at 5462 m water depth in the Central Indian Ocean Basin (CIOB)

ABSTRACT A pilot miner, which is designed to collect manganese nodules on the deep seabed, intends to collect manganese nodules while traveling on cohesive soft soil. When operating a pilot miner, one needs to maintain traffic-ability at low traction speed for manoeuver operation as well as operates the vehicle straight in order to increase collecting efficiency by keeping high traction speed. Thus, if a pilot miner is designed in one property, it will become superfluous design due to conflict of incompatible properties. In this paper, multi-objective design optimization considering both collecting and maneuver operation is proposed for optimization of a pilot miner.

ABSTRACT This paper proposes a geometric path tracking algorithm for mining robot. In Korea, the pilot mining robot has been developed for collecting manganese nodules from deep seabed. The pilot mining robot demands a localization algorithm to determine an accurate position and an automatic path tracking algorithm. The fundamental performances of two algorithms are verified by using a ground tracked vehicle to reduce the time and cost for in-situ test. Ultrasonic position system (UPS) is selected to measure the position. UPS is very similar with the measuring principle of LBL. The localization is realized by data-fusion of UPS (data period of 0.6sec) and motor encoder (data period of 0.1sec). It focuses on how to decide weighting values of two position data having different periods in order to produce better position information. For tracking the specified path, two algorithms, the follow-the-carrot and the pure pursuit , are comparatively investigated. The follow-the-carrot algorithm finds a line passing between the center point of vehicle and the target point, and controls the vehicle to follow the line with constant speed. The pure pursuit algorithm is that vehicle is controlled through radius of a circle contacting with forward vector of the vehicle and passing between the center point of vehicle and the target point. The appropriate algorithm for driving on soft-soil can be selected and proven by numerical simulation and experiment.

ABSTRACT An AUV (Autonomous Underwater Vehicle) was used for the first time for exploration of polymetallic nodule in Japanese license area of the Clarion Clipperton Fracture Zone. Seafloor topographic map with 1 meter contour line was produced in two areas of about 20km2 each by AUV survey equipped with MBES, SSS and SBP. Photographs, continuously covering the seafloor taken by AUV, together with seafloor topographic map produced from MBES of the AUV enable us to understand detail manner of distribution of polymetallic nodule. By this method, more accurate resource estimation is possible. Furthermore, information of micro-topography helps for designing ore collector.

ABSTRACT An underwater mining system which is a crawler based system consisting of a mining machine moving on the sea bed collecting polymetallic nodules, crushing and pumping the crushed nodules through a flexible riser to the mother ship by a slurry pump has been developed. The slurry pump is a single stage positive displacement type driven by an independent hydraulic system that pumps nodules. Pressure drop studies for clear water and slurry flow with solids through flexible hoses of varied bend angles and various bend radii were conducted using the solids pump in an experimental test setup. The studies were conducted for the most likely occurring bend angle of 70°, 20° and 60° with a bend radius of 5 times the hose diameter for various flow rates. The results of 20° bend angle were compared with the steady state pressure drop values obtained using Computational Fluid Dynamics using FLUENT™ software. The results from the tests were useful in conducting subsea tests on underwater mining machine at 1032 m depth.

ABSTRACT Seafloor massive sulfides (SMS) which contain Au, Ag, Cu, Zn, and Pb have been interested in as a target of commercial mining these 15 years. Japan has large potential of SMS and a national R&D project for the mining has been active these 5 years. However, the economy of SMS mining is very bad, because the waste tailing disposal cost is very expensive in Japan. A slurry flushing method is experimentally examined in this study for the improvement of the economy. During the flushing, because of density difference between the metal-rich ore and the waste rock, a kind of gravity separation is possible. The results suggest a possibility of the actual application.

ABSTRACT In this article, we are introducing the method of the localization of the deep-ocean pipe end-point. The set of various sensors located along the pipe are used for measuring the data describing the shape of the pipe. Several variants of calculation algorithm have been developed for the processing the gathered information. The simulation results describing the error characteristics of the input and output variables are included as well. The article contains also the basic information about the technical realization concept of the proposed method.

ABSTRACT This paper describes the operating system of KIOST pilot mining robot in an inshore test of 2012. The pilot mining robot mainly consists of two unit modules having an identical functions, mechanical structure and hydraulic system. The operating system consists of subsystems on surface vessel such as A-frame, umbilical cable and traction winch, power generator and remote control system. This paper focuses on the remote control system composed of three VANs and operating S/W of the mining robot for the inshore test. In order to supply high-voltage into each module of the robot, two electric power VANs are constructed. For control and monitoring the robot under water, one control VAN is set up on board. A computer system in the control VAN is composed of two PXI (PCI eXtensions for Instrumentation) controllers of National Instruments and several industrial PCs. The two PXIs are charged on the control of the robot, i.e. the operator commands and treatment of the transferred data from the mining robot, respectively. The remote control S/W is based on LabVIEW with FPGA (Field Programmable Gate Array) module and real-time module. Particularly, for the efficient observation of the working of mining robot, the monitoring function on board is drastically departmentalized.

ABSTRACT Based on the kinematic model of the deep sea tracked miner, a time-optimal control algorithm is proposed. During locomotion, the driving velocity and direction of the vehicle cannot change abruptly, or it will cause excessive slippage of the track. In other words, the vehicle must move smoothly during locomotion. This means that the dynamic constraints of the miner should be taken into account in the control strategy. An intermediate curve is proposed as a temporary tracking trajectory which satisfies the boundary conditions that at the target position the first, second, and third derivative must be zero. Therefore, a cubic spline curve is put forward which could meet the limits. After the analysis of the curve co-efficiency, a time-optimal control algorithm is presented and implemented in MATLAB, and a series of computer simulation has been done. By simulation analysis, the curve co-efficient of λ=0.66 is chosen for it has better validity and accuracy. Through comparison with PID control strategy in previous work, the superiority of this algorithm is confirmed.

ABSTRACT: In order to validate the simulation results and develop heave compensation control strategy, heave compensation model tests were performed. The model test installation included the mining ship motion simulator, the heave compensation system, the lifting pipe simulator, the buffer simulator and the water pool. The mining ship motion simulator was able to perform under the predetermined attitude path smoothly. The heave compensation system includes a heave compensated platform which is to compensate heave motion and a gimbaled platform which is to accommodate pitch and roll. Heave compensation tests of mining ship motion under harmonic wave and random wave were carried out. PID control is selected as the control strategy here. Tests under random wave show that the heave compensation effect is more than 60% and reach the requirement which is set to 50%. The model tests results indicate that this heave compensation system is effective and feasible. INTRODUCTION At present, the pipeline lifting mining system is the most popular mining system. The nodules collected by the miner are lifted by the fluid rising force through the lifting pipeline to the mining ship. Under the sea wave, the lifting pipeline moves with the motion of mining ship, which causes large axial stress on lifting pipeline. To make mining operation secure, a heave compensation system is absolutely necessary. Since the 1960s, various studies and analysis have been carried out about heave compensation systems of pipelines in deep-ocean mining. In 1968, a heave compensation system between travelling block and hook used in oil drilling platform was proposed by VETCD Company, USA. It was composed of hydraulic cylinders, accumulator, locking device etc. The hydraulic cylinder displacement is larger than the heave amplitude of wave height and the load of hydraulic cylinders is nearly 600 tons. In 1976, a heave compensation device for marine use was proposed by William David Stevenson of Scotland Brown Brother Company (Stevenson, 1976). It included a passive load supporting system and an active force adjusting system.

ABSTRACT: This paper is concerned with a numerical simulation of tracked vehicles for studying of driving performance on an inclined plane. In this paper, a tracked vehicle model of a miner of a deep-sea mining system is selected as an example for a numerical analysis model. Cohesive soft soil model and hard soil model are used in this paper. In order to investigate and analyze dynamic responses of tracked vehicles with respect to the change of the buoyancy position, the numerical simulation of the tracked vehicle was performed using commercial software. The numerical model of the tracked vehicle is composed of chassis module, track subsystem module and buoyancy module. Terramechanics of the soil model is implemented using the user defined subroutine of commercial software. Hydrostatic forces of the tracked vehicle are included in the simulation model. A series of dynamic simulations is conducted with respect to driving velocities, soil properties, gradient of inclined plane, and position of buoyancy and so on. INTRODUCTION Because of depletion of the land mineral resources, interest in deepseabed mineral resources is increasing. Especially, in recent years, according to increases of expectation value about SMS deposits, research and development work has been performed to occupy SMS deposits in advance around advanced country (J.P. Feenan. 2009, J.W.van Bloois et al. 2009, Y. Fouquet et al. 2009). Also analysis models for dynamic simulations of mining systems have been developed (Hong et al. 2002, Kim et al. 2003, Choi et al. 2003, Kim et al. 2005). However, the earlier model was developed for flat ground, so driving performance of a tracked vehicle model at inclined ground for SMS mining is unknown. In this paper, for the purpose of dynamic performance analysis of a two tracked vehicle, a model that is similar to MineRo® model is used for SMS deposits.

ABSTRACT: For the ecological risk assessment of mining of Seafloor Massive Sulfides (SMS), three kinds of ecological risk that could be caused by the mining were identified using a mining plan. To assess the effect of the direct disturbance of seafloor on benthic organisms, the ecosystem model that deals with recovery process of benthos from elimination with the direct disturbance was developed. This model is available for the assessment of sedimentation of particles suspended by mining and discharging of waste water from mining support vessels. The ecosystem model that can deal with a kind of typical organisms in chemosynthetic ecosystems is to be employed for the assessment of a change in DO in benthic layers by discharging of waste water. In addition, diffusion models of suspended particles in ocean were developed. Combining the ecosystem model with the diffusion models, the ecological response on certain areas far from the mining or discharging points could be assessed. These efforts are expected to be contributed to the ecological risk assessment of SMS mining. INTRODUCTION On and under deep seafloor of oceans in the world, there are mineral and energy resources such as Seafloor Massive Sulfides (SMS) and Methane Hydrate. SMS are formed by deposition of metal sulfides precipitated from hydrothermal fluids venting from seafloor. Methane Hydrate is an icy crystalline solid consisting of methane and water to be stable at high-pressure and low-temperature conditions corresponding to shallow geological formations beneath the seafloor deeper than several hundred meters depth. Recent rising of price of metal and fossil fuel resources due to the economic development of emerging countries has promoted the proposition of development of these resources. There are many hydrothermal vent fields in offshore of island countries in the western Pacific such as Papua New Guinea, New Zealand and Japan.

ABSTRACT: Kuroko-type seafloor massive sulfides including gold, silver, copper, zinc, and lead exist in the EEZs of the Pacific island countries. The ones in Japan's EEZ are expected to be the largest and very much attractive for the future resources. However, there are many problems to be solved for the commercial development. The effective method for finding ore bodies in the survey on seafloor and the location and method of the ore selection are the examples of the problems. A fundamental study of ultra-violet fluorescence sensing indicates the possibilities of applications on seafloor. The time, energy, and cost saving effects of the earlier ore selection are considered. INTRODUCTION Kuroko-type seafloor massive sulfides (SMS) in the western Pacific have received much attention as resources for gold, silver, copper, zinc, and lead (Lenoble, 2000). Since the end of the 1980s, the Kuroko-type SMS have been found in the back-arc basin and on oceanic island-arc areas. The typical representatives found are in the Okinawa Trough and on the Izu-Ogasawara Arc near Japan (Halbach et al., 1989; Iizasa et al., 1999), in the Lau Basin and the North Fiji Basin near Fiji (Fouquet et al., 1991; Bendel et al., 1993), and in the East Manus Basin near Papua New Guinea (PNG) (Kia and Lasark, 1999). The company gathered investment money and announced to start the commercial mining from 2010 ( http://www.nautilusminerals.com ). On the basis of geological information of the Sunrise Deposit of the Myojin Knoll on the Izu-Ogasawara Arc (Iizasa et al., 1999) and geotechnical characteristics of the Kuroko-type SMS (Yamazaki and Park, 2003), some preliminary economic validation analyses of the SMS mining in small production scale were reported by one of the authors (Yamazaki et al., 2003; Yamazaki and Park., 2005; Yamazaki 2007). The results showed high profitability of the SMS mining.

ABSTRACT: An Improved dynamic model of the total deep ocean mining system is established. The pipeline subsystem is built as a 3D discrete element model, which is divided into 3D rigid elements linked by flexible connectors. The flexible connector without mass is represented by 6 spring-damper elements. The external hydrodynamic forces from the longitudinal and lateral directions are both considered and modeled based on the Morisson formula and applied to the mass center of each discrete rigid element. The seafloor tracked miner is built as a simplified 3D single-body model with 6 degrees of freedom. While the trackterrain interaction is modeled by partitioning the track-terrain interface into a certain number of mesh elements with three mutually perpendicular forces, including the normal force, the longitudinal and the lateral shear forces, acting on the center point of each mesh element. With consideration of the operational safety and collection efficiency, two new moving paths for the miner on the seafloor are proposed, which can be simulated with the newly established single-body dynamic model of the miner. Integrating the discrete element model of the pipeline and the single-body model of the miner, a new improved dynamic model of the total deep ocean mining system is finally formed. Two new mining operation process modes of the total mining system, which combine of the active straight-line and turning motions of the miner and the ship, and of the passive towed motions of the pipeline, are proposed and simulated with the new improved 3D dynamic model. Some critical simulation results are obtained, such as the motion trajectory of each key subsystem during the operation process and the velocities of the buoyancy module, which in a way can provide specific guidance and useful reference for the practical deep ocean mining system analysis, operation and control.

ABSTRACT: The Federal Institute for Geosciences and natural Resources (BGR) has been exploring manganese nodules in a 75.000 km2 area in the central equatorial Pacific since 2006. The economic potential of the nodules results from their high and rather uniform Cu+Ni+Co content. Exploration activities focus on a detailed assessment of nodule abundance using a combined utilization of remote acoustic methods, close-up video mapping and selective box core sampling. In this paper, we briefly describe the technology used and present first results. INTRODUCTION In 2006 the BGR has signed a 15-years contract with the International Seabed Authority (ISA) of the United Nations for the exclusive right to explore manganese nodules in a 75.000 km2 area in the central equatorial Pacific (Fig. 1). Based on three cruises carried out so far as well as on data from the 1970ies and 1980ies, it can be stated that most of the nodule samples have Cu+Ni+Co contents that scatter between 2.5 and 3.0% clearly indicating the overall appearance of valuable nodules in the license area. However, the nodules are not equally distributed on the seabed but their coverage changes irregularly. To assess the commercial viability of future nodule mining requires a detailed knowledge of nodule distribution of the investigated area. To explore vast areas of the seafloor as it is necessary for nodule exploration, methods with high resolution (such as video survey) must be linked with methods of low resolution (such as vessel-mounted survey). VESSEL-MOUNTED ACOUSTICS For bathymetric mapping of the 75.000 km2 area the hull-mounted multibeam (swath) echosounding system Simrad EM 120 of Hawaiibased R/V Kilo Moana has been used in 2008 and 2009. It took us several weeks to prepare the first bathymetric map with total coverage of the exploration area (Rühlemann et al., 2009).

ABSTRACT: The principal objective of this paper was to investigate the dynamic responses of an articulated tracked vehicle, when crawling on undulating and inclined ground. The configuration of the articulated tracked vehicle had two separate tracked vehicle systems connected by joints. The articulated tracked vehicle was modeled by using commercial software of multi-body dynamic analysis. A terramechanics model of cohesive soft soil was implemented according to the relationships of normal pressure to sinkage, of shear resistance to shear displacement, and of dynamic sinkage to shear displacement. In an effort to evaluate the dynamic responses of an articulated tracked vehicle crawling on undulating and inclined ground, a series of dynamic simulations were conducted for an articulated tracked vehicle model with respect to the initial velocity, gradient of inclined plane, soil property, joint type, steering ratio and so on. INTRODUCTION Polymetallic manganese nodules (PMN), seafloor massive sulfide (SMS), cobalt-rich manganese crusts (CMC) are widely ocean mineral resources in the deep-sea. Polymetallic manganese nodules are half buried in soft sediments on the ocean floor in approximately 5,000m in the CCFZ (Clarion Cliperton Fracture Zone). Seafloor massive sulfides are frequently found in the EEZs (Exclusive Economic Zone) of southwestern Pacific countries and in the ocean ridges of the Atlantic. Cobalt-rich manganese crusts are covering the surface of numerous seamounts in 800–2,500m depth in EEZs and Public Sea. The PMN are spread at the surface of the seafloor, on the other hand, SMS and CMC are distributed over seamounts or undulating surfaces of seamounts. There is a lot of study with the mining of polymetallic manganese nodules (Brink and Chung, 1981; Chung, 1996, 2003; Herrouin et al., 1989; Amann et al., 1991; Liu and Yang, 1999; Hong and Kim, 1999; Deepak et al., 2001; Handschuh et al., 2001).