Journal of Mechanical Science and Technology 26 (10) (2012) 3291~3298 www.springerlink.com/content/1738’494x DOI 10.1007/s12206’012’0810’2 Track velocity control of crawler type underwater mining robot through shallow’water test † Suk’Min Yoon, Sup Hong, Sung’Jea Park, Jong’Su Choi, Hyung’Woo Kim and Tae’Kyeong Yeu *          (Manuscript Received July 18, 2011; Revised March 22, 2012; Accepted June 14, 2012) ’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’’  The concept of continuous mining for manganese nodules suggests three sub’operations in total mining: collecting, lifting, onboard treatment. The combination of three components could be shaped by self’propelled seafloor mining robot, flexible conduit and buffer, lifting pumps and pipe, and mining platform. Particularly, the self’propelled robot tracking the mining paths on the seafloor is the key to accomplish the continuous mining. This paper discusses track velocity control of remotely operated mining robot, which is a basic and indispensable requirement for path tracking. The track velocity control is realized by PI controller from gain tuning formulas based on the model identification. First, to investigate the nature of the tracking system, a laboratory test is executed with the robot hung in air by overhead crane. Next, the transfer function of the tracking system is identified by the open’loop response and the closed’loop response. Through familiar tuning formulas based on the identified system parameters, PI gains are tuned. Finally, among the tuned PI gains, the one of best performance is set as the track velocity controller. : Cohen’coon tuning method; Crawler type underwater mining robot; First’order plus dead time (FOPDT) model; PI controller; Track velocity control; Pulse width modulation (PWM)    Polymetallic nodules (PMN), seabed massive sulfides (SMS), cobalt’rich manganese crusts (CMC) are the represen’ tative deep’sea marine mineral resources. The major nine metals – copper, nickel, cobalt, manganese, lead, zinc, gold, silver and platinum – except lead is the target amid the deep’ sea mineral resources. The needs for development of social overhead capital (SOC), enhancement of energy efficiency and environment preservation require a firm supply of indus’ try mineral resources. The major land’based deposits are, however, restricted in several resource’rich countries, e.g., Australia, China, U.S., Russia, Chile, Peru, South Africa, Congo, New Caledonia and some others. The monopoly and oligopoly in metal productions might cause significant prob’ lems in proper supply in a global economy. Among the marine mineral resources, the commercial production of the manga’ nese nodule deposited in 5000m seawater confronts us with technological problems of high complexity [1]. The concept of continuous mining for manganese nodules, i.e., quasi’constant mass flow of nodules from seafloor sedi’ ment to surface, suggests three sub’operations in total mining: collecting, lifting, onboard treatment. The combination of the three components could be shaped by self’propelled seafloor mining robot, flexible conduit, buffer, lifting pumps and pipe and mining platform in principal configuration. The collecting technology is to gather the nodules spread on the seabed and transfer them into a buffer, the intermediate storage tank at the down’end of lifting pipe. The flexible conduit between the mining robot and the buffer provides some freedom in the robot’s maneuverability. The self’propelled robot tracking the mining paths on the seafloor is the key to accomplish the con’ tinuous mining concept [2, 3]. In South Korea, a self’propelled mining robot named !  was developed in 2007. The robot consists of two track’ ing systems, hybrid pick’up device, electro’hydraulic assem’ blage, underwater sensors, electric’electronic units for control and monitoring, and control station on vessel, etc. Here, the tracking system for traveling on soft soil is composed of body, hydraulic motor, proportional valve and controller, and tur’ bine’type flowmeter. The hydraulic motor working the track’ ing system is controlled by proportional valve. The track ve’ locity is measured by the flowmeter reading the flowrate of oil in outlet line of the motor. The control and monitoring unit is configured by remote embedded controller and host controller. The data transmission between the two controllers is executed by TCP/IP communication through fiber optic (FO) lines. The * Corresponding author. Tel.: +82 42 866 3872, Fax.: +82 42 866 3819 E’mail address: yeutk@kiost.ac.kr † Recommended by Associate Editor Sangyoon Lee © KSME & Springer 2012