• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.253-260
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• 2015

There are many efforts to mechanize the process for underwater port construction due to the severe and adverse working environment. This paper presents an underwater construction robot to level rubbles on the seabed for port construction. The robot is composed of a blade and a multi-functional arm to flatten the rubble mound with respect to the reference level at uneven terrain and to dig and dump the rubbles. This research analyzes the kinematics of the blade and the multi-functional arm including track and swing motions with respect to a world coordinate assigned to a reference depth sensor. This analysis is conducted interfacing with the position and orientation sensors installed at the robot. A hydraulic control system is developed to control a track, a blade and a multi-functional arm for rubble leveling work. The experimental results of rubble leveling work conducted by the robot are presented in land and subsea. The working speed of the robot is eight times faster than that of a human diver, and the working quality is acceptable. The robot is expected to have much higher efficiency in deep water where a human diver is unable to work.

• The KIPS Transactions:PartA
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• v.16A no.4
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• pp.255-262
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• 2009

We present an autonomous entertainment dolphin robot system based on ubiquitous sensor networks(USN). Generally, It is impossible to apply to USN and GPS in underwater bio-mimetic robots. But An Entertainment dolphin robot which presented in this paper operates on the water not underwater. Navigation of the underwater robot in a given area is based on GPS data and the acquired position information from deployed USN motes with emphasis on user interaction. Body structures, sensors and actuators, governing microcontroller boards, and swimming and interaction features are described for a typical entertainment dolphin robot. Actions of mouth-opening, tail splash or water blow through a spout hole are typical responses of interaction when touch sensors on the body detect users' demand. Dolphin robots should turn towards people who demand to interact with them, while swimming autonomously. The functions that are relevant to human-robot interaction as well as robot movement such as path control, obstacle detection and avoidance are managed by microcontrollers on the robot for autonomy. Distance errors are calibrated periodically by the known position data of the deployed USN motes.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.9-10
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• 2012

This paper presents an observer to measure the lengths of cylinders of an underwater robot for harbour construction using a pressure sensor. In harbour constructing, we place heavy armour stones weighing over 2~3 tons on the surface of the bank to protect it from storming wave. This work typically done by a diver is difficult and dangerous so that we have developed Stone Diver which is the underwater robot for harbour construction. The robot needs a position sensor to control the hydraulic cylinder. The position sensors mounted outside the cylinders cause poor durability in construction site where shock and dust usually occur. However, the pressure sensor mounted inside a waterproof box improves the durability. Based on the dynamic parameters and the pressures in the cylinder, the observer measures the cylinder's position. This paper presents the positional accuracy of the pressure based observer and the performance of the underwater robot to assemble the armour stones.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.865-871
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• 2012

This paper presents an observer to estimate the displacement of hydraulic cylinders of an underwater robot for harbour construction using a pressure sensor. In harbour constructing, we place heavy armour stones weighing over 2~3 tons on the surface of the bank to protect it from storming wave. This work typically done by a diver is difficult and dangerous so that we have developed Stone Diver which is the underwater robot for harbour construction. The robot needs a displacement sensors to control the position of hydraulic cylinders. The position sensors mounted outside the cylinders cause poor durability in construction site where shock and dust usually occur. However, the pressure sensor mounted inside a waterproof box improves the durability. Based on the dynamic parameters and the pressures in the cylinder, the observer estimates the cylinder's position. This paper presents the positional accuracy of the pressure based observer and the performance of the underwater robot to assemble the armour stones.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.575-578
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• 2001

원격 조작이나 해저 수중 탐사에서 실제와 같이 거리감을 인식하며 제어하기 위하여, 3차원 입체 영상 카메라 장치를 사용하고 있다. 기본적인 구성 형태인 Stereoscopic Camera 시스템은 기구적으로 주시각 제어와 초점 제어가 이루어 지고 있으며, 획득영상에 대하여 영상 distortion 보정, 압축 처리 등의 영상 신호처리가 행하여진다. 양안 카메라의 수평 위치를 일치시켜 수평적으로 동일 위치의 pixel들이 정확한 epipolar line을 형성할 경우에, 주시각 제어가 용이하고 보정 및 영상처리 등의 연산량이 대폭 감소된다. 이와 같은 calibration 과정을, 기존의 시스템에서는, 주로 영상 획득 포기에 패턴을 사용하여 실시하거나, 물리적 수평 장치와 sensor 등의 보조 장치를 이용하여 calibration을 행한다. 그러나, 기계적으로 정밀하게 정렬을 한다고 하여도 두 카메라의 광축 및 CCD조립상 상이점과 특성의 불일치로 인하여 실제 획득된 영상에서는 변이와 회전이 포함된 영상을 얻게된다. 본 논문에서는 Stereoscopic Camera의 위와같은 정렬 오류의 문제점을 분석한 후, 제안 방식으로서 두 카메라의 획득되는 영상을 직접 영상 처리하여 수직 방향 및 회전 오류를 최소화 시켜 정렬하는 새로운 방법을 제시하며, 실험적으로 제안 방식의 효율성을 보인다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.50-60
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• 2015

A Block-Time-Bounded Time Division Multiple Access (BTB-TDMA) medium access control protocol, which estimates the propagation delay of nodes according to their location and moving velocity information, has been proposed for underwater acoustic networks. BTB-TDMA provides nodes with their transmission schedules by a time block that is a time unit, newly designed for BTB-TDMA. In this paper, we investigate how the receiver collision, that is induced by the asymmetry between node's uplink and downlink propagation delay due to its mobility, affects the performance of BTB-TDMA. To do this, we analytically obtain the collision rate, the channel access delay, and the channel utilization by considering the asymmetry of propagation delay. Then, simulations are extensively performed with respect to the length of a time block by varying the number of nodes, the network range, and the node's velocity. Thus, the simulation results can suggest performance criteria to determine the optimal length of a time block which minimizes the collision rate and concurrently maximizes the channel access delay and the channel utilization.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.3
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• pp.133-141
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• 2020

In this paper, the communication method of data information accepted by underwater drones and the implementation method to console display of data information were described, and the function of integrated monitoring system interface and the design and implementation of sonar interface were explained. The operation and posture of underwater drones can be controlled using a controller connected to the console, and the distance information between underwater drones and obstacles is obtained from sonar so that they can be visually displayed on the console screen along with camera images. The integrated monitoring navigation console is implemented to suit improvements, making it convenient and easy for workers to use. In addition, by upgrading integrated monitoring and control software functions, the company added user-specific project management functions and the output of reports for hull inspection to make them different and competitive from other underwater drones.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.269-277
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• 2007

Wireless sensor network system is expected to get high attention in research for now and future owing to the advanced hardware development technology and its various applicabilities. Among variety of sensor network systems, the seashore and marine sensor network, which are extended to get sampling of marine resources, environmental monitoring to prevent disaster and to be applied to the area of sea route guidance. For these marine applications to be available, however, the provision of precise location information of every sensor nodes is essential. In this paper, the sequential localization algorithm for obtaining the location information of marine sensor nodes. The sequential localization is done with the utilization of a small number of beacon nodes along the seashore and gets the location of nodes by controling the sequences of localization and also minimizes the error accumulation. The key idea of this algorithm for localization is that the localization priority of each sensor nodes is determined by the number of reference nodes' information. This sequential algorithm shows the improved error performance and also provide the increased coverage of marine sensor network by enabling the maximum localization of sensor nodes as possible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.372-378
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• 2016

A mound was constructed to install a caisson and sofa blocks underwater. The mound riprap, which were of uniform grade, size, shape, and specific gravity, formed the foundation for the support superstructure. Also, rubble leveling works were performed before installing structures such as caissons. In this study, underwater construction equipment was developed with a remotely controlled operating system and underwater environment monitoring system for unmanned underwater rubble leveling work. The performance of the developed equipment was verified using on-land and underwater tests. In addition to the performance verification, the construction process and economic efficiency of the equipment should be checked before applying it to the real construction field for commercial purposes. In this paper, a construction process using the developed equipment was proposed and compared with the existing rubble leveling method. The results demonstrated that the new construction method has higher economic efficiency and safety than the existing construction method.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.451-458
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• 2012

In this paper, the design study of a new convertible six d.o.f underwater robot which can be a ROV or AUV according to underwater work purpose is presented. A structure design about the ROV and the AUV and its design on the control system is presented. In case of the AUV, an analysis on thruster forces in accordance with operating speed has been performed. A sensor fusion board which can proceed various sensor signals to identify correct positions and speeds has been developed and a total control system including EKF(Extended Kalman Filter) has been designed and developed.