• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1085-1091
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• 2014

This paper presents the guidance and control design for automatic carrier landing of a UAV (Unmanned Aerial Vehicle). Differently from automatic landing on a runway on the ground, the motion of a carrier deck is not fixed and affected by external factors such as ship movement and sea state. For this reason, robust guidance/control law is required for safe shipboard landing by taking the relative geometry between the UAV and the carrier deck into account. In this work, linear quadratic optimal controller and longitudinal/lateral trajectory tracking guidance algorithm are developed based on a linear UAV model. The feasibility of the proposed control scheme and guidance law for the carrier landing are verified via numerical simulations using X-Plane and Matlab/simulink.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.314-322
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• 2009

Nowadays, maritime communication systems need high data rate, reliability, and consistency in order to equivalently provide navigating ships with diverse multimedia services as in terrestrial communication systems. For this purpose, we conceptualize and design the maritime network for ships equipped with a multiband communication system which cost-effectively supports multimedia services according to several radiofrequency bands, such as HF, VHF, and satellite frequencies. We also introduce two service scenarios targeted for the maritime network; ship multimedia service (SMS) and real-time maritime logistics location tracking (RML2T). In addition, we specify related works according to three lower network layers (i.e., physical, data-link, and network layers) upon designing the network.

• Journal of the Korea Society of Computer and Information
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• v.16 no.9
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• pp.69-76
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• 2011

According to the related reports, about 60 percents of ship collisions have resulted from operating mistake caused by human factor. Specially, the report said that negligence of observation caused 66.8 percents of the accidents due to a human factor. Hence automatic detection and tracking of an object from an IR images are crucial for safety navigation because it can relieve officer's burden and remedies imperfections of human visual system. In this paper, we present a method to detect an object such as ship, rock and buoy from a sea IR image. Most edge directions of the sea image are horizontal and most vertical edges come out from the object areas. The presented method uses them as a characteristic for the object detection. Vertical edges are extracted from the input image and isolated edges are eliminated. Then morphological closing operation is performed on the vertical edges. This caused vertical edges that actually compose an object be connected and become an object candidate region. Next, reference object regions are extracted using horizontal edges, which appear on the boundaries between surface of the sea and the objects. Finally, object regions are acquired by sequentially integrating reference region and object candidate regions.

• The Journal of Korea Robotics Society
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• v.8 no.1
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• pp.51-57
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• 2013

Recently, the number of jellyfish has been rapidly grown because of the global warming, the increase of marine structures, pollution, and etc. The increased jellyfish is a threat to the marine ecosystem and induces a huge damage to fishery industries, seaside power plants, and beach industries. To overcome this problem, a manual jellyfish dissecting device and pump system for jellyfish removal have been developed by researchers. However, the systems need too many human operators and their benefit to cost is not so good. Thus, in this paper, the design, implementation, and experiments of autonomous jellyfish removal robot system, named JEROS, have been presented. The JEROS consists of an unmanned surface vehicle (USV), a device for jellyfish removal, an electrical control system, an autonomous navigation system, and a vision-based jellyfish detection system. The USV was designed as a twin hull-type ship, and a jellyfish removal device consists of a net for gathering jellyfish and a blades-equipped propeller for dissecting jellyfish. The autonomous navigation system starts by generating an efficient path for jellyfish removal when the location of jellyfish is received from a remote server or recognized by a vision system. The location of JEROS is estimated by IMU (Inertial Measurement Unit) and GPS, and jellyfish is eliminated while tracking the path. The performance of the vision-based jellyfish recognition, navigation, and jellyfish removal was demonstrated through field tests in the Masan and Jindong harbors in the southern coast of Korea.

• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.447-452
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• 2013

Vessel traffic system uses multiple sea surveillance radars as a primary sensor to obtain maritime traffic information like as ship's position, speed, course. The systematic errors such as the range bias and the azimuth bias of the two-dimensional radar system can significantly degrade the accuracy of the radar image and target tracking information. Therefore, the systematic errors of the radar system should be corrected precisely in order to provide the accurate target information in the vessel traffic system. In this paper, it is proposed that the method compensates the range bias and the azimuth bias using AtoN information installed at VTS coverage. The radar measurement residual error model is derived from the standard error model of two-dimensional radar measurements and the position information of AtoN, and then the linear Kalman filter is designed for estimation of the systematic errors of the radar system. The proposed method is validated via Monte-Carlo runs. Also, the convergence characteristics of the designed filter and the accuracy of the systematic error estimates according to the number of AtoN information are analyzed.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.2
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• pp.169-184
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• 2002

In order to extract bearing information from the directional sensors of DIFAR(directional frequency analysis and recording) that is a kind of passive sonobuoy, the cardioid beamforming algorithm applicable to DIFAR system was studied in the frequency domain. the algorithm uses narrow-band signals propagated though the media from the acoustic sources such as ship machineries. The proposed algorithm is expected to give signal to noise ratio of 6dB when it uses the maximum response axis(MRA) among the Cardioid beams. The estimated bearings agree very well with those from GPS data. Assuming the bearings from GPS data to be real values, the estimation errors are analyzed statistically. The histogram of estimation errors in each frequency have Gaussian shape, the mean and standard deviation dropping in the ranges -1.1~$6.7^{\circ}$ and 13.3~$43.6^{\circ}$, respectively. Estimation errors are caused by SMR degradation due to propagation loss between the source and receiver, daily fluctuating geo-magnetic fields, and non-stationary background noises. If multiple DIFAR systems are employed, in addition to bearing, range information could be estimated and finally localization or tracking of a target is possible.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.9
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• pp.776-787
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• 2002

Automation of welding process in shipyards is ultimately necessary, since the welding site is spatially enclosed by floors and girders, and therefore welding operators are exposed to hostile working conditions. To solve this problem, a welding mobile robot that can navigate autonomously within the enclosure has been developed. To achieve the welding task in the closed space, the robotic welding system needs a sensor system for the working environment recognition and the weld seam tracking, and a specially designed environment recognition strategy. In this paper, a three-dimensional laser vision system is developed based on the optical triangulation technology in order to provide robots with 3D work environmental map. Using this sensor system, a spatial filter based on neural network technology is designed for extracting the center of laser stripe, and evaluated in various situations. An environment modeling algorithm structure is proposed and tested, which is composed of the laser scanning module for 3D voxel modeling and the plane reconstruction module for mobile robot localization. Finally, an environmental recognition strategy for welding mobile robot is developed in order to recognize the work environments efficiently. The design of the sensor system, the algorithm for sensing the partially structured environment with plane segments, and the recognition strategy and tactics for sensing the work environment are described and discussed with a series of experiments in detail.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.883-888
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• 2012

Recently, the logistics industry in Asia is growing rapidly mostly with Chinese economic development. A variety of studies have been carried out to reduce the logistic cost under the situation that the global freight traffic continues to increasing. The Short Sea Shipping(SSS) system, a multi modal transport system centered around coastal shipping to realize high value-added logistics, achieved considerable success in EU. To implement the SSS system in Korea, it is necessary to develop the various essential technologies related to development of efficient ships and port facilities, including equipment for loading and unloading containers, operating and managing systems for freight terminals and technologies for tracking and securing containers. The present paper focuses on the survey of the current essential technologies available for implementation of the SSS system and suggests the direction of future development in the technologies.

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.178-184
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• 2010

Today, there has been a decrease in international shipping because of the weakening in global economies. Therefore, shipowners are thinking more about Floating Production Storage and Offloading (FPSO), which can perform functions related to the transporting, storage, and tracking of crude oil from oil wells. Given the huge expense of these special ships, shipowners require workers who can solve problems quickly and secure sustainable production functions in this age of globalization. Furthermore, it is important to design, construct, and maintain facilities so that a ship remains in operation over a long term. This paper discusses a system that uses knowledge-based AR to help workers improve their understanding and deal with pipeline equipment problems safely. In addition, it displays a 3CAD model and status information for products to improve their recognition on the FPSO that they intend to inspect. At the same time, the system works quickly and offers solutions for dangerous circumstances or malfunctions. It thus helps to maintain the functionality of the FPSO throughout its life-cycle.

• Journal of the Korean earth science society
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• v.24 no.5
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• pp.467-476
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• 2003

For the seafloor acoustic image mapping of side scan sonar, the beginning step of the procedure is to fix the absolute sonar (tow-fish) position since the sonar is not hull mounted but towed astern. The technical algorithm used to calculate the actual sonar position without any other additional sub-system, i.e., the underwater acoustic position tracking system or the sonar attitude measuring device, was proposed. In the seafloor image mosaic mapping results using the sonar track (not ship track) developed in this study, any ambiguity or inconsistency of seafloor features was not found. The incidental effect from the sonar position determination procedure orients the towing direction of sonar to be smooth, consequently the swath pattern on the across-track direction becomes stable and the blanking phenomenon of the insonification area is reduced conspicuously. This technical method is considered to be an useful tool when applied toother underwater towing vehicle surveys.