• Journal of Ocean Engineering and Technology
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• v.24 no.2
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• pp.10-17
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• 2010

Conventionally, because it is difficult to control a ship in shallow water and because attempting to do so creates unwanted environmental effects, maneuvering ships in the harbor area for berthing is usually done with the assistance of tugboats. In this paper, we propose a new method for berthing ships automatically by using bow and stern thrusters. Specifically, a steering motion model of a ship is considered, and parameters in the equation are evaluated by the system identification technique. An optimal controller based on observations was designed from the linearization of the non-linear ship motion in the horizontal plane. It is used to reduce the uncertainty about the ship's dynamics and reduce measurement requirements. The performance of the controller was also analyzed for its robustness relative to avoiding disturbing the environment due to winds, currents, and wave-drift forces. Experiments were conducted to estimate the potential for identifying result and the design of the controller. Specifically, in this paper, the system modeling and tracking control approach are discussed based on a two-degree-of-freedom (2DOF) servo-system design.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.261-262
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• 2012

In this research, intelligent protection system for laser boat is introduced. The function of system is to measure the distance and velocity of object from our boat and generate control signals to avoid collision with moving targets. A novel approach to estimate object's position from our ship is tackled on this paper. To do this laser sensors are used to measure distance from ship to targets. The ship position and velocity is estimated by th Kalman filter algorithm. In the real phase, the filtering method will be applied to process signal gathered by laser sensors. Simulation to estimate ship's position and velocity under noise are executed and the results are introduced to show the effectiveness of the algorithm.

• The Journal of Korea Robotics Society
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• v.17 no.1
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• pp.48-57
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• 2022

In this paper, we propose a legged landing platform for the quadcopter taking off and landing in the ship environment. In the ship environment with waves and winds, the aircraft has risks being overturned by contact impact and excessive inclination during landing on the ship. This landing platform has four landing legs under the quadcopter for balancing and shock relief. In order to make the quadcopter balanced on ships, the position of each end effector was controlled by PID control. And shocks have mainly happened when quadcopter contacts the ship's surface as well as legs move fast. Hence, impedance control was used to cope with the shocks. The performance of the landing platform was demonstrated by a simulation and a prototype in three sea states based on a specific size of a ship. During landing and tracking the slope of the ship's surface, oscillations of rotation and translation from the shock were mitigated by the controller. As a result, it was verified that transient response and stability got better by adding impedance control in simulation models and prototype experiments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.572-580
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• 2015

RF skin tracking of instrumentation RADAR cannot acquire stable track data, because of effect of multipath interference especially elevation direction. In this paper, low altitude target tracking method using laser tracking system is suggested to overcome this restriction. The effect of multipath can be reduced by increasing angle resolution with laser characteristics of very short pulse and narrow beamwidth. RF skin track, beacon track and laser track data for the integrated calibration target on the ground and target ship on the sea are gathered. And they are compared and analyzed to confirm the performance of laser tracking system. As a result, it shows that the suggested laser track method has better performance than RF skin track under multipath conditions.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.627-633
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• 2007

This paper describes position tracking system of a container trailer approaching to a gantry crane for loading or unloading a container into or from a ship, respectively. Proposed position tracking system informs the trailer driver of right position to stop the car under a gantry crane. To measure the location of a trailer, we used Cricket Mote modules which adopted RF and ultrasound technology. We present an elaborate method to improve position errors occurring at sensing and calculate three dimensional position by triangulation along with how to reduce location tracking interval for real-time monitoring. The location information was transmitted to a Personal Digital Assistant (PDA) periodically through Bluetooth communication for guidance of the trailer driver. In indoor and outdoor tests, position errors were less than 3 cm and location tracking interval was 0.5 second on average.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.4
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• pp.446-456
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• 2024

This paper addresses a novel approach to performance enhancement of the naval gun fire control system(FCS) by using the projectile tracking filter without any distortion of radar measurements. Under the assumption that the maneuvering between the projectile and the ship equipped with the radar is not quite large, this method is based on the concept of polar-coordinate target tracking, which separates the range estimation filter and the direction cosine estimation filter. Note that using polar-coordinates allows tracking to be performed in the same coordinate system from which the radar line-of-sight(LOS) measurements are obtained, unlike the conventional tracking process in Cartesian. Also, it is easy to implement in real-time and guarantees consistent estimates due to its linear filter structure. With the help of the above method, therefore, the proposed filter is able to improve the overall performance of FCS which requires stability of projectile estimates within a short engagement time. The effectiveness of the presented scheme is validated through computer simulations.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.40-46
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• 2010

It is an important element increasing ship production to manage an accurate position of transporters(TP) and ship blocks in a shipyard. However, most works are presently being performed by judgment of a system manager and skilled workers. This paper introduced about the system for tracking an accurate position of the transporters and the blocks which are main mobile objects in the shipyard, and proposed a method to decide whether or not a loading/unloading state of the blocks, which is one of the most important functions of the tracking system. Three sensors were used in order to implement the method. One is a RFID reader to identify a target block, another is a RFID reader to estimate a position of the TP as it recognizes a underground tag. The other is a ultrasonic sensor to detect an object. Two experiments were carried out in the shipyard. After correcting errors found on the first experiment. we confirmed that the result could be applied to the shipbuilding yard from the final experiment.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.151-156
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• 2006

Accurate vessel traffic observation is indispensable to carry out vessel traffic management, design of vessel traffic route, planning of port construction, etc. In order to observe the vessel traffic accurately without many efforts such as the use of a ship or car equipped with special radar observation system and the preparation of observation staff, the authors have been developing completely automated remote radar/AIS network system covering the main traffic area in Tokyo Bay. The composite radar image observed at Yokosuka and Kawasaki radar stations with AIS information can be seen on web site of Internet. In addition to the development of radar/AIS observation system, the software to analyze observed vessel traffic flow has been developed. This software has various functions such as automatic tracking of ship's positions, automatic estimation of ship's size, automatic integration of radar image and AIS data, animation of ships' movements, extraction of dangerous ship encounters, etc. The configuration and functions of the developed remote radar/AIS network system are shown first in this paper. Then various functions of the software to analyze vessel traffic are introduced, and some analyzed results on the vessel traffic in Tokyo Bay are described demonstrating the effectiveness of the developed system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.18-20
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• 2021

In order to prevent collision accidents of ships, which has been increasing recently, research on artificial intelligence-based autonomously operated ships (Maritime Autonomous Surface Ship, MASS) is underway. However, most of the studies related to autonomous ships mainly target medium-to-large ships due to the size and cost of the autonomous navigation system, and the sensors used here have a problem in that it is difficult to mount them on small ships. Therefore, this paper provides a path tracking system equipped with GPS and IMU sensors for autonomous operation of small ships. GPS and IMU sensors are utilized to determine the exact position of the vessel, which allows the proposed system to manually control the small vessel model to create a path and then when the small vessel travels the same path. Use the Pure Pursuit algorithm to follow the path. As a result, In this research, it is expected that a lightweight and low-cost sensor can be used to develop an autonomous operation system for small ships at low cost.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.249-251
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• 2012

Augmented Reality (AR) enables the enhanced realism and interaction by providing the overlaid digital information on the user's view of the physical world. In this paper, we propose an AR-based ship design visualization system for presenting ship 3D model in smart phones or table PCs. The proposed system compute corner points and feature points by contour finding method and harris corner detector, and build a ship-design drawing database. By using SURF algorithm, key feature points are extracted from ship-design drawing image which is obtained by mobile camera. Then ship-design drawing image is recognized by matching the feature points stored in DB and extracted key feature points. 3D ship structures are visualized by overlaying the ship-design drawing image on the smart phone or table PC's screen. Compared to conventional 2D ship-design, proposed system helps to easily understand the structures of the ship and reduce the business design period. Thus, Enhanced competitiveness of business is expected.