• Journal of the Society of Naval Architects of Korea
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• v.61 no.4
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• pp.247-257
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• 2024

The present study suggests a data-driven multivariate identification method based on principal component analysis and shows an application to ship dynamics modeling in maneuver. A reduced order model of ship dynamics is built by linear combination of three principal components acquired from large angle zigzag maneuver test. For a given kinematic state with three variables, a proper span is found by least square method, therefore accompanying hydrodynamic force and moment is determined. Suggested dynamics model correctly estimates hydrodynamic force and moment, thus it showed good agreement in maneuver simulation with that of conventional ship dynamics model obtained by system identification of captive model tests.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.419-429
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• 2023

The pinnacle of rapidly changing and advancing maritime transportation technology is expected to be the Maritime Autonomous Surface Ship (MASS). The implementation of various services within the MASS is likely to be feasible through the ship-centric network known as the S2X communication system. However, existing communication systems face issues such as service traffic saturation and failure to meet demanded functionalities, necessitating the proactive introduction of additional communication technologies. In this study, the concept of S2X communication for the MASS was redefined, deriving required functionalities and ultimately selecting frequencies suitable for utilization. Candidate frequency groups suitable for the derived communication requirements were identified, and communication frequencies prioritized for the initial application were chosen through expert consensus. It is anticipated that through further research, including experimentation to validate these frequencies, they could be utilized in implementing services for autonomous ship navigation in the future.

• The Journal of Korea Robotics Society
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• v.17 no.4
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• pp.493-499
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• 2022

This paper presents the design for the kinematic structure of a system for an automatically moored 6000 ton autonomous ship in a port, and the process and results of optimal design for the link cross-sectional shape. We propose an automatic mooring system with a PPP type serial manipulator structure capable of linear motion in the XYZ axis. The mooring force applied by the mooring system was derived with dynamics simulation tool "ADAMS". The design goal is the minimization of the cross-sectional area of the link. Constrains include compressive stress and shear stress. The optimization problems were solved by using the sequential quadratic programing method implemented in the fmincon package. The shape of the cross section was assumed to be rectangle. Through future research, we plan to manufacture automatic mooring system for 6000ton class autonomous ship.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.1
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• pp.58-65
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• 2019

The stability, reliability and efficiency of a smart ship are important issues as the interest in an autonomous ship has recently been high. An automatic collision avoidance system is an essential function of an autonomous ship. This system detects the possibility of collision and automatically takes avoidance actions in consideration of economy and safety. In order to construct an automatic collision avoidance system using reinforcement learning, in this work, the sequential decision problem of ship collision is mathematically formulated through a Markov Decision Process (MDP). A reinforcement learning environment is constructed based on the ship maneuvering equations, and then the three key components (state, action, and reward) of MDP are defined. The state uses parameters of the relationship between own-ship and target-ship, the action is the vertical distance away from the target course, and the reward is defined as a function considering safety and economics. In order to solve the sequential decision problem, the Deep Deterministic Policy Gradient (DDPG) algorithm which can express continuous action space and search an optimal action policy is utilized. The collision avoidance system is then tested assuming the $90^{\circ}$intersection encounter situation and yields a satisfactory result.

• Journal of Navigation and Port Research
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• v.44 no.6
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• pp.460-468
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• 2020

Research related to the technology developed for the Maritime Autonomous Surface Ship (MASS) is currently underway. Although one of those core technologies is collision-avoidance technology for ship operators at sea, no research has been done to objectively quantify its effectiveness. Therefore, this study was conducted to develop an evaluation model to examine the collision-avoidance ability of MASS. Ship-control experts performed a ship-handling simulation for each ship encounter type using the Full Mission Ship-handling Simulator (FMSS). We used the resulting data and technical statistics, to develop an evaluation model that utilized FMSS to quantify the operational capability of the collision-avoidance technology. This evaluation model also can be used at sea to assess deck officers' ability to use the technology and to improve and develop other MASS technologies.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.2
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• pp.121-128
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• 2021

According to the increasing interest and demand for the Autonomous Surface Vessels (ASV), the autonomous navigation system is being developed such as obstacle detection, avoidance, and path planning. In general, autonomous navigation algorithm controls the ship by detecting the obstacles with various sensors and planning path for collision avoidance. This study aims to construct and prove autonomous algorithm with integrated various sensor using the Robot Operating System (ROS). In this study, the safety zone technique was used to avoid obstacles. The safety zone was selected by an algorithm to determine an obstacle-free area using 2D LiDAR. Then, drift angle of the ship was controlled by the propulsion difference of the port and starboard side that based on PID control. The algorithm performance was verified by participating in the 2020 Korea Autonomous BOAT (KABOAT).

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.76-77
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• 2021

In line with the development of autonomous ships, it is necessary to train professional ship management supervisors to prepare for the transition to the ship's safety management system. Therefore, this study intends to investigate the capabilities required of ship management supervisors in preparation for introduction to autonomously operated ships for ship management supervisors in the field, and to suggest future capability development plans.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.386-393
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• 2023

Recently, the demand for autonomous navigation technology has increased, and related research is also increasing. Autonomous ships generally follow the planned route, calculate the avoidance route according to the risk situation while sailing, and follow a calculated route. In general, an automatic steering device is used to follow the route, and among the operational automatic steering device methods, the route control mode is the most appropriate method to apply to autonomous ships. Therefore, in this study, we developed a route-tracking algorithm to apply an avoidance route using the navigation control mode of an automatic steering device. The algorithm was developed by dividing the straight and turning sections. A performance test was conducted to satisfy the performance suggested by IEC 62065, the relevant international standard, using simulator equipment that had acquired international certification to verify its performance. The results of the performance verification confirmed that the cross-track error, which represents the straight distance between the ship and the route, satisfied the performance standards suggested by IEC 62065 when the ship followed the route.

• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.353-360
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• 2019

Technology-driven development of a new system makes it difficult for users and stakeholders to identify or intervene in the development process, resulting in systems with unnecessary functions and poor quality services. Applying the software architecture design process to the initial design of the navigation system platform of autonomous ships enables the development of a system that reflects the required functions and service quality of the stakeholders. The design, which includes all of the subsystems that make up an autonomous ship platform, is close to an enterprise architecture. Thus, we strived to design a navigation system platform suitable for the design range of the software architecture. This study analyzed the definition of functional requirements, and quality attributes by applying the software architecture design procedure. This study was conducted to identify the characteristics of the navigation system and platform needs, and the stakeholders were identified. To derive the functional requirements and constraints of the platform, a quality attributes workshop was held engaging stakeholders, and the results of the analysis of functional requirements and quality attributes were listed. Based on the results of this study, the architect can establish the evidence and technical solutions that are integral for the architecture development, and will facilitate the creation of quality attribute scenarios.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.81-81
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• 2018