• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.135-144
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• 2021

In railway systems, it is common to obtain train location information through an infrastructure-based train detection system. However, this system has a problem that may provide incorrect location information due to non-detection and erroneous detection, which may cause an accident. Therefore, in this study, we propose a method of providing train location information using a sensor-based integrated navigation system. In order to provide accurate information; however, the reliability of the integrated navigation system must be verified. Therefore, in this paper, we develop a simulator that can generate a reference trajectory and sensor data based on the real trajectory and analyze the performance of the integrated navigation system according to various scenarios on the real trajectory.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.123-130
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• 2015

In this study, a carrier smoothed global positioning system / dead reckoning (CSGPS/DR) integrated system for high-precision trajectory estimation for the purpose of vehicle navigation was proposed. Existing code-based GPS has a low position accuracy, and carrier-phase differential global positioning system (CPDGPS) has a long waiting time for high-precision positioning and has a problem of high cost due to the establishment of infrastructure. To resolve this, the continuity of a trajectory was guaranteed by integrating CSGPS and DR. The results of the experiment indicated that the trajectory precision of the code-based GPS showed an error performance of more than 30cm, while that of the CSGPS/DR integrated system showed an error performance of less than 10cm. Based on this, it was found that the trajectory precision of the proposed CSGPS/DR integrated system is superior to that of the code-based GPS.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.367-374
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• 2018

A trajectory-based scheduling system is proposed for air traffic management using next generation aviation data communication link. Based on the service concept of 4-dimensional trajectory data link (4DTRAD) using air traffic serveices (ATS) datalink Baseline 2, a procedure for trajectory-based operation of an en-route flight is established and described in detail. To mitigate air traffic controllers' workload which might be caused by various and complicated data utilization, a prototype of the scheduling system, which predicts the aircraft trajectory based on the flight intents received by air traffic service system and provides advisory information for air traffic control, was developed. The simulation environment for trajectory based operation was built to validate the scheduling functionality of the prototype.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.386-395
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• 2016

In trajectory-based navigation systems, a huge amount of trajectory data is needed for efficient route explorations. However, it would be very hard to collect trajectories from all the possible start and destination combinations. To provide a practical solution to this problem, we suggest a method combining collected GPS trajectories data into additional generated trajectories with new start and destination combinations without road information. We present a trajectory combination algorithm and its implementation with Scala programming language on Spark platform for big data processing. The experimental results proved that the proposed method can effectively populate the collected trajectories into valid trajectory paths more than three hundred times.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.49-56
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• 2023

As interest in autonomous ships continues to grow, researchers around the world are dedicating themselves to the development of relevant technologies. However, these technologies are not yet perfect. Several technical problems remain unresolved. To address these problems, this study presents the implementation of a ship trajectory algorithm for group navigation, where followers can navigate by following the trajectory of a leader. The algorithm works by storing the leader's trajectory as a follow-point and by calculating the azimuth using the line-of-sight guidance law to reach it. A course-keeping controller based on PD control is implemented to follow the target course and a speed control algorithm is designed to prevent collisions. Sea experiments were conducted using 1 m class small RC model boats to verify the proposed algorithm. The follower successfully navigated by following the leader's trajectory and maintained the designated distance to the forward boat. This study is significant in that it implements an algorithm for the follower to follow the trajectory of the leader rather than directly following it as in conventional methods, and verifies it through sea experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.457-462
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• 2005

Industrial and economical importance of CP(Cellular Phone) is growing rapidly. Combined with IT technology, CP is currently one of the most attractive technologies for all. However, unless we find a breakthrough to the technology, its growth may slow down soon. RT(Robot Technology) is considered one of the most promising next generation technology. Unlike the industrial robot of the past, today's robots require advanced technologies, such as soft computing, human-friendly interface, interaction technique, speech recognition, object recognition, and many others. In this study, we present a new technological concept named RCP(Robotic Cellular Phone), which combines RT & CP, in the vision of opening a new direction to the advance of CP, IT, and RT all together. RCP consists of 3 sub-modules. They are $RCP^{Mobility}$, $RCP^{Interaction}$, and $RCP^{Interaction}$. $RCP^{Mobility}$ is the main focus of this paper. It is an autonomous navigation system that combines RT mobility with CP. Through $RCP^{Mobility}$, we should be able to provide CP with robotic functionalities such as auto-charging and real-world robotic entertainments. Eventually, CP may become a robotic pet to the human being. $RCP^{Mobility}$ consists of various controllers. Two of the main controllers are trajectory controller and self-localization controller. While Trajectory Controller is responsible for the wheel-based navigation of RCP, Self-Localization Controller provides localization information of the moving RCP. With the coordinate information acquired from RFID-based self-localization controller, Trajectory Controller refines RCP's movement to achieve better RCP navigations. In this paper, a prototype system we developed for $RCP^{Mobility}$ is presented. We describe overall structure of the system and provide experimental results of the RCP navigation.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.6
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• pp.529-536
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• 2004

Autonomous navigation of an indoor mobile robot using the global ultrasonic system is presented in this paper. Since the trajectory error of the dead-reckoning navigation grows with time and distance, the autonomous navigation of a mobile robot requires to localize the current position of the robot, so that to compensate the trajectory error. The global ultrasonic system consisting of four ultrasonic generators fixed at a priori known positions in the work space and two receivers on the mobile robot has the similar structure with the well-known satellite GPS(Global Positioning System), and it is useful for the self-localization of an indoor mobile robot. The EKF(Extended Kalman Filter) algorithm for the self-localization is proposed and the autonomous navigation based on the self-localization is verified by experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.5
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• pp.480-488
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• 2006

Industrial and economical importance of CP(Cellular Phone) is growing rapidly. Combined with IT technology, CP is one of the most attractive technologies of today. However, unless we find a new breakthrough in the technology, its growth may slow down soon. RT(Robot Technology) is considered one of the most promising next generation technologies. Unlike the industrial robot of the past, today's robots require advanced features, such as soft computing, human-friendly interface, interaction technique, speech recognition object recognition, among many others. In this paper, we present a new technological concept named RCP (Robotic Cellular Phone) which integrates RT and CP in the vision of opening a combined advancement of CP, IT, and RT, RCP consists of 3 sub-modules. They are $RCP^{Mobility}$(RCP Mobility System), $RCP^{Interaction}$, and $RCP^{Integration}$. The main focus of this paper is on $RCP^{Mobility}$ which combines an autonomous navigation system of the RT mobility with CP. Through $RCP^{Mobility}$, we are able to provide CP with robotic functions such as auto-charging and real-world robotic entertainment. Ultimately, CP may become a robotic pet to the human beings. $RCP^{Mobility}$ consists of various controllers. Two of the main controllers are trajectory controller and self-localization controller. While the former is responsible for the wheel-based navigation of RCP, the latter provides localization information of the moving RCP With the coordinates acquired from RFID-based self-localization controller, trajectory controller refines RCP's movement to achieve better navigation. In this paper, a prototype of $RCP^{Mobility}$ is presented. We describe overall structure of the system and provide experimental results on the RCP navigation.

• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.87-96
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• 2018

A trajectory control system plays an important role in controlling motions of marine vehicle when a series of way points or a path is given. In this paper, a sliding mode control (SMC)-based trajectory tracking controller for marine vehicles is presented. A small-sized unmanned ship is considered as a control object. Both speed and heading angle of a ship should be controlled for tracking control. The common point of related researches was to separate ship's speed and heading angle in control methods. In this research, a new control law from a general sliding mode theory that can be applied to MIMO (multi input multi output) system is derived and both speed and heading angle of a ship can be controlled simultaneously. The propulsion force and rudder force are also applied in modeling stage to achieve accurate simulation. Disturbance induced by wind is also tackled in the dynamics considering robustness of the proposed control scheme. In the simulation, we employed a way-point method to generate ship's trajectory and applied the proposed control scheme to ship's trajectory tracking control. Our results confirmed that the tracking error was converged to zero, thus demonstrating the effectiveness of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.4
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• pp.363-368
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• 2005

This paper proposes an LOS(line-of-sight) guidance system of a ship for path following. From the viewpoint of a control configuration, guidance is a special type of compensation algorithm that is placed in front of the controller to accomplish navigational objects. A guidance system generates a reference trajectory for trajectory tracking or path control and decides the desired velocity, position and heading angle. A control system executes commands based on a reliable guidance law during navigation. An LOS vector from the vessel to a point on the path between two way-points in straight-line navigation or a point among turning circle in turning navigation is selected, and then a heading angle is calculated to converge the desired path based on the LOS vector. The LOS guidance law is defined for the straight-line and the turning circle, respectively. The effectiveness of the suggested LOS guidance system is assured through computer simulation.