• The Journal of Korea Robotics Society
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• v.7 no.4
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• pp.231-242
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• 2012

This paper proposes particle filter(PF) method using acoustic signal for localization of an underwater robot. The method uses time of arrival(TOA) or time difference of arrival(TDOA) of acoustic signals from beacons whose locations are known. An experiment in towing tank uses TOA information. Simulation uses TDOA information and it reveals dependency of the localization performance on the uncertainty of robot motion and senor data. Also, comparison of the PF method with the least squares method of spherical interpolation(SI) and spherical intersection(SX) is provided. Since PF uses TOA or TDOA which comes from measurement of external information as well as internal motion information, its estimation is more accurate and robust to the sensor and motion uncertainty than the least squares methods.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.169-173
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• 2020

Location-based services are used as core services in various fields. In particular, in the field of public services such as emergency rescue, accurate location estimation technology is very important. Recently, the technology of tracking the location of self-isolation subjects for COVID-19 has become a major issue. Therefore, location estimation technology using personal smart devices is being studied in various ways, and the most widely used method is to use GPS. Other representative methods are using Wi-Fi, Pedestrian Dead Reckoning (PDR), Bluetooth Low Energy (BLE) beacons, and LTE signals. In this paper, we introduced a positioning technology using deep learning based on LTE Channel State Information-Reference Signal (CSI-RS) data, and confirmed the possibility through an outdoor location estimation experiment using a commercial LTE signal.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.916-919
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• 1996

An real-time active beacon localization system for mobile robots is developed and implemented. This system permits the estimation of robot positions when detecting light sources by PSD(Position Sensitive Detector) sensor which are placed sparsely over the robot's work space as beacons(or landmarks). An LSE(Least Square Estimation) method is introduced to calibrate the internal parameters of a model for the beacon and robot position. The proposed system has two operational modes of position estimation. One is the initial position calculation by the detection of two or more light sources positions of which are known. The other is the continuous position compensation that calculates the position and heading of the robot using the IEKF(Iterated Extended Kalman Filter) applied to the beacon and dead-reckoning data. Practical experiments show that the estimated position obtained by this system is precise enough to be useful for the navigation of robots.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.126.3-126
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• 2001

A new method to govern the navigation of a mobile robot is proposed based on the following two procedures: one is to achieve vision information by using a 2 D-O-F camera as a communicating medium between a man and a mobile robot and the other is to analyze and to behave according to the recognized hand gesture commands. In the previous researches, mobile robots are passively to move through landmarks, beacons, etc. To incorporate various changes of situation, a new control system manages the dynamical navigation of a mobile robot. Moreover, without any generally used expensive equipments or complex algorithms for hand gesture recognition, a reliable hand gesture recognition system is efficiently implemented to convey the human commands to the mobile robot with a few constraints.

• The Journal of Aerospace Industry
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• s.65
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• pp.89-106
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• 2003

항공기의 자동 착륙 알고리즘을 위한 고 정밀 유도방식에 IBLS(Integrity Beacons Landing System)나 MLS(Microwave Landing System)와 같은 유도 제어 방식을 사용하여 유인 항공기나 무인 항공기의 유도 착륙에 사용하고 있다. 당 연구에서는 무인항공기의 자동 착륙을 위한 실제적인 요구사항들이 분석되었고, 자동 착륙 유도장치로 IBLS와 MLS가 선택되어 각각의 기능과 특성들이 수학적으로 모델링 되었다. 또한 고전제어와 최적제어의 2가지 방식으로 무인항공기의 자동 착륙을 통제하기 위한 autopilot이 설계되어 그 유효성과 특징들이 분석되었다. IBLS, MLS, autopilot, 그리고 이러한 자동 착륙 유도제어 시스템이 적용되는 대상체인 무인항공기와 대기환경 및 외란에 대한 수학적 모델들은 Simulink와 ANSI C를 사용하여 단위 S/W 모듈들로 작성되었고, 여기에 GUI모듈이 추가되어 하나의 통합 시뮬레이션 S/W가 완성되었다. 모의시험평가는 총 2단계로 구성되었는데, 대기 외란이 주어졌을 때 IBLS와 MLS의 유효성을 1차적으로 검증하였고, 2단계 모의수치실험에서는 MLS 유도센서 방식에 따른 고전제어기 및 최적제어기의 항공기 종 방향 운동에 대한 강인성 비교를 시도하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.428-428
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• 2000

A robust intelligent algorithm for AGV navigation control is presented here based on both magnetic and gyro sensors to track a reference trajectory. Since the proposed system uses an intermittent array of short magnetic tape strips, it lends itself to a very easy installation and maintenance compared to other types of positioning references such as electric wire, magnets, RF and laser beacons. The neural network is to predict the lateral deviation of the AGV in the intervals where no magnetic tape references are available. Further, the use of intelligent control ensures a robust and flexible control performance. Computer simulation of AGV control demonstrates its adequate tracking performances even where the sensor information is not available. Real experiments using Samsung AGV are also on the way for real verification

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.79-82
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• 2005

Fresnel lens has number of applications in the optical systems because of its advantages. It is nearly flat lens that has small weight. It is conventionally used in lighthouse beacons, condensing unit of overhead projector and etc. Recently, demands of small size optical systems such as display units, information storage systems, optical detecting units had increased. Conventional manufacturing process of high quality Fresnel lens is direct machining. But it is not suitable for mass production because of high cost and long cycle time. Replication process is more suitable for mass production. But the Fresnel lens has number of sharp blade shape prism. In the replication process, this blade shape causes defects that can affect optical efficiency. In this study, replication process of blade shape pattern that has maximum height of $280{\mu}m$, aspect ratio 1.4 for Fresnel lens application.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1223-1236
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• 2014

With the extension of wireless technology, vehicular ad hoc networks provide important services for the dissemination of general data and emergency warnings. However, since, the vehicle topology frequently changes from a dense to a sparse network depending on the speed of the moving vehicles and the time of day, vehicular ad hoc networks require a protocol that can facilitate the efficient and reliable dissemination of emergency messages in a highly mobile environment under dense or intermittent vehicular connectivity. Therefore, this paper proposes a new vehicular broadcast protocol, called BL-CAST, that can operate effectively in both dense and sparse network scenarios. As a low overhead multi-hop broadcast protocol, BL-CAST does not rely on the periodic exchange of beacons for updating location information. Instead, the location information of a vehicle is included in a broadcast message to identify the last rebroadcasting vehicle in an intermittently connected network. Simulation results show that BL-CAST outperforms the DV-CAST protocol in terms of the end-to-end delay, message delivery ratio and network overhead.

• Journal of Ubiquitous Convergence Technology
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• v.1 no.1
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• pp.42-46
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• 2007

In this paper, we proposed an efficient short address allocation mechanism for WiBEEM devices using NAA(Next Address Available) algorithm. The proposed addressing mechanism is based upon the NAA information that is delivered over the beacons every time it is transmitted at the beginning of each super-frame. The NAA-based addressing mechanism is not a systematic way of allocating short addresses to newly joining devices and thus tree-routing cannot be supported. However, it has great advantages when U-City core services including U-Parking Lot System or ATIS(Advanced Traveler Information System) services that require high-speed mobility are considered. Moreover, the proposed addressing mechanism can provide significant expandability of the wireless network to various applications and fast device discovery.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.127-129
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• 2018

RadarBeacons are navigational equipment that helps the navigators avoid dangerous rocks, such as heavy fog, nighttime, etc. when ships operate, or when visibility is bad. The existing antenna was researching the development of the advanced radar eacon (Enhanced Radar Beacon) for improving the development of the next generation racon with the AIS (Automatic Identification System) function.