• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1363-1370
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• 2018

In visible light (VL) positioning based on angle of arrival (AOA) estimation for smart indoor service, the AOA parameters obtained at the receiver has sometimes a random and distributed angle form instead of a point angle form due to the multipath transfer of the actual visible light and short positioning distance. The AOA estimation of a VL signal with a random and parametric distributed angle form may give incorrect AOA parameter estimates, which may result in poor VL positioning performance. In this paper, we classify the AOA parameters of the received VL signal into three forms according to the actual positioning channel environment and consider the short-range VL positioning method. We propose a subspace-based AOA parameter estimation technique and a data fusion method, and analyzed the proposed method by simulation and the measurement of the real VL channel characteristics.

• Journal of the Optical Society of Korea
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• 제19권6호
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• pp.586-591
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• 2015

In recent years, along with the rapid development of LED technology, indoor positioning systems based on visible light communication (VLC) have been researched. In this paper, we propose an accurate indoor positioning method using white-light LEDs and a dual image sensor. Indoor LED lights are located at the ceiling in a room and broadcast information on their positions using VLC technology. A mobile device with a dual image sensor receives LED position information by VLC and estimates its position and azimuth angle. Simulation and experimental results are given to show the performance of the proposed indoor positioning system.

• 한국정밀공학회지
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• 제20권10호
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• pp.141-147
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• 2003

This paper represents an absolute positioning system using a light navigation path for mobile robot. The absolute positioning system is composed of the projector unit which generates a laser beam using laser diode and mobile robot with the optical detector which has some optical sensors. The projector unit is fixed over the navigating plane of mobile robot to generate the light navigation path, and the optical detector located upper part of mobile robot detects the generated laser beam from the projector. The navigation of mobile robot is controlled by the micro-processor which compares the detected present position from the detector with the previously programmed navigation path. And experimental results show that our sensor system can be used for the absolute positioning system of the mobile robot.

• 대한공간정보학회지
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• 제24권2호
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• pp.25-35
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• 2016

Since a sophisticated location determination technology (LDT) is necessary for accurate positioning in urban area environments, numerous studies related to the LDT using the RFID (Radio Frequency IDentification) technology have been implemented for real-time positioning and data transferring. However, there are still lots of unsolved questions especially regarding what to use as base stations and what are corresponding results under the intrinsic complexity of alignment and configuration of components used for the RFID positioning. This study proposes the street light fixtures as base stations where the RFID receivers will be embedded for the mobile tracking scheme. As street light fixtures are usually installed at a certain distance interval, they can be used as base stations for the RFID receiver installation. Using the principle of the single row triangle network, the RFID receiver organization is determined based on the experiments such as recognition distance measurement and tag position accuracy estimation at inside and outside of the single row triangle network. The results verify that the mobile tracking scheme which uses RFID-embedded street light fixtures, suggested and configured in this study, is effective for the real-time outdoor positioning.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.277-290
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• 2019

The demand for indoor positioning is increasing day by day. However, the widely used positioning methods today cannot satisfy the requirements of the indoor environment in terms of the positioning accuracy and deployment cost. In the existing research domain, the localization algorithm based on three-dimensional space is less accurate, and its robustness is not high. Visible light communication technology (VLC) combines lighting and positioning to reduce the cost of equipment deployment and improve the positioning accuracy. Further, it has become a popular research topic for telecommunication and positioning in the indoor environment. This paper proposes a surface centroid TOA localization algorithm based on the VLC system. The algorithm uses the multiple solutions estimated by the trilateration method to form the intersecting planes of the spheres. Then, it centers the centroid of the surface area as the position of the unknown node. Simulation results show that compared with the traditional TOA positioning algorithm, the average positioning error of the surface centroid TOA algorithm is reduced by 0.3243 cm and the positioning accuracy is improved by 45%. Therefore, the proposed algorithm has better positioning accuracy than the traditional TOA positioning algorithm, and has certain application value.

• 한국통신학회논문지
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• 제38B권8호
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• pp.672-678
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• 2013

LED 기술의 급속한 발전으로 LED를 이용한 다양한 응용서비스 연구가 진행되고 있는데, 그 중 실내 측위 기술은 최근 가장 많은 관심을 받고 있는 연구 분야이다. 특히 가시광 무선 통신 기반의 실내 측위 기법 연구는 삼각 측량 기술을 접목하여 높은 측위 정확도를 제시하였는데, 기존 연구의 경우 LED 패널의 ID를 고정적으로 운용하고, 파일럿 신호 전송 시 별도의 ID 정보를 송신하는 구조를 가지고 있다. 따라서 LED 조명 장치 설계 시 ID 정보를 고려한 배치가 요구되기 때문에 인프라 구축의 복잡성을 가중시킨다. 이에 본 논문에서는 별도의 ID 전송 없이 VLC-TDoA 기반 실내 측위가 가능한 개선된 측위 알고리즘을 제안한다. 제안 알고리즘의 성능 평가를 위해 컴퓨터 모의실험을 수행하였고, 그 결과 $5{\times}5{\times}3m^3$의 실험 공간에서 약 3.6cm의 평균 측위 오차가 나타남을 확인하였다.

• 한국위성정보통신학회논문지
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• 제5권2호
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• pp.69-74
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• 2010

본 논문에서는 LED 조명 기반의 실내 측위 시스템을 제안하였다. LED가 빛을 방출하며 고속의 switching이 가능하다는 반도체 조명이라는 특징을 이용하여 각각의 LED 조명에 고유의 8 비트 ID를 부여 후, 이를 방출되는 조명 빛에 변조하여 보내주었다. 수신기는 16 개의 LED 조명으로부터 조합된 정보를 수신하게 되고, 수신된 정보와 각각의 ID 정보 간의 correlation coefficient를 이용하여 $4\;m\;{\times}\;4\;m\;{\times}\;2\;m$의 공간에서 100 cm 및 50 cm resolution을 가지는 위치인식 시스템을 시뮬레이션을 통해 구현하여 보았다. 제안된 측위 시스템은 간단한 알고리즘을 사용하였고, LED 조명 인프라를 사용하여 구축함으로써 설치비용 절감이 가능할 것이라 기대된다.

• 제어로봇시스템학회논문지
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• 제22권2호
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• pp.75-82
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• 2016

Visible light communication (VLC) using LED lamps is suitable for implementing an indoor positioning system in an indoor environment where the global positioning system (GPS) signal does not reach. In this paper, we present an indoor positioning system for mobile robots using a VLC beacon and fuzzy rules. This system consists of an autonomous mobile robot, VLC modules, and device application software. Fuzzy rules are applied to plan the global and local paths along which the mobile robot navigates indoors. The VLC transmitter modules are attached to the wall or the ceiling as beacons to transmit their own location information. The variable pulse position modulation (VPPM) algorithm is used to transmit data, which is a new modulation scheme for VLC providing a dimming control mechanism for flicker-free optical communication. The mobile robot has a receiver module to receive the location information while performing its mission in the environment where VLC transmitters are deployed.

• 한국통신학회논문지
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• 제39B권11호
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• pp.755-762
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• 2014

가시광 통신(VLC, Visible Lighting Communication) 시스템은 백색광 LED(Light Emitting Diode)와 스위칭 구동 회로를 이용한 변조 기법을 사용하여 조명 기능과 무선 디지털 통신 기능을 동시에 수행할 수 있는 차세대 통신 기술이다. 본 논문에서는 가시광 통신이 가능한 백색광 LED와 스테레오 이미지 센서를 이용한 실내 측위 알고리즘을 제안한다. 실내의 천장에 있는 백색광 LED는 자신의 위치 정보를 브로드캐스트하고, 이동체는 스테레오 이미지 센서에 맺히는 상과 전달받은 정보를 이용하여 이동체의 3차원 위치정보와 방위각을 구한다. 시뮬레이션을 통해 3차원 위치정보를 기존의 방안들과 비교하였다. 더불어, 제안한 알고리즘의 방위각 오차 특성을 분석하였다.

• 대한임베디드공학회논문지
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• 제10권2호
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• pp.101-108
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• 2015

In this paper, a robust traffic light detection method is proposed by using vision sensor and DGPS(Difference Global Positioning System). The conventional vision-based detection methods are very sensitive to illumination change, for instance, low visibility at night time or highly reflection by bright light. To solve these limitations in visual sensor, DGPS is incorporated to determine the location and shape of traffic lights which are available from traffic light database. Furthermore the geometric relationship between traffic light and vision sensor is used to locate the traffic light in the image by using DGPS information. The empirical results show that the proposed method improves by 51% in detection rate for night time with marginal improvement in daytime environment.