• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권4호
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• pp.1090-1105
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• 2012

A multi-modal sensing M2M healthcare monitoring system for the continuous monitoring of patients under their natural physiological states or elderly persons with chronic diseases is summarized. The system is designed for homecare or the monitoring of the elderly who live in country side or small rest home without enough support from caregivers or doctors, instead of patient monitoring in big hospital environment. Further insights into the natural cause and progression of diseases are afforded by context-aware sensing, which includes the use of accelerometers to monitor patient activities, or by location-aware indoor tracking based on ultrasonic and RF sensing. Moreover, indoor location tracking provides information about the location of patients in their physical environment and helps the caregiver in the provision of appropriate support.

• 제어로봇시스템학회논문지
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• 제12권9호
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• pp.868-875
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• 2006

The localization is one of the most important issues for mobile robot. This paper describes a novel localization system for the development of a location sensing network. The system comprises wirelessly controlled infrared landmarks and an image sensor which detects the pixel positions of infrared sources. The proposed localization system can operate irrespective of the illumination condition in the indoor environment. We describe the operating principles of the developed localization system and report the performance for mobile robot localization and navigation. The advantage of the developed system lies in its robustness and low cost to obtain location information as well as simplicity of deployment to build a robot location sensing network. Experimental results show that the developed system outperforms the state-of-the-art localization methods.

• Journal of Ubiquitous Convergence Technology
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• 제2권2호
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• pp.67-77
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• 2008

Representation of various types of information in an interactive virtual reality environment on mobile devices had been an attractive and valuable research in this new era. Our main focus is presenting spatial indoor location sensing information in 3D perception in mind to replace the traditional 2D floor map using handheld PDA. Designation of 3D virtual reality by Virtual Reality Modeling Language (VRML) demonstrates its powerful ability in providing lots of useful positioning information for PDA user in real-time situation. Furthermore, by interpolating portal culling algorithm would reduce the 3D graphics rendering time on low power processing PDA significantly. By fully utilizing the CC2420 chipbased sensor nodes, wireless sensor network was established to locate user position based on Received Signal Strength Indication (RSSI) signals. Implementation of RSSI-based indoor tracking method is low-cost solution. However, due to signal diffraction, shadowing and multipath fading, high accuracy of sensing information is unable to obtain even though with sophisticated indoor estimation methods. Therefore, low complexity and flexible accuracy refinement algorithm was proposed to obtain high precision indoor sensing information. User indoor position is updated synchronously in virtual reality to real physical world. Moreover, assignment of magnetic compass could provide dynamic orientation information of user current viewpoint in real-time.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1606-1611
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• 2005

The goal of this paper is to develop a self localization of mobile robot using UHF RFID landmark. We present landmark, a location sensing archetype system that uses UHF Radio Frequency Identification (UHF RFID) technology for locating objects inside buildings. The major advantage of landmark is that it improves the overall accuracy of locating objects by utilizing the concept of reference tags. Based on experimental analysis, we demonstrate that passive UHF RFID is a viable and cost-effective candidate for indoor location sensing. We conduct a series of experiments to evaluate performance of the positioning of the landmark System. In the standard setup, we place RF Reader which has two antennas and 25 tags in our lab. This research uses the assumption-based coordinates (ABC) algorithm[3] for determining the localization of robot. Also, we show how Radio Frequency Identification (UHF RFID) can be used in robot-assisted indoor navigation for the visually impaired. The experiments illustrate that passive UHF RFID tags can act as reliable landmark that trigger local navigation behaviors to achieve global navigation objectives.

• 한국산학기술학회논문지
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• 제13권1호
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• pp.364-369
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• 2012

유비쿼터스 컴퓨팅 시대로 진입하면서 사물의 위치 정보가 더욱 중요시 되고 있다. 대표적인 실내 위치 인식 시스템인 크리켓은 노드 간의 거리를 인식하기 위해서 RF 신호와 초음파 신호를 주기적으로 전송한다. 하지만 배치되어 있는 센서 노드 수가 증가할수록 신호간의 간섭 및 충돌 횟수가 증가하여 위치 인식 시스템의 정확도를 떨어뜨린다. 본 논문에서는 초음파 위치인식 시스템을 구성하기 위해, 무선 센서 네트워크 표준인 IEEE 802.15.4 MAC 프로토콜을 사용하였다. 신호간의 간섭과 충돌 횟수를 감소시키기 위해, 노드 번호와 이동통신에서 사용하는 주파수 재사용 방식을 변형하여 오차율을 감소시키는 알고리즘을 제안하였다. 성능평가 결과 제안한 알고리즘이 기존의 크리켓시스템보다 수율과 에너지 효율 면에서 더 좋은 성능을 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1771-1774
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• 2005

Recently, RFID has become popular in the field of remote sensing applications. Location awareness is one of the most important keys to deploying RFID for advanced object tracking. Generally, multiple reference RF stations or additional sensors are used for the location sensing with RFID, but, particularly in indoor environments, spatial layout and cost problems limit the applicability of those approaches. In this paper, we propose a novel method for location sensing with active RFID systems not requiring the need for reference stations or additional sensors. The system triangulates the position of RF signal source using the signal pattern of the loop antenna connected to the power detector. The power detector consists of a signal strength detector and a signal analysis unit. The signal analysis unit indicates the signal strength and serial number using the signal from the strength detector, and provides the direction of the signal to the application target. We designed three different signal analysis units depending on the threshold type. The developed system can sense the direction to the transponder located over 10 m away within the maximum error of $5^{\circ}$. It falls within a reasonable range in our normal office environment.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.348-353
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• 2008

무선센서 네트워크 기술의 응용이 크게 증가함에 따라 저전력 IEEE 802.15.4 호환 무선방식을 활용하는 실내 위치추적기술이 최근에 큰 관심을 모으고 있다. 기존의 실내 위치감지 정보는 2D 영상 기준으로서 정보의 실질적인 전달에 제한적인 기능을 나타내었다. 본 논문에서는 PDA에 대화형 가상현실기술에 바탕을 둔 고정밀 3차원 RSSI 기반의 화면 구성에 초점을 두고있다. 개발된 시스템은 관심영역에서 RF신호의 감쇄를 계산하여 위치정보를 얻은 다음, 이를 3D 실내 가상맵에서의 사용자의 위치로 나타내도록 설계되었다. 이 연구에서는 3차원 모델링을 위해 개발된 VRML(가상현실 모델링 언어)이 3D 실내환경을 설계하는데 활용되었다.

• ETRI Journal
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• 제38권3호
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• pp.560-567
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• 2016

To solve the problem of parameter optimization in image sensor-based visible light positioning systems, theoretical limits for both the location and the azimuth angle of the image sensor receiver (ISR) are calculated. In the case of a typical indoor scenario, maximum likelihood estimations for both the location and the azimuth angle of the ISR are first deduced. The Cramer-Rao Lower Bound (CRLB) is then derived, under the condition that the observation values of the image points are affected by white Gaussian noise. For typical parameters of LEDs and image sensors, simulation results show that accurate estimates for both the location and azimuth angle can be achieved, with positioning errors usually on the order of centimeters and azimuth angle errors being less than $1^{\circ}$. The estimation accuracy depends on the focal length of the lens and on the pixel size and frame rate of the ISR, as well as on the number of transmitters used.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.8-11
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• 2021

본 논문은 실내환경에서 로봇의 센싱영역을 벗어난 곳에 위치하는 사용자에게 접근하여 배달서비스를 제공하기 위해 로봇의 최적 위치를 추정하는 방법을 제안한다. 먼저, 사용자의 위치를 추정하기 위해 비콘-태그 모듈정보에 삼변측량법을 적용하여 실내환경에서 위치를 추정하였고, 사용자 추정위치로부터 최적의 로봇 이동목표(Goal)를 설정하기 위해 보로노이 그래프(GVG)의 생성 노드정보를 기반으로 사용자 위치, 장애물, 이동경로 정보의 연산을 통해 최종 위치를 추정하였다. 실제 로봇플랫폼의 목적지 이동을 통해 해당 서비스로봇의 위치정밀도를 검증하였다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2015년도 제52차 하계학술대회논문집 23권2호
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• pp.279-281
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• 2015

Location awareness is an important capability for mobile-based indoor services. Those indoor services have motivated the implementation of methods that need high computational load cost and complex mechanisms for positioning prediction. These mechanisms, such as opportunistic sensing and machine learning, require more energy consumption to achieve accuracy. In this paper, we propose the Bluetooth Low Energy indoor zone detection (BLEIZOD) technique. This method exploits the concept of proximity zone to reduce the load cost and complexity. Our proposed method implements the received signal strength indicator (RSSI) function more effectively to gain accuracy and reduce energy consumption.