• ETRI Journal
• /
• 제33권4호
• /
• pp.528-536
• /
• 2011

In this paper, we analyze the location accuracy of real-time locating systems (RTLSs) in multipath environments in which the RTLSs comply with the ISO/IEC 24730-2 international standard. To analyze the location error of RTLS in multipath environments, we consider a direct path and indirect path, in which time and phase are delayed, and also white Gaussian noise is added. The location error depends strongly on both the noise level and phase difference under a low signal-to-noise ratio (SNR) regime, but only on the noise level under a high SNR regime. The phase difference effect can be minimized by matching it to the time delay difference at a ratio of 180 degrees per 1 chip time delay (Tc). At a relatively high SNR of 10 dB, a location error of less than 3 m is expected at any phase and time delay value of an indirect signal. At a low SNR regime, the location error range increases to 8.1 m at a 0.5 Tc, and to 7.3 m at a 1.5 Tc. However, if the correlation energy is accumulated for an 8-bit period, the location error can be reduced to 3.9 m and 2.5 m, respectively.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2005년도 ICCAS
• /
• pp.1797-1801
• /
• 2005

SLAM(Simultaneous localization and mapping) and AI(Artificial intelligence) have been active research areas in robotics for two decades. In particular, localization is one of the most important issues in mobile robot research. Until now expensive sensors like a laser sensor have been used for the mobile robot's localization. Currently, as the RFID reader devices like antennas and RFID tags become increasingly smaller and cheaper, the proliferation of RFID technology is advancing rapidly. So, in this paper, the smart floor using passive RFID tags is proposed and, passive RFID tags are mainly used to identify the mobile robot's location on the smart floor. We discuss a number of challenges related to this approach, such as RFID tag distribution (density and structure), typing and clustering. In the smart floor using RFID tags, because the reader just can senses whether a RFID tag is in its sensing area, the localization error occurs as much as the sensing area of the RFID reader. And, until now, there is no study to estimate the pose of mobile robot using RFID tags. So, in this paper, two algorithms are suggested to. We use the Markov localization algorithm to reduce the location(X,Y) error and the Kalman Filter algorithm to estimate the pose(q) of a mobile robot. We applied these algorithms in our experiment with our personal robot CMR-P3. And we show the possibility of our probability approach using the cheap sensors like odometers and RFID tags for the mobile robot's localization on the smart floor.

• 한국정보통신학회논문지
• /
• 제22권11호
• /
• pp.1442-1447
• /
• 2018

RFID를 이용한 실내 위치 인식 시스템은 실내의 위치를 예측하는 방식이기 때문에 장애물 등 주변 환경에 의해 오차가 발생한다. 본 논문에서는 역전파 신경망을 이용하여 오차를 줄이고자 한다. 신경망은 층간의 가중치를 조정하고 훈련시켜 리더를 보유한 물체의 실제위치와 실험을 통해 예상되는 위치간의 오차를 줄인다. 본 논문에서는 중앙값을 사용한 방법과 방사 형태를 사용한 방법을 신경망의 입력으로 사용하는 구성을 제안하였다. 두 가지 방법 중 장애물이 있는 환경에서 어떤 방법이 실제 위치를 인식하는 데에 더 효율적인지 확인하고 오차를 줄이고자 한다. 그 결과 중앙값을 이용한 방법이 오차가 더 적었으며, 데이터 개수가 많을수록 오차가 더 줄어드는 것을 확인하였다.

• 산업공학
• /
• 제23권3호
• /
• pp.239-245
• /
• 2010

This paper considers a localization problem of a moving tag on RFID(Radio Frequency Identification) systems, where a positioning engine collects TDOA(Time-difference of Arrival) signal from a target tag to estimate the position of the tag. To localize the tag in the RFID system, we develop two heuristic algorithms and evaluate their performance in the estimation error and computational time by using randomly generated numerical examples. Based upon the performance evaluation, we can conclude our algorithms are valuable for localization the moving target.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.1034-1039
• /
• 2005

SALM(Simultaneous localization and mapping) and AI(Artificial intelligence) have been active research areas in robotics for two decades. In particular, localization is one of the most important tasks in mobile robot research. Until now expensive sensors such as a laser sensor have been used for mobile robot localization. Currently, the proliferation of RFID technology is advancing rapidly, while RFID reader devices, antennas and tags are becoming increasingly smaller and cheaper. So, in this paper, the smart floor using passive RFID tags is proposed and, passive RFID tags are mainly used for identifying location of the mobile robot in the smart floor. We discuss a number of challenges related to this approach, such as tag distribution (density and structure), typing and clustering. In the smart floor using RFID tags, the localization error results from the sensing area of the RFID reader, because the reader just knows whether the tag is in the sensing range of the sensor and, until now, there is no study to estimate the heading of mobile robot using RFID tags. So, in this paper, two algorithms are suggested to. The Markov localization method is used to reduce the location(X,Y) error and the Kalman Filter method is used to estimate the heading($\theta$) of mobile robot. The algorithms which are based on Markov localization require high computing power, so we suggest fast Markov localization algorithm. Finally we applied these algorithms our personal robot CMR-P3. And we show the possibility of our probability approach using the cheap sensors such as odometers and RFID tags for mobile robot localization in the smart floor

• ETRI Journal
• /
• 제33권3호
• /
• pp.382-392
• /
• 2011

This paper proposes the streaming radio frequency identification (RFID) protocol to support robust data streaming in a passive communication, which is extended from the ISO18000-6 Type C RFID standard. By observing and modeling the unique bit error behavior through detailed analysis in this paper, we found that performance is significantly limited by inaccurate and unstable link frequencies as well as low SNR which are inevitable for passive devices. Based on the analysis, we propose a simple and efficient protocol to adaptively insert extra error control sequences in a packet for tolerating tough link condition while maximizing the throughput and preserving the minimal implementation cost. To evaluate effectiveness of our proposal in real-time streaming applications, we experimented on real-time H.264 video streaming and prototyped the system on FPGA. To our best knowledge, our paper is the first work to take analytical approach for maximizing the throughput and demonstrate the possibility of the realtime multimedia streaming transmission in the passive RFID system.

• 한국컴퓨터정보학회논문지
• /
• 제19권6호
• /
• pp.109-117
• /
• 2014

냉동창고는 일반 창고와 달리 냉각설비를 갖춘 단열된 건물의 창고로서, $0^{\circ}C$이하의 다양한 유형의 냉장/냉동고에 물품들을 입고, 적재, 출고하는 일련의 업무가 운영된다. 최근 냉동창고에 RFID 기술이 도입됨으로써 창고 내 물품관리를 네트워크화, 지능화할 수 있게 되었다. 그러나 RFID 시스템으로 인한 물리적 인식 실패뿐만 아니라 논리적 인식 실패로 인한 물류정보 불일치가 발생하게 되면 RFID 냉동창고 관리시스템의 신뢰도가 떨어지고 업무의 효율이 감소하게 된다. 본 논문에서는 RFID 냉동창고 관리 시 발생하는 다양한 종류의 오류들을 즉각적으로 탐지할 수 있는 슈퍼바이저 시스템의 개발내용에 대해 기술한다. 이는 RFID 냉동창고 관리업무상 발생할 수 있는 오류들의 제약조건들을 미리 설정하고 오류의 알림을 받을 수 있는 마스터 슈퍼바이저와 냉동창고 내 업무를 처리하는 작업자가 오류에 대한 알림을 받고 그 자리에서 오류를 직접 확인하고 처리할 수 있는 모바일 슈퍼바이저로 구성된다. 본 논문에서는 슈퍼바이저 시스템이 RFID 냉동창고 관리시스템 상의 오류들을 탐지/분석하는 시간을 줄임으로써 신뢰성을 높이기 위한 평균복구시간을 줄일 수 있음을 보인다.

• 제어로봇시스템학회논문지
• /
• 제12권10호
• /
• pp.968-974
• /
• 2006

We are moving into the era of ubiquitous computing. Ubiquitous Sensor Network (USN) is a base of such computing paradigm, where recognizing the identification and the position of objects is important. For the object identification, RFID tags are commonly used. For the object positioning, use of sensors such as laser and ultrasonic scanners is popular. Recently, there have been a few attempts to apply RFID technology in robot localization by replacing the sensors with RFID readers to achieve simpler and unified USN settings. However, RFID does not provide enough sensing accuracy for some USN applications such as robot navigation, mainly because of its inaccuracy in distance measurements. In this paper, we describe our approach on achieving accurate navigation using RFID. We solely rely on RFID mechanism for the localization by providing coordinate information through RFID tag installed floors. With the accurate positional information stored in the RFID tag, we complement coordinate errors accumulated during the wheel based robot navigation. We especially focus on how to distribute RFID tags (tag pattern) and how many to place (tag granularity) on the RFID tag-floor. To determine efficient tag granularities and tag patterns, we developed a simulation program. We define the error in navigation and use it to compare the effectiveness of the navigation. We analyze the simulation results to determine the efficient granularities and tag arrangement patterns that can improve the effectiveness of RFID navigation in general.

• 한국전자파학회논문지
• /
• 제21권3호
• /
• pp.321-330
• /
• 2010

본 논문에서는 컴프레시브 RFID 신호를 탐지하기 위한 컴프레시브 수신기의 이론적 배경과 구체적 구현 방법, 그리고 분산 지연선과 chirp LO의 설계 방안에 대해 기술하였다. 컴프레시브 수신기의 주요 구성품 중 하나인 분산 지연선을 대역폭 6 MHz, 분산 지연 시간 $13{\mu}s$으로 설계하여 $LiNbO_3$ 재질 기반의 SAW(Surface Acoustic Wave) 기술을 통해 구현하였고, DDS(Direct Digital Synthesizer)를 이용하여 chirp LO를 구현하였다. 또한 RFID 리더에 내장되어 연동될 수 있도록 컴프레시브 수신기를 구성하였다. 시험 결과, 단일 신호 입력시 주파수 오차는 최대 25 kHz, 수신 감도는 -44 dBm, 500 kHz 간격으로 동시에 입력되는 6개의 신호에 대한 주파수 오차는 최대 75 kHz로서 제작된 컴프레시브 수신기가 밀집된 RFID 운영 환경에 적합함을 보였다.

• 대한산업공학회지
• /
• 제40권4호
• /
• pp.415-423
• /
• 2014

In recent decades, RFID (Radio Frequency IDentification) technology has been recognized as one of the most core competencies in implementing ubiquitous society. However, Korea has not seen good success in diffusion of RFID even though Korean government continues funding many projects to diffuse the technology in industries. Most previous researches overestimate the growth of Korean RFID market in contrary to real market situation. This study aims to analyze the Korean RFID market and find a reasonable forecasting model for it. Our experimental results show that Bass forecasting model provides the more realistic estimates than any other models and the analyses of forecasting error provide useful information for the better forecasting. We also observed that government policy plays a crucial role in the diffusion of RFID technology in Korea.