Distributed Event Detection Algorithm considering Tradeoff between Accuracy and Cost

나현숙(Hyeon-Suk Na),녀뚜안안(Nhu Tuan Anh) 한국정보과학회 2011 정보과학회논문지 : 정보통신 Vol.38 No.2

본 논문에서는 무선 센서 네트워크상의 이벤트 감지 문제를 푸는 동시에, 정확도와 비용간의 trade-off를 조절할 수 있는 이벤트 감지 분산 알고리즘을 제안한다. 제안된 알고리즘은 관심영역에 랜덤하게 분포시킨 많은 수의 센서들로 감시되는 무선 네트워크를 모델로 하며, 센서들은 0/1-센서로서 낮은 성능의 배터리를 가지며, 감시, 통신, 그리고 아주 간단한 사칙연산만을 수행하는 정도의 극히 제한된 기능성을 갖는다. 이벤트 감지 문제에서는 언제나, 이벤트가 일어나는 순간 그것을 감지하고, 주변의 이웃들에게 이를 알려 그 이상의 이벤트들도 감지할 수 있도록 하는 센서들이 필요하다. 총 파워비용을 줄이거나 모니터링 시간을 최대화하기 위한 스케쥴링 방법들은 광범위하게 연구되어 왔다. 우리의 방법론은 다음과 같다. 일정한 밀도로 분포되도록 미리 선택한 센서들-여기서는 critical sensor라고 부름-은 언제나 깨어있도록 하고, 이들이 이벤트를 감지하면 이를 주변의 이웃들에게 알려 각자의 감지영역을 체크하도록 메시지를 전송한다. 메시지를 받은 센서들은 자신의 감지영역을 체크하고 어떤 조건들을 만족하는지 여부에 따라 깨어날 것인지 계속 sleeping 모드에 있을 것인지를 결정한다. 각 센서에서 실행되는 이 알고리즘은 매우 간단하며 필요에 따라 기껏해야 2 bit의 메시지를 전송하게 된다. 제안된 알고리즘에서 각 센서들은 주어진 네트워크에 의해 초기에 결정되는 하나의 정보-통신 반경 내 센서의 개수 혹은 이웃의 수-를 제외하고는, GPS 정보나 이웃들로부터의 상대적인 위치정보나 거리 등과 같은 정보들은 전혀 이용하지 않는다. 이 알고리즘의 또 하나의 장점은 위에서 설명한 “wake-up 모드가 되기 위한 어떤 조건”에 사용되는 두 가지 역치값들의 적용에 있는데, 이 역치값들을 조절함에 의해서, 우리는 이벤트 감지의 정확도와 통신 비용간의 trade-off를 조종할 수 있기 때문이다. In this paper, we present a distributed algorithm for detecting events in wireless sensor network that provides trade-off between detection accuracy and costs. Our model is that the region of interest is monitored by a large number of randomly distributed 0/1 sensors with low-power battery, limited functionality and memory, just enough for sensing, communicating and performing simple arithmetic operations. For any event detection problem, one needs some sensors awake to detect the event at the time that it happens, and to wake up its neighbors to detect further events. Scheduling for the network to save the total power-cost or to maximize the monitoring time has been studied extensively. Our scheme is that some predetermined uniformly distributed sensors, called critical sensors, are awake all the time and when a critical sensor detect any event, it broadcasts to the neighbors to check their sensing area. Then the neighbors check their area and decide with certain criteria whether they wake up or remain in sleeping mode . This algorithm running in each sensor is very simple and uses at most 2 bit of broadcasting. Sensors do not need any information such as GPS data or the relative position from the neighbors, but the number of its communication neighbors which is initially determined when the network is set. Another advantage of our algorithm is that we adapt two kinds of measure for the wake-up decision. By adjusting the threshold values, our algorithm can be applied for many applications because these thresholds provide trade-off between the accuracy of event detection and the cost of energy and communication.

정보 융합 칼만-Consensus 필터를 이용한 분산 센서 네트워크 구현

송재민,하찬성,황지홍,김태효,Song, Jae-Min,Ha, Chan-Sung,Whang, Ji-Hong,Kim, Tae-Hyo 한국융합신호처리학회 2013 융합신호처리학회 논문지 (JISPS) Vol.14 No.4

무선 센서 네트워크에서 동적 시스템에 대한 consensus 알고리듬은 센서 네트워크의 데이터 융합을 위해 신축적인 알고리듬을 적용할 수 있다. 본 논문은 분산 센서 데이터 기반의 평균적인 consensus 특성을 이용하여 n개의 센서 계측치들의 평균을 추적하기 위해 센서 네트워크의 노드들로 구성되는 하나의 분산 데이터 융합 필터를 구현하였다. 본 consensus 필터는 센서 네트워크에서 분산 칼만 필터링에 의한 구조로 데이터 융합의 문제를 해결한다. consensus 필터의 최적 수렴특성, 잡음 전파의 감소 및 빠른 입력신호들의 추적 능력을 보여준다. 필터링 처리 결과를 확인하기 위해 지그비 통신을 이용하여 각 센서의 출력신호와 필터링 처리 결과 및 각 센서의 개별적 신호들을 통합하고 consensus 필터링 처리 결과를 보였다. In wireless sensor networks, consensus algorithms for dynamic systems may flexibly usable for their data fusion of a sensor network. In this paper, a distributed data fusion filter is implemented using an average consensus based on distributed sensor data, which is composed of some sensor nodes and a sink node to track the mean values of n sensors' data. The consensus filter resolve the problem of data fusion by a distribution Kalman filtering scheme. We showed that the consensus filter has an optimal convergence to decrease of noise propagation and fast tracking ability for input signals. In order to verify for the results of consensus filtering, we showed the output signals of sensor nodes and their filtering results, and then showed the result of the combined signal and the consensus filtering using zeegbee communication.

Design and evaluation of a distributed TDR moisture sensor

Bin Zhang,Xinbao Yu,Xiong Yu 국제구조공학회 2010 Smart Structures and Systems, An International Jou Vol.6 No.9

This paper describes the development and evaluation of an innovative TDR distributed moisture sensor. This sensor features advantages of being responsive to the spatial variations of the soil moisture content. The geometry design of the sensor makes it rugged for field installation. Good linear calibration is obtained between the sensor measured dielectric constant and soil physical properties. Simulations by the finite element method (FEM) are conducted to assist the design of this sensor and to determine the effective sampling range. Compared with conventional types of moisture sensor, which only makes point measurement, this sensor possesses distributed moisture sensing capability. This new sensor is not only easy to install, but also measures moisture distribution with much lower cost. This new sensor holds promise to significantly improve the current field instruments. It will be a useful tool to help study the influence of a variety of moisture-related phenomena on infrastructure performance.

Design and evaluation of a distributed TDR moisture sensor

Zhang, Bin,Yu, Xinbao,Yu, Xiong Techno-Press 2010 Smart Structures and Systems, An International Jou Vol.6 No.9

This paper describes the development and evaluation of an innovative TDR distributed moisture sensor. This sensor features advantages of being responsive to the spatial variations of the soil moisture content. The geometry design of the sensor makes it rugged for field installation. Good linear calibration is obtained between the sensor measured dielectric constant and soil physical properties. Simulations by the finite element method (FEM) are conducted to assist the design of this sensor and to determine the effective sampling range. Compared with conventional types of moisture sensor, which only makes point measurement, this sensor possesses distributed moisture sensing capability. This new sensor is not only easy to install, but also measures moisture distribution with much lower cost. This new sensor holds promise to significantly improve the current field instruments. It will be a useful tool to help study the influence of a variety of moisture-related phenomena on infrastructure performance.

분산센서망에서 표적을 탐지한 센서의 기하학적 구조를 이용한 표적위치 추정

류창수(Chang Soo Ryu) 대한전자공학회 2016 전자공학회논문지 Vol.53 No.2

시스템 성능 지수 및 동적 전력분산 제어를 통한 무선센서를 이용한 에어컨 네트워크 시스템의 성능 개선

최호식 ( Ho-seek Choi ),권우현 ( Woo-hyen Kwon ),윤병근 ( Byung-keun Yoon ) 한국센서학회 2019 센서학회지 Vol.28 No.1

Wireless sensors have been developed in numerous ways for enhancing the convenience of installation, management and maintenance of sensors. Energy harvesting wireless sensors, which can collect energy from the external environment for permanent usage without the need of recharging and exchanging batteries, have been developed and employed used in Internet of Things and at various industrial sites. Energy harvesting wireless sensors are significantly affected by the sensor lifespan to sudden variation in the external environment. Furthermore, reduction in the sensor operating timespan can greatly affect the characteristics of the devices connected through a network. In this paper, a system performance index is proposed that can comprehensively evaluate the lifespan of a solar cell wireless sensor, determine the characteristics of devices connected to the associated network, and recommend dynamic power distribution control for improving the system performance index. Improvement in the system performance index was verified by applying the proposed dynamic power distribution control to an air conditioner network system using a solar cell wireless sensor. Obtained results corroborate that the dynamic power distribution control can extend the lifespan of the incorporated wireless sensor and reduce the air conditioner’s power consumption.

무선센서를 이용한 에어컨 네트워크 시스템에서 성능 지수와 동적 전력분산 제어를 통한 에어컨 에너지 절감

최호식(Ho-Seek Choi),권우현(Woo-hyen Kwon) 대한전자공학회 2019 전자공학회논문지 Vol.56 No.2

Analyzing in-plane temperature distribution via a micro-temperature sensor in a unit polymer electrolyte membrane fuel cell

Wang, H.Y.,Yang, W.J.,Kim, Y.B. Applied Science Publishers 2014 APPLIED ENERGY Vol.124 No.-

This study investigates the development of an in situ micro-temperature sensor, and analyzes the in-plane temperature distribution in a unit polymer electrolyte membrane fuel cell (PEMFC). To measure in-plane temperature distribution accurately, a polyimide-based micro-temperature sensor is designed and fabricated. The developed sensor is a resistance temperature detector with a flexible polyimide substrate. It exhibits high sensitivity and flexibility, and can be easily installed inside a cell. The sensor is sufficiently small to measure the temperature inside the PEMFC. After the sensors are calibrated, six sensors with one unit are inserted into the cell to measure in-plane temperature distribution. Six locations are chosen to represent the temperature distributions in the inlet, center, and outlet of the channel. The effect of inserting the sensor into the fuel cell is investigated by measuring the polarization curves with and without the sensor. A 3D computational fluid dynamics (CFD) fuel cell model with the same geometry and electrochemical properties as those of the PEMFC is also developed and analyzed to compare in-plane temperature distribution with the experimental results. A 3D CFD-PEMFC model accuracy can be obtained by comparing the temperature distribution results with the experimental results.

A distributed piezo-polymer scour net for bridge scour hole topography monitoring

Loh, Kenneth J.,Tom, Caroline,Benassini, Joseph L.,Bombardelli, Fabian A. Techno-Press 2014 Structural monitoring and maintenance Vol.1 No.2

Scour is one of the leading causes of overwater bridge failures worldwide. While monitoring systems have already been implemented or are still being developed, they suffer from limitations such as high costs, inaccuracies, and low reliability, among others. Also, most sensors only measure scour depth at one location and near the pier. Thus, the objective is to design a simple, low cost, scour hole topography monitoring system that could better characterize the entire depth, shape, and size of bridge scour holes. The design is based on burying a robust, waterproofed, piezoelectric sensor strip in the streambed. When scour erodes sediments to expose the sensor, flowing water excites it to cause the generation of time-varying voltage signals. An algorithm then takes the time-domain data and maps it to the frequency-domain for identifying the sensor's resonant frequency, which is used for calculating the exposed sensor length or scour depth. Here, three different sets of tests were conducted to validate this new technique. First, a single sensor was tested in ambient air, and its exposed length was varied. Upon verifying the sensing concept, a waterproofed prototype was buried in soil and tested in a tank filled with water. Sensor performance was characterized as soil was manually eroded away, which simulated various scour depths. The results confirmed that sensor resonant frequencies decreased with increasing scour depths. Finally, a network of 11 sensors was configured to form a distributed monitoring system in the lab. Their exposed lengths were adjusted to simulate scour hole formation and evolution. Results showed promise that the proposed sensing system could be scaled up and used for bridge scour topography monitoring.

Concrete pavement monitoring with PPP-BOTDA distributed strain and crack sensors

Genda Chen,Yi Bao,Fujian Tang,Yizheng Chen,Weina Meng,Ying Huang 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.3

In this study, the feasibility of using telecommunication single-mode optical fiber (SMF) as a distributed fiber optic strain and crack sensor was evaluated in concrete pavement monitoring. Tensile tests on various sensors indicated that the SMF-28e+ fiber revealed linear elastic behavior to rupture at approximately 26 N load and 2.6% strain. Six full-scale concrete panels were prepared and tested under truck and three-point loads to quantify the performance of sensors with pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA). The sensors were protected by precast mortar from brutal action during concrete casting. Once air-cured for 2 hours after initial setting, half a mortar cylinder of 12 mm in diameter ensured that the protected sensors remained functional during and after concrete casting. The strains measured from PPP-BOTDA with a sensitivity coefficient of 5.43 10-5 GHz/ were validated locally by commercial fiber Bragg grating (FBG) sensors. Unlike the point FBG sensors, the distributed PPP-BOTDA sensors can be utilized to effectively locate multiple cracks. Depending on their layout, the distributed sensors can provide one- or two-dimensional strain fields in pavement panels. The width of both micro and major cracks can be linearly related to the peak strain directly measured with the distributed fiber optic sensor.