Wireless Sensor Module Research Articles

Characterization of Body Movement for the Real Time Fall Detection Using Wireless Sensor Module

As fall is an accident being taken place ordinarily to the elderly, it is important to prevent fractures as a result of fall by detecting fall behavior in advance. The objective of this study is to distinguish activity of daily life (ADL) from fall by using wireless sensor module. This study intends to determine fall status before the body contacts ground surface after the fall starts. In this study, natural fall and acceleration being taken place during ADL were analyzed by using tri-axial accelerometer, tilt sensor and bluetooth module so that the body will not be bound at the time of fall. Test was performed on a soft mattress so that subjects will not be injured during the test process and fall was induced through rapid movement of mattress by using a pneumatic actuator. A sensor for detecting body movement was attached to the back and waist of the subject. Fall status was determined by using acceleration value being generated from the body and direction of fall was judged by angle value. As a result of the test, in case of using this system, fall status and its direction could be correctly detected.

Design and Implement Wireless Temperature Sensor Network Based on Distributed Platform

Design and implement a distributed platform based on wireless temperature sensor network via mass data storage of distributed platform, distributed computing and machine learning etc., while using a wide range of WCDMA network system and the 3G network’s quickly transmission rate, the advantages of stable signal.The system include the distributed computing storage platform based on hadoop,Using WCDMA DTU and embedded technology to develope wireless remote temperature sensor module, design and implement the temperature data of prison acquisition platform based on web. The results show that using distributed storage platform and WCDMA network to develop temperature sensor module and using web to develop temperature acquisition system that solve the problem of low efficiency, slowly computation speed cause by mass data storage and large data analysis in the temperature sensor network.These all meet the current new requirements of data expansion.

Development and Calibration of A Particulate Matter Measurement Device with Wireless Sensor Network Function

A Zigbee-based ubiquitous sensor network (USN) has many industrial applications and provides flexible measuring environments. In particular, the USN system can replace existing measuring devices in harsh environments such as subway stations. To monitor the intensities of various pollutants and air qualities in subway tunnels, this study applied the USN technique. A novel wireless sensor module, PMX, was designed and manufactured to simultaneously detect PM10 and PM2.5. Measurements were conducted at a subway station in Seoul. The PM concentrations using PMX were measured, analyzed, and compared with those obtained using an established commercial dust spectrometer (Grimm Aerosol Technik, 1.109). The measurements were performed from 24 March 2010 to 9 April 2010. PMX and the dust spectrometer measured PM10 levels of 98.3 and 40.7 ㎍/㎥, respectively, and PM2.5 concentrations of 86.5 and 16.6 ㎍/㎥, respectively. The monitored PM levels were investigated in a bimodal form during the sampling period. The PM10 and PM2.5 average correlations between PMX and the dust spectrometer were r2=0.81 and r2= 0.97, respectively. The two systems showed a similar time series trend, even though the measured values differed. A simple correlation analysis of the two data groups showed coefficients of determination of 0.7 for PM10 and 0.9 for PM2.5. The PMX data were mostly concentrated around the trend curve. Therefore, calibration of PMX data was required prior to use in the field. For the calibration, simple linear regression and nonlinear regression were used. The resulting correlation coefficients of simple linear regressions were 0.8 for PM10 and 0.9 for PM2.5, whereas those for nonlinear regressions were 0.7 for PM10 and 0.9 for PM2.5. The higher correlation coefficient for PM10 by the nonlinear regression indicates that it is the better method for calibrating the system developed in this study

IHPG Algorithm for Efficient Information Fusion in Multi-Sensor Network via Smoothing Parameter Optimization

This investigate proposed a innovative Improved Hybrid PSO-GA (IHPG) algorithm which it combined the advantages of the PSO algorithm and GA algorithm. The IHPG algorithm uses the velocity and position update rules of the PSO algorithm and the GA algorithm in selection, crossover and mutation thought. This study explores the quality monitoring experiment by three existing neural network approaches to data fusion in wireless sensor module measurements. There are ten sensors deployed in a sensing area, the digital conversion and weight adjustment of the collected data need to be done. This experiment result can improve the accuracy of the estimated data and reduce the randomness of computing by adjustment optimization of smoothing parameter. According to the experimental analysis, the IHPG is better than the single PSO and GA in comparison the various neural network learning model.

218 磁歪式振動発電デバイスを用いた低周波数振動で動作する無線センサシステムに関する研究(セッション8 ボルト緩み評価診断・橋梁点検)

We are developing vibrational energy harvesting system using iron-based magnetostrictive material (Galfenol) utilized as power supply for wireless sensor module of automobile and industrial machinery. The harvester consisting of Galfenol plate wound with coil, yoke and magnet features simple, small, highly robust and high power output. Our conventional harvester based on cantilever can generate high power output at high frequency resonance, however, does not match the use in automobile and industrial machinery with 10w frequency vibration. In this paper, we propose harvester equipped with adjusting tip mass mechanism and resonator for the operation in low frequency vibration. The harvester with the mechanism has three low frequency resonances determined by tip mass, mass and spring of the resonator. We verified the prototype using Galfenol plate of 2 by 0.5 by 22 mm with the mechanism (tip mass of 7.4g) has resonant frequency around 63 Hz and can generate high power output at low frequency and wide bandwidth.

A Wireless Sensor Enabled by Wireless Power

Through harvesting energy by wireless charging and delivering data by wireless communication, this study proposes the concept of a wireless sensor enabled by wireless power (WPWS) and reports the fabrication of a prototype for functional tests. One WPWS node consists of wireless power module and sensor module with different chip-type sensors. Its main feature is the dual antenna structure. Following RFID system architecture, a power harvesting antenna was designed to gather power from a standard reader working in the 915 MHz band. Referring to the Modbus protocol, the other wireless communication antenna was integrated on a node to send sensor data in parallel. The dual antenna structure integrates both the advantages of an RFID system and a wireless sensor. Using a standard UHF RFID reader, WPWS can be enabled in a distributed area with a diameter up to 4 m. Working status is similar to that of a passive tag, except that a tag can only be queried statically, while the WPWS can send dynamic data from the sensors. The function is the same as a wireless sensor node. Different WPWSs equipped with temperature and humidity, optical and airflow velocity sensors are tested in this study. All sensors can send back detection data within 8 s. The accuracy is within 8% deviation compared with laboratory equipment. A wireless sensor network enabled by wireless power should be a totally wireless sensor network using WPWS. However, distributed WPWSs only can form a star topology, the simplest topology for constructing a sensor network. Because of shielding effects, it is difficult to apply other complex topologies. Despite this limitation, WPWS still can be used to extend sensor network applications in hazardous environments. Further research is needed to improve WPWS to realize a totally wireless sensor network.

On-Body Channel Measurement Using Wireless Sensors

The on-body channel was characterised at various points on the human torso in an anechoic chamber using a pair of wireless sensor modules. The performance of wireless IEEE 802.15.4 sensor nodes operating in the 2.45 GHz ISM frequency band (2.40-2.4835 GHz) is presented over each of the 16 different channels. It is shown that the response at individual carrier frequencies is dependent not only on the initial antenna response, as determined by the on-body measurement in isolation, but also on the overall system performance. Measurement results are also compared with those from the conventional technique using a Vector Network Analyzer.

A compact and low cost dosimetry system based on MOSFET for in vivo radiotherapy

A compact and low-cost dosimetry system based on MOSFET for in vivo radiotherapy has been developed and characterized. This electronic system consists of a wireless sensor module containing a general-purpose MOSFET and a microcontrolled reader unit. Various methods, developed in previous works, to extend the linear range and reduce noise and thermal drift have been implemented and tested in the present system. A complete dose response characterization of the system has been carried out, including thermal drift, fading effect, linear range, sensitivity, and angular dependence for a 60Co source and for 6MV and 18MV photon beams provided by a linear accelerator. As a result, a procedure to use the system has been built, including the recalibration conditions to enhance the dosimeter life. The system provides suitable values for monitoring in vivo radiotherapy treatments in a reliable way. Although the present system has specifications that are comparable to those of some available commercial dosimetry systems, also based on MOSFET, the sensors here considered have a larger range of use.

A biologically inspired intelligent environment architecture for mobile robot navigation

Localisation in conventional autonomous robot navigation using centralised on-board intelligence faces many challenging issues. Steering away from the centralised on-board solution, this paper proposes a distributed approach by deploying distributed wireless nodes that comprise of vision sensors and embedded computers to process images, localise the robot and dynamic obstacles, navigate and control the robot. This schema releases massive on-board information processing required by conventional autonomous robot to its operation environment. The objective is to enable robots with limited intelligence to carry out complex navigation functions. The architectural design and realisation for connecting wireless vision sensors in the environment for global robot navigation path planning and local motion control is described. The paper gives a review of the proposed algorithms. The details of the wireless sensor network connectivity, system functions and modules, organisation and connection of the system components are described. The hardware and software realisation and experiment results are also discussed.

Virtual Sense: A Java-Based Open Platform for Ultra-Low-Power Wireless Sensor Nodes

Idleness has to be carefully exploited in wireless sensor networks (WSNs) to save power and to accumulate the energy possibly harvested from the environment. State-of-the-art microcontroller units provide a wide range of ultra-low-power inactive modes with sub-millisecond wakeup time that can be effectively used for this purpose. At the same time they are equipped with 16-bit RISC architectures clocked at tens of MHz, which make them powerful enough to run a Java-compatible virtual machine (VM). This makes it possible to bring the benefits of a virtual runtime environment into power-constrained embedded systems. VMs, however, risk to impair the effectiveness of dynamic power management as they are seen as always-active processes by the scheduler of the operating system in spite of the idleness of the threads running on top of them. Avoiding to keep sensor nodes busy when they could be idle is mandatory for the energetic sustainability of WSNs. While most of the tasks of a sensor node are inherently event-driven, the functioning of its hardware-software components is not, so that they require to be redesigned in order to exploit idleness. This paper presents VirtualSense, an open-hardware open-source ultra-low-power reactive wireless sensor module featuring a Java-compatible VM.

Inkjet Printed, Self Powered, Wireless Sensors for Environmental, Gas, and Authentication-Based Sensing

In this paper, inkjet-printed flexible sensors fabricated on paper substrates are introduced as a system-level solution for ultra-low-cost mass production of UHF Radio Frequency Identification (RFID) Tags and wireless sensor nodes in a “green” approach that could be easily extended to other microwave and wireless applications. The authors briefly touch up the state-of-the-art area of fully integrated wireless sensor modules on paper and show several active and power scavenging platforms to power on wireless sensors that could potentially set the foundation for the truly convergent wireless sensor ad hoc networks of the future.

A Wireless Sensor Network-Based Infrastructure for Real-Time and Online Pipeline Inspection

The aim of this paper is to present a secure wireless sensor network-based infrastructure for fast and accurate detection of eventual leaks that might occur in multiphase pipelines (i.e., pipelines which carry simultaneously more than one fluid). The system is scalable to monitor long distances of pipelines. It consists of a newly designed low-cost pipeline set which is composed of an inner pipe that carries the multiphase fluid, surrounded by a second outer pipe that holds the leak detection unit. This latest comprises an air-ultrasonic sensor which continuously senses the presence of the leak. The location of the leak is determined by a bidirectional microphone. Both these sensors are interfaced to a wireless sensor module which performs control, signal processing, and transmission tasks. Hence, the second contribution of this paper is to provide a new secure and reliable communication protocol that takes into consideration the nature of the network in terms of packets patterns and hardware constraints of the communicating nodes. Online tests in a laboratory scale flow loop indicate that the system is capable to accurately determine the location of the leak and its rate (in 1/min) in fast response time for different scenarios of leaks.

Power output enhancement of a vibration-driven electret generator for wireless sensor applications

We developed a compact vibration-driven electret generator that excelled at a power output. It succeeded in the operation of wireless sensor modules only on electricity from electret generators. This electret generator can supply enough power to operate a wireless sensor module without an external power source. It was necessary for enabling this operation to enhance the power output of the electret generator. We enhanced the power output by decreasing the parasitic capacitance. To decrease the parasitic capacitance, we fabricated a collector substrate using concave electrodes. We decreased it from 25 to 17 pF. As a result, the power output from our generator was enhanced from 40 to 100 µW considerably at an acceleration of 0.15 g (1.47 m s−2) and a resonance frequency of 30 Hz.

Thermoelectric Powered Autonomous Wireless Sensor Module for Temperature Monitoring

Wireless sensor networks are frequently used to monitor temperature and other manufacturing parameters in recent years. However, the limited battery life posts a constraint for large sensor networks. In this work, thermoelectric energy harvester is designed to effectively convert the heat into electrical energy to power the wireless sensor node. Bismuth telluride thermoelectric modules are optimized for low temperature conditions. Charge pump and switching regulator based power management module is designed to efficiently step up the 500mV thermoelectric voltage to 3.0V level for wireless sensor nodes. This design employs electric double-layer capacitor based energy storage with considerations on practical wireless sensor node operation. The implemented energy harvester prototype is proposed for Tyndall wireless sensor system to monitor temperature and relative humidity in manufacturing process. The prototype was tested in various conditions to discover the issues in this practical design. The proposed prototype can expect a 15 years operative lifetime instead of the 3-6 months battery lifetime.

고속 병렬형 PS-LFSR을 적용한 u-헬스케어 보안 시스템 구현

유비쿼터스 컴퓨팅 기술과 헬스케어 기술이 접목되어 시간과 장소에 구애받지 않고, 지속적인 건강관리가 가능한 u-헬스케어 기술이 급부상하고 있으며, 한국의 최첨단 정보 환경을 기반으로 하여 향후 급증할 의료수요에 대처하기 위한 u-헬스케어 기반기술이 절실한 실정이다. 특히, u-헬스케어 분야에서 다루는 정보는 주로 건강이나 생명과 밀접한 관계가 있는 관련 정보로서 극히 개인적인 사항을 주로 포함한다. u-헬스케어 서비스가 보안 및 프라이버시 측면에서 많은 취약점과 위협이 존재한다는 점을 볼 때, 데이터 보호를 위한 기술적 대안이 기본적으로 요구된다. 이에 본 논문에서는 안전한 u-헬스케어 시스템을 위해 u-헬스케어 센서모듈을 설계 및 제작하고, USN의 안전성 및 데이터 보호를 위해 NLM-128 알고리즘을 TinyOS상에서 소프트웨어적으로 구현하여 USN 센서노드에 탑재하였다. 그리고 NLM-128 알고리즘에 고속 병렬형 PS-LFSR을 적용하여 암호화 시간을 단축 시켰다. u-헬스케어 응용을 위한 USN 보안센서노드는 환자의 몸에 부착되어 각종 생체 신호를 계측할 수 있으며, 계측된 생체신호들은 무선메쉬네트워크(Wireless Mesh Network)를 통해 통합서버로 전송되며, 그 결과는 실시간으로 모니터링이 가능하였다. The emerging of ubiquitous computing and healthcare technologies provides us a strong platform to build sustainable healthcare applications especially those that require real-time information related to personal healthcare regardless of place. We realize that system stability, reliability and data protection are also important requirements for u-healthcare services. Therefore, in this paper, we designed a u-healthcare system which can be attached to the patient's body to measure vital signals, enhanced with USN secure sensor module. Our proposed u-healthcare system is using wireless sensor modules embedded with NLM-128 algorithm. In addition, PS-LFSR technique is applied to the NLM-128 algorithm to enable faster and more efficient computation. We included some performance statistical results in term of CPU cycles spent on NLM-128 algorithm with and without the PS-LFSR optimization for performance evaluation.

웹 환경에서 임베디드 시스템을 이용한 VOC센서 원격 신호 모니터링 시스템 개발

디지털 기술의 눈부신 발전과 인터넷 서비스의 다양화로 인하여 USN 시스템에서 임베디드 웹서버를 이용한 모니터링 시스템에 관한 연구가 활성화 되고 있는 추세이다. USN 시스템 구성 시 무선센서 모듈들을 사용할 경우 센서를 정상적으로 동작시키기 위해 히팅 전력이 필요한 센서에서는 과도한 전력 소모에 의해 효율적이지 못하다. 본 연구에서는 웹 환경에서 임베디드 시스템을 이용한 VOC 센서 신호 원격 모니터링 시스템개발을 목적으로 USN 시스템에서 센서 모듈들로부터 직렬버스 방식으로 오염 데이터 스트림을 처리하는 방법을 제안하였다. 센서 모듈의 전력을 직렬버스 라인과 함께 전력을 공급하도록 반연구적으로 실시간 적인 오염 감시를 할 수 있는 장점을 보유하고 있다. 오염 검출 대상은 페인트와 같은 화학물질에서 다량 검출되는 Toluene가스를 대상으로 하였으며 센서 모듈은 FIGARO사의 TGS-2602 VOC(Volatile Organic Compounds)센서로 구성하고 검출된 신호는 직렬버스 방식인 RS-485를 이용하여 임베디드 웹서버로 전송하였다. 검출된 신호는 사용자가 웹상에서 실시간으로 모니터링 할 수 있도록 하기위하여 VOC 센서 모듈과 임베디드 웹서버(EMPOS-II)를 연동하여 인터넷이 연결되어 있는 어느 곳에서나 유해 물질 검출 여부를 모니터링하고 감시할 수 있는 원격 VOC 센서 신호 모니터링 시스템을 구성하였다. Recent advances in digital technology and diversified internet services have resulted in a rapid growth of research on monitering systems using embedded web servers in USN systems. In designing USN systems equipped with wireless sensor modules requiring extra power for heating sensors for their appropriate operations, excessive power consumption introduces inefficiency to the entire system. In this paper, using embedded systems in web environment, we develop a remote-monitoring system with VOC (Volatile Organic Compounds) sensor signal, and propose a real time method of processing sensor-data streams by way of the serial bus from the sensor module in the USN system. The proposed system has an advantage of monitering the harmful gases on real-time basis and can be used semi-permanently by providing the sensor module with power through the serial bus. The harmful gas to be detected by the VOC sensor module is Toluene and the sensor module is composed of TGS-2602 VOC(Volatile Organic Compounds) sensors of FIGARO. The detected signal is transferred to the embedded web server using the RS-485 serial communication device. The proposed remote VOC monitering system is designed to coordinate in such a way that the VOC sensor module and embedded web server (EMPOS-II) work together effectively for real time monitering of harmful gases on the web at any places where the internet is connected.

Acoustic emission diagnosis system and wireless monitoring for damage assessment of concrete structures

Concrete is the most widely used materials for building civil structures. First, this study aims to identify the differences of AE event patterns caused by both actual crack development and the other sources. Secondly, it was focused to develop acoustic emission diagnosis system for assessing the deterioration of concrete structures like a bridge. Thirdly, a feasible study was done for the application of wireless acoustic emission sensor module to concrete structures. In this work, the algorithm for determining the damage status of concrete structures was developed and some criteria for decision making were also suggested. For the future application of wireless monitoring, a compact wireless acoustic emission sensor module was developed and applied to the concrete beam for performance test. Finally, based on the self-developed diagnosis algorithm, new AE system for practical AE diagnosis was demonstrated for assessing the conditions of damage and distress in concrete structures.

Fiber Bragg Grating Based Wireless Sensor Module With Modulated Radio-Frequency Signal

A fiber Bragg grating (FBG) sensing scheme based on the measurement of radio-frequency (RF) signal is presented for wireless sensing applications. A fiber ring combined with multiple sensing FBGs is proposed to form a microwave photonic notch filter based sensor module. With an additional FBG as a tunable reference element, the modulated RF signal in the sensor module is utilized to interrogate the wavelength shift of sensing FBGs. Preliminary experiments of the FBG sensor module on the strain measurement are demonstrated and show the effectiveness and flexibility of the sensing scheme.

지그비 기반 센서 네트워크를 이용한 침수감지용 광 이중센서 개발

In this paper, a remote submersion warning system based on multi-mode optical fiber(MMF) sensors and a wireless sensor network(WSN) are proposed. To improve the reliability and stability of the sensors, the dual optical fiber sensors combined to the optical coupler are demonstrated. A slave zigbee as a wireless sensor module was used as a platform to monitor and record the signal from the MMF sensors and then transmits these information to a master zigbee wirelessly. The monitoring system running the <TEX>$LabVIEW^{(R)}$</TEX> software was connected to the internet to support the short message service(SMS) through extensible markup language(XML) web service. No matter where the managers are, they can always receive the real-time remote-monitoring data for safety check.

Radio Path-Loss Modeling for a 2.4 GHz In-Field Wireless Sensor Network

Wireless sensor network (WSN) technology is a promising solution for large-scale, real-time, and continuous soil property data acquisition. However, the applications are still very limited due to a lack of understanding of in-field data transmission performance of a WSN. In this study, commercial 2.4 GHz wireless sensor modules (referred to as motes) and a hand-held spectrum analyzer were used to set up a test platform to evaluate radio propagation performance. Indexed packets transmitted from a module were captured by the spectrum analyzer to measure path-loss through received signal strength (RSS) and synchronously received by another module, called the base station, to calculate packet delivery rate (PDR). Experiments were conducted in a wheat field of an experimental farm of Oklahoma State University. Canopy height, transmitter height, receiver height, and transmitter-to-receiver distance (T-R distance) were considered as impact factors on radio propagation. Correlation analysis was used to evaluate the relationship between path-loss and PDR. The results indicated that, as plant height increased, path-loss and PDR became more correlated with each other. A distance of 70 m was defined as a stable communication distance for 2.4 GHz in-field WSN applications. Four models were developed to predict the path-loss based on the log of T-R distance and transmitter and receiver heights under conditions of clear line-of-sight and three different plant canopy heights. The R2 values of the models were 0.601, 0.599, 0.674, and 0.776, respectively. Their standard errors of the estimate were 3.761, 3.199 3.518, and 2.889, respectively.