Wireless Impedance Sensor Node Research Articles

Piezoelectric on Natural Fiber Reinforced Epoxy Composite for Wireless Energy Harvesting

Energy harvesting have a variety of application areas such as aircraft,automotive, medical this energy provides a route for the realization of autonomous and self-powered low power electronic devices, for wireless sensor networks, it eliminates the need for wireless or replacement batteries. The purpose of this paper is to develop and improve the capacity of energy harvesting. In this study, an MFC harvesting elements were laid up with the Natural fiber/epoxy composites that will be fabricated prapag at the fabrication stage, and co-within an autoclave that can convert mechanical vibrations to electrical energy will study to supply power a wireless impedance sensor node. Finally, a series of experimental tests will be verified.

Smart wireless sensing and assessment for civil infrastructure

Recently, there has been increasing need for adopting smart sensing technologies to structural health monitoring (SHM) applications for civil infrastructure. In this paper, the state of the art in smart wireless sensing and assessment techniques for civil structures are reviewed focusing on full-scale applications. Three types of smart wireless sensing technologies are discussed: wireless acceleration sensor-based SHM, wireless impedance-based SHM and an optics-based non-contact actuation and sensing technique. At first, vibration-based SHM using a dense array of wireless acceleration sensors is implemented to a cable-stayed bridge. The modal identification of the bridge and cable tension estimation are carried out using the ambient acceleration data. Measured data during a typhoon is also discussed. Secondly, impedance-based SHM using piezoelectric active sensors is presented focusing on hardware and software issues. A wireless impedance sensor node is presented for local SHM and neural network-based smart assessment algorithm is proposed to detect multi-type damages. Finally, a wireless power and data transmission method using laser and optoelectronic technologies is presented for non-contact measurement of guided waves and impedance, and subsequent damage detection. This method is embodied in a small printed circuit board, and the performance is validated on a lab-scale steel truss member.

Smart PZT-interface for wireless impedance-based prestress-loss monitoring in tendon-anchorage connection

For the safety of prestressed structures such as cable-stayed bridges and prestressed concrete bridges, it is very important to ensure the prestress force of cable or tendon. The loss of prestress force could significantly reduce load carrying capacity of the structure and even result in structural collapse. The objective of this study is to present a smart PZT-interface for wireless impedance-based prestress-loss monitoring in tendon-anchorage connection. Firstly, a smart PZT-interface is newly designed for sensitively monitoring of electro-mechanical impedance changes in tendon-anchorage subsystem. To analyze the effect of prestress force, an analytical model of tendon-anchorage is described regarding to the relationship between prestress force and structural parameters of the anchorage contact region. Based on the analytical model, an impedance-based method for monitoring of prestress-loss is conducted using the impedance-sensitive PZT-interface. Secondly, wireless impedance sensor node working on Imote2 platforms, which is interacted with the smart PZT-interface, is outlined. Finally, experiment on a lab-scale tendon-anchorage of a prestressed concrete girder is conducted to evaluate the performance of the smart PZT-interface along with the wireless impedance sensor node on prestress-loss detection. Frequency shift and cross correlation deviation of impedance signature are utilized to estimate impedance variation due to prestress-loss.

Wireless Impedance Sensor Node and Interface Washer for Damage Monitoring in Structural Connections

In this study, a technique using wireless impedance sensor node and interface washer is proposed for monitoring damage in structural connections of bridges. In order to achieve the objective, the following approaches are implemented. First, a wireless impedance sensor node is designed for automated and cost-efficient monitoring in structural connections. Second, impedance-based algorithms are embedded in the wireless impedance sensor node for autonomous monitoring of structural connections. Third, a tensile-force monitoring technique using an interface washer is proposed to overcome limitations of the wireless impedance sensor node such as measureable ranges with narrow frequency band, and the proposed technique is numerically validated. Finally, the performance of the wireless impedance sensor node and the interface washer is experimentally evaluated in cable-anchor connection and bolted connection models.

Impedance-based structural health monitoring incorporating neural network technique for identification of damage type and severity

Impedance-based structural health monitoring (SHM) has come to the forefront in the SHM community because of its practical potential for real applications. In the impedance-based SHM technique, it is very important to select the optimal frequency range most sensitive to the expected structural damage, and more quantitative information on the structural damages might be needed compared to the conventional damage index. Therefore, this study proposes an innovative neural network (NN)-based pattern analysis tool (1) to identify damage-sensitive frequency ranges autonomously and (2) to provide detailed information such as the damage type and severity. The importance of selecting the optimal frequency range was first investigated experimentally using a simply-supported aluminum beam. The performance of the proposed NN-based approach was validated throughout damage identifications of loose bolts and notches on a bolt-jointed aluminum beam and a lab-scale pipe structure. Finally, the proposed NN-based algorithm was embedded into a wireless impedance sensor node to detect real damage in a full-scale bridge. Overall, the proposed approach incorporating a wireless impedance sensor node was used to evaluate the damage type and severity in multi-type and multiple structural damage cases.

무선 임피던스 센서노드를 이용한 강-볼트 접합부의 임피던스기반 손상모니터링에 미치는 온도 영향

This paper presents the effect of temperature on the impedance-based damage monitoring of steel-bolt connections using wireless impedance sensor nodes. In order to achieve the objective, the following approaches are implemented. First, a temperature-compensated damage monitoring scheme that includes a temperature compensation model and damage detection method is described. The temperature compensation model is designed by analyzing the linear regressions between the temperatures and impedance signatures. The correlation coefficient of the impedance signatures is selected as the damage index to monitor the damage occurrence in the target structures. Second, a wireless impedance sensor node is described for the design of the hardware components and embedded software. Finally, the performance of the temperature-compensated impedance-based damage monitoring scheme is evaluated for detecting a loose bolt in the steel-bolt connections on a lab-scale steel girder under various temperatures.

Impedance-based wireless debonding condition monitoring of CFRP laminated concrete structures

Carbon fiber reinforced polymer (CFRP) laminated concrete structures are used widely in a range of engineering fields because of their many advantages. However they always carry the risk of structural collapse initiated from the debonding conditions that might occur between the CFRP and concrete surface. This study employed an electro-mechanical impedance-based wireless structural health monitoring (SHM) technique by applying PZT ceramic patches to identify the debonding conditions of a CFRP laminated reinforced concrete beam. In the experimental study, the CFRP-reinforced concrete specimens were fabricated and the impedance signals were measured from the wireless impedance sensor node according to the different debonding conditions between the concrete and CFRP. Cross correlation (CC)-based data analysis was conducted to quantify the changes in impedance measured at the PZT patches due to the debonding conditions. The results confirmed that an impedance-based wireless SHM technique can be used effectively for monitoring the debonding of CFRP laminated concrete structures.

Quantitative Corrosion Monitoring Using Wireless Electromechanical Impedance Measurements

This article presents an experimental study for wireless monitoring of corrosion damage that might frequently occur in metallic structures. A simple beam structure made from an aluminum alloy was selected for corrosion-monitoring testing and a small lead-zirconate-titanate (PZT) patch-type sensor was surface-mounted to the structure. To obtain an electromechanical impedance data at the PZT sensor, a wireless impedance sensor node that consists of a miniaturized impedance-measuring chip, a microprocessor, and a radio frequency (RF) telemetry was employed. Three different corrosion cases with a different corroded area were artificially inflicted on the beam structure using hydrochloric (HCI) acid, and the electromechanical impedance data were collected in sequence from the wireless impedance sensor node. To quantify the corroded area, the variations of the resonant frequency that represents structural dynamic information were continuously tracked during all the damage cases. Conclusively, it has been found that the amount of the resonant frequency shift got increased when the corroded area got increased. The above experimental results verified that the proposed approach using the amount of resonant frequency shift at the measured electromechanical impedance can be effectively utilized for quantitative analysis of the corroded area in metallic structures.

Multi-scale wireless sensor node for health monitoring of civil infrastructure and mechanical systems

This paper presents recent developments in an extremely compact, wireless impedance sensor node (the WID3, <TEX>$\underline{W}$</TEX>ireless <TEX>$\underline{I}$</TEX>mpedance <TEX>$\underline{D}$</TEX>evice) for use in high-frequency impedance-based structural health monitoring (SHM), sensor diagnostics and validation, and low-frequency (< ~1 kHz) vibration data acquisition. The WID3 is equipped with an impedance chip that can resolve measurements up to 100 kHz, a frequency range ideal for many SHM applications. An integrated set of multiplexers allows the end user to monitor seven piezoelectric sensors from a single sensor node. The WID3 combines on-board processing using a microcontroller, data storage using flash memory, wireless communications capabilities, and a series of internal and external triggering options into a single package to realize a truly comprehensive, self-contained wireless active-sensor node for SHM applications. Furthermore, we recently extended the capability of this device by implementing low-frequency analog-to-digital and digital-to-analog converters so that the same device can measure structural vibration data. The compact sensor node collects relatively low-frequency acceleration measurements to estimate natural frequencies and operational deflection shapes, as well as relatively high-frequency impedance measurements to detect structural damage. Experimental results with application to SHM, sensor diagnostics and low-frequency vibration data acquisition are presented.

Development of a low-cost multifunctional wireless impedance sensor node

In this paper, a low cost, low power but multifunctional wireless sensor node is presented for the impedance-based SHM using piezoelectric sensors. Firstly, a miniaturized impedance measuring chip device is utilized for low cost and low power structural excitation/sensing. Then, structural damage detection/sensor self-diagnosis algorithms are embedded on the on-board microcontroller. This sensor node uses the power harvested from the solar energy to measure and analyze the impedance data. Simultaneously it monitors temperature on the structure near the piezoelectric sensor and battery power consumption. The wireless sensor node is based on the TinyOS platform for operation, and users can take MATLAB interface for the control of the sensor node through serial communication. In order to validate the performance of this multifunctional wireless impedance sensor node, a series of experimental studies have been carried out for detecting loose bolts and crack damages on lab-scale steel structural members as well as on real steel bridge and building structures. It has been found that the proposed sensor nodes can be effectively used for local wireless health monitoring of structural components and for constructing a low-cost and multifunctional SHM system as place and forget wireless sensors.

RF Energy Transmission for a Low-Power Wireless Impedance Sensor Node

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The proper management of energy resources is essential for any wireless sensing system. With applications that span industrial, civil, and aerospace infrastructure, it is necessary for sensors and sensor nodes to be physically robust and power efficient. In many applications, a sensor network must operate in locations that are difficult to access, and often these systems have a desired operational lifespan which exceeds that of conventional battery technologies. In the present study, the use of microwave energy is examined as an alternate method for powering compact, deployable wireless sensor nodes. A prototype microstrip patch antenna has been designed to operate in the 2.4 GHz ISM band and is used to collect directed radio frequency (RF) energy to power a wireless impedance device that provides active sensing capabilities for structural health monitoring applications. The system has been demonstrated in the laboratory, and was deployed in field experiments on the Alamosa Canyon Bridge in New Mexico in August 2007. The transmitted power was limited to 1 W in field tests, and was able to charge the sensor node to 3.6 V in 27 s. This power level was sufficient to measure two piezoelectric sensors and transmit data back to a base station on the bridge. </para>

Wireless impedance sensor nodes for functions of structural damage identification andsensor self-diagnosis

Economic and reliable online health monitoring strategies are very essential for safeoperation of civil, mechanical and aerospace structures. This study presents onlinestructural health monitoring (SHM) techniques using wireless impedance sensor nodesequipped with both functions of structural damage identification and sensor self-diagnosis.The wireless impedance sensor node incorporating a miniaturized impedance measuringchip, a microcontroller and radio-frequency (RF) telemetry is equipped with thecapabilities for temperature sensing, multiplexing of several sensors, and local dataanalysis. The feasibility of the sensor node for structural damage identification is firstlyinvestigated through a series of experimental studies inspecting loosened bolt damage andcut damage cases. Additionally, a temperature effects-free sensor self-diagnosis algorithm isembedded into the sensor node and its feasibility is examined from the experimentsmonitoring the integrity of each piezoelectric sensor on a wireless sensor network.

Development of an extremely compact impedance-based wireless sensing device

This paper describes the development of the next generation of an extremely compact,wireless impedance sensor node for use in structural health monitoring (SHM) andpiezoelectric active-sensor self-diagnostics. The sensor node uses a recently developed,low-cost integrated circuit that can measure and record the electrical impedance of apiezoelectric transducer. The sensor node also integrates several components, including amicrocontroller for local computing, telemetry for wirelessly transmitting data, multiplexersfor managing up to seven piezoelectric transducers per node, energy harvesting and storagemediums, and a wireless triggering circuit into one package to truly realize acomprehensive, self-contained wireless active-sensor node for various SHM applications. Itis estimated that the developed sensor node requires less than 60 mW of total power formeasurement, computation, and transmission. In addition, the sensor node isequipped with active-sensor self-diagnostic capabilities that can monitor the conditionof piezoelectric transducers used in SHM applications. The performance of thisminiaturized device is compared to our previous results and its broader capabilities aredemonstrated.

Development of an impedance-based wireless sensor node for structural healthmonitoring

This paper presents the development and application of a miniaturized impedance sensornode for structural health monitoring (SHM). A large amount of research has beenfocused on utilizing the impedance method for structural health monitoring. Thevast majority of this research, however, has required the use of expensive andbulky impedance analyzers that are not suitable for field deployment. In thisstudy, we developed a wireless impedance sensor node equipped with a low-costintegrated circuit chip that can measure and record the electrical impedance of apiezoelectric transducer, a microcontroller that performs local computing and a wirelesstelemetry module that transmits the structural information to a base station.The performance of this miniaturized and portable device has been compared toresults obtained with a conventional impedance analyzer and its effectiveness hasbeen demonstrated in an experiment to detect loss of preload in a bolted joint.Furthermore, for the first time, we also consider the problem of wireless powering of suchSHM sensor nodes, where we use radio-frequency wireless energy transmission to deliverelectrical energy to power the sensor node. In this way, the sensor node doesnot have to rely on an on-board power source, and the required energy can bewirelessly delivered as needed by human or a remotely controlled robotic device.