Algorithms for time synchronization of wireless structural monitoring sensors

Lei, Ying; Kiremidjian, Anne S.; Nair, K. Krishnan; Lynch, Jerome P.; Law, Kincho H.

doi:10.1002/eqe.432

Cited by 42 publications

(26 citation statements)

References 13 publications

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“…Synchronization of response data is necessary to ensure the accuracy of the engineering analyses performed on the response data. In particular, calculation of system modes is sensitive to errors in the synchronization of multi-output structural systems [26]. To address this limitation, the embedded firmware of the wireless monitoring system employs a beacon signal to which independent wireless sensors can synchronize their local clocks.…”

Section: Network Time Synchronizationmentioning

confidence: 99%

Performance monitoring of the Geumdang Bridge using a dense network of high-resolution wireless sensors

Lynch

Wang

Loh

et al. 2006

Smart Mater. Struct.

229

114

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As researchers continue to explore wireless sensors for use in structural monitoring systems, validation of field performance must be done using actual civil structures. In this study, a network of low-cost wireless sensors was installed in the Geumdang Bridge, Korea to monitor the bridge response to truck loading. Such installations allow researchers to quantify the accuracy and robustness of wireless monitoring systems within the complex environment encountered in the field. In total, 14 wireless sensors were installed in the concrete box girder span of the Geumdang Bridge to record acceleration responses to forced vibrations introduced by a calibrated truck. In order to enhance the resolution of the capacitive accelerometers interfaced to the wireless sensors, a signal conditioning circuit that amplifies and filters low-level accelerometer outputs is proposed. The performance of the complete wireless monitoring system is compared to a commercial tethered monitoring system that was installed in parallel. The performance of the wireless monitoring system is shown to be comparable to that of the tethered counterpart. Computational resources (e.g. microcontrollers) coupled with each wireless sensor allow the sensor to estimate modal parameters of the bridge such as modal frequencies and operational displacement shapes. This form of distributed processing of measurement data by a network of wireless sensors represents a new data management paradigm associated with wireless structural monitoring.

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Section: Network Time Synchronizationmentioning

confidence: 99%

Performance monitoring of the Geumdang Bridge using a dense network of high-resolution wireless sensors

Lynch

Wang

Loh

et al. 2006

Smart Mater. Struct.

229

114

View full text Add to dashboard Cite

show abstract

“…The time synchronization error possesses certain innate randomness, which makes it challenging to completely eliminate in data after processing. Although asynchronous data would oftentimes not affect the identification of damping ratios and natural frequencies, such data usually result in errors in identified mode shapes [19,23]. Therefore, the time synchronization accuracy of WSN should be carefully assessed through field experimental studies.…”

Section: Time Synchronization Assessmentmentioning

confidence: 99%

Feasibility of Output-Only Modal Identification Using Wireless Sensor Network: A Quantitative Field Experimental Study

Shen

Lei

et al. 2012

International Journal of Distributed Sensor Networks

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Although significant advancements have been achieved in wireless sensor network (WSN) in the past decades, there is still a strong need for in-depth analysis on wireless time synchronization and data quality during field testing. In this paper, an academic WSN is adopted for output-only modal identification of two full-scale bridges in Xiamen, China. This paper first assesses the accuracy of time synchronization performed by the WSN through a centralized beacon signal and then studies wireless data quality using two quantitative performance indexes. The relationship between vibration amplitude and quality of wireless sensor data is investigated. With ambient bridge accelerations acquired by wireless sensing units, modal properties of the two bridges are identified using the stochastic subspace identification (SSI) method and the enhanced frequency domain decomposition (EFDD) method. Accuracies of the modal identification results are evaluated through comparison with modal properties identified from tethered sensing data. The comparison shows close match in natural frequencies and mode shapes, although relatively large difference in damping ratios exists between results from wireless and tethered sensing data. An overall close match between the wireless and tethered results demonstrates the feasibility of using WSN for the ambient vibration testing of full-scale bridges.

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“…Errors in synchronization between data streams lead to corruption of the phase information contained in the data signals. This can adversely affect the accuracy of some processing algorithms commonly associated with modal analysis (Ginsberg 2001), input-output or multiple-output modeling (Lei et al 2005), or feedback control (Lian et al 2005). This task is made more difficult in wireless networks where signal propagation times are stochastic and direct communications between all units in the network may not be possible (Raghavendra et al 2004).…”

Section: Embedded Software Designmentioning

confidence: 99%

Rapid-to-deploy reconfigurable wireless structural monitoring systems using extended-range wireless sensors

Kim¹,

Swartz²,

Lynch³

et al. 2010

Smart Structures and Systems

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Wireless structural monitoring systems consist of networks of wireless sensors installed to record the loading environment and corresponding response of large-scale civil structures. Wireless monitoring systems are desirable because they eliminate the need for costly and labor intensive installation of coaxial wiring in a structure. However, another advantageous characteristic of wireless sensors is their installation modularity. For example, wireless sensors can be easily and rapidly removed and reinstalled in new locations on a structure if the need arises. In this study, the reconfiguration of a rapid-to-deploy wireless structural monitoring system is proposed for monitoring short-and medium-span highway bridges. Narada wireless sensor nodes using power amplified radios are adopted to achieve long communication ranges. A network of twenty Narada wireless sensors is installed on the Yeondae Bridge (Korea) to measure the global response of the bridge to controlled truck loadings. To attain acceleration measurements in a large number of locations on the bridge, the wireless monitoring system is installed three times, with each installation concentrating sensors in one localized area of the bridge. Analysis of measurement data after installation of the three monitoring system configurations leads to reliable estimation of the bridge modal properties, including mode shapes.

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Algorithms for time synchronization of wireless structural monitoring sensors

Cited by 42 publications

References 13 publications

Performance monitoring of the Geumdang Bridge using a dense network of high-resolution wireless sensors

Performance monitoring of the Geumdang Bridge using a dense network of high-resolution wireless sensors

Feasibility of Output-Only Modal Identification Using Wireless Sensor Network: A Quantitative Field Experimental Study

Rapid-to-deploy reconfigurable wireless structural monitoring systems using extended-range wireless sensors

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