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Smart Structures and Systems Volume 6, Number 5, July-August 2010 , pages 675-687 DOI: https://doi.org/10.12989/sss.2010.6.5_6.675 |
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Ultra low-power active wireless sensor for structural health monitoring |
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Dao Zhou, Dong Sam Ha and Daniel J. Inman
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| Abstract | ||
| Structural Health Monitoring (SHM) is the science and technology of monitoring and assessing the condition of aerospace, civil and mechanical infrastructures using a sensing system integrated into the structure. Impedance-based SHM measures impedance of a structure using a PZT (Lead Zirconate Titanate) patch. This paper presents a low-power wireless autonomous and active SHM node called Autonomous SHM Sensor 2 (ASN-2), which is based on the impedance method. In this study, we incorporated three methods to save power. First, entire data processing is performed on-board, which minimizes radio transmission time. Considering that the radio of a wireless sensor node consumes the highest power among all modules, reduction of the transmission time saves substantial power. Second, a rectangular pulse train is used to excite a PZT patch instead of a sinusoidal wave. This eliminates a digital-to-analog converter and reduces the memory space. Third, ASN-2 senses the phase of the response signal instead of the magnitude. Sensing the phase of the signal eliminates an analog-to-digital converter and Fast Fourier Transform operation, which not only saves power, but also enables us to use a low-end low-power processor. Our SHM sensor node ASN-2 is implemented using a TI MSP430 microcontroller evaluation board. A cluster of ASN-2 nodes forms a wireless network. Each node wakes up at a predetermined interval, such as once in four hours, performs an SHM operation, reports the result to the central node wirelessly, and returns to sleep. The power consumption of our ASN-2 is 0.15 mW during the inactive mode and 18 mW during the active mode. Each SHM operation takes about 13 seconds to consume 236 mJ. When our ASN-2 operates once in every four hours, it is estimated to run for about 2.5 years with two AAA-size batteries ignoring the internal battery leakage. | ||
| Key Words | ||
| structural health monitoring; SHM; wireless sensor node; impedance-based method; temperature compensation. | ||
| Address | ||
| Dao Zhou and Dong Sam Ha; Center for Embedded Systems for Critical Applications (CESCA), Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA Daniel J. Inman; Center for Intelligent Material Systems and Structures (CIMSS), Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA | ||