Real-time monitoring of structural vibration using a novel fiber optic accelerometer system

This paper presents the use of a novel fiber optic accelerometer system to monitor civil engineering structures in real time. This sensor system integrates the Moiré fringe phenomenon with fiber optics to achieve accurate and reliable measurements. A low-cost signal processing unit implements unique algorithms to further enhance the resolution and increase the dynamic bandwidth of the sensors. There are two major benefits in using this fiber optic accelerometer system for monitoring civil engineering structures. One is its immunity to electromagnetic (EM) interference making it suitable for difficult applications in such environments involving strong EM fields, electrical spark-induced explosion risks, and cabling problems, prohibiting the use of conventional electromagnetic accelerometers. The other benefit is its ability to measure both low- and high-amplitude vibrations with a constantly high resolution without pre-setting a gain level, as usually required in a conventional accelerometer. This benefit makes the sensor system particularly useful for real-time measurement of both ambient vibration (that is often used for structural health monitoring) and strong motion. This paper presents the prototype hardware and software development, characterization tests, and applications to real-time damage assessment, demonstrating the uniquely high performance of the Moiré fringe fiber optic sensor system.