Abstract
A Fiber Bragg Grating (FBG) interrogation system with a self-adaption threshold peak detection algorithm is proposed and experimentally demonstrated in this study. This system is composed of a field programmable gate array (FPGA) and advanced RISC machine (ARM) platform, tunable Fabry–Perot (F–P) filter and optical switch. To improve system resolution, the F–P filter was employed. As this filter is non-linear, this causes the shifting of central wavelengths with the deviation compensated by the parts of the circuit. Time-division multiplexing (TDM) of FBG sensors is achieved by an optical switch, with the system able to realize the combination of 256 FBG sensors. The wavelength scanning speed of 800 Hz can be achieved by a FPGA+ARM platform. In addition, a peak detection algorithm based on a self-adaption threshold is designed and the peak recognition rate is 100%. Experiments with different temperatures were conducted to demonstrate the effectiveness of the system. Four FBG sensors were examined in the thermal chamber without stress. When the temperature changed from 0 °C to 100 °C, the degree of linearity between central wavelengths and temperature was about 0.999 with the temperature sensitivity being 10 pm/°C. The static interrogation precision was able to reach 0.5 pm. Through the comparison of different peak detection algorithms and interrogation approaches, the system was verified to have an optimum comprehensive performance in terms of precision, capacity and speed.
Highlights
Due to their inherent advantages, such as high sensitivity, compact size, low cost and immunity to electromagnetic interference, Fiber Bragg Grating (FBG) sensors have been applied widely in the field of engineering [1], including railway traffic [2], monitoring of cardiac activity [3], fabricating of acceleration sensors [4,5], liquid level sensors for measuring aviation fuel levels [6], humidity sensors [7], strain sensors [8] and so on
A practical FBG interrogation system based on a field programmable gate array (FPGA)+advanced reduced instruction set computer (RISC) machine (ARM) platform, tunable F–P
To improve the practical accuracy of the system, we employed a F–P filter to overcome the low precision of a broadband light source
Summary
Due to their inherent advantages, such as high sensitivity, compact size, low cost and immunity to electromagnetic interference, FBG sensors have been applied widely in the field of engineering [1], including railway traffic [2], monitoring of cardiac activity [3], fabricating of acceleration sensors [4,5], liquid level sensors for measuring aviation fuel levels [6], humidity sensors [7], strain sensors [8] and so on. The interrogation techniques for FBG sensors have received increasing attention in recent years. The current research status of FBG interrogation may be summarized as follows: Roy utilized wavelength-modulated tunable distributed feedback lasers and a fiber-optic. Mach–Zehnder (M–Z) interferometer to realize low-cost, high-accuracy FBG interrogation [9]. Chen proposed a real-time interrogation system with wavelength division multiplexing (WDM) and frequency division multiplexing (FDM) for a large-scale fiber laser sensor array [10]. As many as 275 FBG sensors were interrogated, the final precision was only 3.6 με. Triana designed an interrogation system for multiplexing FBG networks based
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