Design Of Fiber Grating Sensing Signal Demodulation System Based On ARM

In recent years, as a novel sensing optical fiber technology, Fiber Bragg Grating (FBG) sensor has become a very hot research topic. The FBG is widely used in large-scale civil engineering, aerospace industry, power industry and other industry fields. Moreover, it is playing an increasingly prominent role in scientific research and engineering applications.The Key issue of FBG is how to accurately detect the small deviations from the FBG center wavelength. Conventional detection methods use optical instruments to complete. However, it is very expensive and lack of the enough compactness. Therefore, it is not suitable for practical engineering applications. Although some other types of demodulation can solve partial problems, but they are still very slow, without multiple interfaces and lack of various functionalities. They cannot meet the system requirements of speed and accuracy. Hence, developing a FBG sensor signal demodulation system with high-precision, high resolution, high performance and low-cost could be a urgent research direction. What’s more, it should accurately measure multiple points too. In this thesis, an ARM-based signal demodulation of fiber grating sensor system is proposed by using embedded system technology, which has practical significance and academic value.In this paper, we firstly review the research background by introducing coupled mode theories, sensing principles and related technical indicators of FBG. Then, several common demodulation methods are compared. In the following section, a tunable based Fabry-Perot filter FBG sensor system is highlighted. Finally, we give a brief introduction about embedded system components, such as embedded processors, peripherals and operating systems, the design of the application development process, μC/OS-Ⅱ operating system migration conditions and the main tasks.The hardware of the system is built based on ARM920T and S3C2440A micro-processor core with power and reset circuit, memory circuit, a serial circuit, USB modules and JTAG interface as the external circuit. In software design, we used Lab VIEW and MATLAB to produce a FBG sensor demodulation signal which includes noise. We propose a signal processing pipeline which based on the data collection, filtering, peak-detection, fitting and positioning. The main study is focused on filtering and fitting. On the basis of transplanting μC/OS-Ⅱ system to S3C2440A microprocessor, we successfully compile and debug every part of the system in software and hardware, respectively. Experimental results show that the design of fiber grating sensing signal demodulation system based on ARM is feasible, the theory is correct and the method is effective.