The Design And Research Of The Fiber Grating Demodulating System And Algorithm

To the Internet of Things and cloud computing as the representative of the information age is in a period of rapid development,the sensor as a device to receive outside information,the role is particularly important.Fiber Bragg Grating(FBG)is widely used as a new type of sensor technology in the monitoring of the structure of oil exploration,bridge,tunnel,structure and so on,as well as the monitoring of the structure of aeroengine and large machinery.Because the measured physical quantity of the sensor is corresponding to the shift amount of the center wavelength of the reflection spectrum,it is the key to monitor and find the peak point quickly and accurately in the actual project.It is also the core problem in the fiber grating sensing system.To this end,how to carry out high-speed,high-precision to find the peak point,this paper made the corresponding algorithm to improve,mainly for peak search algorithm and development platform for a detailed study and design.In the FBG data acquisition process,the fiber grating wavelength signal will have a large noise interference,resulting in fluctuations near the peak point,resulting in the asymmetry of the reflection spectrum.Aiming at the error of the peak finding algorithm caused by the asymmetry of the reflection spectrum of the fiber grating,an asymmetric Gaussian fitting peak finding algorithm based on FPGA state machine is proposed.The algorithm performs the filtering of the data through the mutual conversion between the state machines,and then introduces the asymmetric Gaussian model to give the peak compensation correction formula.Through the MATLAB simulation experiment,the following five kinds of peak search algorithms are compared and analyzed: direct comparison peak search algorithm,Gaussian fitting search algorithm,adaptive half-peak detection peak finding algorithm,based on Steger peak search algorithm and the proposed algorithm are The average error value of the peak value under constant temperature,and the average error value in the case of changing temperature and noise.The experimental results show that the accuracy of the algorithm can be controlled within 0.5 pm,and the velocity and stability have significant advantages compared with the above algorithm.The demodulation system designed in this paper is finally debugged and implemented based on the SoC FPGA platform.In the Quartus ? software integrated SoC design tool Qsys built to complete the required hardware module to add and related parameters of the configuration.In the embedded system development suite SoC EDS,the improved peak-finding algorithm is programmed on the basis of C++ programming language,and the demodulation system can complete the data preprocessing and peak-finding task.The system is stable.In Labview the results of the host computer show that the proposed SoC FPGA wavelength demodulation system design is feasible.