基于改进 EMD 方法的 FBG 传感网络光谱基线校正研究

针对光纤布拉格光栅(FBG)传感网络中，由于环境条件导致的光谱信号基线漂移问题，本文提出一种基于改进经验模态分解(EMD)的光谱信号校正方法。用该方法对仿真数据处理，处理后光谱可通过设置阈值划分出各FBG反射峰区，验证了改进EMD方法的可行性。通过实验采集在光纤通路损耗及端面反射影响下、产生基线漂移情况的FBG传感网络光谱信号，并使用改进EMD法、小波软阈值法和惩罚最小二乘法进行实时的光谱校正处理，运用高斯非线性拟合法计算正常和校正后光谱的各FBG中心波长。结果显示，运用改进EMD法校正后计算的各FBG中心波长，传感信号存活率分别提高48.9%和61.6%,平均偏差和偏差标准差最小，分别为4.33、6.28和6.01、6.58 pm。该方法校正后的光谱信号能为物理量检测提供可靠信息。

Research on spectral baseline correction of FBG sensor network based on the improved EMD method

The baseline of the fiber Bragg grating (FBG) sensor network spectrum signal drifts, which is caused by the environmental conditions. To address this issue, this study proposes a spectrum baseline correction method based on the improved empirical mode decomposition (EMD). When this method is used to process simulation data, the spectrum after processing can be divided into the reflection peak regions of each FBG by setting the threshold value. The feasibility of the improved EMD method is verified. The spectral signals of the FBG sensor network with baseline drift under the influence of optical fiber path loss and end reflection are collected by experiments. The improved EMD method, the wavelet soft threshold method and the penalty least square method are used to achieve the real-time correction of the spectrum. The Gaussian nonlinear fitting method calculates the center wavelength of each FBG of the normal and corrected spectra. Results show that the survival rates of the sensing signal are increased by 48. 9% and 61. 6% , with the average deviation and deviation of each FBG center wavelength calculated after the use of the improved EMD method. The standard deviation values are the smallest, which are 4. 33, 6. 28 and 6. 01, 6. 58 pm. The spectral signal corrected by this method could provide reliable information for physical quantity detection.