指数修正高斯拟合寻峰算法处理FBG传感信号

Processing FBG Sensing Signals with Exponent Modified Gaussian Curve Fitting Peak Detection Method

光纤布拉格光栅(FBG)传感系统因其检测精度高、重复性好和适应性强等优点而被广泛应用于不同领域。由于FBG传感器为波长调制型传感器,因此对于外界参量的检测即为FBG中心波长的检测,而FBG中心波长值对应于FBG反射光谱的峰值。因此,系统解调的核心即为FBG反射光谱的峰值检测,而高精度的寻峰算法是系统解调的关键技术。现有的寻峰算法对FBG反射谱进行峰值检测时,都是以FBG反射谱为标准高斯型为前提的。但由于实际制作工艺及环境的影响,FBG反射光谱并不是标准高斯型光谱,而是非对称的高斯型光谱,其非对称特性往往会对寻峰精度有一定的影响。针对现有算法这一缺陷,提出了一种指数修正高斯(EMG)拟合寻峰算法。利用三次判定定位实现粗定位,同时剔除假峰和无效峰值;在此基础上以粗定位点为中心进行光谱重构,再利用积分判定峰值偏向;然后根据不同的峰值偏向以给定的指数修正函数进行相应的峰值修正。实验仿真结果表明:定温条件下或变温条件下,与直接寻峰算法、高斯拟合算法和文献中的算法相比,EMG算法的峰值检测误差最小,寻峰精度提高。考虑了FBG反射光谱非对称特性对寻峰的影响,从光谱自身特性的角度,既克服了传统寻峰算法的局限性,又保证了高精度的寻峰效果。

The system based on Fiber Bragg Grating（FBG）sensor is used in various fields,because of its advantages of high detection accuracy,good repeatability and adaptability.While the FBG sensor is a wavelength modulation type sensor,so the outside parameter detection is the center wavelength of FBG detection.At the same time,the FBG center wavelength corresponding to the peak value of the FBG reflection spectrum.Therefore,the core of demodulation system is the demodulation of FBG reflection spectrum during peak-seeking,and the high-precision peak detecting algorithm is the key technology of the system demodulation.The current peak detecting algorithms has a precondition for peak detection on FBG reflective spectrum,that the FBG reflective spectrum was a standard Gaussian model.But FBG reflective spectrum is not a standard Gaussian spectrum owing to the practical manufacture process and the individual environment;actually,it is an asymmetrical Gaussian spectrum.The experiment would achieve a lower accuracy because of this asymmetric property during peak-seeking.Based on the defect of the existing algorithm,an Exponent Modified Gaussian（EMG）Curve Fitting peak detecting algorithm is proposed in this paper.In the proposed algorithm,the coarse location was first determined by three times judgments and it can remove the false peak and peak invalid at the same time.Based on this,as the center of the coarse localization point to reconstruct the spectrum,and using the integral to judge the peak bias;then according to different peak bias,it revised the peak by the prepared exponential modified function.Simulation results show that at normal temperature or under variable temperature conditions,by comparing with direct peak searching algorithm,Gaussian fitting algorithm and the algorithm proposed by literature,the error of EMG peak detection algorithm is the minimum and high peak detecting precision.The algorithm proposed in this paper considers the FBG reflection spectrum characteristic of asymmetric effect.From its spectrum character,the EMG algorithm solves the problem of the limits of traditional peak detecting algorithm,meanwhile also guarantees a high-precision peak search results.