Research On Demodulation And Localization Based On Fiber Grating Sensing System

With the rapid development of social economy,sensor technology is widely used in all aspects of social life.Fiber Bragg Grating(FBG)is the fastest growing and most widely used sensor in the field of optical Fiber sensing.It has the advantages of low optical signal transmission loss,suitable for harsh environment,strong multiplexing capability,etc.,therefore,it is widely used in aerospace,energy and chemical industry,Electric Power Monitoring,construction engineering and structural health monitoring and other fields.In order to solve the problem of accurately locating the damage location of material structure in engineering,the multi-point monitoring of engineering health condition is needed in large-scale engineering,a Fiber Bragg grating sensor network location monitoring system is designed to monitor the location of material and structure damage in engineering applications.Based on the in-depth understanding of fiber grating sensing technology at home and abroad,this paper studies the sensing principle of fiber grating,compares various fiber grating demodulation technologies and their respective advantages and limitations,for practical feasibility and engineering applicability Considering the considerations,the tunable F-P filter demodulation method is finally selected as the demodulation method in this article,and the overall demodulation scheme of the distributed fiber grating sensing system is determined.The signal processing part is an important part of the sensor demodulation system.Aiming at the noise processing problem of the acquisition signal part of the fiber grating sensor demodulation system,an improved wavelet threshold denoising method is used to decompose and reproduce the acquired sensor signal.Structure to achieve the purpose of denoising.Simulation verification shows that the method not only overcomes the discontinuity of the hard threshold function itself,but also avoids the inherent deviation problem of the soft threshold function,improves the signal reconstruction accuracy,and achieves the expected effect on the sensor signal preprocessing.Aiming at the problem of identifying the damage location of material structures in engineering applications,this paper proposes a fiber grating sensor network positioning method based on RSSI weighted centroid.This method takes the material structure damage plate as a model.Under the impact load,the center wavelength of the fiber grating drifts.The change of the center wavelength is demodulated to obtain the response signal intensity of the impact point.The final impact point is obtained through weighted fusion calculation and regional positioning.coordinate.Finally,a fiber Bragg grating sensor demodulation network location monitoring system is constructed,and the impact location method of distributed FBG sensor network based on weighted center of mass(RSSI)is used to test the structural damage impact model.The results show that the location method of FBG sensing demodulation system can accurately identify the impact damage location,and the location monitoring effect is obvious,which provides a reference for the structural damage location measurement in engineering application.