Research Of High Capacity Fiber Bragg Grating Sensing Network Oriented To Application Of The Internet Of Things

Internet of Things is the network for information interaction of things through sensing network and computer network, it is applied in intelligent transportation, environment monitoring, government affairs, intelligent fire extinguishing, industry monitoring, food tracing et. al., and it is the information infrastructure in21st century. Sensing technology, information transmission technology and Intelligent information processing technology is the base of internet of things, so large capacity optical FBG sensing network is researched in this thesis orienting the demand of the sensor and sensing network for internet of things, aiming the deficiency of traditional fiber sensing network on system capacity and multi parameter measurement et. al..The main contents of this thesis include:(1) Theoretic analysis and simulation of large capacity FBG sensing network are researched, and the result shows that large capacity sensing network based on ultra low reflective FBG performs better.(2)OTDR(optical frequency domain reflectometor) sensing network based on Ultra low reflective FBG is designed and manufactured, online FBG array writing method is tried, and the function of the network is tested.(a) Experiment for testing its location function shows that the location will perform very well.(b) Experiment for testing its strain response shows that its strain response also performed well.(c) Experiment for testing its wave shift noise shows that a typical accuracy of0.02nm is gained, so the noise affects the wave measurement accuracy heavily.(d) Experiment for testing its measurement speed shows that, for the fire warning application, mono scanning time is within4s, so the system is fairly fast.(3)OFDR(optical frequency domain reflectometor) sensing network based on FBG is designed and manufactured, theoretic analysis and simulation is also done, and an optimized scheme is tested, the result of testing shows that the optimized sensor raised the useful bandwidth and effective scanning time, and improve the smoothness during the scanning.To combine the merit of OTDR and OFDR, a new scheme of distributed sensing system is designed.High capacity and multi-parameter FBG sensing network technology, automation, communication, data processing technology and bridge safety evaluation technology are applied on bridge engineering, and composed into internet of things to monitor critical parameters of safety situation, and the parameters are analyzed for traffic control, directing engineering decision and bridge maintaining.