Research On Theory And Key Technology Of Intelligent Fiber Sensor Network

Recently,fiber sensor plays an irreplaceable role in so many areas because of its unique advantages.It has characteristics as follows:large bandwidth,low transmission loss,small volume and light weight,which gives fiber sensors the ability to form a network sensing in large areas and extreme environments,such as aerospace,bridge,tunnel and oil tank,based on its sensing principle and network topology.The intelligence of fiber sensor network reflects on following aspects: automatic control of the sensor network,self-diagnosis and self-healing function when failures happen.So far,the research on fiber sensor network is mainly about specific type of sensor and few kinds of topology,besides self-diagnosis and self-healing is also a problem.Network needs to accomplish the functions of self-diagnosis and self-healing to ensure the sensors keep working when failures happen.So it is important to carry out a research on intelligent fiber sensor network.This paper includes the following several aspects:1.To analyze the robustness of several basic network topologies and to propose two calculation methods to express the intrinsic robustness T value of simple topology and evaluate the weighted average robustness of fiber sensor network separately.We obtain the factors affecting the robustness of sensor network by simulating a failure probability of fiber sensor,adjusting the amount of redundant fibers,different combinations of parameters.All analysis above lays the foundation of theoretical basis of optimizing the structure for the fiber sensor network.2.To propose a fiber sensor network with self-diagnosis function,the network can locate the failure site by calculating the changes of the light intensity detected by PD array.There are no active devices in the network.We explain the working principle of this network,discuss the affects to the network as well as the corresponding relations between the failure site and the change of intensity when failures happen.In experiment,we validate the feasibility and validity of the network.3.Design a multi-bus intelligent fiber sensor network with the function of self-diagnosis and self-healing function.The network works under the control of master and slave nodes,multiplexing distributed and other types of fiber sensors with the automatic self-diagnosis and self-healing function.At the meantime,operators can control the network by sending commands to the embedded chip in the master node from the upper computer with automatic alarming.The control nodes include several modules: signal sending and receiving circuits,optical switch control and signal processing modules.Besides,we have to design the communication protocol between nodes as well as the human-machine interface.In the experiment,we multiplex the distributed fiber sensor DMZI,OFDR and FBG sensor to verify the feasibility of the network.4.Then we propose a multi-ring fiber sensor network topology which has more efficient control and stronger robustness compared with the bus topology.And we make a hybrid fiber sensor by multiplexing a distributed fiber sensor and a FBG in one common fiber sensing temperature and vibrations at the same time,the experimental results proves its feasibility.