Research On The Adjustable Range Draw-wire Type Fiber Bragg Grating Displacement Senser

Displacement measurement is widely used and it is one of the most basic testing techniques.In order to solve the problem of displacement monitoring in complex electromagnetic environment,an adjustable range pull rope type fiber Prague grating displacement sensor based on the FBG strain characteristic is designed in this paper.The displacement sensor has the characteristics of adjustable range,high precision and flexible measuring method.And it solves the problem of cross sensitivity of fiber grating to temperature and stress.The main contents of this paper are as follows:Firstly,the research history of fiber grating is introduced in this paper.Then the structure of several kinds of displacement sensors is discussed.The development status of fiber Bragg grating displacement sensor is deeply studied,and the working principle and distinguishing feature of several kinds of fiber Bragg grating displacement sensors are analyzed.Secondly,the sensing mechanism of FBG is analyzed by using the mode coupling theory,and the temperature and strain characteristics of FBG are studied.Based on the analysis of the advantages and disadvantages of different demodulation methods,the demodulation method used in the demodulation system is determined.Thirdly,a kind of fiber Prague grating displacement sensor is designed,and the structure and working principle of the displacement sensor are analyzed.The performance of the displacement sensor is verified by experiments.Based on the measured data,the static working parameters and temperature coefficients of the displacement sensor are analyzed and calculated.Finally,combining with the demodulation method of fiber Bragg grating,the fiber Bragg grating demodulation system based on a fiber Fabry-Perot tunable filter(FFP-TF)demodulation method is established.The STM32 control program and the host computer program based on MFC are compiled.And it realizes the function of serial communication between STM32 and PC.The host computer program can display the real-time displacement measurement data and draw the curve of displacement.