Research On Flexible 3D Shape Sensing System And Key Technologies Based On FBG

The technology of variable configuration aircraft is the frontier of world aviation science and technology.The key to deformation control is flexible skin shape monitoring,but for the existing traditional methods,for example,electric sensors and other non-contact measurement technologies which have lots of problems,such as electromagnetic interference,non-active monitoring,non-real-time monitoring and other problems to be solved.In order to solve these problems,the key technology of multi-core fiber Bragg grating shape sensing is studied in this paper.The main research contents are as follows:1.Based on the strain sensing mechanism of Fiber Bragg Grating(FBG),a mathematical model of strain spatial curvature is established,and the reconstruct ion of the space surface is simplified to a curve reconstruction step by step.The measurement of spatial curvature is completed based on FBG sensor,and the reconstruction and monitoring of the surface are realized.2.Based on the photosensitivity of fib er,the grating formation mechanism of FBG is analyzed,and the similarities and differences between multi-core fiber and single core fiber in the fabrication of FBG are compared.The writing platform of multi-core FBG sensor is designed and built,and cores of multi-core fiber monitoring and rotation device are added to complete the writing of multi-core FBG.For the layout of the multi-core grating core,in order to be able to demodulate the sensing signal on each core,R-soft simulation software is used to simulate the model field distribution of multi-core fiber fan in / fan out device in theory.3.Multichannel signal demodulation method based on multi-core fiber grating.According to the geometric structure of flexible skin and the characteristics of three-dimensional deformation,and the wavelength division multiplexing method of fiber grating sensing,a multi-core fiber optic three-dimensional shape sensing network structure and a high-speed data transmission method are established for flexible skin deformation sensing.According to the performance requirement of multi-core optical fiber three-dimensional flexible sensor for the tunable light source,the principle of signal demodulation based on optical frequency domain reflection method is studied,the signal distortion and correction algorithm in a high-speed acquisition is studied,and a high-speed demodulation method for multi-core optical fiber three-dimensional shape sensor network is established.At the same time,a modified calibration method which can reduce the influence of package error is proposed.4.The experiment of flexible skin shape sensing is carried out.The standard curvature calibration plate is used to measure the curvature of the multi-core fiber grating sensor.Through the flexible sensing method based on the multi-core fiber grating proposed in this paper,the three-dimensional shape fitting and reconstruction experiments of three specific flexible skin structures are carried out,including the soft silicone skin,the polyimide film skin and a soft manipulator based on 3D printing technology.generally,the strain curvature sensing mechanism of FBG,the grating mechanism of multi-core FBG,the field distribution of fan-in/fan-out of multi-core fiber are theoretically analyzed.The mathematical model of surface reconstruction and the manufacturing platform of multi-core FBG are established,and the 3D shape reconstruction based on multi-core FBG was realized.