Shape Perception And Reconstruction For Flexible Plate Structure Based On Discrete Orthogonal FBG Network

Large plate-like structure is widely used in industrial fields, especially in the field of aerospace engineering, such as solar panels of the space station, the wing of the fixed wing aircraft, antenna array of large phased array radar for spacecraft. Plate-like structure is consisted of light structural materials, with large area, low stiffness, low vibration damping, low resonance frequencies and intensive modals. While it needs holding high precision in the continuous working condition, and has a strict technical requirements for shape maitaining. However, the above characteristics can easily lead to morphology changes and intense low-frequency vibration for the space environment and disturbances. In addition, conventional monitoring methods are difficult to adapt to the morphology of the above-mentioned technical requirements. Therefore, a new form of real-time monitoring method for structural reliability is essential to the security and maintenance of safety. Currently, smart surface structure based on distributed FBG(Fiber Bragg Grating) sensor network is an important research direction to solve the above problems. The basic idea of this method is to obtain structural information by optimizing the layout of the morphological changes of FBG sensor network, real-time perception and shape reconstruction is finished on the basis of surface reconstruction algorithm. Non-visual shape perception methods are applied to achieve real-time monitoring of large flexible structures. Therefore, the relevant technical methods of exploration and research have important scientific value, innovative and application prospects.This paper is supported by National Natural Science Foundation. FBG intelligent flexible plate-like structure is the research object. To fulfill the requirements of active real-time sensing and reconstruction for structure shape changing, an optimized discrete FBG sensor network was built to realize real-time shape perception and reconstruction visualization. On basis of in-depth study and implementation of technology exploration, experimental structural model and the experimental platform were built for experimental analysis and verification. Theoretical methods and key technologies involved: dynamic analysis for experiment structural model, FBG sensor network configuration and layout optimization method, space surface reconstruction based on modal displacement superposition, space surface reconstruction based on orthogonal curve network, structural shape reconstruction effect evaluation, sensor calibration method, structurevisualization technology morphological reconstruction; FBG sensor network design, the experimental structure model design and production, experimental platform, monitoring system software and hardware development.The main contents can be summarized as shape reconstruction method based on structural shape, FBG sensor network optimization layout and design, remodeling effect and accuracy assessment methods, experimental platform and hardware and software development, laboratory analysis and verification. The main research work and contributions done by paper are as follows:(1) Based on the principle of FBG sensing principle, transformed relationship between the measured grating wavelength and strain is obtained. The distributed information about the discrete orthogonal strain of the plate is achieved. The structural orthogonal curvature information is obtained by studying the inherent relationship between curvature and strain on discrete measurement points. Surface curvature continuity is achieved on the orthogonal directions by studying the interpolation processing methods of curvature data. Based on the above research and related technological achievements, a set of distributed discrete strain and curvature information data acquisition and processing system is constructed.(2) Modal approach is studied for surface reconstruction, focusing on the solution method for strain displacement transformation matrix for structural reconstruction. Surface reconstruction method based on orthogonal curvilinear algorithm is studied, focusing on orthogonal recursive methods and geometric method of curvilinear motion coordinate system. Respectively, for the two plate shape reconstruction algorithm and related simulation analysis and verification, including operations efficiency, reconstruction effect of static deformations and dynamic quantitative analysis, is carried out and the feasibility and effectiveness of the algorithms for shape reconstruction are verified which provides basic theoretical and experimental basis.(3) Experimental models are constructed for the structure dynamics analysis, while the number of FBG sensors is studied based on the FBG sensing principle. What’s more, combined with the structural characteristics of shape and surface reconstruction algorithms, sensor network layout optimization criteria and constraints is explored, and then determine the FBG sensor network optimization objective function. The basic principles of particle swarm optimizationalgorithm and technology methods is studied to explore the multi-objective optimization methods for the design and production of FBG sensor network.(4) Research static characteristic data analysis methods on the effect of the shape reconstruction algorithm is studied focusing on the calculating methods based on the comprehensive evaluation method for reconstruction precision error and a method for a single point of variance. The shape reconstruction effects of structural dynamic characteristic is studied focusing on the method of dynamic precision evaluation base on LMS algorithm, by constructing FIR filter model and solving channel model parameters to obtain the parameters of signal amplitude attenuation characteristic, phase delay and noise doping, and the results show that the relevant methods have a precise evaluation results.(5) FBG sensor packaging and calibration technology is researched to implement the design of the FBG sensor network; the experimental model is designed and created; high-precision automatic measuring system is developed; a real-time visualization software system for shape reconstruction is developed. A high-precision, high-performance platform for experiments is built by integrating the above hardware and software equipment, which provides technical support for exploring relevant theory.(6) For the exploration of the theory methods and techniques, experimental verification and analysis is carried on. The Experimental results show that the flexible plate reconstruction method base on orthogonal discrete FBG sensor network is practicable, and the static deformation and low frequency vibration modes shape changes can be reconstructed exactly. In addition, the structural shape reconstruction has vivid visual effects, and achieves the desired research objectives.