基于衍射光栅的高速光纤光栅解调系统的研究

发布时间：2018-07-16 19:08

【摘要】：光纤光栅传感及解调技术已经成为检测技术领域研究的一大重点。目前国内外已经推出了基于不同解决方案的解调产品，但是这些产品多以静态解调仪器为主，解调速度并不高，结构复杂且价格昂贵，高速高精度的解调系统是未来的发展趋势。本课题以衍射光栅式的光纤光栅解调技术为基础，开展了高速光纤光栅解调系统的研究，介绍了光纤光栅解调系统的结构和衍射光栅的工作原理。提出了一种利用IBSEN I-MON系列衍射光栅模块，采用FPGA(现场可编程门阵列)构建光纤光栅解调系统。该系统充分利用FPGA可以进行并行运算，可定制化的优点，实现了光纤光栅信号的高速高精度解调。本课题设计了解调系统的硬件电路，包括FPGA最小系统电路，ADC采集电路，DM9000以太网传输电路，光开关切换电路，温度补偿电路，电源电路。编写了相应的嵌入式数据处理和控制程序，并利用Labview构建上位机数据接收和显示软件，实现数据采集、解调、传输、显示及存储功能。研究了光纤光栅传感系统波长解调算法，针对高速解调的需求，在分析了光纤光栅传感器波长信号特点的基础上，提出了改进型高斯拟合算法，在不影响精度的同时，有效地减小了曲线拟合的计算量。同时算法中涉及的最小二乘问题采用适合于硬件实现的Cholesky矩阵分解求解法。通过实验验证了改进型高斯拟合算法在光纤光栅信号解调中可靠有效。该光纤光栅解调系统解调精度可达1pm，，单通道解调速度最高2kHz，取得了良好的预期效果。
[Abstract]:Fiber grating sensing and demodulation technology has become a major research focus in the field of detection technology. At present, demodulation products based on different solutions have been introduced at home and abroad, but most of these products are static demodulation instruments, the demodulation speed is not high, the structure is complex and the price is expensive. High speed and high precision demodulation system is the development trend in the future. Based on the fiber grating demodulation technology of diffraction grating, the research of high speed fiber grating demodulation system is carried out. The structure of fiber grating demodulation system and the working principle of diffraction grating are introduced. A fiber grating demodulation system using IBSEN I-MON series diffraction grating module and FPGA (Field Programmable Gate Array) is proposed. The system makes full use of the advantages of parallel operation and customizability of FPGA to realize high speed and high precision demodulation of fiber Bragg grating signal. The hardware circuit of demodulation system is designed, including FPGA minimum system circuit, ADC acquisition circuit, optical switch switching circuit, temperature compensation circuit and power supply circuit. The corresponding embedded data processing and control program is written, and the upper computer data receiving and displaying software is constructed by LabVIEW to realize the functions of data acquisition, demodulation, transmission, display and storage. The wavelength demodulation algorithm of fiber Bragg grating sensor system is studied. According to the demand of high speed demodulation, an improved Gao Si fitting algorithm is proposed on the basis of analyzing the characteristics of wavelength signal of fiber grating sensor, which does not affect the precision at the same time. The calculation amount of curve fitting is reduced effectively. At the same time, the least squares problem is solved by Cholesky matrix decomposition method, which is suitable for hardware implementation. The experimental results show that the improved Gao Si fitting algorithm is reliable and effective in fiber grating signal demodulation. The demodulation accuracy of the fiber grating demodulation system can reach 1 pm, and the single channel demodulation speed is the highest 2 kHz.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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