光纤光栅解调系统和数据处理方法的理论与实验研究

【作者】 滕峰成；

【导师】 吴惕华； 李志全；

【作者基本信息】 燕山大学 ， 控制理论与控制工程， 2007， 博士

【摘要】 随着光纤传感技术的发展,光纤光栅传感器以其抗电磁干扰、耐腐蚀、高绝缘性、测量范围广、便于复用成网、可以解决许多传统传感器无法解决的问题等优点,在土木工程、航空航天、石油化工、电力、医疗、船舶工业等领域取得了广泛应用,成为传感领域内发展较快的技术之一。本文主要对光纤光栅传感解调系统与数据处理方法进行了理论和实验研究,具体内容如下:从光纤光栅的传输理论出发,对光纤光栅的轴向应变特性、温度特性、交叉敏感特性进行了详细的理论分析,推证了相应的传感模型。根据光栅横向受力分布情况,分别对横向均匀受力和非均匀受力情况下的反射谱变化状态进行了讨论,从中提取出反映外部信号的反射谱特征信息量,并研究了该特征信息量与传感量之间的关系。根据高双折射光纤的扭转特性和光纤光栅的耦合特性,提出了高双折射光纤光栅的耦合模型,分析了其反射谱特性与扭转角度关系,并应用传输矩阵的方法进行了验证。对由2×2和3×3耦合器构成M-Z干涉仪进行光纤光栅波长解调的方法进行了研究,建立了相关的系统传感模型,进行了相关的理论分析,设计了解调系统的相关光路、电路。结合本系统的具体情况在对传统相位展开技术进行分析研究的基础上提出了一种改进的快速相位展开的方法,运用所提出解调方案和相位展开方法对振动解调系统的几种典型状态特性进行了分析研究。将由2×2和3×3耦合器构成M-Z干涉仪进行光纤光栅波长解调的方法分别与可调谐F-P滤波器技术和连续波调频技术相结合,设计了相应的分布式光纤光栅振动传感网络系统。基于遗传算法的基本原理和光纤光栅传感理论,针对光纤光栅在不同条件下的反射谱变化特性,系统的分析研究了遗传算法在光纤光栅传感系统中的应用方法。建立了相关的传感系统数学模型,确立了与遗传算法相对应的目标函数及个体适应度的评估策略,研究对算法的改进与修正措施,分析了各参数对算法的影响关系,对于光纤光栅轴向应变传感系统利用遗传算法实现了波长解调,对于光纤光栅横向受力传感系统利用遗传算法通过谱型寻优实现了应力测量。构造了光纤光栅特性分析实验系统、振动解调实验系统和遗传算法应用研究实验系统,设计了相应的硬件电路、数据采集处理和分析软件。应用所设计的系统分别对光纤光栅横向受力和扭转特性,基于2×2和3×3耦合器的单光栅自由振动解调,基于2×2和3×3耦合器和F-P滤波器技术的光纤光栅振动解调,基于2×2和3×3耦合器和FMCW技术的光纤光栅振动解调,光纤光栅轴向应变遗传算法解调和光纤光栅横向均匀受力遗传算法谱型分析进行了实验研究。更多还原

【Abstract】 With the development of optical sensor technology, fiber Bragg grating (FBG) sensor has the advantages of resistance to electromagnetic interference, corrosion resistance, excellent insulation, wide measuring range, easy for multiplexing, solving problems that other sensors can’t solve, etc, these sensors as one of the faster-developing technology are widely applied in the field of civil engineering, aerospace, petrochemicals, electric power, medical treatment, shipbuilding industry, and so on. In this dissertation, theoretical and experimental studies on FBG sensing demodulation system and data processing method were carried out, which specifically includes:Embark on the transmission of FBG, the detailed theoretical analysis was carried out based on the axial strain characteristic, temperature characteristic and cross-sensitivity characteristic, and the corresponding mathematical model were derived. According to the distribution of transverse force, the dissertation discussed the spectra changing state under transverse uniform force and inhomogeneous force respectively, distills feature information volume which reflects external signals, and studies the relation between the feature information volume and sensing volume. Based on the characteristic twisted HiBi fiber and coupled mold theory of FBG, the coupled equation of twisted HiBi fiber grating was proposed, the relation between spectra response and twist angle was analyzed and proved by transfer matrix method.The FBG wavelength demodulation method with M-Z interferometer constituted of 2×2 and 3×3 couplers is studied, the interrelation system sensing model is established and the correlative theoretical analysis was carried on. The optical path and electro circuit related with demodulation system is designed. On the basis of traditional phase-unwrapping technique combined with the particular condition, a fast phase-unwrapping method is proposed. Several typical state characteristics of vibration demodulation system are analyzed and studied using the proposed demodulation scheme and phase-unwrapping method. The FBG wavelength demodulation method with M-Z interferometer constituted of 2×2 and 3×3 couplers was combined with tunable F-P filter technique and frequency continuous wave (FMCW) technique respectively, and the corresponding distributed FBG vibration sensing network is designed.Based on the basic principle of GA and FBG theory, considering the characteristics of FBG’s reflected spectrum under the difference condition, the application method of GA in FBG sensing system was systemic analyzed and studied. The relevant mathematical model of sensing system was established, and the objective function and individual fitness evaluation policy interrelated with GA were also established. The improvement and correction measurement to GA were analyzed, and the effects of each parameter on GA were analyzed. The wavelength demodulation can been realized using GA in FBG axial strain sensing system, and the stress measuring using GA in FBG sensing system under transverse force through spectra optimizing.The experimental system of characteristic analysis on FBG, vibration and GA’s application study was constructed, and the corresponding hardware electro circuit and software of the date acquisition, processing and analysis were designed. Using the designed system, we respectively on the experimentally study on the characteristic of FBG under transverse force and torsion, the free vibration demodulation of signal FBG based on 2×2 and 3×3 couplers, the vibration of FBG based on 2×2 and 3×3 couplers and F-P filter technique, the vibration of FBG based on 2×2 and 3×3 couplers and FMCW technique, the demodulation of FBG under axial strain using GA, and the spectra analysis of FBG under transverse uniform force using GA.更多还原