光纤陀螺偏振态耦合的热损伤机理与在线补偿控制研究

The polarization state of light signal inside the fiber optic gyroscope susceptible to stress, deformation, distortion, temperature and other factors, the fiber component defect, causing polarization mode coupling, the accuracy and reliability of the FOG is affected severely by the phenomena of noise, signal drift, signal attenuation. The project studies on the mechanism of thermal damage and real-time fuzzy compensation method. The multi-scale analysis method with operator custom-design wavelet finite element is put forward. the method can meet the damage singularity. The thermal damage model of the coupled polarization state FOG and the system mathematical model are established. The stress-strain caused by the thermal damage of FOG's polarization state coupling is gained exactly. According to FOG various system parameters, the dynamic models of the thermal damage FOG polarization states coupled is built. Frequency characteristics and dynamic response of FOG is analysed exactly. Fuzzy sliding mode control rule is used to adaptive compensation and control the system parameter perturbation and external disturbance. FOG fuzzy adaptive dynamic model is proposed to predict the amount of error, access to real-time compensation. Study the wavelet basis optimization method based on the characteristics of the fiber optic gyro output signal, propose adaptive threshold filtering algorithm online real-time filtering method based on wavelet transform, achieve FOG output signal line real-time analysis and fuzzy compensation.

光纤陀螺内部光信号的偏振态易受到应力、形变、扭曲、温度和光纤成分缺陷等因素的影响，引起偏振态模式耦合，表现为噪声、信号漂移、信号衰减等现象，对光纤陀螺的精度和可靠性产生严重的影响。本项目将研究光纤陀螺偏振态耦合热损伤机理与实时模糊补偿方法，提出满足损伤奇异性的算子自定义小波有限元多尺度分析方法，建立光纤陀螺偏振态耦合的热损伤模型，精确求解光纤陀螺偏振态耦合的热损伤引起的应力应变。根据光纤陀螺的各系统参数指标，建立光纤陀螺偏振态耦合模糊动态模型，精确分析光纤陀螺频率特性、动态响应等，并采用模糊滑模控制律对系统参数扰动和外界干扰进行自适应补偿控制，提出光纤陀螺模糊自适应动态模型误差量的预测方法，获得实时补偿量。研究基于光纤陀螺输出信号特性的小波基优化选择方法，提出基于小波变换的自适应阈值滤波算法的在线实时滤波方法，实现光纤陀螺输出信号的在线实时分析与模糊补偿。

光纤陀螺由于其工作机理及外部环境的干扰，使其内部产生不稳定、不均匀的应力场、温度场以及应力和温度的耦合场，在光纤陀螺输出信号中表现为漂移和噪声，严重影响光纤陀螺的精度和可靠性。本项目在以前研究的基础上，从三个方面进行了更深入的研究：一、研究有限元多尺度分析的方法，并在此基础上对光纤陀螺系统进行结构设计和热设计，分析光纤陀螺的内部应力场、温度场和耦合场，为优化设计方案提供依据；经过分析可知光纤陀螺的光纤线圈的偏振态对应力和温度最为敏感，项目对光纤线圈进行了设计、分析和实验，从设计机理和工艺装配两方面减小或消除环境作用下光纤陀螺的噪声和漂移。二、为了减小光纤陀螺的漂移误差，项目通过把带有可调参数的伸缩器引入模糊自适应控制器，设计了高精度、快速响应，适合光纤陀螺误差特性的控制方法；设计了四态调制的数字闭环控制方法，对光纤陀螺的漂移误差进行精确地跟踪和补偿。三、为了减小光纤陀螺的噪声，项目设计了ASE光源，并通过实验验证了光源参数的稳定性；设计了基于小波变换的自适应滤波算法，引入了滑动数据窗消除了小波变化实时性差的限制，并与无限冲击响应相结合，在光纤陀螺动静态测试中，均能获得良好的滤波效果。