闭环光纤陀螺死区及光功率交扰误差的研究

摘要

数字闭环光纤陀螺引入的死区问题限制了其向更高性能惯性导航系统的应用.采用数学模型分析了数字闭环光纤陀螺死区的成因是反馈相关误差干扰,通过simulink仿真工具对死区现象进行了仿真,对比陀螺死区测试对模型进行了验证.以此为基础提出了电光合串扰造成死区的干扰模式,分析了干扰误差源的信号频域特征并使用频谱分析仪对受干扰的光功率信号进行了相关频点的测试,同时对比了干扰抑制后无死区的光功率信号相关频点的测试结果.通过抑制相关误差前后的测试结果对比,验证了与数字闭环反馈阶梯波相关的误差输入是死区形成的根本原因,除了电路交叉耦合之外,电路对光强的调制干扰也会造成死区问题.在采用针对干扰信号频率特性的退耦及PCB设计后,闭环光纤陀螺死区由0.2°/h降低至0.02°/h,满足系统应用需求.%The dead zone has severely influenced the application of the digital closed-loop fiber optic gyroscope (DCFOG) in high performance inertial navigation system.A mathematic model focusing on feedback related interence was established to analyze the dead zone in fiber optic gyroscope and was verified through FOG dead zone measurement of its simulation data by simulink.Based on this,an optical power interference model was proposed, and the frequency characteristic of the interference source analyzed and compared to the optic power affected.Further, an interfer suppressed PCB layout shows a much less coupling and dead zone.All measurement shows that the feedback phase step signal dependent error is the primary cause of the dead zone;besides the electric crosstalk,the phase step dependent modulation of optic power can also bring error to gyro signal processing and cause dead zone.After the targeted design of decoupling and error modulation, the dead band reduces from 0.2°/h to 0.02°/h, which meets the requirements of the application.