谐振式光纤陀螺频率跟踪失锁控制研究

Out-of-Lock Frequency-Tracking Control of Resonant Fiber-Optic Gyro

针对目前谐振式光纤陀螺中存在的跟踪失锁问题开展研究,分析了频率跟踪失锁原因及机理,研究表明频率跟踪同步过程中的电流变化以及背向散射、偏振耦合等非互易性噪声引起的谐振峰对称性改变是导致尖峰脉冲和零偏变化的主要原因;随后,提出了基于半导体激光器温度闭环反馈的失锁控制方案,通过温度闭环实现激光器中心频率对光纤谐振腔单个谐振频率的长期跟踪同步,消除频率跟踪失锁引入的陀螺输出误差;对失锁控制总体技术方案、信号处理流程及实现方法进行了详细叙述;最后,成功搭建陀螺原理样机,对采用频率跟踪失锁方案前后的陀螺静态性能进行实验测试,测试表明频率跟踪失锁控制方案将陀螺输出脉冲幅值突变量从3000(°)/h降低到200(°)/h,陀螺输出零偏变化从600(°)/h降低到0,完全消除了频率二次锁定过程中的零位变化,陀螺精度大幅降低到4.9(°)/h(100 s平滑积分时间)。

Herein,we study the out-of-lock frequency-tracking problem in a resonant fiber-optic gyro(RFOG).First,we analyze the reason and mechanism of out-of-lock frequency tracking,and find that the change of the current in frequency-tracking synchronization and the symmetry change caused by non-reciprocal noises,such as backscatter and polarization coupling,are the main reasons for the peak pulse and zero-bias change,respectively.Second,we propose a scheme for out-of-lock frequency-tracking control of the RFOG based on temperature closed-loop feedback of the semiconductor laser.The long-term tracking synchronization of the laser central frequency with the fiber resonator′s single-resonant frequency can be realized by temperature closed-loop control;thus,the gyro output error caused by out-of-lock frequency tracking is eliminated.The overall technical scheme,signal processing flow,and implementation method of out-of-lock control are described in detail.Finally,we construct a successful RFOG prototype and test the static performance of the RFOG both before and after implementing the out-of-lock control.The test results show that this out-of-lock frequency-tracking control scheme can reduce the output pulse amplitude mutation of the RFOG from 3000(°)/h to 200(°)/h and the output zero-bias change of the RFOG from 600(°)/h to 0(°)/h,which completely eliminates the zero-position change in the frequency secondary locking process;consequently,the gyro precision is significantly reduced to 4.9(°)/h(for 100-s smooth integration time).