提高高精度光纤陀螺磁场适应性的方法研究

Research on method of improving magnetic field adaptability of high-precision IFOG

光纤环在磁场中产生磁致非互异性误差,成为制约高精度干涉型光纤陀螺(以下简称高精度光纤陀螺)应用的主要因素之一,而误差与磁场强度、光纤扭转率有关。由于光纤扭转导致的光纤环磁场灵敏度达到10 (°)·h^(-1)·Gs^(-1)以上,即使采用坡莫合金对磁场屏蔽,屏蔽效能仅能达到30 dB左右,难以满足高精度光纤陀螺的应用需求。文中通过等效电路模型和有限元仿真分析了屏蔽材料连接缝隙对屏蔽效能的影响,通过公式计算了扭转率对磁场灵敏度的影响。根据分析,提出了将屏蔽材料由螺钉连接改为激光焊接并对光纤进行退扭的改进方法。通过光纤退扭,光纤环磁场灵敏度降低了89.3%;通过对连接缝隙激光焊接,屏蔽效能由31 dB提高到64 dB以上,磁场灵敏度由0.026 5 (°)·h^(-1)·Gs^(-1)降低到了0.000 4 (°)·h^(-1)·Gs^(-1)以下,且变温环境下陀螺零偏稳定性提高了7.5%以上。改进措施能够提高光纤环在磁场和温度环境下的精度,满足高精度光纤陀螺性能要求。

The magnetic non-reciprocity error of fiber coil is one of the main factors that restrict the application of high-precision IFOG,and the error is related to the strength of magnetic field and the twist rate of fiber.The magnetic field sensitivity of fiber coil is more than 10(°)·h^(-1)·Gs^(-1)due to the twisting of the fiber,even if permalloy is used to shield the magnetic field,the shielding effectiveness can only reach about 30 dB,which cannot meet the requirements of high-precision IFOG.The influence of the connection gap between shielding materials on shielding effectiveness was analysed by an equivalent circuit model and finite element simulation,the influence of the twist rate on the magnetic field sensitivity was deduced by formula.Through these analyses,the improvements were proposed that changed the connection of shielding materials from screw connection to laser welding and made the fiber de-twist.Through the measurement of fiber de-twist,the magnetic field sensitivity of the fiber coil was reduced by 89.3%;Through the improvement of laser welding,the shielding effectiveness was improved from 31 dB to at least 64 dB,the magnetic field sensitivity was reduced from 0.0265(°)·h^(-1)·Gs^(-1)to less than 0.0004(°)·h^(-1)·Gs^(-1),and the bias stability of the IFOG in different temperature was improved by more than 7.5%.These improvements can improve the precision of the fiber coil in the magnetic field and temperature environment,meeting the performance requirement of high-precision IFOG.