抖动偏频激光陀螺整周期采样对捷联惯导姿态解算的影响

Influence Analysis of Dithered Laser Gyro Whole Cycle Sampling Demodulation on SINS Attitude Computation Accuracy

抖动偏频激光捷联惯导系统中,三个激光陀螺之间机械抖动频率一般互不相同.当陀螺输出采用整周期锁存方式时,导航计算机定时采样系统采集到的三个陀螺信号,隐含着陀螺输出的不同步,在捷联惯导解算中将产生姿态解算的不可交换误差,在圆锥运动环境下误差更加严重.介绍了整周期采样时陀螺输出的不同步现象,在圆锥运动条件下对不同步问题进行仿真,仿真结果表明不同步是引起姿态解算误差的主要因素,不同步误差远远超过同步采样条件下的姿态解算误差,因此在捷联惯导系统角运动剧烈时应当予以重视.

In dithered laser gyro strapdown inertial navigation system(LSINS), the mechanical dither frequencies of three laser gyros are always different form each other. Using dithered laser gyro whole cycle sampling demodulation method, the angular data sampled by navigation computer timing sample system imply that the outputs of the three laser gyros are asynchronous, hence noncommutative error occurs in LSINS attitude updating algorithm. The error becomes even worse under coning motion environment. The asynchronous behave of laser gyro outputs is introduced and analysed. Under coning motion circumstance, some simulations are carried out. The simulation results show that the laser gyro asynchronous sampling error plays an important part in LSINS attitude updating algorithm. The attitude updating error by asynchronous sampling method is far greater than that of ideal sampling method. Conclusion is drawn that more attention must be paid to LSINS sampling demodulation in high angular dynamic environment.