Influence analysis of dithered laser gyro whole cycle sampling demodulation on SINS attitude computation accuracy

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.