惯导系统大方位失准角下的初始对准探讨

Study on the Initial Alignment of INS Under Large Heading Uncertainty

从惯导系统任意方位失准角度下的ψ角误差方程出发,详细推导了静基座条件下惯导系统大方位失准角度的Φ角误差方程。利用此Φ角误差方程,分析了大方位失准角度情况下与小方位失准角度情况下初始对准过程的异同,指出了这两种情况下水平回路的误差传播过程类似,因而其水平对准方法也一样;而方位对准回路则区别较大,北向和东向速度误差均能够与大方位失准角耦合。由此提出了一种改进的方位罗经自对准方案,此方案对于任意的方位失准角度均能正确收敛到零。改进后的方案已经在某四频激光陀螺惯性导航系统上得到实际的验证和应用,有效保证了恶劣环境下惯导系统方位对准的可靠性。

Error equation of φ-angle on stationary base are deduced under large heading uncertainty, according to the error equations of φ-angle under arbitrary heading misalignment of inertial navigation system. Differences between initial alignments under large heading uncertainty and under small heading uncertainty are analyzed by using the φ-angle error equations. It is pointed out that the level alignments under the two situations are identical due to the similar error propagations of level loops, while the azimuth alignments differ greatly due to the coupling of north and east velocity with the large heading uncertainty. A modified azimuth gyroscopic self alignment scheme is proposed, under which alignment error can converge to zero for arbitrary azimuth misalignment angles. Application of the modified scheme on an INS of four-mode differential laser gyros proves its validity and reliability in the azimuth alignment under rough environment.