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传统捷联惯性导航系统单位置初始对准系统不完全可观测,不可观测的东向陀螺零偏造成航向估计的主要误差。双位置初始对准可以改善系统的可观测性,但一般需要精确的转位机构,不便于工程应用。该文提出一种基于北向陀螺零偏自观测的双位置初始对准方法,只需陀螺载体在近似水平的任意两个位置停留片刻,从第1位置提取北向陀螺零偏信息传递给第2位置作为观测量,即可提高东向陀螺零偏的可观测度并提高航向对准精度。为了寻找最优转角,提出一种全面可观测度分析方法,将可观测度细分为表征不同条件下同一状态可观测程度的相对可观测度和表征状态收敛速度的可观测阶两部分,利用相对可观测度分析得出最佳转角为±90°,并进行了仿真实验验证。实测实验结果表明:相比于单位置对准,双位置对准将航向误差由0.268°降低到0.041°,并可估计出水平陀螺零偏。
The initial alignment system of the traditional strapdown inertial navigation system (Inertial Navigation System) is not completely observable. The unobservable eastward gyro bias causes the main error of heading estimation. Initial alignment of dual position can improve the observability of the system, but usually requires accurate indexing mechanism, which is not convenient for engineering application. In this paper, a dual-position initial alignment method based on zero-bias gyro bias is proposed. The gyro carrier only needs to stay for a moment at any two positions in the approximate horizontal position, extract the northward gyro zero bias information from the first position and transfer it to the second position As the observational quantity, the observability of the east gyro zero bias can be increased and the heading alignment accuracy can be improved. In order to find the optimal rotation angle, a comprehensive observability analysis method is proposed. Observables are subdivided into two parts: the relative observability which characterizes the observability of the same state under different conditions and the observable order that characterizes the state convergence rate. The relative observability analysis shows that the best angle of rotation is ± 90 °, and the simulation experiment is carried out. The experimental results show that compared with the single-position alignment, the dual-position alignment reduces the heading error from 0.268 ° to 0.041 ° and estimates the horizontal gyro bias.