外场标定条件下捷联惯导系统误差状态可观测性分析

Observability analysis for error states of SINS under outer field conditions

为了适应惯导系统的长期稳定使用和避免从机组上拆装的麻烦,实现惯组的外场标定是非常有意义的。在不依赖转台等设备的条件下,分析了仅依靠速度误差和位置误差信息时激光陀螺捷联惯组的误差参数的可观测性问题。首先从外场条件下系统误差的动态方程出发分析了捷联惯组的误差状态(姿态误差以及陀螺和加速度计的六个常值漂移)的可观测性并且进一步分析了误差状态估计的收敛速度以及受观测噪声的影响程度。分析表明,单一位置条件下在没有精确初始姿态误差信息的情况下惯性仪表零偏是不可观测的,为了较精确地估计出惯组的误差系数需至少将惯组摆放三个位置。最后对理论分析结果进行了仿真验证。

To adapt the long-term usage and avoid the dismounting troublesome, it is of great importance to implement outer field calibration for inertial navigation system. The paper analyzed the observability of the error states for the laser gyro strapdown inertial navigation system （SINS）. First, it analyzed the observability of the error states （attitude errors and bias errors of the inertial instruments） based on the dynamic equations of the system. Then it discussed the convergence rate of the states and the effects of the measuring noise. The analyses show that the bias errors of the instruments are not observable in one position if the accurate initial attitude errors are not obtained. In order to estimate the bias errors, the system should be set on at least three different positions. At last, the simulations are made which prove the analysis results.