基于EM算法的组合导航系统容错方法

A Fault-Tolerance Method for Integrated Navigation System Based on EM Algorithm

针对SINS/GPS组合导航系统中,GPS提供的量测信号存在容易受到干扰而导致滤波精度下降的问题,提出一种基于EM算法的组合导航系统容错方法。该方法对各个分量的量测噪声建立二维高斯混合模型,并引入一个指示变量表示量测值从异常分布中采样的概率。根据系统状态方程、上一时刻状态估计值以及当前时刻测量值,利用EM算法求解当前时刻量测真值的极大似然估计,并结合序贯滤波算法对每一个分量的量测值进行精细检测与修正。车载实验表明,该方法能够有效提高SINS/GPS组合导航系统在GPS信号异常情况下的融合精度与可靠性。

In the SINS/GPS integrated navigation system,the measurement signals provided by GPS are easily disturbed,which leads to the degradation of filtering accuracy.To solve this problem,a fault-tolerance method for the integrated navigation system based on EM algorithm is proposed.By establishing a two-dimensional Gaussian mixture model for each component of the measurement noise,an indicator variable is introduced to indicate the probability of measurement value sampling from abnormal distribution.Based on the state equation of the system,the state estimate of the last moment and the measurement value of the current moment,the EM algorithm is utilized to calculate the maximum likelihood estimate of the true measurement at the current moment.Besides,the sequential filtering algorithm is applied to finely detect and correct the measurement value of each component.Experiment aboard cars shows that the proposed method can effectively improve the fusion accuracy and reliability of the SINS/GPS integrated navigation system in the case of GPS signal anomaly.