In response to the challenge of diminished accuracy in integrated navigation for smartphones due to satellite signal interference in complex environments,this article proposes a robust extended Kalman filter enhanced by fault recovery.Firstly,this method uses equivalent weight factors to adjust observation weights in real-time,effectively reducing the impact of gross errors on combination navigation accuracy.Considering the low redundancy of observations in smartphone-based loosely-coupled navigation,this algorithm divides the detection range into three segments for fault-free,bias,and anomalies.In the absence of faults,no further processing is undertaken.When a deviation occurs,the observation value is reduced in weight.For anomalies,the predicted innovation is used to repair the fault amplitude and correct the observation value.Practical experimental results show that when a satellite experiences a single-epoch fault,the robust filter method can effectively improve the positioning accuracy of the smartphone PDR/GNSS combination navigation.The maximum error in the north direction is reduced from 7.27 m to 3.20 m,and the maximum position error in the east direction is reduced from 24.01 m to 6.60 m.In the case of multiple-epoch consecutive faults in GNSS positions,the proposed fault recovery-enhanced robust filter method shows an average reduction of over 50％in positioning error compared to the classical robust filter method.
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