Measurement discarding strategy for GNSS/IMU integration

In conventional GNSS/IMU(global navigation satellite system/inertial measurement unit) integration,the updating frequency is constant and measurements are used to execute updates when they are received.As a result,the integration accuracy is vulnerable to measurement degradation caused by GNSS signal outages.This paper presents a double-threshold measurement discarding strategy,which monitors both the state estimation and the measurement quality.Measurements will be discarded and the integrated system will work in the INS(inertial navigation system) mode alone when the state estimation is accurate enough or the measurements are less accurate.Real data tests and simulations confirm that the measurement discard strategy using EKF(extended Kalman filtering) has better navigation performance in measurement degradation situations.