Autonomous Integrity Monitoring of INS/GPS Integrated Navigation System under Multipath Environment

Inertial navigation solution when fused with GPS solution will result into highly accurate hybrid/integrated navigation solution. Unfortunately, when the aircrafts of landing/take-off in urban environments or on table top runways, the hybrid solution suffer huge disturbance of GPS multipath error. The problems of multipath are often reported on several ground vehicles also. The present paper proposed an integrated navigation solution with detection of multipath error which got introduced in some of measurements of GPS receiver. Further, the effect of this on hybrid navigation solution is studied and detailed analysis is presented. Polynomial kalman filter (PKF) based error detection mechanism is studied and simulation results are presented. The method uses position and velocity information as measurements in identification of GPS multipath error at the early stages, so that the solution of hybrid navigation system will not get degraded with erroneous measurements from GPS receiver. Large errors for reinitialization of hybrid navigation during GPS outages are addressed through gross error check followed by polynomial kalman filter in addition to regular Extended kalman filter (EKF) of INS+GPS integration scheme. The proposed method of detection of multi path error in an aircraft application is demonstrated through simulation test results for a typical aircraft trajectory.