Application of Local Observability Theory in the In-Flight Alignment of INS/GPS

Based on the study on the observability, the local observability theory has been used in INS/GPS integrated system, the condition number of local observability matrix in various maneuver modes have been computed, and the optimal maneuver mode has been found. It has been shown by the research results that, by means of implementing sine level maneuver flight, the local observability of the attitude errors can be increased, the flight alignment time can be reduced obviously, and the attitude errors can be cut down greatly. When the alignment time is about 120s,the mean values of attitude errors in the directions of east, north and up are 12.34″,12.19″,-28.31″,　and their standard deviations are 0.97″,1.05″,0.62″.