Airborne Weapon Ins / Gps Integrated Navigation System Moving Base Initial Alignment Method

Guided by the INS/GPS integrated navigation system, weapons can achieve high accuracy and low costs. The transfer alignment is usually used in the inertial system of the aircraft carried weapons. If the information of the INS/GPS integrate navigation system were fully used, the alignment does not need the information transferred by the aircraft. And the INS/GPS will become an absolutely independent navigation system.The alignment of the INS/GPS gives the INS computer the initial conditions to calculate the navigate information, and estimates the initial errors to correct the results. As small quantity, the error model of the INS can be considered as a linear time variant system. The initial states can be estimated only if the system is observable. For the INS/GPS error model, if the velocity errors can be measured by the information of the GPS, the observable degree of the vertical platform angle error become great enough to estimate the misalignments, when the aircraft have horizontal acceleration. So the aircraft must have horizontal maneuver during the alignment of the INS/GPS.Without the information transferred by the aircraft, the initial attitude errors would be so large that they become the main errors of the inertial navigation system. In a short period, the platform angle errors are constants, and can be estimated by the least squares estimation (LSE) method. By judge the solvability of the LSE equations, the data can be select which are measured during the maneuver period. Then the estimation can be stable and accurate.The simulation results of the INS/GPS alignment proved the LSE method is available. High accuracy can be achieved by it.