Research On Transfer Alignment Technology For The Strapdown Inertial Navigation System On Moving Base

With the development of precision attack and anti-satellite technology, strapdown inertial navigation system (SINS) has been widely applied to various tactical missiles because of its simple structure, low cost and auto-navigation capacity. Initial alignment is one of the key-techs in inertial navigation. The duration and the misalignment of the transfer alignment will determine the preparation period and the navigation precision the missile can reach in flight. Using the information of the calibrated aircraft INS to calibrate another INS on board the missile is the main initial alignment approach for air-launching missiles. Based on various classical transfer alignment models, the paper mainly deals with the methods of SINS on air-launching missiles and focuses its study on the following aspects.1. The paper analyzes the dynamics equations of the inertial navigation system and Psi-angle error model which suits the transfer alignment of SINS.2. The paper further studies the compensation of lever-arm effect error, the influence of wing flexure in the output of inertial instruments, and the modeling of gyro drift and accelerometer bias.3. The paper designs a simulation of the velocity matching under the conditions of five typical flight maneuver models. The simulation results show that the estimated precision of misalignment angle depends on what maneuvering is taken. In addition, the paper also simulates the angular rate matching under wingrock maneuver model and then compares the simulation results with the improved attitude change matching method. The comparison shows that, at the same noise level, the attitude change matching is better than the angular rate matching in terms of estimated precision of misalignment angles.4. Since single matching method has its disadvantage, the paper suggests a combined matching method, which is more rapid and efficient for transfer alignment. Accordingly, the paper simulates three combined-parameter matching methods under wingrock maneuver, namely, the velocity plus attitude matching, the velocity plus attitude matching and the specific plus angular rate matching. By comparison, the paper concludes that the velocity plus attitude matching method is the most effective and has the most practical value as transfer alignment approach for air-launching missiles.