Initial alignment algorithm for SINS based on quaternion Kalman filter

An anti-disturbance initial alignment algorithm for swing-base strapdown inertial navigation system(SINS) is presented,and the essential of the proposed approach is attitude determination(AD) using vector observations.It is easy to show that the apparent gravity expressed within an Inertial Space forms a cone whose main axis is the rotational axis of the earth.So,by the examination of gravity movement,the true heading can be found.Employing the gravity vector projective relation with the initial attitude-quaternion,the linear pseudo-measurement equation is built up.The initial attitude-quaternion is a constant parameter and the quaternion kinematics equation is linear and precise.The above characteristics yield a linear KF that eliminates the usual linearization procedure and is less sensitive to initial estimation errors.The turntable rocking simulation experiments are carried out which demonstrates the efficiency of the quaternion filter.