Approach to The Attitude Quaternion Updating Algorithm of Strapdown Inertial Navigation System

The algorithm to update the attitude quaternion of strapdown inertial navigation system is developed and updating the attitude quaternion is separately considered the rotation vector calculation.The quaternion at current step is calculated by using multi steps Adams-Moulton Method.Since this multi-step method cannot be self-started,so the first initial 3 steps are computed by single-step Heun's method.And also develop the quaternion algorithm error equation using calculated value of the predictor and corrector stage of attitude algorithm.From the numerical test result of coning motion,the algorithm is exactly normalized and the algorithm drift rate is reliable for low frequency motion.