A quaternion-based initial orientation estimation system suitable for one special dynamic state: Using low cost magnetometer and accelerometer

This work presents a new method for estimating the initial orientation of one micro air vehicle (MAV) whose navigation system is powered in a dynamic condition, using low cost three-axis magnetometer and three-axis accelerometer. Although the earth's magnetic field offers a steady reference vector to determine the attitude, only one vector is insufficient to get accurate values. To solve this problem, the variation of the MAV's acceleration is added to the reference vector. And our focus is on how to combine the direction of magnetic field and acceleration into an entirety effectively, and use this method in a special dynamic state, parachuting. The challenge is that the whole estimation process must be accomplished in dynamic state and there is no external calibration information. Thus, advanced Gauss-Newton is adopted to improve the efficiency, and a model of parachuting is built to describe the variation of acceleration. The results of simple simulation on computer and experiment show that the method has a good performance in a simple surrounding.