Derivative ratio attitude solution algorithm of tri-orthogonal magnetic sensor for spinning projectile

Abstract The tri-orthogonal geomagnetic attitude measurement model of a spinning projectile cannot be directly solved by a numerical method; therefore, it is usually in an auxiliary status in the attitude measurement system. In addition, a coning motion appears during the actual flight process of the spinning projectile. This is often ignored in conventional geomagnetic attitude measurements. To improve practicability, a tri-orthogonal geomagnetic attitude measurement model under the condition of coning motion was established, and a derivative ratio algorithm was proposed. The attitude angle errors from the coning motion were analyzed and corrected. The simulation and experimental results show that relatively accurate attitude angles can be obtained by the algorithm using only the outputs of the tri-orthogonal magnetic sensor. The algorithm is simple and efficient and is suitable for the actual measurement of the attitude angle for a high-dynamic-spinning projectile.