A New Initial Alignment Scheme for Dual-Axis Rotational Inertial Navigation System

Dual-axis rotational inertial navigation system could improve navigation performance by modulating the inertial sensor errors with rotatable gimbals. The accuracy of the system is directly affected by the initial alignment accuracy. Benefit from the dual-axis transposition mechanism, the initial alignment accuracy is improved effectively by rotating inertial measurement unit (IMU) during the alignment process. In this article, a six-position alignment scheme based on dual-axis rotation is proposed. The novel initial alignment scheme is designed to suppress the influence of IMU errors on initial alignment accuracy, especially the alignment accuracy of azimuth. A new initial alignment algorithm for dual-axis rotation alignment is redesigned in this article to solve the problem of azimuth error divergence caused by traditional alignment algorithm when IMU rotates around the horizontal axis. The alignment scheme and algorithm proposed in this article are verified by simulation and experiment.