Initial Alignment of SINS with Large Misalignment Errors Using Unscented Kalman Filter

The feature of propagate of large misalignment of strapdown inertial navigation system is nonlinear.In order to improve initial alignment algorithm of SINS with large misalignment,this article proposes a method based on Unscented Kalman Filter.Under the assumptions of the additive noises in both state process and measurement process and the linear measurement mode,the simplified Unscented Kalman Filter(UKF) is presented for the SINS initial alignment model of AQE with large misalignment.The method of multiple feedbacks to SINS with the UKF state estimates is proposed to increase the alignment accuracy in the process of initial alignment.The simulation results demonstrate that the SINS initial alignment can be accomplish aided by GPS,even if azimuth of error reaches 20°,and using three precision alignment,the high alignment accuracy is available.