A Fast SINS Initial Alignment Scheme for Underwater Vehicle Applications

TLDR

High‑accuracy, rapid SINS alignment remains a challenge for underwater vehicles. The paper proposes a DVL‑aided SINS initial alignment scheme to achieve rapid, accurate alignment. The scheme employs DVL velocity for coarse alignment, a backtracking framework for fine alignment using recorded data, and an inertial‑reference‑frame model to reduce data volume, enabling real‑time application. The method improves alignment accuracy and meets the alignment requirements for underwater vehicles.

Abstract

To achieve high Strapdown Inertial Navigation System (SINS) alignment accuracy within a short period of time is still a challenging issue for underwater vehicles. In this paper, a new SINS initial alignment scheme aided by the velocity derived from Doppler Velocity Log (DVL) is proposed to solve this problem. In the stage of the coarse alignment, the velocity of DVL is employed to reduce the impact of the linear motion. With a backtracking framework, the fine alignment runs with the data recorded during the process of the coarse alignment and thus will speed up the overall alignment process. In addition, by using this new scheme, it is equivalent to length the alignment time for both coarse and fine alignments, so the accuracy of the alignments will be improved. In order to reduce the volume of the data that has to be recorded, a new model for SINS fine alignment is derived in the inertial reference frame which makes it feasible for real time applications. The experimental results are presented for both unaided static and in-motion alignment using DVL aiding. It is clearly shown that the proposed method meets the requirement of SINS alignment for underwater vehicles.