A new polar alignment algorithm based on the Huber estimation filter with the aid of BeiDou Navigation Satellite System

Bin Zhao,Jianye Liu,Tianyu Zhao,Chunlei Gao,Qinghua Zeng

doi:10.1177/15501477211004115

Abstract

For aircrafts equipped with BeiDou Navigation Satellite System/Strapdown Inertial Navigation System integrated navigation system, BeiDou Navigation Satellite System information can be used to achieve autonomous alignment. However, due to the complex polar environment and multipath effect, BeiDou Navigation Satellite System measurement noise often exhibits a non-Gaussian distribution that will severely degrade the estimation accuracy of standard Kalman filter. To address this problem, a new polar alignment algorithm based on the Huber estimation filter is proposed in this article. Considering the special geographical conditions in the polar regions, the dynamic model and the measurement model of BeiDou Navigation Satellite System/Strapdown Inertial Navigation System integrated alignment system in the grid frame are derived in this article. The BeiDou Navigation Satellite System measurement noise characteristics in the polar regions are analyzed and heavy-tailed characteristics are simulated, respectively. Since the estimation accuracy of standard Kalman filter can be severely degraded under non-Gaussian noise, a Kalman filter based on the Huber estimation is designed combining grid navigation system and generalized maximum likelihood estimation. The simulation and experiment results demonstrate that the proposed algorithm has better robustness under non-Gaussian noise, and it is effective in the polar regions. By employing the proposed algorithm, the rapidity and accuracy of the alignment process can be improved.

Highlights

The polar regions are becoming more and more important for all mankind, and the polar flight ability is of great significance.[1,2,3] The lack of high-precision navigation is one of the most prominent problems in polar navigation
Where fG is the misalignment angle in G frame and f_G represents the derivation of fG; dvG is the velocity error in G frame and dv_G represents the derivation of dvG; viG is the angular velocity of G frame relative to i frame, and vGiG is the projection of viG on G frame; Cv can be expressed as
As shown in the simulation and experiment results, the new polar alignment algorithm based on the Huber estimation filter proposed in this article is much superior to that based on the Kalman filter

Summary

Introduction

The polar regions are becoming more and more important for all mankind, and the polar flight ability is of great significance.[1,2,3] The lack of high-precision navigation is one of the most prominent problems in polar navigation. One is that the traditional north-oriented frame will lose effectiveness because of the rapid convergence of meridians.[10] The other is that the stationary base alignment cannot be achieved due to the decrease of the horizontal component of rotational angular velocity of the earth. BDS can provide navigation services independently in the polar regions.[19] In recent years, BDS/SINS integrated navigation system is increasingly used in many fields due to their integrated performance outweighs the drawbacks of the individual systems.[6,20,21] For aircrafts equipped with BDS/SINS integrated navigation system, BDS information can be used to initialize SINS and achieve autonomous alignment. The main contribution of this article is to analyze the BDS measurement noise characteristics in the polar regions and to propose a Kalman filter based on the Huber estimation combining grid navigation system and generalized maximum likelihood estimation.

À cos2Lsin2l

Tg ebr wbr

Findings

Discussion