Comparison of direct navigation mode and indirect navigation mode for integrated SINS/GPS

Abstract

The integrated strapdown inertial navigation system/global position system (SINS/GPS) is a widely used procedure for position, velocity and attitude determination. There are two options for the state estimation procedure by a filtering system model and the integration filter, namely direct navigation mode that estimates the navigation parameters and indirect navigation mode that estimates the error of navigation parameters with a feedback calculation process. To a certain extent, they both have their own advantages. However, determining which one of the two navigation modes will be more celebrated than the other under different conditions is a beneficial but thus far less seriously treated issue. In this study, two navigation modes are systematically studied in terms of the filtering system model, filtering algorithm and application issues. The simulation test and car-mounted experiments for low-precision and high-precision SINS are carried out to compare the performance of two navigation modes under different conditions. The results prove that direct navigation mode outperforms indirect navigation mode in terms of estimation accuracy and stability for poor conditions, but for good conditions, the advantages of direct navigation mode are compromised due to the large computational burden. Therefore, this study is also expected to facilitate the selection of the appropriate navigation model in practice under different conditions.