Enhanced LG-EKF Backtracking Framework for Body-velocity-aided Vehicular Integrated Navigation

High accuracy in-motion alignment and integrated navigation with assistant of body-velocity is a nonlinear state estimation problem as existence of attitude. The Extended Kalman filter (EKF) is a frequently used tool but criticized for its inconsistency problem especially with large initial misalignment angle, which hinders the improvement of navigation accuracy. This paper proposes a backtracking in-motion alignment framework using enhanced Lie group (LG-EKF-w) to replace troublesome EKF. The LG-EKF-w captures the nature of 3-dimension rigid body motion, which guarantees the inconsistency and improves the accuracy of state estimation. Land and sea field experiments evaluates the performance of LG-EKF-w compared to EKF, state transformation extended Kalman filter (ST-EKF) and LG-EKF-i. The results show that LG-EKF-w has faster initial alignment speed compared to EKF and better positioning accuracy under badly aligned conditions.