Improved strong tracking UKF and its application in INS/GPS integrated navigation
HU Gao-g · Journal of Chinese Inertial Technology · 2014
The performance of the standard UKF would be degraded when the system states are abnormal due to the absence of capability to adapt itself to the changing conditions. This paper presents an improved strong tracking UKF(ISTUKF) to overcome the limitation of the standard UKF. The hypothesis testing method is employed in the ISTUKF to identify the abnormal system states, and in case they occur, the suboptimal fading factors are introduced into the prediction covariance to adaptively adjust the Kalman gain matrix to realize the strong tracking of the real state. Compared with the traditional strong tracking UKF, the proposed ISTUKF avoids the cumbersome evaluation of Jacobian matrices involved in the calculation of the suboptimal fading factors, making it more applicable. The proposed ISTUKF is applied to the INS/GPS integrated system for simulation in comparison with the standard UKF. The simulation results demonstrate that the position errors in east and north obtained by the ISTUKF with single suboptimal fading factor are within [-13.7 m, 14.9 m], and the corresponding errors obtained by the ISTUKF with multiple suboptimal fading factors are within [-10.0 m, 12.1 m]. The performance of the proposed ISTUKF is significantly superior to that of the standard UKF, leading to improved position precision.