Pulsar navigation for interplanetary missions using CV model and ASUKF

To improve the navigation performance with the pulsar direction error and the clock error, X-ray pulsar navigation for interplanetary missions is proposed. We analyze the clock error and the system bias caused by the pulsar direction error, and find that the system bias is large but the bias' variation velocity and the clock frequency error within a short time can be viewed as constants. Thus, both the bias and clock error can be modeled as the constant velocity (CV) model, and the augmented state unscented Kalman filter (ASUKF) is utilized here to deal with them and estimate the spacecraft's positions. The simulation results demonstrate that the proposed method can improve the navigation accuracy in the presence of the clock error and the pulsar direction error. (C) 2011 Elsevier Masson SAS. All rights reserved.