Motion Prediction of a Free-Floating Noncooperative Target Considering J2 Perturbation

Motion prediction of space noncooperative target is an important issue for spacecraft on-orbit service. After obtaining high-precision motion prediction results, the chaser can efficiently plan a motion trajectory to approach the target and then capture it. In this paper, a motion prediction method considering J2 perturbation is proposed for a free-floating noncooperative target. The core idea of this method is to identify dynamic parameters of the target, and then realize the motion prediction through a dynamic model of the target that considering J2 perturbation. In the identification of the dynamic parameters, inertia parameters of the target are preliminarily identified first, then a noise-adaptive unscented Kalman filter (UKF) is applied to roughly identify the dynamic parameters, and finally, the identification precision is further improved through optimization. At the end of this paper, the significance of considering J2 perturbation is demonstrated by numerical simulations, and the effectiveness of the proposed method is verified. Simulation results indicate that J2 perturbation has a great influence on the motion prediction of the target and that the proposed method can yield long-time high-precision motion prediction results. Specifically, under the simulation conditions of this paper, the predicted time obtained by the proposed method is longer than 200 s, and the errors of the motion prediction results of the target's attitude and position are less than 2 deg and 0.02 m, respectively.