High precision dynamic model and control considering J2 perturbation for spacecraft hovering in low orbit

Abstract

For spacecraft hovering in low orbit, a high precision spacecraft relative dynamics model without any simplification and considering J2 perturbation is established in this paper. Using the derived model, open-loop control and closed-loop control are proposed respectively. Gauss's variation equations and the coordinate transformation method are combined to deal with the relative J2 perturbation between the two spacecraft. The sliding mode controller is adopted as the closed-loop controller for spacecraft hovering. To improve the control accuracy, the relative J2 perturbation is regarded as a known parameter term in the closed-loop controller. The external uncertainty perturbations except J2 perturbation are estimated by numerical difference method, and the boundary layer method is used to weaken the impact of chattering on the sliding mode controller. The open-loop control of spacecraft hovering with the relative J2 perturbation and without the relative J2 perturbation are simulated and compared, and the results prove that the accuracy of open-loop control with relative J2 perturbation has been significantly improved. Similarly, the simulation of the closed-loop control are presented to validate the effectiveness of the designed sliding mode controller, and the results demonstrate that the designed sliding mode controller including the derived relative J2 perturbation can guarantee the high accuracy and robustness of spacecraft hovering in long-term mission.