Formation keeping control through inter-satellite electromagnetic force

Satellite formation keeping through inter-satellite electromagnetic force provides an attractive alternative for future space missions due to its distinct advantages of no propellant consumption or plume contamination as compared to conventional ap- proaches. However, the internal force nature as well as the high nonlinearity and coupling of electromagnetic force brings new control challenges for this novel technique. In this paper, analysis on the dynamics characteristics and special control issues in the presence of electromagnetic force is carried out on the basis of the derived relatively translational dynamics. Considering the model uncertainties, external disturbances and sensor noise, a combined nonlinear control scheme involving feed-forward and feedback control components is proposed for electromagnetic-force-based formation keeping. The feed-forward compo- nent is directly obtained through desired configuration and dynamics under nominal conditions while the feedback component is realized utilizing active disturbance rejection control methodology with some reasonable improvement. Numerical simulation is presented to verify the feasibility and validity of the combined control scheme.