Study of Dynamic Stability and Control of Electrodynamic Tether for a Larger Spacecraft Reboost

The dynamics analysis and libration suppression of an electrodynamic tether in circular orbits for a large spacecraft reboost are studied. The system is described by a dumbbell model that consists of two end-bodies, which are connected by one straight, massive and inextensible tether. A hybrid control methodology for the motion of electrodynamic tether system is synthesized to diminish the libration motions of the system. The tether current and thrust moment are used and regulated to remain stability of the libration motions and to boost the altitude of orbit continuously. Bellman’s dynamic programming is adopted to firstly develop linear regulators in linearized model, which are capable of damping out the in-planar and out-of-planar motions of the system, the regulators are then applied to the nonlinear system. The optimal control and quasi-optimal control are used for eliminating out-of-plane motion under different orbital inclinations. The results indicate that the quasi-optimal control methodologies have good performance in energy saving of total impulse. The results of simulation are shown to verify the successful of the devised control laws.