Displaced solar orbits for spacecraft propelled by electric sails are investigated. Since the propulsive thrust is induced by the sail\nattitude, the orbital and attitude dynamics of electric-sail-based spacecraft are coupled and required to be investigated together.\nHowever, the coupled dynamics and control of electric sails have not been discussed in most published literatures. In this paper, the\nequilibriumpoint of the coupled dynamical system in displaced orbit is obtained, and its stability is analyzed through a linearization.\nThe results of stability analysis show that only some of the orbits aremarginally stable. For unstable displaced orbits, linear quadratic\nregulator is employed to control the coupled attitude-orbit system. Numerical simulations show that the proposed strategy can\ncontrol the coupled system and a small torque can stabilize both the attitude and orbit. In order to generate the control force and\ntorque, the voltage distribution problem is studied in an optimal framework. The numerical results show that the control force and\ntorque of electric sail can be realized by adjusting the voltage distribution of charged tethers.
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