Model predictive control-based coupled orbit-attitude control for solar sail formation flying in the Earth-Moon system

This paper investigates the problem of coupled orbit-attitude control for solar sail formation flying where the leader follows a solar-sail resonant halo orbit in the Earth-Moon system, whereas the follower is controlled to track a predefined reference relative trajectory around the leader. Taking the reflectivity control devices (RCDs) as joined orbit and attitude control actuators, their force and torque models are first established for a spinning solar sail. In particular, the saturation and coupling of the control variables for the coupled orbit-attitude control are focused. Then the orbit and attitude dynamics of the spinning solar sail are discussed and the equations of relative orbit-attitude motion are given. Furthermore, constraints on the relative attitude angles between the sails and their rates of change are considered for the attitude control. Together with the optimal switch regulations of RCDs, the problem addressed in this paper is essentially a problem of constrained optimal coupled orbit-attitude control. Therefore, the framework of model predictive control (MPC) technique is applied to deal with this problem by solving a convex quadratic programming problem subject to linear constraints. Finally, illustrative scenarios are simulated to show the effectiveness and controllability of the proposed coupled orbit-attitude controller.