Retargeting control of a multi-tethered satellite formation at sun-earth libration point

This paper investigates the nonlinear dynamics and control for three-dimensional retargeting maneuver of a flexible multi-tethered satellite formation at the sun-earth L-2 libration point. In Hill's problem, a fundamental modeling strategy is adopted to develop two dynamic models, a flexible one for dynamic simulation and a rigid one for control design. Both the flexibility of tethers and the attitude motions of satellites have been incorporated into the system dynamics. Not limited to the system under consideration, this flexible model could be generally exploited to describe multi-tethered satellite formation systems with arbitrary configurations. Besides, a nonlinear model-predictive control law for the retargeting problem of concern is developed to achieve the desired attitude of the system. The attitude control of the satellites is performed during retargeting process based on optimal control using a switching on-off method. For the ease of tracking an optimal trajectory of tether libration states and control input, an adaptive gain control law is proposed to retarget the flexible system. Finally, numerical case studies have been carried out to evaluate the dynamic behaviors of the system and to demonstrate the effectiveness of the proposed retargeting controller. (C) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.