Modeling and control of an Earth observation satellite equipped with a spinning flexible antenna

Modern satellites often incorporate complex configurations to meet the increasing demands of Earth observation missions. This study focuses on the dynamic modeling and control of an Earth observation satellite featuring a large, rotating antenna mounted on two flexible booms with a deployable reflector. While the antenna’s rotation significantly expands the scanned area and boosts mission performance, it also introduces complexities in the spacecraft's dynamics, primarily due to inertial loads and coupling effects with the attitude motion. These interactions lead to periodic and steady-state deformations that can degrade observation quality. To address these challenges, the dynamic equations of the multibody spacecraft, including solar panels, are derived using Kane's formulation. The antenna’s flexibility is modeled through modal shapes obtained from finite element analysis (FEM). The proposed model is validated through numerical simulations and comparison with the MSC Adams multibody code, emphasizing the importance of accurately capturing rigid-flexible coupled dynamics to ensure optimal mission performance. The spacecraft’s attitude is controlled via momentum exchange devices that implement a nonlinear feedback control law. The numerical results of an attitude reorientation and nadir-pointing tracking simulation provide indications on the performance of the operational scenario.