Linear parameter-varying gain-scheduled attitude controller for an on-orbit servicing mission involving flexible large spacecraft and fuel sloshing

In this paper, a comprehensive methodology is presented for modeling an on-orbit servicing (OOS) mission scenario and designing a gain-scheduled feedback control system that can robustly meet performance requirements. This methodology accounts for uncertainties in the model, as well as significant changes in inertia and flexibility throughout the mission scenario. To capture the dynamics and interactions of all subsystems in the OOS scenario, a single linear fractional representation (LFR) was developed for the uncertain plant, taking into account the varying geometrical configuration of a robotic arm, flexible appendages and sloshing dynamics. The controller design considers the interactions between subsystems and uncertainties, as well as the time-varying and coupled flexible dynamics. Finally, the paper evaluates the robust stability and worst-case performances of the closed-loop system using a structured singular value analysis.