Modeling and control of multi-stage spacecraft with turntable and active pointing ultra-quiet platform

Constellation communication requires directing communication payloads toward other satellites or switching between multiple satellites, necessitating that satellites possess ultra-high Agility, Stability, and Precision Control (ASPC) and wide-range payload pointing tracking capabilities. However, spacecraft with conventional configurations struggle to simultaneously meet the demands of ASPC and wide-ranging payload pointing control. The maneuverability metrics, including speed and acceleration, are also limited by the capabilities of the onboard attitude control actuators. To address these limitations, an innovative multi-stage pointing control system for spacecraft is proposed in this study, which integrates a two-dimensional turntable with an Active Pointing Ultra-Quiet Platform (PQP). Initially, the dynamics of this multi-stage system are rigorously modeled, leading to the proposition of a multi-stage pointing control structure with separate controllers for each stage. Subsequently, to address the issue of disturbance torques that degrade tracking accuracy, a nonlinear disturbance observer is developed to estimate the disturbance torques acting on the spacecraft body and the turntable, which are introduced into the controller as feedforward compensations. Furthermore, a stability analysis of the closed-loop control system is conducted to ensure its reliability and performance. Finally, simulation scenarios for agile, stable, precise, and wide-ranging pointing control of constellation communication are designed. The feasibility and effectiveness of the proposed control methodology are validated through numerical simulations.