Dynamic modeling and attitude maneuver control on SO(3) for spacecraft with large flexible appendages

The large inertia and high flexibility of large appendages in the flexible spacecraft pose significant challenges for dynamic modeling and achieving high-precision attitude control. This paper focuses on the attitude-tracking problem of spacecraft equipped with large flexible appendages and novel dynamic modeling and attitude maneuver control methods are developed. An accurate high-order dynamic model is established using the referenced nodal coordinate formulation and an associated model reduction technique is proposed to obtain a low-order model that can capture geometric nonlinearity due to large deformations. A high-precision attitude maneuver controller for flexible spacecraft is designed in SO(3) space by introducing model-based flexible compensation terms, which can be conveniently integrated into traditional attitude control algorithms such as PD and sliding mode controllers. A linear modal observer is designed to reduce difficulty during implementation. Two common flexible spacecraft systems are investigated to demonstrate the performance of the proposed modeling and attitude control approaches. Results indicate that accurate modeling of flexible appendages not only affects their dynamic characteristics but also significantly influences the overall attitude dynamics of the spacecraft. The proposed control approach can significantly improve control accuracy and achieve high-precision attitude tracking even in the presence of large deformations.