Rigid-Flexible Coupling Dynamic Modeling and Characteristics Analysis of Thin-Film Spacecraft

Research on the rigid-flexible coupling modeling of the drag-enhanced thin-film spacecraft with an unfolded truss structure is limited, and the motion characteristics remain unclear. To address these challenges, the geometric nonlinear effects of the flexible deformation in the thin-film truss structure are considered. Based on the mixed coordinate method, assumed mode method, and Lagrangian method, a rigid-flexible coupling attitude dynamic model of the spacecraft is established. To facilitate the design of subsequent control laws, the detailed system model is reasonably simplified, leading to a control-oriented dynamic model. The parameter sensitivity analysis demonstrates the influence and evolution trends of key parameters for flexible supporting rods on both the spacecraft's attitude control performance and modal responses. The results indicate that flexible rod vibrations deteriorate the system's dynamic characteristics. As the distance from the connection point to the centroid, the rod length, and the cross-sectional area increase, the rise time, overshoot, and settling time for attitude adjustment all increase, and multi-channel coupling effects are induced. Moreover, the amplitude and attenuation rate of modal displacement are affected differently by these key parameters, which should be balanced during the spacecraft design stage.