Coupling Effect Analysis of Disturbance from Rotating Components in Flexible Satellites

This study investigates the coupling effect between rotating components of a satellite equipped with flexible appendages and the satellite’s unconstrained modes. A modal synthesis method based on mixed coordinates is adopted to establish the dynamic model of a satellite with multiple flexible appendages. The vibration equations under the excitation of disturbance torques induced by rotating components are derived for the flexible appendages in an unconstrained state. The on-orbit unconstrained modal frequencies and their mode shape vectors are calculated. Based on this, the analytical expressions for the satellite’s unconstrained modal responses and attitude angular velocity under the influence of driving disturbances from rotating components are obtained. Furthermore, the coefficient matrix that characterizes the amplification of attitude angular velocity induced by flexible vibration is analyzed when the drive frequency of rotating components is coupled with the satellite’s unconstrained modal frequencies. Taking a sun-synchronous orbit satellite with a single solar array as an example, the on-orbit unconstrained modal frequencies as a function of solar array angles are calculated. By applying harmonic disturbance torque generated by a rotating component, the attitude angular velocity and constrained modal coordinates are obtained through simulation. When the drive frequency of the rotating component matches the satellite’s unconstrained modal frequency, the corresponding mode shape (eigenvector) is analyzed. Based on the eigenvector values, the constrained mode of the solar array exhibiting the maximum coupling vibration is identified. The amplification coefficient matrix of attitude angular velocity resulting from coupling with the drive disturbance of the rotating component is validated. The damping coefficient associated with the unconstrained mode is estimated using the simulation data.