Vibration control for a flexible spacecraft in the presence of external disturbance

In this paper, the vibration reduction of spacecraft with flexible appendages subject to external boundary disturbance and input restriction is focused on. Under Hamilton's principle, a spacecraft system with restricted input is modeled as a set of partial differential equations (PDEs) and ordinary differential equations (ODEs). By Lyapunov direct method, a boundary control is developed to suppress the elastic deflection of flexible appendages. Two disturbance observers are developed to compensate for the influences of external disturbances. Two auxiliary systems are considered for eliminating the influences of input constraints. The uniformly ultimate boundness stability of system states is proved under the designed boundary control. Numerical simulation is carried out to demonstrate the performance of the studied boundary control scheme.