Disturbance-observer-based nonlinear stabilization control of flexible spacecraft attitude system

This paper addresses the stabilization problem of flexible spacecraft attitude system. It´s well known that the undesirable vibration caused by flexible appendages, together with other disturbances such as model uncertainty and space environmental disturbance torque, may greatly degenerate the performance of the spacecraft attitude system. In this paper, the elastic vibration, the model uncertainties and other external disturbances are modeled as the lumped disturbance to the rigid body of the spacecraft, and a composite control scheme is applied to this issue. The approach is composed of two independent procedures. On one hand, a disturbance-observer-based control (DOBC) is adopted for quasi-feedforward compensation of the elastic vibration and other disturbances. On the other hand, the Sum of Squares (SOS) technique is used to construct a controller to stabilize the rigid body.