Disturbance Observer-Based Multivariable Finite-Time Attitude Tracking For Flexible Spacecraft

This paper investigates vibration suppression and attitude tracking for flexible spacecraft under model uncertainty and external disturbance. Firstly, the input shaping technique is developed to suppress the flexible vibration introduced by flexible appendages. Then, an adaptive disturbance observer (ADO) is proposed to estimate the lumped uncertainty in finite time. The main feature of ADO is that it is non-overestimated maintains better property of chattering reduction. Moreover, a multivariable finite-time control scheme based on a novel dynamic sliding dynamic and ADO is designed for attitude tracking of flexible spacecraft. It is shown that the proposed control scheme is independent of the angular velocity measurement. Finally, the efficiency of the proposed control strategy is illustrated by simulations.