Output feedback attitude tracking control for a rigid spacecraft with dynamic uncertainty

In this paper, a nonlinear output feedback control mechanism is developed to address the attitude tracking problem of a rigid spacecraft system which contains uncertainty associated with dynamic model and is under the effect of external disturbance. The control strategy is based on limited assumption on the system dynamics. A set of filters are developed to compensate for the unmeasurable spacecraft´s angular velocity. A semi-global asymptotic attitude tracking result is achieved while all the closed-loop states remain bounded.