Robust adaptive control for attitude tracking of spacecraft with unknown dead-zone

This paper examines attitude tracking problem with unknown actuator dead-zone nonlinearity. A robust adaptive controller with parameter update laws is proposed and analyzed. A smooth inverse of the dead-zone is introduced to compensate for the effect of the dead-zone in controllers design with the adaptive control approach. The dead-zone parameters and the upper bound of the disturbance-like term are estimated by adaptive schemes. The stability of the resulting closed-loop systems is proved by application of Barbalat's Lemma. Numerical simulations are presented to show the effectiveness of the proposed attitude tracking approach.