Periodic Event-Triggered Adaptive Control for Attitude Stabilization Under Input Saturation

In the paper, the periodic event-triggered adaptive controller is proposed for attitude stabilization of a rigid spacecraft with model uncertainties, external disturbances, and input saturation. We adopt the periodic state measurement instead of the continuous one, and it is known that the former is more economical and practical than the latter due to the relaxation of continuous measurements. Moreover, new event-triggered adaptation update laws and the periodic event-triggering strategy are proposed for adaptive sliding mode control (SMC) to guarantee the states in the practical sliding mode. It is illustrated that the states of the attitude control system are ultimately bounded. Further, it is proved that the presented periodic event-triggered strategy is without Zeno phenomenon and there exists a uniform lower bound for each interevent time. Some numerical examples are given to demonstrate the validity of the derived control strategy.