Event-Triggered Disturbance Observer-based Adaptive NN Fault-Tolerant Tracking Control for satellite with Input/Output Constraint

This paper investigates an event-triggered disturbance observer-based adaptive tracking prescribed performance control (PPC) problem for satellite with actuator saturation, fault and external disturbances. The external disturbance can be estimated by designing the new event-triggered nonlinear disturbance observer (ETNDO), which features the capability of automatically adjusting the communication frequency from the disturbance observer to the controller based on the performance of the system. Namely, when the tracking error is relatively large, the update frequency from the disturbance observer to the controller will be increased to keep the tracking error within the prescribed performance function. In addition, when the tracking error is small, the update frequency from the disturbance observer to the controller will be reduced to save communication resources. With the help of the Lyapunov function, the boundedness of all signal of the closed-loop satellite attitude control system (SACS) is achieved. Finally, using a simulation example, the feasibility of the designed controller is verified.