Abstract

This thesis presents a method for fault diagnosis in spacecraft attitude control system. The focus of this diagnosis problem will be on the actuator components. The considered actuator is assumed to be a reaction wheel. Since the attitude model of the spacecraft to be used is a coupled three-axis, three reaction wheels are required to provide actuation signals in this system. A high-fidelity model of the reaction wheel is considered which incorporates the effect of most disturbances involved in practice. A controller is designed to guarantee the stability of the signals in the system. This controller is designed according to nearly ideal model of the reaction wheel in a single axis system. The performance of this controller is validated for the three-axis nonlinear model of the spacecraft attitude control system using nonlinear model of the reaction wheel