This paper presents a study of the reaction wheel momentum desaturation and attitude control under actuator failure using thrusters torque for rigid earth pointing microsatellite. In order to solve the both problems reaction wheels saturation and attitude control, we propose a new fuzzy logic damping and attitude controller using pulse width modulation (PWM) cold-gas thruster (FDACT) and compared to the optimal controller based on infinite linear quadratic regulator (ILQR). Comparison of these approaches are performed to evaluate the performance of the control system during accurate nadir pointing control in terms of attitude error, minimum time and less energy consumption. The simulation results prove and illustrate the effectiveness of the proposed controller and its robustness under actuator failure.

Keywords: Wheel desaturation, microsatellite, fuzzy damping and attitude control using thruster (FDACT)