Amir reza Kosari - Tehran university
سیده الهه خاتون آبادی - Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran
Vahid Bohlouri - Department of Electrical Engineering, Technical and Vocational University, Tehran, Iran

In this paper, the control of a three-axis rigid satellite attitude control system with a fractional order proportional-integral-derivative (PID) controller is investigated in the presence of disturbance and parametric uncertainties. The reaction wheel actuator with the first-order dynamic model is used to control the attitude of the satellite. Uncertainties are considered on satellite moment inertia, actuator model and amplitude and frequency of external disturbances. External disturbances are modeled with two fixed and periodic parts and uncertainty is also considered on the disturbances model. The integer order controller is also used for the same conditions to compare the results with the fractional order controller. The usual Granwald-Letinkov definition is used to solve integrals and fractional order derivatives. The mean absolute of the pointing error of the satellite pointing maneuver has been selected as an objective function of the optimization problem. The controller gains in integer and fractional order are obtained by particle swarm evolution algorithm (PSO) optimization method. The performance criterion has been studied in terms of the controller time response and also in terms of the standard deviation of the mentioned uncertainties and external disturbance. The results show that the fractional order controller performs more accurate and robustness than the integer order controllers in the face of uncertainty and disturbance.

Satellite attitude control, Fractional-Order, PID Controller, Reaction wheel, Uncertainty