Improving a Satellite Attitude Control Using Fractional-Order Controller in the Presence of Environmental Disturbances

In this paper, attitude control of a rigid satellite in the presence of external perturbations and considering the parametric uncertainties with the fractional order controller is investigated. To control the attitude of the satellite, a reaction wheel actuator with a first-order dynamic model is used and uncertainty is considered in the parameters of the satellite’s moment of inertia, the actuator model and external perturbations. For comparative purposes, in addition to the fractional order controller, the integer order controller is also used. Numerical solution is performed by Euler method and Granwald-Letinkov definition is used to solve the fractional order integral and derivative. The coefficients of the integer order and fractional order controllers were extracted by the particle swarm optimization method with the performance criterion of mean of absolute value of error. Fractional order controllers have more degree of freedom than integer order controllers due to their more design parameters. Therefore, according to the results, the appropriate performance of fractional order controllers can be seen in overshoot, settling time and against of perturbations and uncertainty in the satellite attitude control.