Stability of geostationary flying satellite under combined sliding mode and PID control

Attitude control of a satellite is performed by controlling two main parameters, angular speed and altitude. An inappropriate value for each of these parameters can lead the satellite to be lost in space or fall to the earth. This paper presents altitude and speed control of geostationary satellites by means of two controllers, the first one is a PID controller for regulating the altitude and the second one is a sliding mode control for controlling the angular speed. In this paper, the design concerns of altitude and angular speed controller are investigated; simulation for designed controller is performed to justify the designed control system as well.