Design of Satellite's Combined Attitude and Thermal Control System Equipped with FMC Actuators

The purpose of this paper is to design a control systwm with a pre-designed algorithm in order to reach a compromise between satellite attitude and thermal control systems. In addition to the indispensable attitude control system, a thermal control system (TCS) is regarded as a substantial subsystem in any given satellite. The latter is commonly used to effectively reduce the internal heat and/or the thermal tensions caused by solar radiations. In this paper, a novel actuators known as fluid momentum controllers (FMCs) have been utilized to simultaneously produce control torques and develop a cooling mechanism by circulating liquid through a ring. In this research, it has been assumed that the satellite’s internal temperature has reached a critical level to the extent that the FMCs are not able to reduce this temperature sufficiently. In such a case, it is possible to mitigate this problem using a combination of both attitude and thermal control subsystems (CATCS). To accomplish this, a thermal model has been employed to yield the temperature of all six sides of the satellite at each time step and a switching algorithm to design an integrated system. This algorithm uses a particular decision making logic to realize the reconciliation of the two subsystems. Also, a sliding mode controller has been used for the three axis stabilization of the satellite. Simulation results of the integrated attitude and thermal control system indicate that it is possible to conduct an appropriate temperature control while saving power and integrating the two subsystems.