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Satellite Thermal Control subsystem has the responsibility of maintaining the temperature of different parts and other subsystems in an allowable range. The purpose of this paper is to optimally design the satellite thermal control subsystem. In order to achieve this goal, at first a software for thermal analysis of satellite was developed and validated. Receiving orbital data and Satellite’s properties, the software simulates the position of the satellite in any desired orbit and calculates input and output thermal flux. Meanwhile, the software calculates the temperature of each sides of satellite in cold case and hot case. At the end, it computs the minimum and maximum temperature of the satellite. Combination of three commonly used thermal control methods for small satellite was used. Insulation thickness, thickness of radiator’s cover, and the power of radiator are considered as design parameter and allowable temperature of surfaces (minimum and maximum allowable temperature) are considered as design constraints. A weighted function of mass, cost, and power consumption of thermal control system are chosen as objective function that can be an indicator of the cost. Sequential Quadratic Programming as a powerful method in nonlinear optimization was used to optimize thermal control properties.The results demonstrated that the objective function improved dramatically comparing to initial design. High speed, appropriate precision, and extensibility of this software to thermal control design of vast majority of small satellites, makes this research superior. Therefore, this software could be cooperated as the thermal control design module in multidisciplinary design optimization of satellites.

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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.

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