Abstract: This paper presents the design study of a combined attitude and thermal control actuator for small satellites. First, a design scheme of an attitude/thermal control actuator is proposed based on the principle that the annular flow in a fluid loop accelerated by mechanical pumps will exert torques on the satellite and absorb waste heat by circulation. Second, the attitude control torque model of this combined actuator is obtained in accordance with this scheme by using the equations derived for the electromagnetic torque and the fluid pressure with the motor speed as the independent variable. The heat model of this combined actuator is also built since heat dissipation changes with the flow rate of the fluid loop. Third, a closed-loop control system of a certain small satellite is designed based on the proposed combined actuator and an algorithm is defined to decouple the attitude and thermal control. Simulations are performed to demonstrate the effectiveness of the combined actuator for both attitude and thermal control.

Key words: space engineering, satellite, control system synthesis, combined attitude and thermal control system, mechanically-pumped fluid loop, fluidic momentum controller, fluid control, gear pump