Wheel Unloading by Gravity-Gradient Torque

摘要

Momentum wheels are widely used as an actuator to control the attitude of an artificial satellite. Since wheels are internal torquers, they tend to accumulate angular momentum while they cancel External disturbances. Because there is an upper limit to the momentum accumulation, momentum Unloading is necessary. For this purpose, certain external torquers are additionally required. Usually, thrusters or magnetic torquers are used. It is known that gravity-gradient torque is a Computable external torque. By making use of this torque, momentum unloading can be achieved Without requiring additional torquers while the satellite attitude is tilted by the wheels. This paper Studies a control method to unload the accumulated momentum of the wheels by utilizing the gravity Gradient torque and discusses its fundamental algorithm and unloading capability.