Development of Magnetic Bearing Momentum Wheel for Ultra-Precision Spacecraft Attitude Control

This paper describes a magnetic bearing momentum wheel (MBMW) for ultra-precise stabilization of spacecraft attitude. For suppressing bearing reaction torque, which disturbs the spacecraft attitude stability, the control bandwidth of the magnetic bearings is designed to be as narrow as possible. Using a prototype of the MBMW, sufficiently quiet and stable rotation up to 8,000 r/min. (64 Nms) is accomplished. Moreover, the accurate measurement of the bearing reaction force and torque showed that small reaction torque remains even if the MBMW rotates in the super-critical speed range. Considering not only the wobbles of the sensor measurement surface but also those of the rotor surface of the bearing, the cause of this residual reaction torque is clarified.