Experimental and system study of Reaction Wheels. Part I: Measurement and statistical analysis of force and torque irregularities

Torque and force irregularities of running reaction wheels were studied. In this first part of the study report results from noise measurements at constant wheel speeds on various types of current technology European reaction wheels, both with ball- and magnet bearings and with DC or AC drive motor, are presented. The measured noise in radial and axial force and in torque about the rotation axis at constant wheel speeds was statistically analysed and presented as spectral plots. Differences in noise characteristics between the irarious wheel types are indicated. As shown the larger part of the noise is wheel speed dependent, both in frequency and power. Major noise causes are DC motor commutation and ball bearing retainer movements.