Design of an Active Balancing System for Rotating Orbital Devices

This paper presents the design of an active balancing system for rotating orbital devices, motivated by recent space applications for spacecraft endowed with rotating payloads. The main motivation behind this work is the Copernicus Imaging Microwave Radiometry mission, which will feature a large rotating microwave radiometer to provide observations of sea-surface temperature, sea-ice concentration, and sea-surface salinity. Due to the presence of highly uncertain inertial asymmetries in the rotating device, potentially large internal forces and torques can appear at interface between the spacecraft and the rotor, which can cause a significant degradation of the system performance and can even affect its stability. To counteract such unbalance effects, an active balancing system made of a suitable set of actuated movable masses and sensors is developed in this work. Exploiting the time-periodic nature of the underlying dynamics, a harmonic controller has been designed to command the positions of the actuated masses in such a way that the effects of rotor unbalance are significantly reduced. After extensive numerical simulations, accounting for both parametric uncertainties and exogenous disturbances in the model, a dedicated breadboard has been developed and experimental validation of the control law has been carried out.