Disturbance Filtering and Identification on the Naval Postgraduate School 3-Axis Spacecraft Simulator

This paper investigates spacecraft disturbance rejection filtering for both persistent and decaying disturbances. The current study both validates the previously developed “dipole” disturbance rejection filter on a realistic non-linear spacecraft model, and extends the results to a new class of decaying disturbances. Although not designed specifically for decaying disturbances, prior investigations have demonstrated that the traditional “dipole” disturbance rejection filter attenuates both persistent periodic disturbances and decaying disturbances. Here we introduce a new filter which we call the decaying disturbance rejection filter, which has greater attenuation than the traditional filter for decaying disturbances. The new filter is also based on the internal model principle like the traditional filter. Also, it is shown that both the traditional and the new filter are not robust to frequency uncertainty. As a result, new closed-loop system identification methods are introduced to experimentally identify the disturbance frequency to be used within the filter design for both filter types.