Precision spacecraft pointing using single-gimbal control moment gyroscopes with disturbance

Whereas previous work has shown that gain stabilization methods in the attitude control of spacecraft can mitigate external disturbances of a fixed frequency, recent work in cases where the frequency of the disturbance is time variant is summarized here. Specifically, the application of gain stabilization in the form of a variable periodic disturbance rejection filter is shown to be a viable method of mitigating these disturbances. To use this filter for the time-variant case, the character of the source of the disturbance needs to be known a priori with some accuracy, An implementation for a spacecraft steered by single-gimbal control moment gyroscopes where the disturbance is related to the gimbal rate is demonstrated, In addition, performance of the subject filter is demonstrated in the presence of estimation error and phase shift.