A method of reducing periodic disturbances in the feedback quantity of a controlled system is disclosed. The method includes receiving a feedback signal and repeatedly deriving respective magnitudes of harmonic components of the feedback signal to produce corresponding error signals. The error signals and harmonic components are used to generate harmonic control signals. The harmonic control signals are used to create a plurality of negative feedback loops acting to reduce the error signals. The present disclosure thus provides negative feedback control in the frequency domain. In one specific disclosed embodiment, the control is tied to the periodic domain resulting from the rotation of an actuator motor shaft.