The issue of rejecting periodic disturbances arises in various applications dealing with
rotating machinery[ A novel adaptive
feedforward controller "AFC# design method for rejecting periodic disturbance is proposed[ It can be added to an existing feedback control system without altering the original closed loop characteristics\ such as the stability margin and transfer functions[ An adaptive algorithm derived for the proposed controller based on the steepest gradient descent method turns out to be identical to the popular delayed!x
LMS algorithm[ A number of computer simulations were carried out to demonstrate the salient features of the proposed AFC compared to the conventional one[ The proposed method can be useful for control engineers in designing an adaptive feedforward controller for the rejection of the periodic disturbances.