Internal model control of lightly damped systems subject to periodic exogenous signals

This paper presents an internal model control (IMC) design for lightly-damped systems subject to periodic exogenous signals. For such systems, the conventional design of the so-called IMC filter in the IMC structure can result in oscillatory behavior even when the closed-loop transfer function is designed to be well damped. To circumvent this problem, several band-pass filters are incorporated into the IMC filter based on knowledge of the frequencies of the plant's resonance modes and exogenous signals. The track-following system of an optical disk drive is employed to illustrate the design of the proposed IMC filter. Experimental results confirm the effectiveness of the proposed design.