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High performance controller design of HDD based on precise modeling using differential iteration method

In the positioning system of a hard disc drive (HDD), many resonance modes exist, and they are very close each other. Therefore, it is difficult to obtain a precise model when the curve fitting method was used and it is difficult to suppress both the effect of these resonances and that of any disturbances. In this paper, a differential iteration method that was one experimental modal analysis technique in the frequency domain is applied to obtain the precise model of a positioning system of a HDD. Three controllers 1) a controller which was designed using a robust controller design method, 2) a lead-lag filter that adds on the inverse model that was calculated using a precise model of the positioning system of a HDD, and 3) a lead-lag filter that adds on the notch filter to suppress the effect of resonance in the high frequency range were used to compare the control performance. We compare the results of each controller in numerical simulation.