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

Abstract

I n positionin.g system of a HDD, many resonance modes exist, and they are very much close each other. Therefore, it is dificult to obtain the precise model when the curve fitting method was used and it is dificult to suppress both the effect of these resonance and that of any disturbances. I n this paper, a differential iteration method that was one of an experimental modal analysis technique in frequency domain is applied to obtain the precise model of a positioning system of a HDD. Three controllers 1 ) a controller which designed robust controller design method, 2) a Lead-Lagfilter that add on the inverse model that was calculated using pwcise model of the positioning system of a HDD, and 3) a Lead-Lag filter that add on the notch filter to suppress the effect of resonance in high frequency range were used to compare the control performance. W e compare between tlie results with each con,troller in numerical simulation.

Rejection of Repeatable Run-Out in HDDS Using Inverse Frequency Dynamics

“…(1), the differential iteration method (Nagamatsu, 1993) that is a method for deciding accurate modal parameters by repeated calculation while all unknown modal parameters are changed to the linear term was used (Kawafuku et al, 2003). …”