Suppression of resonance in hard disk drive servo system with feedback resonant controller: a benchmark model study

Abstract

In order to achieve the precision desired, the bandwidth of the read-write head positioning servomechanism of hard disk drive (HDD) is required to be very high to minimise the effects of external disturbances. However, any attempt to increase the bandwidth is hindered by increased gain in frequencies of mechanical resonances leading to oscillatory response. If not compensated properly, excessive or unbounded oscillation may even lead to instability. Cascade compensation is the popular method for compensating multiple resonant modes. However, this method requires a very precisely identified plant model. On the contrary, feedback controller works better in such situation which does not require a very accurate plant model. This paper presents a feedback resonant controller designed in a simple way to suppress the resonant modes of voice coil motor (VCM) actuator used in HDD servo system. Simulation results substantiate the effectiveness of the proposed design methodology.