LQG/LTR frequency loop shaping to improve TMR budget

In this paper, we introduce a systematic method of designing a track-following servo system for hard disk (HD) drives using discrete-time linear-quadratic Gaussian/loop-transfer recovery (LQG/LTR) design technique, and some statistical knowledge on disturbances. The newly designed controller was implemented on a commercial HD drive and its performance was compared to the resided compensator. An improvement of 10% in track misregistration (TMR) budget was observed.