Tuning of a hard disk drive servo controller using fixed-structure H-infinity controller optimization

As the storage capacity of hard disk drives (HDDs) increases dramatically, the demand for positioning control accuracy of a read/write head of HDD is becoming more stringent. This paper presents a timing methodology for fixed -structure controllers using the H-infinity optimization. The timing of a P ID (Proportional phis Integral plus Derivative) controller for head positio ning of an HDD is presented as an application example. The H-infinity optim ization problem of fixed-structure controllers can be locally solved by usi ng the transformation into an H-infinity synthesis problem of static output feedback control. Simulation and experimental results show the effectivene ss of the proposed approach as a fine timing method to improve controller p erformance without requiring profound knowledge and experiences in manual l oop-shaping.