A comparative study of the use of the generalized hold function for HDDs

This paper is concerned with the application of H_∞ control with generalized hold function (GHF) to track-following control of hard disk drives (HDDs). In HDDs, the sampling frequency is limited primarily by the fact that a high sampling frequency tends to decrease the available data storage capacity of the devices, since the position error signal (PES) must be stored on the disk. Under such conditions, GHF provides a possible way to enhance servo performance without requiring more PES data. In this paper, we investigate its possibility comparing the results with other conventional H_∞ control design results, including continuous/discrete-time and single/multi-rate control. Our results show that this controller has better performance due to the nature of the control input of the GHF.