ABSTRACT

This chapter explains issues related to design of digital controller and presents different algorithms to solve problems specific to hard disk drive (HDD) servomechanism. It provides an insight of the control problem for HDD servomechanism with the help of a few different design approaches and several advanced control strategies. The specifications for HDD servomechanism are continuously becoming more and more stringent to meet the demands for increasing track density and diversification of applications. The chapter discusses pros and cons of different micro-actuators suitable for application in HDD and also presents different approaches to design controller for dual-stage actuators. The head positioning servomechanism of an HDD uses the Voice Coil Motor actuator to move read-write head from one track to another and to regulate its position over the center of the track. HDDs are mass produced systems and the actuators are also mass produced.