MAGNETIC HARD DISK DRIVE TECHNOLOGY AND TWO
STAGE ACTUATOR CONTROL
Professor William Messner
Department of Mechanical Engineering
Carnegie Mellon University
The storage density of state-of-the-art commercial magnetic hard disk
drives is a phenomenal 10 Gigabits/in^2 (16 Megabits/mm^2) and currently
doubles approximately every twelve months. This presentation will first
review the basics of in disk drive technology and discuss how thermal
stability of magnetic media has important implications for the servo
system. The talk will then examine two potentially revolutionary
technologies for improving the performance of the disk drive servo
systems.
Following a brief examination patterned media for improved position
sensing
there will be by an in-depth look at two-stage actuation for higher
bandwidth servos.
The two-stage actuator portion of the talk will introduce several
microactuator technologies and then show the development the PQ Method
for
controller design for dual-input/single-output (DISO) systems. The PQ
Method is a new approach which specifically exploits the structure of
DISO
sytems. Unlike many other existing methods, the PQ Method allows
designers
to directly and intuitively address several important issues in DISO
systems, and it is well-suited to frequency domain design for either
continuous-time or discrete-time systems. The talk will will
demonstrate
the method for controller design for an disk drive two-stage actuator
test
rig and show experimental results.