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.