J-025

Track Following Control of Large Capacity Flexible Disk Drive with Disturbance Observer Using Two Position Sensors

Authors: Jun Ueda, Akihiko Imagi, Hitoshi Tamayama
Affiliation: Advanced technology R&D center, Mitsubishi Electric Corporation

Abstract
In this paper, we propose a track following control for large capacity FDDs with a disturbance observer using two position sensors; an optical tracking sensor for large capacity mode and a magnetic scale for compatible mode. Disk drive requires high resistance against vibration and drive tilting. One of the effective solutions is a disturbance observer. However, as tracking sensor outputs only a tracking error signal, there exists a problem in that the information required to design 2DOF controller is lacking. As two position sensor systems are indispensable in building a backwards-compatible large capacity FDD, a 2DOF track following controller can easily be designed. We show that Disturbance observer based controller with single positioning sensor is nothing more than a 1 DOF high gain controller which can easily become unstable and our proposed controller improves disturbance reduction satisfactorily.

Jun Ueda
uedajun@mec.crl.melco.co.jp