Disk Drive Control
Photo: Courtesy IBM

Bits  of information are stored on and retreived from computer disk  drives using a magnetic read/write head.  This information is arranged on concentric tracks, nominally circular in shape.  Positioning the read/write head over the
appropriate track is a controls problem which has a significant impact on the performance of the drive.

Normal operation of a disk drive will require access to many different tracks.  The faster the read/write head can be moved between tracks, the faster information can be stored or retrieved.  There are economic and physical constraints on this task.  The fast transition between data tracks is usually called "seeking".

The sensitivity of the position of the read/write  head to external disturbances is also an important consideration in the design of controllers for disk drive servos.  As computer disk drives become more mobile in laptop or handheld applications, new bumps and vibrations become common disturbances which must not affect the positioning control of the read/write head.  Maintaining the read/write head over a particular data track is usually called "following".

The designed controller needs to address the concerns of both seeking and following for the final disk drive performance to be both fast and reliable. Work in this lab deals with the analysis of and design of controllers for disk drives.
 

Current research projects include:

•  Performance Tradeoffs for Repetitive Control Applied  to Disk Drive Servos (Jiagen Ding)

• Multirate Control (Yuping Gu)
• Overview
• Relevant Papers:
• High performance Tracking Control
• Analysis of Multi-rate Discrete Equivalent of Continuous Controller
• Multi-rate Feedforward Tracking Control for Plants with Nonminimum Phase Discrete Time Models
• Digital Redesign of Continuous Time Controller Multirate Sampling and High Order Holds

• Track Access and Following Controllers for Disk File Systems (Li Yi)

            

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