Data transducer position control system for rotating disk data storage

Abstract

A servo calibration method is disclosed for a disk drive including a rotating data storage disk journalled to a frame and having a multiplicity of concentric data tracks defined on a major surface thereof and an actuator structure under the control of a programmed servo control microprocessor in response to coarse position information fed back to the microprocessor by a position encoder, and to fine position information fed back to the microprocessor by a data transducer reading from servo information prerecorded on the major surface of the disk, the actuator structure for moving the data transducer to each selected one of the data tracks during track seeking operations and for maintaining the transducer aligned with the data track during track following data read and/or write operations. Carried out during initialization, the method includes the steps of: automatically seeking to a region of radially outermost tracks, reading fine position information recorded in the single sector of each of a plurality of outermost tracks, and recording the outer track fine position information in memory; automatically seeking to a region of radially innermost tracks, reading fine position information recorded in the single sector of each of a plurality of innermost tracks, and recording the inner track fine position information in memory; for each data track to which a seek is initially commanded, which track lies between the outermost track region and the innermost track region, calculating with the microprocessor means a track centerline correction value lying between the outer track fine position information and the inner track fine position information, and applying the track centerline correction value so calculated as an offset value to the rotary actuator to correct any discrepancy between nominal track centerline defined by the position encoder.