Patent ID: 6243226
Filing Date: 2001-06-05
Classification: G11B

Abstract:
A digital servo control method for controlling a voice coil motor for moving a head to a target track for every predetermined sampling period in a data storage system using disk recording media, said method comprising the steps of:reading track position information for detecting a gray code of a current track on said disk recording media to derive a track position of said head;selecting a target track for determining a moving distance for moving said head from said track position to said target track;selecting one of a search mode, a transition mode and a track following mode as a result of said moving distance; andenabling one of a search mode interrupt service routine, a transition mode interrupt service routine and a track following mode interrupt service routine for applying a control signal to said voice coil motor according to the selected one of said search mode, transition mode and track following mode for controlling the velocity of said head for traversing said moving distance, said search mode interrupt service routine comprising the steps of:generating a first control signal for moving said head;reading track identification data in response to movement of said head to determine a current track position;deriving a target velocity from a look-up table according to said moving distance;determining a difference between a position of said target track and said current track position for generating an estimated velocity based on said difference;generating a reduced velocity by reducing said target velocity by an amount equal to said estimated velocity and increasing said reduced velocity by a predetermined gain for generating a new control signal;determining whether said difference between said target track position and said current track position is less than or equal to a predetermined number of tracks; andperforming said transition mode interrupt service routine when said difference between said target track position and said current track position is less than or equal to said predetermined number of tracks.