Patent Document ID: 20030128458
Application ID: 10169864
Patent Flag: 0

Claim One:
1. A method to control a disk drive having a head for reading or writing data from a disk, a moveable actuator motor to provide output torque for positioning the head relative to a pre-selected data track on the disk, and a disk drive servo system that provides a command signal to the actuator motor, the disk drive servo system including a head position signal generator responsive to the position of the head and a position controller that generates the command signal to the actuator motor to move the head to a desired position, the method comprising: operating the position controller as a proximate time-optimal controller (PTOC) during a track seeking mode to rapidly move the head to a selected track; operating the position controller as a robust compensator during a track following mode to compensate for torque disturbances; and operating the position controller in a continuous bridge mode when transitioning from the track seeking mode to the track following mode to provide continuity of the command signals to the actuator motor when transitioning from the track seeking mode.