A tool (20) is provided for mounting in and testing a fixture (12) used for mounting a device, such as a disk drive, having an arm which is movable to selected locations by an actuator. The tool has a movable member (25) which is movable to mimic movement of an arm of such a device mounted in the fixture (12). Movement of the tool (20) in the fixture (12) as a reaction to movement of the movable member (25) is measured and compared with a standard to enable the fixture to be passed or failed.

A method of compensating for non-linear torque characteristics of an actuator servo control system in a hard disk drive. The method includes initializing all variables in a memory, which are necessary to operate the actuator servo control system, when power is turned on; unlatching a transducer head which is located in a parking zone; measuring voice coil motor torque constants of each track area of a disk, starting from an inner track area to an outer track area, calculating gains of the actuator servo control system using the voice coil motor torque constants and storing the gains of the actuator servo control system in the memory; and compensating for non-linear torque characteristics of the actuator servo control system, based on the gains of the actuator servo control system of each track area of the disk which are stored in the memory, when the transducer head shifts from track to track, during a track seek mode, to perform one of a read operation and a write operation.

A head position control system for a dual stage actuation disk drive system. A feedback system is provided for modifying a primary and a secondary input command signal to produce primary and secondary error signals. A controller receives the primary error signal and transmits primary actuator arm positioning information to the primary actuator. A secondary controller receives the secondary error signal and transmits secondary actuator arm positioning information to the secondary actuator. The feedback system creates a position error signal (PES) using information from servo wedges and runout information and the PES is used to produce the secondary error signal. The feedback system produces a reconstructed error signal including angular position information for the primary actuator arm by processing a back electromotive force signal from the primary actuator. The primary error signal is produced by modifying the primary input signal with the reconstructed error signal.

A method and apparatus for writing a servo signal for controlling the position of a head on a disk during the manufacture of a hard disk drive. The present invention provides a method and apparatus for writing servo information on a magnetic disk through a magnetic head by driving an actuator of a hard disk drive (HDD) directly without employing a servo writer using control of a laser. Furthermore, when there is need for increasing the density in tracks per inch (TPI) to obtain a high capacity HDD, HDD manufacturers do not have to produce a new servo writer, thereby reducing production cost.

A data storage device adapted to compensate for physical disturbances has a storage medium, a read-write mechanism positionable relative to the storage medium, and a disturbance observer. The read-write mechanism is adapted to read and write data. The disturbance observer compensates a position of the read-write mechanism according to low-frequency components of physical disturbances.