Abstract: A data recording disk file includes rotatable disks with concentric data tracks thereon. The data disk file includes servo information recorded on at least one of the disks, at least one head for reading the servo information during rotation of the disk, and a voice coil motor (VCM) attached to the head for positioning the head relative to the data tracks. A servo is driven by signals read from the head to control the VCM. The servo includes a processor employing an estimator model for estimating the parameters of the VCM and for generating, from the estimated parameters and the servo information, a digital control signal. The digital control signal is converted to an analog control signal. The control signal is applied to a power amplifier which generates an input current for use by the VCM. The processor provides solely a single estimator model which operates in both saturated mode and linear mode depending on the magnitude of the digital PES.

Abstract: A data recording disk file includes rotatable disks with concentric data tracks thereon. The data disk file includes servo information recorded on at least one of the disks, at least one head for reading the servo information during rotation of the disk, and a voice coil motor (VCM) attached to the head for positioning the head relative to the data tracks. A servo is driven by signals read from the head to control the VCM. The servo includes a processor employing an estimator model for estimating the parameters of the VCM and for generating, from the estimated parameters and the servo information, a digital control signal. The digital control signal is converted to an analog control signal. The control signal is applied to a power amplifier which generates an input current for use by the VCM. The processor provides solely a single estimator model which operates in both saturated mode and linear mode depending on the magnitude of the digital PES.

Abstract: A disk file digital servo control system incorporates means for measuring the time between samples of read/write head position error signals (PES), and uses a value of that measured time as part of the computation of the digital control signal. The digital servo control system has a microprocessor which runs a control signal algorithm, a portion of which is a state estimator for estimating the position, velocity and acceleration of the head. The state estimator requires the use of estimator constants determined from physical parameters of the disk file, including the PES sampling time. By using the actual measured PES sampling time, rather than a constant value of nominal PES sampling time, the estimator constants can be modified to improve the accuracy of the computed control signal. This results in improved performance of the control system to move the head to the target track whenever there are variations in the nominal PES sampling time caused by variations in the disk file drive motor speed.