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: An adaptive feedforward method of canceling and calibrating harmonic disturbances in a magnetic disk drive storage system includes expressing harmonic disturbances to the system as d(t) and expressing an output of the system as y(t). A control signal u(t) is used to cancel the harmonic disturbance d(t), where u(t) is the estimated value of d(t) such that u(t) is an estimated value of d(t). Estimated coefficients a.sub.i and b.sub.i of u(t) are updated using the derivatives of the estimated coefficients and a constant adaptation gain g.sub.i for the ith frequency component of the disturbance. The values of estimated coefficients are implemented in real time. The control signal u(t) is combined with the system output signal y(t) to cancel u(t) from y(t). The functions representing d(t), y(t), and u(t) are included in drive code for the system.

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.