Patent
Disk drive with voice coil motor rise time manager
TLDR
In this paper, a disk drive with a moving arm actuator driven by a voice coil motor is controlled by periodically modeling the coil current rise time. But the model of the current is based on a linear approximation to the exponential rise time of the coils current.Abstract:
A method to adaptively reduce error introduced by the coil current rise time. A disk drive with a moving arm actuator driven by a voice coil motor is controlled by periodically modeling the coil current rise time. An adjustment to a commanded current value is based on the model of the coil current rise time and a magnitude change in commanded value. The model of the coil current is based on a linear approximation to the exponential rise time of the coil current. The commanded value is adjusted to compensate for the error in the control effort. For small commanded value differences no compensation is made for the coil current rise time. For medium command value differences a slope intercept equation is used to compute the compensated commanded value. For large commanded value differences half of an estimate of the maximum largest physical current change is used. The adjustment is made by the estimator in a position error signal feedback control system. The voice coil rise time adjustment is made to a voice coil motor control signal. The actuator velocity estimate is also improved with the model of the coil current rise time.read more
Citations
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References
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Patent
Disk file digital servo control system with coil current modeling
TL;DR: In this paper, a disk file digital servo control system utilizes a state estimator wherein the voice coil motor (VCM) current is modeled, rather than measured, thereby eliminating the need for analog-to-digital conversion of the actual VCM current.
Patent
Digital servo control system for a data recording disk file with improved saturation modelling
TL;DR: In this article, a digital control servo system for read/write head positioning in data recording disk files of the type which use voice coil motor (VCM) actuators for positioning the head, with improved modelling of the servo systems in saturated seek mode.