Seagate Technology Incorporated

International Business Machines Corporation

Evert Steen Cooper

Roy Lynn Wood

Randall D Hampshire

Svetlana I Kovinskaya

A method for positioning a control object using an optimum jerk profile to reduce excitation of mechanical resonances. A base set of control profiles is selected to describe jerk, acceleration, velocity and displacement of the control object during a seek. Notch functions are applied to the base jerk profile to provide a modified jerk profile having a value of zero at selected times during which maximum current is to be applied to move the control object. Normalized control profiles describing acceleration, velocity and displacement are generated from the modified jerk profile and thereafter used to move the control object. To suppress specific resonant frequencies of interest, the elapsed time of the seek is selected to coincide with a time at which a combination of the excitation energies associated with the resonant frequencies is at a minimum.

Control object positioning using an optimum jerk profile to reduce excitation of mechanical resonances

An apparatus and method are disclosed for improving servo performance of a disc drive. The disc drive includes a head adjacent a rotatable disc on which data are stored on a plurality of tracks. A servo circuit is provided to control the position of the head by generating an actual (raw) position error signal (PES) nominally characterized as nonlinear over a portion of the width of a selected track and indicative of position of the head relative to the selected track. The servo circuit further generates a predicted PES as an approximation of the actual PES, and then controls head position through summation of the actual PES with the predicted PES. The servo circuit includes a burst signal generator which generates predicted burst signals as approximations of actual burst signals determined from readback signals from the head as the head reads servo burst patterns on the disc. Substantial portions of the servo circuit operation are preferably carried out by a programmable processor device, such as a digital signal processor.

Modeling position error nonlinearity to improve servo performance

This switch monitoring circuitry is particularly applicable to switching circuitry for operating a bipolar load device, frequently an inductor, on a source of direct current with four switches arranged to alternate the polarity of potential across the load device in a predetermined periodicity. Such circuitry often is arranged with diode devices individually connected across the switches, especially where the load device is an inductor. The monitoring circuitry specifically described comprises basic logical circuitry having coincidence gating circuits for activating status indicating circuitry; or for controlling associated circuitry for protecting or for compensating the switching circuitry; or for alarming operating personnel of malfunctioning switches.

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Morgan Hill, CA, United States of America

Evert Steen Cooper