Abstract: Narrow band dwell occurs when air bearings corresponding to a set of read and/or write heads within a hard disc drive remain within a fixed narrow band of one or more storage platters for an extended period of time. The air bearings displace lubricant on the storage platters and may redeposit the lubricant as droplets on the platters. The presently disclosure technology is directed to monitoring a hard disc drive for narrow band dwell, and in some implementations, implementing operations to mitigate narrow band dwell. More specifically, the presently disclosure technology may detect an overflying air-bearing slider position, apply a lubrication film displacement formula to a narrow band of the storage platter, apply a lubrication film reflow formula to one or more other narrow bands of the storage platter, and track lubrication film thickness over time in each of the narrow bands of the storage platter.

Abstract: Narrow band dwell occurs when air bearings corresponding to a set of read and/or write heads within a hard disc drive remain within a fixed narrow band of one or more storage platters for an extended period of time. The air bearings displace lubricant on the storage platters and may redeposit the lubricant as droplets on the platters. The presently disclosure technology is directed to monitoring a hard disc drive for narrow band dwell, and in some implementations, implementing operations to mitigate narrow band dwell. More specifically, the presently disclosure technology may detect an overflying air-bearing slider position, apply a lubrication film displacement formula to a narrow band of the storage platter, apply a lubrication film reflow formula to one or more other narrow bands of the storage platter, and track lubrication film thickness over time in each of the narrow bands of the storage platter.

Abstract: Method and apparatus for accelerating a multi-phase motor having a rotatable rotor are disclosed. A first commutation state in which the rotor resides is identified, after which a Proportional, Integral and Derivative (PID) control routine is executed for closed loop control of an acceleration of the rotor from a stopped position to an intermediate velocity, after which back electromotive force (Bemf) commutation is used to control the motor. The PID control routine utilizes a loop gain value optimized through voltage feedback indicative of a response of windings of the rotor to an application of a drive current across the windings. Based on the voltage feedback a controller programmed with the PID control routine provides an updated commanded current for each successive commutation state of the motor for use by a motor driver circuitry, which drives the motor through each commutation state until attainment of the intermediate velocity.

Abstract: Method and apparatus for compensating for a decrease in the torque constant of an actuator motor in a data storage device. An actuator supports the head adjacent a data recording surface on which a plurality of tracks are defined. A servo circuit outputs current to the actuator motor to carry out a seek to move the head from an initial track to a destination track in accordance with a velocity profile having a nominal deceleration trajectory along which the head is decelerated to reach the destination track. The servo circuit operates to adjust an initial value of gain to a second value in response to a selected parameter, and scales the nominal deceleration trajectory to a derated deceleration trajectory in relation to the second value of the gain. The derated deceleration trajectory is preferably selected in relation to the difference between the second value of gain and a predetermined threshold.

Abstract: Method and apparatus for accelerating a multi-phase motor having a rotatable rotor are disclosed. A first commutation state in which the rotor resides is identified, after which a Proportional, Integral and Derivative (PID) control routine is executed for closed loop control of an acceleration of the rotor from a stopped position to an intermediate velocity, after which back electromotive force (Bemf) commutation is used to control the motor. The PID control routine utilizes a loop gain value optimized through voltage feedback indicative of a response of windings of the rotor to an application of a drive current across the windings. Based on the voltage feedback a controller programmed with the PID control routine provides an updated commanded current for each successive commutation state of the motor for use by a motor driver circuitry, which drives the motor through each commutation state until attainment of the intermediate velocity.

Abstract: Method and apparatus for compensating for a decrease in the torque constant of an actuator motor in a data storage device. An actuator supports the head adjacent a data recording surface on which a plurality of tracks are defined. A servo circuit outputs current to the actuator motor to carry out a seek to move the head from an initial track to a destination track in accordance with a velocity profile having a nominal deceleration trajectory along which the head is decelerated to reach the destination track. The servo circuit operates to adjust an initial value of gain to a second value in response to a selected parameter, and scales the nominal deceleration trajectory to a derated deceleration trajectory in relation to the second value of the gain. The derated deceleration trajectory is preferably selected in relation to the difference between the second value of gain and a predetermined threshold.