Patent ID: 7580217

Claim:
A method for operating a disk drive, the disk drive including (a) a rotatable disk having a plurality of data tracks containing servo positioning information; (b) a recording head movable across the disk, the head being capable of reading data and servo positioning information in the data tracks; (c) an actuator for moving the head, the actuator having a gain representing its response to a control signal; (d) a servo control processor responsive to a position error signal (PES) from the servo positioning information for generating a digital actuator control signal; (e) memory accessible by the processor; (f) a feedback controller stored in memory and comprising a set of parameters including an actuator gain parameter; (g) a digital-to-analog converter (DAC) for converting the digital actuator control signal to an analog actuator control signal; (h) a sensor responsive to external disk drive disturbances for generating an analog sensor signal for summing with the analog actuator control signal; and (i) an analog-to-digital converter (ADC) for converting the analog sensor signal to a digital sensor signal to the processor; the processor-implemented method comprising: calculating, from the digital sensor signal and actuator gain parameter, a modified feedforward signal; and generating, in response to the calculated modified feedforward signal, a digital actuator control signal.