Disk drive determining head touchdown threshold based on curve fitting prediction error

摘要

A disk drive is disclosed comprising a head actuated over a disk. An analog touchdown (TD) signal is compared to a TD threshold in order to generate a calibrated TD threshold for a plurality of different dynamic fly height (DFH) settings. The calibrated TD thresholds and corresponding DFH settings are fitted to an estimated curve. At least one of the TD threshold and the DFH setting is adjusted, and a corresponding next point in the estimated curve is predicted. An actual next point corresponding to the adjustment is determined, and a prediction error is generated based on a difference between the predicted next point and the actual next point. A touchdown of the head on the disk is detected when the prediction error exceeds a prediction threshold.