A variable head to disk spacing controller for magnetic recording on rigid disks

An apparatus is presented that allows the spacing dependence of magnetic recording devices to be studied by positioning the head at arbitrary (and continuously variable) heights above a rigid magnetic disk operating at a high, constant linear velocity. The spacing between the head and the disk is sensed electronically, and deviations from the desired height are removed by a sophisticated electromechanical control system. No air bearing is used. This control system utilizes an adaptive learning machine to build a model for the topography of the disk, and then uses this model to anticipate repeatable runout. As much as a 40-dB reduction in residual spacing error relative to that possible with a conventional control system can be achieved