Disk drive servo sensing gain normalization and linearization

Abstract

An apparatus, system and method are described for generating a continuous and linear position signal generated from stitched position error signal (PES) components, for use by a servo control system in positioning a transducer with respect to a storage surface. Continuity is achieved by providing a normalization stage in the servo control loop for correcting discontinuities at the stitch points with minimal impact to the PES zero-crossing points. According to a first preferred embodiment normalization is applied using an algorithm determined by the width of the read transducer. According to a second preferred embodiment, normalization is selectively applied near the stitch points of the PES components, but is not applied at their zero-crossing points. In another preferred embodiment, a first normalization algorithm is applied near the stitch points, and a second normalization algorithm is applied at the zero-crossing points. In a fourth embodiment, a smoothing function is applied between the stitch points and zero-crossings to smooth the transition from normalized to unnormalized signal contributions or from signal contributions normalized in a first manner to signal contributions normalized in a second manner. A further aspect of the present invention is to determine whether the PES exceeds a nominal value and if so, to hold the PES at the nominal value at each stitch point.