Abstract: A method and apparatus for normalizing the acceleration constant used by a servo control system in a disc drive are disclosed. The method and apparatus involve performing a test seek and summing the position error measured at sample periods during the deceleration phase of the test seek. A correction factor applied to the acceleration constant is adjusted if the sum of the position errors differs from the sum of position errors measured from a nominal seek. Adjusting the correction factor to cause a position error sum that is close or equal to the sum from the nominal seek provides a relatively symmetrical seek arrival without additional correction factor offsets or gain variances.

Abstract: The present invention is a method of correcting radial position error signal (PES) values by utilizing predetermined error correction values located at predetermined locations in advance of their associated servo fields. Calculated correction values are written to zero-acceleration path (ZAP) fields on the disc during the manufacture process. ZAP fields are positioned before the servo fields whose PES they are designed to correct. The ZAP field is comprised of two or more correction data elements to correct subsequent PES values. As the read/write head flies along a track, it reads a ZAP field, and stores the PES correction data in local random access memory (RAM). Subsequently, the corresponding servo field is read and the stored PES correction data is used to correct the PES. Two types of ZAP fields are written on the disc—one type for read operations, another type for write operations.