DISK FILE SERVO CONTROL SYSTEM WITH FAST REDUCTION OF REPEATABLE HEAD POSITION ERROR

摘要

Abstract of the DisclosureAn improvement to a disk file servo control systemremoves repeatable error from the read/write head positionerror signal (PES) during track following. The disk fileincludes a microprocessor 60 and associated memory devices62, 64. A table of values of a sine function having afrequency equal to the disk rotational frequency is storedin a memory device. The microprocessor 60 receives eachsample of PES from the servo control system and values fromthe sine function table in the memory device and computes agroup of tap weights, each tap weight being a function ofthe PES sample, the value of a sine or cosine function witha frequency at one of the harmonics of the disk rotationalfrequency, a learning rate factor and the correspondingvalue of the tap weight for the previous PES sample. Foreach PES sample, the tap weights in a group are added togenerate a repeatable error correction signal Uc which issummed with the control signal U to the head actuator,thereby generating a modified control signal Um which causesthe head to follow the true track centerline. Therepeatable error components are thus removed from the PES.