The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 07, 1986
Filed:
Jul. 16, 1985
Michael L Workman, San Jose, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
An improvement to a disk file servo control system removes repeatable error from the read/write head position error signal (PES) during track following. The disk file includes a microprocessor 60 and associated memory devices 62, 64. A table of values of a sine function having a frequency equal to the disk rotational frequency is stored in a memory device. The microprocessor 60 receives each sample of PES from the servo control system and values from the sine function table in the memory device and computes a group of tap weights, each tap weight being a function of the PES sample, the value of a sine or cosine function with a frequency at one of the harmonics of the disk rotational frequency, a learning rate factor and the corresponding value of the tap weight for the previous PES sample. For each PES sample, the tap weights in a group are added to generate a repeatable error correction signal U.sub.c which is summed with the control signal U to the head actuator, thereby generating a modified control signal U.sub.m which causes the head to follow the true track centerline. The repeatable error components are thus removed from the PES.