Browse Prior Art Database

Automatic Calibration of Disk File Servo Gain

IP.com Disclosure Number: IPCOM000041921D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Brecke, RA: AUTHOR [+5]

Abstract

The purpose of auto-calibration is to have a disk file self-adjust the velocity circuit accuracy, since both the access time of a seek and the ability of the actuator mechanism to capture on track at the end of the seek without excessive overshoot are directly related to the actuator velocity. The calibration of disk files without automatic calibration requires that both the servo card and the disk enclosure be separately calibrated, since servo head width also affects the velocity measurement accuracy of the file. To do so, each file must have a method of compensating for head width such as a selectable resistor board mounted on the disk enclosure frame and adjusted during the manufacturing cycle. Also, the servo card requires two potentiometers for velocity measurement circuit adjustments.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 58% of the total text.

Page 1 of 2

Automatic Calibration of Disk File Servo Gain

The purpose of auto-calibration is to have a disk file self-adjust the velocity circuit accuracy, since both the access time of a seek and the ability of the actuator mechanism to capture on track at the end of the seek without excessive overshoot are directly related to the actuator velocity. The calibration of disk files without automatic calibration requires that both the servo card and the disk enclosure be separately calibrated, since servo head width also affects the velocity measurement accuracy of the file. To do so, each file must have a method of compensating for head width such as a selectable resistor board mounted on the disk enclosure frame and adjusted during the manufacturing cycle. Also, the servo card requires two potentiometers for velocity measurement circuit adjustments. The figure shows the basic circuit for the automatic calibration method for velocity circuit accuracy adjustment. After the file is powered up, the system goes through two file calibration steps. The first step is a calibration conducted while the servo is moving the heads to the home position on the disk. The microprocessor measures track-crossing times at this low velocity and compares the measured time with a reference time stored in read-only memory. The difference between these two times is used in an algorithm that calculates the values for the eight bits that are sent to the digital- to-analog converter (DAC). The DAC outpu...