Method and apparatus for controlling a multiple-stage actuator for a disk drive
US6005742A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 16, 1998 |
| Grant date | Dec 21, 1999 |
| Priority date | — |
| Expiry date | Jul 16, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B21/085
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for controlling a multiple-stage actuator for a disk drive which does not require an additional sensor for measuring the relative position between adjacent actuator stages. In a two-stage actuator system, a position-type secondary actuator (SA) rides piggyback on a primary actuator (PA). The repeatable runout is measured and used as a feedforward signal to the PA. If the PA is a rotary actuator, the feedforward signal is preferably arc corrected for the arc that the head transverses from the inner radius to the outer radius of the disk. Added to the feedforward signal is the moving average of the drive signal applied to the SA. Because the SA is of the position-type having a neutral position, this moving average is proportional to the time cumulative drift present in the two-stage actuator system, and forces the PA in a direction that minimizes deviation of the SA from its neutral position. This minimizes the range requirement for the SA, the main purpose of which is to reduce non-repeatable runout.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.