Method for maximizing feedforward orthogonality for minimizing servo system nuller instability
US5708581A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 12, 1996 |
| Grant date | Jan 13, 1998 |
| Priority date | — |
| Expiry date | Jul 12, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B5/59622
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An n-around nuller in a disk drive track-follow loop servo system is optimized by maximizing its feedforward orthogonality (channel separation). Sine and cosine terms (signals) are injected into the track-follow loop, thereby creating the separate channels (signals), to reduce the amplitude of the n-around component. The Fourier sum is then taken in connection with a phase delay variable and integrated to produce the proper feedback for maximizing orthogonality and minimizing instability. Specifically, the feedforward cosine term is low-pass filtered to find its average value. A step is then fed into the feedforward sine term and the response of feedforward cosine is observed. Feedforward cosine is then integrated to evaluate how much "cross talk" there is between the two channels. Once the integral sum is found, it is used as a feedback element for tuning the sine and cosine terms injected into the channels, thereby maximizing feedforward orthogonality and minimizing servo system nuller instability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.