MA Additional Filter for Disk Head Positioning Accuracy
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Solution Overview
Problem
The positioning accuracy of heads in magnetic disk devices using two-stage actuators with multi-rate control is insufficient due to modeling errors between expected and actual sensitivity characteristics.
Innovation Solution
An MA additional filter is designed and added between the MA controller and the MA control target, which involves measuring and correcting the multi-rate sensitivity characteristic to minimize head position error by selecting an appropriate filter that reduces the maximum gain value and frequency spectrum cumulative value below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multi-rate control is implemented in a two-stage actuator system, then the control speed and responsiveness are improved, but the positioning accuracy of the head deteriorates due to modeling errors between expected and actual sensitivity characteristics
Solution Approach 1:
The patent implements feedback by measuring the actual multi-rate sensitivity characteristic of the MA control target and using this measured data to create a corrected sensitivity characteristic. This feedback loop allows the system to compensate for modeling errors between expected and actual behavior, thereby maintaining positioning accuracy while preserving the speed benefits of multi-rate control
Solution Approach 2:
The patent changes the sensitivity characteristic parameter by creating a corrected sensitivity characteristic based on measured data. This involves adjusting the multi-rate sensitivity characteristic to account for actual system behavior, thereby resolving the contradiction between control speed and positioning accuracy through parameter optimization
2Device complexity
If the MA controller directly controls the MA control target without an additional filter, then the device complexity is reduced, but the positioning accuracy deteriorates due to uncorrected sensitivity characteristic deviations
Solution Approach 1:
The patent introduces an MA additional filter as an intermediary component between the MA controller and the MA control target. This filter serves as a mediator that corrects the control signal based on the measured and corrected sensitivity characteristic, thereby improving positioning accuracy without significantly increasing overall system complexity
Solution Approach 2:
The patent performs preliminary action by measuring the actual sensitivity characteristic and creating a corrected sensitivity characteristic before implementing control. This pre-correction of the sensitivity characteristic allows the MA additional filter to be designed with optimal parameters, improving positioning accuracy while maintaining relatively simple device structure
Data Source
AI summary
According to one embodiment, first, a frequency to be corrected by an MA additional filter is specified based on a head position error spectrum and a multi-rate sensitivity characteristic, in a state before the MA additional filter is added. Then, a candidate in which a peak of the multi-rate sensitivity characteristic is equal to or less than a threshold value and a head position error is minimized is determined as the MA additional filter to be used, in a state in which each of a plurality of candidates of the MA additional filter is added.