Magnetic Disk Head Position Control with Multi-Frequency Vibration Filtering
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Solution Overview
Problem
Conventional magnetic disk devices experience unstable operation due to multiple vibration frequencies in head positioning control, as existing adaptive filters can only handle one vibration frequency, leading to instability when multiple frequencies are applied.
Innovation Solution
A magnetic disk device with a filter processing unit that estimates and filters multiple vibration frequencies in series and parallel, using a second-order IIR type adaptive filter to calculate position errors and adjust filter coefficients, enabling effective handling of multiple disturbance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single adaptive filter with one transfer function is used for vibration filtering, then the device complexity is low, but the system becomes unstable when multiple vibration frequencies are present
Solution Approach 1:
The single adaptive filter is segmented into multiple adaptive filters, each with its own transfer function tuned to a specific vibration frequency. This segmentation allows each filter to independently handle a particular frequency component, preventing the instability that occurs when a single filter tries to handle multiple frequencies simultaneously.
Solution Approach 2:
The filter system is designed with multi-functionality to handle multiple vibration frequencies. Each adaptive filter in the plurality can process different frequency components, making the overall system capable of universally addressing various disturbance frequencies that may occur during head positioning control.
2Reliability
If multiple adaptive filters are used to handle multiple vibration frequencies, then the system stability improves, but the device complexity increases
Solution Approach 1:
The filter processing unit is segmented into multiple independent adaptive filter modules, each responsible for a specific frequency range. This modular segmentation allows the system to handle multiple vibration frequencies simultaneously while maintaining manageable complexity through structured organization.
Solution Approach 2:
Multiple adaptive filters are merged into a unified filter processing unit that collectively handles all vibration frequencies. The individual filters work together in coordination, combining their capabilities to provide comprehensive vibration suppression across the entire frequency spectrum while maintaining system stability.
Data Source
AI summary
According to one embodiment, a magnetic disk device reads servo information from a recording surface of a magnetic disk using a head, detects a position of the head based on the servo information, and estimates a vibration frequency of a disturbance applied to the head and filtering the estimated vibration frequency from a drive signal of the head. In the filtering, a position error is calculated using a target position of the head given when driving the head and the detected position of the head, a plurality of the vibration frequencies is estimated by executing the vibration frequency estimation based on the position error in a plurality of stages in series, and estimation results of the vibration frequencies are filtered in parallel from the drive signal of the head.