Adaptive Track Follow Control for Disk Drive Vibration Rejection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Disk drives face challenges in maintaining track follow performance under varying disturbance conditions, such as vibrations, especially as data area density increases and in mobile devices where audio vibrations are prevalent, leading to difficulties in designing a single track follow controller effective across different frequency ranges.
Innovation Solution
An adaptive track follow control system with selectable frequency modes, comprising a state estimator and disturbance evaluator, which analyzes disturbances and selects the optimal frequency mode to reject vibrations, ensuring effective track follow performance across conventional operational vibration and audio vibration tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single track follow controller is designed for conventional operational vibrations, then it performs well under low-frequency disturbances, but it fails to provide adequate rejection for high-frequency audio vibrations
Solution Approach 1:
The track follow controller is designed with multiple selectable frequency modes (low-pass, band-pass, high-pass filters) that can be dynamically switched based on the operating conditions. This allows the controller to adapt its frequency response characteristics to match the dominant vibration frequencies, whether from conventional operational sources or audio vibrations from speakers.
Solution Approach 2:
The controller changes its operational parameters (filter cutoff frequencies, gain settings) depending on the detected disturbance frequency. By adjusting these parameters, the same hardware controller can effectively reject both low-frequency operational vibrations and high-frequency audio vibrations without requiring separate dedicated controllers for each frequency range.
2Quantity of substance
If tracks per inch (TPI) is increased to improve data area density, then storage capacity increases, but track follow difficulty increases under disturbance conditions
Solution Approach 1:
The system continuously monitors the position error signal (PES) and uses this feedback to adjust the control output. The feedback loop, combined with the selectable frequency modes, allows the controller to respond adaptively to disturbances, maintaining stable track following even with higher TPI where the head has less margin for error under vibration conditions.
3Adaptability or versatility
If the disk drive is mounted near speakers in mobile devices, then integration in mobile devices is achieved, but audio vibrations propagate to the disk drive and impact performance
Solution Approach 1:
The control bandwidth is segmented into different frequency ranges using separate filter modes. By dividing the frequency spectrum into low-pass, band-pass, and high-pass sections, the controller can selectively address different vibration sources. This segmentation allows the system to handle audio vibrations from speakers without compromising the ability to reject other types of disturbances.
Data Source
AI summary
A disk drive comprises a track follow control system having a plurality of selectable frequency modes, the track follow control system configured to receive a position error signal and to output a control signal based on the position error signal, wherein the control signal is used by a head assembly to position a head over a disk. The disk drive also comprises a state estimator configured to receive the control signal and a position signal indicating a position of the head, to estimate a disturbance based on the control signal and the position signal, and to output an estimated disturbance signal based on the estimated disturbance. The disk drive further comprises a disturbance evaluator configured to receive the estimated disturbance signal, and to select one of the frequency modes of the track follow control system based on the estimated disturbance signal.