Disk Drive Shock Feed Forward Adaptive Filters
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Solution Overview
Problem
Mechanical shocks can cause disk drive heads to write data outside intended tracks, leading to corruption or off-center data, making it difficult to read, and existing technologies do not effectively prevent such issues during low-frequency shocks.
Innovation Solution
A disk drive system with a shock detection channel that uses a piezoelectric shock sensor and dual filter paths to differentiate between high-frequency shock events that inhibit writing and low-frequency shocks that allow compensation for maintaining accurate track positioning during data writing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shock detection is used to inhibit writes during high-frequency shocks, then data corruption is prevented, but writing capability is lost during low-frequency shocks that could be compensated
Solution Approach 1:
The shock detection system is segmented into two independent processing paths: a high-pass filter path for detecting high-frequency shocks that require write inhibition, and a low-pass filter path for detecting low-frequency shocks that can be compensated. This segmentation allows the system to treat different shock types differently, preventing data corruption from high-frequency shocks while maintaining writing capability during low-frequency shocks through compensation.
2Reliability
If writes are inhibited during all detected shocks, then data corruption is prevented, but legitimate writes during compensatable low-frequency shocks are blocked
Solution Approach 1:
Different quality control measures are applied to different shock frequency bands. High-frequency shocks trigger a strict local quality measure (write inhibition) to prevent corruption, while low-frequency shocks trigger a more permissive local quality measure (compensation only) that maintains write operation continuity. This local differentiation of quality control strategies optimizes both data protection and operational efficiency.
3Device complexity
If the shock detection system uses a single threshold, then implementation is simple, but it cannot differentiate between high-frequency and low-frequency shock events
Solution Approach 1:
The detection system dynamically adapts its response based on the frequency characteristics of detected shocks. By using dynamic filtering (high-pass and low-pass) rather than static thresholding, the system can differentiate between high-frequency and low-frequency shock events and apply appropriate responses. This dynamic approach enhances adaptability while maintaining reasonable implementation complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively prevents data corruption from mechanical shocks by inhibiting writes during high-frequency shocks and compensating for low-frequency shocks, ensuring accurate data writing and reading by maintaining head position on the track.
Implementation Method 1
A disk drive system with a shock detection channel that uses a piezoelectric shock sensor
Data Source
AI summary
A disk drive device has a shock sensor that detects mechanical shocks to a disk drive device to provide a shock output signal representative of such mechanical shocks. The shock output signal may be filtered to pass signals having a low frequency component of approximately between 1 and 4 KHz. Low frequency mechanical disturbances may be compensated for during writing to a track on the disk drive as a function of such low frequency component. In one embodiment, higher frequency shocks may be processed on a separate shock channel to inhibit or allow write operations. Different filters may be used on each of the shock channels.