Disk Drive Shock Detection with Adjustable Sensitivity
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Solution Overview
Problem
Physical shocks to disk drives can cause the head to deviate from the target track, leading to data corruption and unnecessary write operation aborts due to false shock detection triggered by system noise, which degrades disk drive performance.
Innovation Solution
Implementing a dual shock detection system with adjustable sensitivity, where a first shock detector with higher sensitivity is decreased when excessive events are detected, and a second shock detector with lower sensitivity is used to confirm a decrease in shock amplitude before increasing the first detector's sensitivity, thereby reducing false shock events and maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shock detector with high sensitivity is used to detect physical shocks, then shock detection accuracy is improved, but false shock detection due to system noise increases
Solution Approach 1:
The patent applies dynamics by making the shock detector's sensitivity adjustable rather than fixed. The controller dynamically modifies the shock detector's sensitivity based on detected shock events, transitioning between high sensitivity for accurate detection and lower sensitivity to avoid false detections from system noise
Solution Approach 2:
The patent implements feedback by using the output from the shock detector to control the detector's own sensitivity. When shock events are detected, the controller receives feedback and adjusts the sensitivity accordingly, creating a closed-loop system that adapts to prevent false detections
2Measurement precision
If shock detection sensitivity is increased to detect smaller shocks, then detection capability is improved, but unnecessary write operation aborts increase
Solution Approach 1:
The sensitivity of the shock detector is made dynamic rather than static. The controller adjusts sensitivity based on the frequency of detected shock events, allowing the system to maintain high detection capability when needed while reducing false positives that would trigger unnecessary write operation aborts
Solution Approach 2:
The patent changes the sensitivity parameter of the shock detector based on operating conditions. By monitoring shock event frequency and adjusting the sensitivity parameter accordingly, the system optimizes the balance between detecting real shocks and avoiding false detections that would interrupt write operations
Data Source
AI summary
A disk drive is disclosed comprising a head actuated over a disk, and control circuitry comprising a first shock detector and a second shock detector. A first number of shock events is detected based on the first shock detector, and when the first number of shock events exceeds an upper event threshold, a sensitivity of the first shock detector is decreased. After decreasing the sensitivity of the first shock detector, a second number of shock events is detected based on the second shock detector operating at a higher sensitivity than the first shock detector. When the second number of shock events falls below a lower event threshold, the sensitivity of the first shock detector is increased.