Hard Disk Drive Head Unload Management via Seek Count Monitoring
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Solution Overview
Problem
Modern electronic storage devices face premature failure due to wear patterns that weaken the head actuation mechanism, leading to permanent damage when the heads remain engaged with the media during power down, causing Head-On-Media (HOM) failures.
Innovation Solution
The electronic system employs a control circuitry that monitors seek counts and detects pivot grease bumps by analyzing the head actuation motor's current and fine positioner's offset voltage, using increased velocity unloads and boomerang seeks to safely park the heads on the head loading ramp, preventing HOM failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the head actuation mechanism is used continuously for heavy usage, then storage capacity and functionality are improved, but wear patterns develop that weaken the ability to properly park the head actuation mechanism
Solution Approach 1:
The system performs preliminary detection of grease bumps before the head unload operation. The control circuitry analyzes motor current and offset voltage during seek operations to identify grease bump conditions in advance, allowing the system to prepare appropriate unload strategies before the critical unload phase occurs.
Solution Approach 2:
The control circuitry continuously monitors motor current and offset voltage feedback during head positioning operations. This feedback mechanism allows real-time detection of grease bump conditions by analyzing deviations in current consumption and positioner voltage, enabling adaptive adjustment of unload parameters.
2Loss of energy
If power is removed while heads remain engaged with media, then energy consumption is reduced, but permanent failure modes occur including media motor failure, material transfer, or slider detachment
Solution Approach 1:
When a grease bump is detected, the system executes an accelerated unload sequence that rapidly moves the head assembly through the problematic grease bump region. This rushed-through approach prevents the head from stalling on the grease bump and ensures complete unload before power removal, eliminating the risk of HOM failures while maintaining energy efficiency.
Solution Approach 2:
The system applies preliminary counter-actions to prevent harmful effects. By detecting grease bumps in advance and adjusting unload parameters accordingly, the system prevents the head from becoming stuck on grease bumps during power-down, thereby avoiding catastrophic failures such as media motor failure or slider detachment.
3Device complexity
If traditional unload methods are used without grease bump detection, then device complexity is reduced, but premature unload failures occur due to pivot grease bumps
Solution Approach 1:
The system uses its existing operational parameters (motor current and offset voltage) to self-diagnose grease bump conditions. No additional sensors or complex detection hardware are required; the control circuitry leverages feedback already present during normal seek operations to identify unload problems and adjust accordingly.
Solution Approach 2:
The system dynamically changes unload parameters based on detected conditions. When grease bumps are identified through current and voltage analysis, the control circuitry adjusts motor velocity, torque, and timing parameters to ensure successful head unload, transforming a static unload process into an adaptive one without adding hardware complexity.
Data Source
AI summary
An apparatus includes: a media; a head assembly over the media; a head actuation motor coupled to the head assembly; control circuitry, coupled to the head actuation motor, configured to position the head assembly; and a head loading ramp, adjacent to the media; wherein: the control circuitry is further configured to: generate a seek count; and park the head assembly, off of the media, on the head loading ramp, controlling a speed of the head actuation motor based on the seek count.