Disk Drive Actuator Current Management via Adaptive Seek Profiles
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Solution Overview
Problem
Concurrently operating multiple voice coil motors (VCMs) in disk drives can cause overcurrent conditions due to overlapping seek profiles, leading to power consumption issues and potential emergency power failures when the combined current draw exceeds supply limits, resulting in reduced performance and increased access latency.
Innovation Solution
Implementing a de-rated seek profile for at least one VCM to adjust the acceleration or deceleration phase, thereby reducing the combined current draw and avoiding overcurrent conditions, while maintaining seek performance and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple voice coil motors operate concurrently with overlapping seek profiles, then head positioning speed and throughput are improved, but combined current draw exceeds supply limits causing overcurrent conditions and potential power failures
Solution Approach 1:
The patent applies dynamics by making the seek profile adjustable and adaptive. The system dynamically modifies the seek profile of at least one VCM based on detected overcurrent conditions, transitioning from a fixed performance-optimized profile to an adjusted profile that reduces current demand during critical time periods while maintaining head positioning functionality.
Solution Approach 2:
The patent changes operational parameters by adjusting the seek profile parameters (acceleration, deceleration, velocity) of the VCMs. When overcurrent is detected, the system modifies these parameters to reduce the combined current draw, specifically altering the time-varying current characteristics of the seek operation to prevent power supply failures.
2Loss of energy
If the seek profile is adjusted to reduce current draw, then overcurrent conditions are avoided and power consumption is reduced, but seek performance may be compromised
Solution Approach 1:
The patent applies partial action by selectively adjusting the seek profile only for one or more VCMs when overcurrent conditions are detected, rather than uniformly reducing performance for all actuators. The adjustment is applied partially in time (during the seek operation) and partially in magnitude (modifying but not eliminating acceleration and deceleration phases), thereby reducing power consumption while preserving essential seek functionality.
Solution Approach 2:
The system dynamically adapts the seek profile based on real-time power supply conditions. The adjustment is not static but responsive to detected overcurrent conditions, allowing the system to optimize between power consumption and seek performance by modifying acceleration and deceleration characteristics only when necessary to prevent overcurrent failures.
3Speed
If acceleration phase is increased to reduce seek time, then head positioning speed is improved, but combined current draw during overlapping seeks exceeds supply limits
Solution Approach 1:
The patent applies preliminary action by detecting overcurrent conditions and preemptively adjusting the seek profile before power supply failures occur. The system monitors the combined current draw of concurrently operating VCMs and proactively modifies the acceleration phase parameters to prevent exceeding power supply limits, rather than reacting after the problem manifests.
Solution Approach 2:
The system changes the acceleration phase parameters of the seek profile to balance speed and power consumption. By adjusting acceleration characteristics and associated current draw profiles, the system optimizes the trade-off between head positioning speed and combined power consumption, ensuring that acceleration rates remain within safe current limits during overlapping seek operations.
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 solution effectively prevents overcurrent conditions by adjusting seek profiles, ensuring reliable operation and reducing power consumption without compromising seek time or throughput, thus enhancing the overall performance and reliability of disk drives.
Implementation Method 1
a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM)
Data Source
AI summary
A data storage device is disclosed comprising a first actuator configured to actuate a first head over a first disk surface, and a second actuator configure to actuate a second head over a second disk surface. A first seek of the first head over the first disk surface is initiated during a first seek time based on a first seek profile. A second seek of the second head over the second disk surface is initiated during a second seek time based on a second seek profile. When the second seek time at least partially overlaps the first seek time and at least the second seek profile is a de-rated seek profile, the second seek profile is adjusted to avoid an overcurrent condition.