Magnetic Disk Seek Timing Control for Vibration Phase Cancellation
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Solution Overview
Problem
Magnetic disk devices face challenges in precisely controlling actuators due to rotation vibration caused by voice coil motors during seek operations, leading to difficulties in accurately positioning magnetic heads.
Innovation Solution
A magnetic disk device with a controller and vibration sensor that predicts current and residual vibrations, adjusting the start timing of seek operations to ensure the phases of these vibrations are anti-phase, thereby reducing composite vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If seek operations are performed continuously without timing adjustment, then productivity is improved, but vibration increases causing positioning precision to deteriorate
Solution Approach 1:
The patent applies periodic action by adjusting the start timing of seek operations based on the vibration period of the voice coil motor. The controller predicts vibration phases and delays seek start timing so that current seek vibration is out of phase with residual vibration from previous seeks, creating a periodic timing pattern that reduces composite vibration while maintaining continuous operation capability
Solution Approach 2:
The patent changes the temporal parameter of seek operations by dynamically adjusting the start timing based on predicted vibration phases. The controller calculates break time based on VCM vibration characteristics and modifies the timing parameter of subsequent seek operations to achieve phase opposition, thereby reducing composite vibration without sacrificing productivity
2Manufacturing precision
If vibration compensation timing is added to reduce composite vibration, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback by using the vibration sensor to detect actual VCM vibration and comparing it with predicted vibration. The controller adjusts seek start timing based on this feedback, creating a closed-loop system that compensates for vibration while maintaining simplicity in the overall device architecture
Solution Approach 2:
The patent replaces complex mechanical vibration isolation mechanisms with a control-based approach. Instead of adding physical damping elements or isolation structures, the system uses timing adjustment based on vibration prediction to achieve the same effect, reducing mechanical complexity while improving precision
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
This approach allows for precise control of the actuator, reducing vibration and improving the accuracy of magnetic head positioning by minimizing composite vibration through the strategic timing of seek operations.
Implementation Method 1
a vibration sensor. The controller predicts a first vibration caused by seeking that is currently underway, based on a current seeking control signal, predicts a second vibration based on vibration detected by the sensor
Implementation Method 2
adjusts a start timing of the present seeking so that a phase of the first vibration does not match a phase of the second vibration
Data Source
AI summary
A magnetic disk device includes a magnetic disk having a plurality of tracks, a magnetic head used for writing data on the magnetic disk and reading data from the magnetic disk, a controller configured to control seek operations of the magnetic head, and a vibration sensor. The controller predicts a first vibration caused by a currently executed seek operation, based on a seek control signal, predicts a second vibration based on vibration detected by the sensor, and determines an adjusted start time of the currently executed seek operation so that a phase of the first vibration does not match a phase of the second vibration.