Magnetic Head Seek Control for Actuator Vibration Settling
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Solution Overview
Problem
Vibrations during seek operations in magnetic disk devices can cause positioning errors in the magnetic head, leading to incomplete settling determinations and reduced performance due to vibrations transmitted from the actuator.
Innovation Solution
A controller system with acceleration and vibration detection sections to identify and correct vibrations in the actuator by adjusting the drive current timing, including methods to insert a constant speed period or adjust the deceleration timing to align with predicted vibration phases, ensuring accurate settling determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the seek operation is performed quickly to improve productivity, then the positioning precision deteriorates due to vibrations in the actuator
Solution Approach 1:
The system performs preliminary actions by detecting vibrations during the seek operation and predicting future vibration states. Based on these predictions, the settling determination timing is adjusted in advance to occur when vibrations are minimal, ensuring accurate positioning determination before the next operation begins.
Solution Approach 2:
The system continuously monitors actuator vibrations during seek operations and uses this feedback to dynamically adjust the settling determination timing. By comparing actual vibration levels with predicted vibration patterns, the system optimizes the timing of positioning determinations to occur during low-vibration periods, thereby maintaining precision despite high-speed operations.
2Device complexity
If the settling determination timing is fixed to simplify control, then the measurement precision deteriorates due to vibrations occurring at determination moments
Solution Approach 1:
The settling determination timing is transformed from a fixed value to a dynamic variable that adapts to actual vibration conditions. The control section adjusts determination timing based on detected vibration levels and predicted vibration patterns, allowing the system to automatically select optimal measurement moments without complex manual configuration.
Solution Approach 2:
The system performs self-adjustment by autonomously determining optimal settling determination timing based on its own vibration detection and prediction capabilities. The control section uses internally generated vibration predictions and actual detection data to automatically optimize measurement timing, eliminating the need for external calibration or complex preset configurations.
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
Accurate detection and correction of vibrations reduce positioning errors, improve data read/write reliability, and enhance processing speed by ensuring timely settling determinations.
Implementation Method 1
an actuator which holds the magnetic head to move in the radial direction of the magnetic disk with voice coil motor drive
Implementation Method 2
a vibration detection section which detects vibration occurring in the actuator, based on a difference between the accelerations detected by the acceleration calculation section
Data Source
AI summary
According to one embodiment, a magnetic disk device includes an actuator which holds a magnetic head to move in a radial direction of a magnetic disk with voice coil motor drive, and a controller. The controller moves a magnetic head from a current position to a target position by controlling the voice coil motor drive. The controller calculates an acceleration of the magnetic head, based on a position history of the magnetic head, and calculates an acceleration of the magnetic head, based on a value of a drive current of the voice coil motor. The controller detects vibration occurring in the actuator, based on a difference between the calculated accelerations.


