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

VSEngineering Contradiction Analysis

1Productivity

If the seek operation is performed quickly to improve productivity, then the positioning precision deteriorates due to vibrations in the actuator

Engineering Contradiction:
Improveseek operation speedVSAvoidpositioning precision
Core Design Contradiction:
ProductivityVSManufacturing precision

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.

Inventive Principle:
Principle #10Preliminary action

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.

Inventive Principle:
Principle #23Feedback

2Device complexity

If the settling determination timing is fixed to simplify control, then the measurement precision deteriorates due to vibrations occurring at determination moments

Engineering Contradiction:
Improvecontrol complexityVSAvoidpositioning measurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

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.

Inventive Principle:
Principle #15Dynamics

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.

Inventive Principle:
Principle #25Self-service

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

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

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

Methodology Applied
Scientific EffectVibration detection through acceleration comparison: Accelerometer

Data Source

PatentUS12518792B2Magnetic disk device and method of controlling the same
Publication Date: 2026.01.06 KK TOSHIBA
  • US12518792B2 patent drawing
  • US12518792B2 patent drawing
  • US12518792B2 patent drawing

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.