Multi-Actuator Disk Seek Control for Vibration and Speed Trade-off

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Solution Overview

Problem

In multi-actuator magnetic disk devices, limiting jerk to reduce vibration-induced position errors leads to delayed seek times and deteriorated command access performance, as vibration from one actuator can shake another, causing errors during data access operations.

Innovation Solution

Implementing a dual-control system where one actuator performs seek control with high jerk when the other is not accessing a data sector, and using reordering tables and seek control modes to optimize seek times and reduce interference, allowing for improved command access performance by matching acceleration peaks and adjusting seek control parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If jerk is limited to reduce vibration-induced position errors, then head position accuracy is improved, but seek time is delayed and command access performance deteriorates

Engineering Contradiction:

Improvehead position accuracyVSAvoidseek time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system dynamically switches between two seek control modes (first seek control with jerk limitation for high accuracy, and second seek control without jerk limitation for fast access) based on the operational state of other actuators. This dynamic adaptation allows the system to optimize between accuracy and speed depending on real-time conditions, resolving the contradiction by making the control strategy context-dependent rather than fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the jerk control parameter dynamically by selecting between different seek control modes. When no other actuator is accessing data, the system transitions from jerk-limited mode to unrestricted mode, effectively changing the acceleration profile parameters to achieve faster seek times without compromising accuracy when needed.

Inventive Principle:

Principle #35Parameter changes

2Speed

If one actuator performs seek operation, then data access speed is improved, but vibration excites other actuators causing tracking head shaking and position errors

Engineering Contradiction:

Improvedata access speedVSAvoidtracking accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The system performs preliminary checking of other actuators' operational states before initiating a seek operation. If another actuator is already accessing data, the system preemptively prevents the seek operation that would cause harmful vibrations, thereby avoiding tracking errors before they occur. This preliminary anti-action ensures that speed improvements do not compromise reliability.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The invention converts the potential harm of vibration into a beneficial coordination mechanism by using the operational state information of other actuators to intelligently control seek operations. The vibration issue is not merely suppressed but utilized as a signal to optimize overall system performance, turning a problematic interaction into a coordinated multi-actuator operation strategy.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS11862197B2Magnetic disk device

Publication Date: 2024.01.02 KK TOSHIBA

AI summary

According to one embodiment, a magnetic disk device which includes two or more independently drivable actuator blocks and performs seek control with a low jerk in which a jerk that is a derivative of acceleration is limited, wherein in a state where a first actuator block is not accessing a data sector of a disk, a second actuator block that is not the first actuator block accesses the data sector of the disk by seek control with a high Jerk.