Disk Locked Clock Vibration Compensation in Hard Drives
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Solution Overview
Problem
Hard drives face performance issues due to internal and external disturbances, such as vibrations, which cause read/write heads to lose track, leading to errors, and existing solutions rely on expensive vibration sensors for compensation.
Innovation Solution
A disk locked clock system generates a timing error signal used by a feedforward microactuator compensator and VCM compensator to produce compensation signals without relying on vibration sensors, effectively decoupling microactuator and voice coil motor control loops to correct for disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vibration sensors are used for disturbance compensation, then tracking accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The patent extracts the disturbance information from the vibration sensor and uses only the necessary timing error signal from the disk locked clock system, eliminating the need for the vibration sensor itself while maintaining tracking accuracy
Solution Approach 2:
The patent creates a timing error signal that copies the essential disturbance information previously obtained from vibration sensors, using the disk locked clock system to generate equivalent compensation data without requiring physical sensors
2Measurement precision
If vibration sensors are used for disturbance compensation, then tracking accuracy is improved, but device cost increases
Solution Approach 1:
The patent removes the vibration sensor component from the system, extracting only the necessary timing error information from the disk locked clock system, thereby reducing device cost while maintaining tracking accuracy
Solution Approach 2:
The patent enables the disk locked clock system to self-generate the timing error signal needed for compensation, eliminating the need for external vibration sensors and reducing overall device cost
3Reliability
If microactuator and VCM control loops are coupled, then disturbance compensation is achieved, but control stability becomes difficult to maintain
Solution Approach 1:
The patent segments the control system by decoupling the microactuator and VCM control loops, allowing each to operate independently while still achieving disturbance compensation through the timing error signal
Solution Approach 2:
The patent introduces the timing error signal as an intermediary that mediates between the disk locked clock system and the decoupled control loops, enabling disturbance compensation without direct coupling between microactuator and VCM controls
Data Source
AI summary
An apparatus includes a disk locked clock system and a feedforward microactuator compensator. The disk locked clock system is configured to estimate a timing error and generate a timing error signal. The feedforward microactuator compensator is configured to generate a microactuator compensation signal, without use of a vibration sensor signal, in response to the timing error signal.