Adaptive Feed-Forward Control for Disk Drive Timing Jitter
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Solution Overview
Problem
Existing disk drive systems face challenges in accurately positioning the head over the disk due to vibrations, which induce timing jitter and position errors, affecting the synchronization of the disk-locked clock and the accuracy of head positioning.
Innovation Solution
A vibration detection system generates a vibration signal, which is filtered using an adaptive filter to produce feed-forward compensation values applied to the timing loop, synchronizing the disk-locked clock with the disk's rotation frequency and compensating for vibrations, thereby improving head positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional timing loops are used without vibration compensation, then the system structure remains simple, but timing jitter and position errors increase due to vibrations
Solution Approach 1:
The vibration sensor detects vibrations before they affect the disk rotation timing, and the adaptive filter pre-processes the vibration signal to generate compensation values that are fed forward to the timing loop, preventing timing jitter before it occurs
Solution Approach 2:
A vibration sensor and adaptive filter are introduced as intermediary components between the vibration source and the timing loop, detecting and compensating for vibrations before they can disrupt the disk-locked clock synchronization
2Manufacturing precision
If adaptive feed-forward control is implemented to compensate for vibrations, then head positioning accuracy improves, but the device complexity increases due to additional components
Solution Approach 1:
The system uses feedback from the vibration sensor through an adaptive filter that continuously adjusts filter coefficients based on the position error signal, creating a closed-loop adaptive control mechanism that optimizes vibration compensation in real-time
Solution Approach 2:
The patent replaces complex mechanical vibration isolation mechanisms with an electronic signal processing approach using vibration sensors, adaptive filters, and feed-forward control algorithms to achieve vibration compensation
3Reliability
If vibration compensation is not applied, then the system operates with lower complexity, but position error signals become inaccurate due to timing jitter
Solution Approach 1:
The timing loop applies vibration compensation values in advance to the disk-locked clock generation, preventing timing jitter before it corrupts the position error signal measurement during servo sector reading
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
The solution effectively compensates for vibrations, enhancing the synchronization of the disk-locked clock and improving the accuracy of head positioning over the disk, reducing timing jitter and position errors.
Implementation Method 1
a vibration detector configured to generate a vibration signal in response to a vibration affecting the data storage device
Implementation Method 2
an adaptive filter is adapted based on the adaptation control signal, wherein the adaptive filter filters the vibration signal to generate feed-forward compensation values
Implementation Method 3
a timing loop configured to generate a disk-locked clock substantially synchronized to a rotation frequency of the disk
Data Source
AI summary
A data storage device is disclosed comprising a head actuated over a disk and a vibration detector configured to generate a vibration signal in response to a vibration affecting the data storage device. A timing loop is configured to generate a disk-locked clock substantially synchronized to a rotation frequency of the disk. An adaptation control signal is generated based on the vibration signal and an error signal of the timing loop. An adaptive filter is adapted based on the adaptation control signal, wherein the adaptive filter filters the vibration signal to generate feed-forward compensation values. The feed-forward compensation values are applied to the timing loop to compensate for the vibration.