Disk Drive Head Seek Noise Reduction via Velocity Measurement
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Solution Overview
Problem
Disk drives generate significant acoustic noise when exiting idle mode due to frequent seek operations, which is a concern for consumer applications like digital video recorders.
Innovation Solution
The disk drive modifies its operation by measuring the radial velocity of the head when exiting idle mode to determine a seek distance and direction, using a seek servo compensator and settle servo compensator initialized with optimized values to reduce noise, and employing a reduced acceleration/deceleration seek profile to minimize acoustic noise during seek and settle operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the disk drive performs frequent seek operations when exiting idle mode, then the head can quickly reach the target track, but acoustic noise is significantly generated
Solution Approach 1:
The patent applies preliminary action by pre-positioning the head at an intermediate track before the final target track when exiting idle mode. This two-stage approach first moves the head to an intermediate position (reducing initial velocity to minimize noise), then completes the seek to the target track. This preliminary positioning action resolves the contradiction by achieving quick overall response while limiting peak acoustic noise through controlled velocity reduction at the intermediate stage.
2Object-generated harmful factors
If the disk drive uses optimized servo compensator values to reduce acoustic noise, then noise is reduced, but the complexity of the control system increases
Solution Approach 1:
The patent applies segmentation by dividing the seek operation into distinct phases (idle mode exit, intermediate positioning, and final target acquisition), each with optimized servo compensator values. Different compensator parameters are used for different segments of the seek operation - with noise-reducing parameters during the intermediate positioning phase and performance-optimized parameters during the final approach. This segmentation allows noise reduction without requiring complete system redesign, as only specific phases use complex optimized parameters.
3Object-generated harmful factors
If the disk drive uses a reduced acceleration/deceleration seek profile, then acoustic noise is reduced, but the time to complete the seek operation increases
Solution Approach 1:
The patent applies dynamics by dynamically adjusting the seek profile based on the operational phase. During the intermediate positioning phase, reduced acceleration/deceleration rates are used to minimize acoustic noise. However, during the final approach to the target track, the system transitions to a more aggressive seek profile with higher acceleration rates to minimize the time penalty. This dynamic adaptation of seek parameters resolves the contradiction by applying noise-reducing dynamics only when necessary, then switching to time-optimized dynamics for the final positioning.
Data Source
AI summary
A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein each track comprises a plurality of servo sectors. When entering an idle mode, the head is floated over the disk, and when exiting the idle mode, a radial velocity of the head is measured, a seek distance is determined in response to the radial velocity, and a seek operation seeks the head the seek distance to a first track.