Disk Drive Servo State Adjustment for Zone Crossing Transients
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing disk drive technologies face challenges in accurately positioning the head over data tracks due to varying servo sector data rates across different zones, leading to transients during zone crossings, which affect the precision and reliability of head positioning.
Innovation Solution
The implementation of a servo control system that adjusts the estimated state of the head during zone crossings by compensating for transients in the circumferential distance between servo sectors, using a flow diagram to adjust the radial position and velocity of the head, and employing programmable read channels with unique configurations for each servo zone to enhance data detection and timing synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the user data rate is increased toward the outer diameter tracks to achieve constant linear bit density, then data storage efficiency is improved, but transients occur during servo zone crossings affecting head positioning precision
Solution Approach 1:
The system performs preliminary detection of servo zone boundaries and pre-adjusts the estimated state (position and velocity) before the head actually crosses the boundary. This anticipatory adjustment compensates for the transient effects that would otherwise occur during zone crossing, maintaining positioning precision while allowing variable data rates across zones.
Solution Approach 2:
The system dynamically changes the estimated state parameters (radial position and velocity) based on the detected servo zone boundary crossing. By adjusting these parameters in response to zone transitions, the system compensates for the transients caused by variable data rates, ensuring continuous accurate positioning throughout the disk surface.
2Productivity
If servo sectors are recorded at varying data rates across different zones, then format efficiency is improved, but transients during zone crossings affect timing synchronization
Solution Approach 1:
The system uses feedback from the detected servo zone boundary information to adjust the estimated state. The servo control system continuously monitors zone boundaries and uses this feedback to make real-time adjustments to position and velocity estimates, maintaining timing synchronization despite variable data rates across different zones.
3Device complexity
If the data rate is constant across each zone, then design complexity is reduced, but positioning accuracy deteriorates during zone transitions
Solution Approach 1:
By detecting servo zone boundaries in advance and pre-adjusting the estimated state before crossing occurs, the system maintains positioning accuracy during transitions without requiring complex continuous variable data rate schemes. This preliminary adjustment approach preserves the simplicity of constant zone-based data rates while fixing the transition accuracy problem.
Data Source
AI summary
A disk drive is disclosed comprising a disk comprising a plurality of servo sectors defining a plurality of servo tracks. The servo tracks form a plurality of servo zones, where a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone. A servo control system servos a head over the disk. An estimated servo state of a servo control system is generated, and when the head crosses from a first servo zone to a second servo zone, the estimated servo state is adjusted to compensate for a transient in a circumferential distance between a servo sector in the first servo zone and a servo sector in the second servo zone.