Hard Disk Seek Control via Dynamic Integral Gain Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional seek control methods in storage apparatuses prolong seek time due to extended settling time and reduced on-track accuracy when increasing integral gain to quickly converge head oscillations, leading to potential write or read errors.
Innovation Solution
A storage apparatus with a movement controlling unit, position controlling unit, gain retaining unit, and gain switching unit that increases integral gain during position control and smoothly switches back to the original gain after a predetermined retention time, optimized based on temperature variations to maintain performance without extending settling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the integral gain is increased to quickly converge head oscillations within the settling slice, then the settling time is reduced and seek performance is improved, but the on-track accuracy deteriorates and head position fluctuations increase after convergence
Solution Approach 1:
The patent applies dynamics by making the integral gain adjustable and time-dependent. The integral gain is set to a higher value during the settling period to quickly converge head oscillations, then automatically switched to a lower value after convergence to maintain on-track accuracy. This dynamic adjustment of control parameters resolves the contradiction between fast settling and accurate tracking.
Solution Approach 2:
The patent uses preliminary action by detecting head convergence into the settling slice before fully committing to the lower integral gain. The system monitors head position and determines when convergence has occurred, then switches the integral gain accordingly. This preliminary detection ensures that the gain switch happens at the optimal moment, achieving both fast settling and maintained accuracy.
2Reliability
If the settling time is extended to absorb variations in convergence time under different environmental conditions, then the reliability is improved, but the seek time is prolonged and performance is deteriorated
Solution Approach 1:
The patent applies parameter changes by adjusting the integral gain based on environmental conditions and convergence status. Instead of extending settling time to handle variations, the system changes the control parameter (integral gain) dynamically - using a higher gain for faster convergence when conditions permit, and adapting to environmental variations through this parameter adjustment rather than time extension.
Solution Approach 2:
The patent uses feedback by continuously monitoring head position to detect convergence into the settling slice. This feedback mechanism allows the system to determine when convergence has occurred and switch the integral gain accordingly, rather than using a fixed extended settling time. The feedback-driven approach achieves reliable convergence adaptation without prolonging seek time.
3Productivity
If the integral gain is increased to allow rapid convergence, then the productivity is improved, but the stability of head position deteriorates after convergence due to increased fluctuations
Solution Approach 1:
The patent applies dynamics by implementing a time-dependent integral gain that transitions from a higher value during convergence to a lower value after convergence. This dynamic parameter adjustment enables rapid convergence initially (improving productivity) while automatically reducing fluctuations after convergence (maintaining stability). The system adapts its control characteristics based on the convergence stage.
Solution Approach 2:
The patent uses periodic action through the automatic switching mechanism that detects convergence and triggers a gain change. The system operates in two distinct phases: a high-gain phase for rapid convergence and a low-gain phase for stable maintenance. This periodic switching between control modes achieves both fast convergence and subsequent stability.
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
Rapid convergence of head oscillations within the settling slice ensures accurate track following without prolonging seek time, maintaining performance even with higher track densities and varying environmental conditions.
Implementation Method 1
a target speed profile is generated based on the number of remaining tracks (track difference) relative to a target track to control a speed of a head actuator by driving with a voice coil motor
Implementation Method 2
a position control is started to position a head to a track center; when arriving at the target track, the speed control is discontinued to enable only the position control
Data Source
AI summary
A movement controlling unit performs movement control of a head toward a target track on a magnetic disk medium driving a head actuator, and a position controlling unit performs position control of the head actuator in accordance with proportional integral calculations such that a deviation of a head position relative to a track center is eliminated when the moving head arrives at the target track. A gain retaining unit retains an integral gain of the proportional integral calculations in an increased state during a predetermined retention time from the start of the position control, and a gain switching unit switches the increased integral gain smoothly to the original integral gain when the retention time has elapsed.