Seek Control Device Frequency Characteristic Adjustment
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Solution Overview
Problem
In disk devices, the existing two-degree of freedom seek control methods face challenges in accurately positioning the head due to shifts between the target trajectory and actual response of the plant, leading to dispersion in seek time and potential overruns or underruns, especially as track density increases.
Innovation Solution
A seek control method that generates a seek trajectory signal and a feedback control signal to adjust the frequency characteristic of the feedback loop, determining and suppressing the representative frequency based on seek time to minimize position shifts and prevent overruns or underruns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the seek trajectory is generated using conventional two-degree of freedom control, then the head positioning speed is improved, but position shift occurs between target trajectory and actual response leading to seek time dispersion
Solution Approach 1:
The patent applies feedback control by monitoring the actual position of the head during seeking and comparing it with the target trajectory. When position deviation is detected, the control system dynamically adjusts the seek trajectory to compensate for the deviation, ensuring the head reaches the target position accurately despite variations in plant characteristics.
Solution Approach 2:
The patent implements dynamic trajectory adjustment during the seeking process. Instead of using a fixed predetermined trajectory, the system continuously modifies the target trajectory based on real-time position feedback, making the control system adaptive to actual plant behavior and reducing position shift.
2Manufacturing precision
If the feedback control loop operates with standard gain settings, then position shift is corrected, but servo frequency band is dropped causing trajectory control interference
Solution Approach 1:
The patent dynamically adjusts the frequency characteristics of the feedback control loop based on the seeking phase. During trajectory control, the system maintains higher frequency band to avoid interference, while during position correction, it adjusts gain settings to prioritize accuracy. This dynamic adaptation allows both high-speed trajectory control and precise position correction without mutual interference.
3Quantity of substance
If the seek distance increases to reach higher track density, then recording capacity is improved, but position shift becomes more significant causing overruns or underruns
Solution Approach 1:
The patent uses continuous position feedback during seeking to detect and correct position shift. By comparing actual position with target trajectory in real-time, the system can compensate for cumulative position errors that occur during long-distance seeking, preventing overruns or underruns even when accessing tracks far from the current position in high-density storage.
Solution Approach 2:
The patent performs preliminary position verification and trajectory adjustment before completing the seek operation. By anticipating potential position shifts based on seek distance and making preliminary corrections to the target trajectory, the system prevents position errors from accumulating to the point of causing overruns or underruns.
Data Source
AI summary
A seek control device controls the seek of a plant to prevent the position shift due to an error between a model for generating seek current and a model of the plant. When the seek trajectory is provided by seek trajectory generation for controlling the seek of a plant, the frequency characteristic of a feed back loop is changed according to the seek time and the gain of the position shift component due to the shift of the actual plant and the model of the plant is increased, so as to suppress the position shift by the feed back loop. Dispersion of the seek time can be decreased, and an overrun or underrun can be prevented.