Disc Device NRRO Suppression Filter Matching
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Solution Overview
Problem
Existing methods for suppressing non-repeatable run-outs (NRRO) in disc drives, such as adding an NRRO suppression filter to the feedback system, do not effectively improve the accuracy of positioning the head to a target position on the disc surface due to mismatched gain and phase at frequencies around the suppression target frequency, leading to fluctuations in the sensitivity function.
Innovation Solution
A disc device with a processor and controller that includes a comparison unit, a first filter (NRRO suppression filter) to estimate and cancel out disturbances, and a second filter (matching filter) to adjust the gain and phase of the estimated disturbance signal, ensuring the gain and phase coincide with the inverse characteristics of the sensitivity function, thereby correcting the operation amount and improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an NRRO suppression filter is added to the feedback system, then non-repeatable run-outs are suppressed, but the gain and phase of the sensitivity function do not coincide with the desired characteristics, reducing positioning accuracy
Solution Approach 1:
A matching filter is introduced as an intermediary component between the NRRO suppression filter and the actuator. This matching filter adjusts the gain and phase of the control signal to compensate for the changes introduced by the NRRO suppression filter, ensuring that the overall sensitivity function maintains the desired characteristics while still achieving NRRO suppression.
Solution Approach 2:
The matching filter dynamically adjusts the gain and phase parameters of the control signal based on the frequency characteristics of the NRRO suppression filter. By changing these parameters in a controlled manner, the system maintains positioning accuracy while suppressing non-repeatable run-outs.
2Object-affected harmful factors
If an NRRO suppression filter is added to cancel disturbances at suppression target frequency, then NRRO is reduced, but fluctuations in the sensitivity function increase at frequencies around the suppression target frequency
Solution Approach 1:
The matching filter serves as a mediator that smooths out the fluctuations in the sensitivity function caused by the NRRO suppression filter. It adjusts the control signal to compensate for the sharp changes in gain and phase around the suppression target frequency, thereby stabilizing the overall system response.
Solution Approach 2:
The matching filter introduces dynamic adjustment of gain and phase parameters that adapt to the frequency characteristics of the system. This dynamic compensation ensures that the sensitivity function remains stable across a wide frequency range, including frequencies around the suppression target where fluctuations would otherwise occur.
Data Source
AI summary
According to one embodiment, a disc device outputs a first signal for canceling out a first disturbance at a predetermined frequency of a position error, outputs a second signal which gain or phase of the first signal are changed, and corrects an operation amount or the position error by using the second signal.