Hard Drive VCM Disturbance Compensation via Position Error Signal Analysis
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Solution Overview
Problem
Hard drives face performance issues due to internal and external disturbances like vibrations, which cause read/write heads to lose track, leading to errors and reduced performance, as existing solutions like vibration sensors and disturbance observers are costly or add complexity.
Innovation Solution
The implementation of frequency analyzer circuitry and filter circuitry that detect dominant frequencies in position error signals to generate compensation signals for voice coil motor control, allowing for real-time disturbance compensation without the need for vibration sensors or disturbance observers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vibration sensors or disturbance observers are used to compensate for disturbances, then disturbance compensation effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The system uses its own position error signal to detect disturbance frequencies and generate compensation signals, eliminating the need for external vibration sensors or complex disturbance observers. The position error signal already contains disturbance information that can be processed to create effective compensation.
Solution Approach 2:
The invention extracts disturbance frequency information from the position error signal using frequency analyzer circuitry, separating the disturbance characteristics from the overall signal to generate targeted compensation signals for specific frequency components.
2Measurement precision
If vibration sensors are used to detect disturbances, then disturbance detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The system repurposes the existing position error signal, which is already generated by the servo control system, to detect disturbance frequencies. This eliminates the need for separate vibration sensors and reduces manufacturing costs while maintaining detection accuracy.
Solution Approach 2:
The position error signal serves dual purposes: controlling the servo system and providing disturbance frequency information. This multi-functionality eliminates the need for dedicated disturbance detection hardware, reducing overall system cost.
3Reliability
If disturbance observers are implemented, then disturbance compensation effectiveness is improved, but device complexity increases
Solution Approach 1:
The invention extracts only the essential disturbance frequency information from the position error signal using frequency analyzers, rather than implementing full disturbance observers. This selective extraction maintains compensation effectiveness while reducing complexity.
Solution Approach 2:
The patent replaces complex mechanical disturbance observation systems with electronic frequency analysis and filter-based compensation. The electronic approach processes signals more efficiently with less computational overhead and system complexity.
Data Source
AI summary
An apparatus includes a frequency analyzer circuitry, filter circuitry, and voice coil motor (VCM) control circuitry. The frequency analyzer circuitry is configured to detect one or more dominant frequencies of a position error signal (PES). The filter circuitry is configured to identify one or more filters in response to detecting the one or more dominant frequencies, apply the one or more identified filters to at least one of a microactuator control signal and PES, and generate a VCM compensation signal in response to the filtered PES or the microactuator control signal. The VCM control circuitry is configured to generate a VCM control signal in response to the VCM compensation signal.