Hard Disk Drive Vibration Detection Using Voice Coil Motor Feedback
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Solution Overview
Problem
Hard disk drives face challenges in detecting vibration without the use of accelerometers, which increase cost and complexity.
Innovation Solution
A circuit within the hard disk drive that provides a control signal to the voice coil motor, incorporating a state predictor and an inversion filter to compute a vibration estimate and compensate for vibrations, eliminating the need for accelerometers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accelerometer is used to detect vibration, then vibration detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The system uses the voice coil motor's own position feedback signal to estimate vibration, making the existing component serve dual purposes. The state predictor and inversion filter process the position signal to extract vibration information, eliminating the need for separate sensors and reducing overall system complexity while maintaining detection accuracy
Solution Approach 2:
The patent introduces a state predictor and inversion filter as intermediary processing elements that transform the position feedback signal into vibration estimates. These intermediaries enable vibration detection without direct physical sensors, bridging the gap between position measurement and vibration detection functions
2Measurement precision
If an accelerometer is used to detect vibration, then vibration detection capability is improved, but manufacturing cost increases
Solution Approach 1:
The position feedback signal from the voice coil motor control system is repurposed to serve both its original function of head positioning and the new function of vibration detection. This multi-functionality eliminates the need for additional accelerometer components, simplifying manufacturing and reducing costs while maintaining vibration detection capability
Solution Approach 2:
The patent merges the vibration detection function with the existing position control system by using the same position feedback signal for both purposes. The state predictor and inversion filter combine information from the position signal to generate vibration estimates, consolidating functions and reducing component count for easier manufacturing
Data Source
AI summary
A hard disk drive with a circuit that provides a control signal to a voice coil motor to move a head across a disk. The disk drive includes a circuit that provides a control signal to the voice coil motor to move the head. The circuit also has a state predictor and an inversion filter that compute a vibration estimate used to detect a vibration in the drive. When a threshold vibration is detected a vibration estimate is combined with the control signal to compensate for the vibration. The circuit detects the vibration without the need for an accelerometer or other sensor.