Mass Balanced Flexure Gimbal for HDD Sway Mode Control
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Solution Overview
Problem
Microactuator mechanisms in hard-disk drives often excite unwanted sway modes of vibration due to mass imbalances, leading to significant head off-track issues and compromised servo bandwidth.
Innovation Solution
A mass-balanced flexure gimbal is introduced, where a mass is attached to the suspension flexure on the side opposing the piezo actuation devices to counteract their mass, thereby balancing the moment force about the gimbal axis, reducing unwanted vibration modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microactuator mechanisms are used for fine head positioning, then positioning precision is improved, but unwanted sway modes of vibration are excited due to mass imbalances
Solution Approach 1:
A counterbalancing mass is attached to the flexure gimbal assembly on the side opposite the piezoelectric microactuator. This counterweight creates a moment that balances the moment generated by the microactuator mass about the gimbal axis, thereby eliminating the mass imbalance that causes sway mode vibration while preserving the microactuator's fine positioning capability
2Measurement precision
If piezo actuation devices are mounted on the slider, then fine positioning capability is achieved, but mass imbalance occurs about the gimbal axis
Solution Approach 1:
The counterbalancing mass is strategically positioned on the flexure gimbal assembly to create a moment that offsets the moment produced by the piezoelectric actuator mass. This restores mass balance about the gimbal axis, eliminating sway vibrations while maintaining the actuator's positioning function
3Object-affected harmful factors
If mass-balanced flexure gimbal is implemented, then sway mode vibration is eliminated, but device complexity increases
Solution Approach 1:
The solution adds a single counterbalancing mass element to the existing flexure gimbal assembly. This minimal addition achieves sway mode elimination without requiring complex structural modifications, maintaining manufacturing simplicity while resolving the vibration issue
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
The mass-balanced flexure gimbal effectively eliminates the sway mode of vibration, reducing head off-track errors and enhancing servo bandwidth by balancing the moment forces, resulting in improved head positioning accuracy.
Implementation Method 1
a mass is attached to the suspension flexure on the side opposing the piezo actuation devices to counteract their mass, thereby balancing the moment force about the gimbal axis
Data Source
AI summary
Approaches to a mass balanced flexure gimbal assembly for controlling the sway mode of the loadbeam portion of the suspension of a head gimbal assembly (HGA) of a hard-disk drive (HDD). The sway mode of concern is that which is excited when a head slider is actuated by a plurality of piezo actuation devices of a secondary actuation system. A suspension includes a mass attached to the suspension flexure and configured for balancing a moment force about the gimbal, about which a slider rotates when microactuated. The mass is located on the side of the slider opposing the side on which the piezo actuation devices are mounted, to counteract the mass of the piezo devices.