Microactuator Track Seeking Using Feedforward Voltage
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Solution Overview
Problem
Existing hard drive systems face inefficiencies in positioning transducers over magnetic recording tracks, particularly during seek operations, as they rely solely on voice coil motors, which are slow due to the large mass they need to move.
Innovation Solution
The use of a voice coil motor in conjunction with a microactuator, such as one made of lead-zirconate-titanate (PZT), that applies a feedforward voltage profile to quickly and accurately position the transducer over desired tracks, reducing seek times by moving only the suspension assembly rather than the entire actuator assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a voice coil motor is used to position the transducer, then the transducer can be positioned over the magnetic recording medium, but the positioning speed is slow due to the large mass of the entire actuator assembly
Solution Approach 1:
The actuator assembly is divided into two independent positioning systems: a voice coil motor for coarse positioning of the entire actuator assembly, and a microactuator for fine positioning of only the suspension assembly and transducer. This segmentation allows the microactuator to achieve fast positioning speeds by moving only the lightweight suspension assembly rather than the entire heavy actuator assembly.
Solution Approach 2:
The patent replaces part of the mechanical voice coil motor system with a piezoelectric microactuator system. The microactuator uses piezoelectric material (PZT) that converts electrical voltage directly into mechanical displacement, eliminating the need to move large mechanical masses and achieving much faster response times for track seeking operations.
2Loss of time
If the entire actuator assembly is moved to position the transducer, then positioning can be achieved, but seek times are increased due to the large mass
Solution Approach 1:
The positioning function is segmented between the voice coil motor (moving the actuator assembly) and the microactuator (moving only the suspension assembly). During track seeking operations, the microactuator rapidly repositions the lightweight suspension assembly to different tracks, dramatically reducing seek times compared to moving the entire heavy actuator assembly.
Solution Approach 2:
The patent extracts the fine positioning function from the main actuator assembly and implements it separately through the microactuator attached to the suspension assembly. This extraction allows the suspension assembly to be moved independently and rapidly without the inertia of the entire actuator assembly, reducing seek times.
3Measurement precision
If a microactuator is added to the actuator assembly, then positioning accuracy and speed are improved, but device complexity increases
Solution Approach 1:
The patent merges the voice coil motor positioning system with the microactuator positioning system into a unified dual-stage actuation system. The VCM provides coarse positioning while the microactuator provides fine positioning, and both systems work together under a single control algorithm that coordinates their actions to achieve high positioning accuracy without requiring completely separate control systems.
Solution Approach 2:
The control system uses feedback from servo information read by the transducer to determine the actual position of the suspension assembly and adjusts the microactuator voltage accordingly. This feedback mechanism enables precise positioning while simplifying control by using the existing servo infrastructure rather than requiring entirely new control systems.
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
This combination enables faster data access rates by reducing seek times and improving positioning accuracy, allowing for quicker transitions between tracks and maintaining precise track following.
Implementation Method 1
The microactuator is made of a piezoelectric material, such as lead-zirconate-titanate (PZT), that transforms a applied voltage to a mechanical displacement
Implementation Method 2
positioning the transducer over a first track using a voice coil motor (VCM)
Data Source
AI summary
A method is disclosed for positioning a transducer over a magnetic recording medium having a plurality of tracks. The method includes positioning the transducer over a first track using a voice coil motor (VCM) and a microactuator. The method further includes applying a feedforward voltage profile to the microactuator to position the transducer over a second track.