High-Precision Tracking Control of Magnetic Head Positioning Mechanism : 1st Report, Comparison of stabilized Positioner with In-Phase Positioner

Abstract

This paper describes two types of head positioning mechanism of hard disk drive comparatively. One is a conventional swing-arm positioning mechanism with a minor-loop analog feedback controller that stabilizes the primary out-of-phase vibration mode. An observer circuit estimates a velocity of the vibration mode from VCM voltage and current. Estimated velocity of the vibration mode is fed back to stabilize the vibration mode. The other one is the in-phase positioning mechanism that has a sub-actuator for track following. A swing arm head positioning mechanism that has both of main-and sub-actuator was manufactured to confirm the effectiveness of the minor-loop feedback and in-phase positioning mechanism. Characteristics of two positioning mechanisms are shown with simulation and experimental results.