Design and Analysis of a Disk Drive Actuator for Commutational Ramp Loading

A voice-coil motor actuator system is designed to perform a unique disk drive ramp load/unload operation. The design eliminates the necessity of increased material requirements common in ramp load disk drives. Therefore, disk drives with lower cost, higher performance actuators can realize the linear shock protection benefits of ramp loading. This study offers a complete, systematic design procedure together with required analysis for manufacture of a commutational ramp load/unload drive. The actuator is designed and optimized to meet specific move-time performance requirements. When used for ramp load/unload, however, there exists a location where input current has no influence on actuator motion. An input polarity reversal is required within the uncontrollable region to sustain the direction of actuator motion. A magnetic, restorative bias is designed that prevents the actuator from resting in the uncontrollable region while providing resistance to rotational shock effects. A state trajectory is designed that, when tracked, moves the actuator through the uncontrollable set for a successful load onto the disk at the desired load velocity. A ramp load controller is designed to track the trajectory and handle the nonlinear effects from bias and friction torque. The unique disk drive is manufactured and experiments are performed to demonstrate effectiveness of the complete design strategy.