Stroke Oriented Controller Design for Dual-stage Actuator of Head Positioning Control System in Hard Disk Drives

Abstract

In this research, we have proposed a stroke-oriented controller design for head positioning control system of hard disk drives (HDDs). A dual-stage actuator composed of a voice coil motor and a piezo actuator is widely used in the head positioning system. The decoupling filter design which decouples the interaction of each the actuator is a representative controller design for the dual-stage actuator. However, it is necessary for the feedback loop related to the piezo actuator to increase the gain in the low frequency range due to design constraints. It can lead to increase a required stroke of the piezo actuator. The proposed controller design can decrease the required stroke of the piezo actuator by utilizing the interaction of each the actuator. To confirm the effectiveness the proposed controller design method, a simulation was performed to compensate for external vibrations. As the results, it was confirmed that the required stroke of the piezo actuator can be reduced by about 65%, while the stability and positioning accuracy of the head positioning control system is almost same as the that of decoupling filter design.