A U-shaped actuation system for dual-stage actuators used in hard disk drives

In this paper, we propose an actuation system, called U-shaped actuation, for dual-stage actuator to suppress the arm mode flutter. We manufactured an actuator using this actuation method and measured the frequency response. We found that the frequency response had an in-phase arm mode frequency and that there was little difference between each head at arm sway and suspension sway mode. Next, we designed a controller and compared its sensitivity function with that of conventional actuation. By applying stabilizing control to the in-phase arm mode, NRRO of the arm flutter of the outer and inner arms was suppressed by 10.9 and 13.2?%, respectively.