Reset Integral-Derivative Control for HDD Servo Systems

Ever-decreasing track width to nanometer level becomes a great challenge for servo systems to fulfill short-span seeking and track-following in hard-disk drives (HDDs). This paper utilizes the reset integral-derivative element (RIDE), an integral-derivative controller whose states are set to zero when its input is zero, in both single- and dual-stage HDD servo systems. The RIDE can reduce the overshoot of step response, which will speed up the short-span seeking operation. Furthermore, the capability to suppress output disturbances in track-following is also found to be improved. Compared with linear control methods for short-span seeking, our results show that the merits of reset design are the simpleness in implementation and the robustness to plant uncertainties