Mid-frequency Disturbance Rejection of HDD Systems

In this paper, we investigate mid-frequency disturbance rejection of hard disk drive servo systems. Generalized first-order reset element (GFORE) is proposed and used to construct a reset phase lead controller. The proposed phase lead controller is then used to compensate the phase lag caused by mid-frequency narrow band compensator without changing the gain property of the overall system. At last, the proposed reset compensator is applied to mid-frequency disturbance rejection of hard disk drive systems. Simulation results show that it can provide large open-loop gain around crossover frequency without degrading the transient response.