An adaptive disturbance rejection method with stability enhancement using adjustable dead-zone for hard disk drives

Abstract

We report a stability enhancement algorithm for adaptive disturbance rejection with applications in hard disk drives. The adaptive disturbance rejection algorithm can compensate for disturbances in real time; however, to deploy the method in the field, difficulties in maintaining the stability of the servo loop in response to variable disturbances must be resolved. To address these issues, we apply an adjustable dead zone in the adaptation scheme. This method provides adaptive control while maintaining stability of the servo loop regardless of the applied disturbance, allowing successful rejection of disturbances in real time. To solve it, a dead-zone algorithm is suggested, which leads to a performance degradation in disturbance rejection. Accordingly, we are suggesting a new design for a Q-filter in the adaptive disturbance observer. This advanced Q-filter makes the structure of the entire system similar to a peak-notch filter. In this paper, we will verify the effect of the suggested method through simulation.