Short seeking by multirate digital controllers for computation saving with initial value adjustment

Multirate control has been proposed to reduce the real-time computation in hard disk drive (HDD) servo systems. It has been showed that computation can be saved greatly without performance degradation by using a multirate controller for track following. This paper proposes a novel method for short seeking control based on multirate track following control and initial value adjustment. This method, which uses the same multirate controller and the same servo structure as track following, adjusts the initial values of the track following controller for short seeking. Real-time computation is greatly saved in two aspects: 1) computation is saved by multirate scheme, and 2) initial value adjustment of the feedback controller makes the use of the feed-forward controller and reference trajectory unnecessary. Simulation and experimental results verify the effectiveness of the proposed method.