1995 Volume 19 Issue 39 Pages 39-46
To enhance formatting efficiency of high density disk drives, the number of embedded servo signals has to be decreased. In this lower sampling rate of the servo system, it is difficult to attain fast track seek by using only a feedback controller. To solve this problem, two degree-of-freedom (2DOF) control, which simultaneously uses feedback and feed-forward control, has been applied to HDD systems. In a 2DOF control system, designing the reference model well can improve the response performance of the lower sampling rate system. This paper presents a 2DOF control system to effectively use a voice coil motor (VCM) through a new reference model, which generates reference trajectories allowing high-speed moving. Experimental results using a typical hard disk drive indicated the validity of the proposed method, especially for short stroke seeks.
