A novel sliding mode servo controller for hard disk drives

This paper presents a novel sliding mode seek controller for hard disk servos. A 3^rd-order velocity reference profile is introduced to improve the 2^nd ones in the conventional Proximate Time-Optimal Servomechanism (PTOS). The proposed approach eliminates the mode-switching mechanism and realizes the smooth mode transit from seeking to following without overshoot. Moreover, the servo system is chattering free. It is well known that PTOS is not effective in short stroke seeks. The proposed control scheme significantly improves the short stroke seeks. In particular, the seek time is dramatically reduced by 2%-60%. The effectiveness of the proposed controller is verified in experiments.