Improved proximate time-optimal sliding-mode control of hard disk drives

An improved proximate time-optimal positioning control approach with discrete-time sliding-mode control theory for a hard disk drive servo is presented. A third order velocity reference profile is introduced to improve the second order ones in the conventional proximate time-optimal servomechanism. The proposed approach eliminates the mode-switching mechanism and dramatically reduces the seek time by 5-50%. Moreover, it is robust to unmodelled dynamics and parameter variations. Its effectiveness is verified in a simulation