Design of optimal time allocation multi holder and its application to hard disk drives

In Hard Disk Drives, a digital control system is usually applied. To improve head positioning accuracy, it is necessary to make the sampling frequency high using conventional methods. However, it is very difficult to increase the sampling frequency, because of the decrease in capacity of the Hard Disk Drive. To solve this problem, a method of improving a head positioning accuracy without making the sampling frequency high is proposed in this paper. In the proposed method, a control signal to the Voice Coil Motor is changed in the optimum condition in the sampling period. The phase delay by discretization is improved and stimulation of the resonance mode of the Voice Coil Motor is avoided. The validity of the proposed method was confirmed by numerical and experimental results using a miniature 2.5-inch Hard Disk Drive.