Abstract
A control system design method for disturbance suppression in a sampled-data positioning system was studied. To avoid complicated calculations involving matrices, this method uses frequency responses of a controlled object and a digital controller for calculating the gain of the sensitivity function in a sampled-data positioning control system. The method can handle inter-sampling vibrations and the characteristics of disturbance suppression beyond the Nyquist frequency in a sampled-data positioning system. As a result, this study indicates limiting conditions for disturbance suppression in the sampled-data positioning control system. This study also indicates the merits of using a multi-rate control system that includes an interpolator, a multi-rate filter, and a multi-rate hold. In order to verify the validity of the proposed method, simulations and experiments for disturbance suppression in the sampled-data positioning control system were conducted on a head-positioning control system in a hard disk drive.
