High-Precision Tracking by Digital Repetitive Control Scheme with Periodic-Type Hold Function

The ripple attenuation problem is investigated by an appropriate selection of the periodic-type hold in the digital repetitive control system. To attenuate the ripple, we propose a design method of the periodic-type hold, where each sampling period in a reference signal period has a different type of the hold. Furthermore, we shaw that the level of the ripple can be reduced by the hold designed by assigning the values of output and/or its velocities at several instants in the steady-state.