Multirate servoing for disturbances which do not satisfy a matching condition

It is well known that servo controllers with disturbance observers perform to reject real input disturbances, but the disturbances need to satisfy a matching condition. In other words, the controllers with conventional disturbance observers cannot reject disturbances which do not satisfy the condition. It is very important fact but it has often been missed for long periods of time. This paper introduces a multirate sampling disturbance rejection control technique. The controller includes a multirate sampling disturbance observer and the controller performs to reject the disturbance which does not satisfy the matching condition. Its design process is described and a simulation results are shown.