A design method of time-delay systems with communication disturbance observer by using Pade approximation

This paper studies a design method of time-delay systems with communication disturbance observer (CDOB). A time-delay compensation method based on network disturbance (ND) concept and CDOB has been proposed and applied to various control systems. It compensates time-delay effect without using time-delay model and the effectiveness is equivalent to that of Smith predictor. Furthermore, it works even when time-delay value is unknown, since it does not need time-delay models. In past works, some design methods of time-delay systems with CDOB have been studied basically by using Nyquist diagram. However, detailed design methods of the transient characteristics have not been researched well due to the characteristics of Nyquist diagrams. In other words, we have not addressed design methods based on detailed pole placements studies in order to arbitrarily design the transient characteristics. In this paper, we study a design method of time-delay systems with CDOB based on pole placements by using Pade approximation. The detailed design of the transient characteristics is accomplished by the analytical results. The adequacy of the presented design method is validated by simulation studies.