Robustness on model error of time delayed control systems with communication disturbance observer - Verification on an example constructed by double integration controlled object and PD controller

This paper discusses robustness on model error of time delayed control systems with communication disturbance observer (CDOB). A feature of the time delay compensation method based on the concept of network disturbance (ND) and CDOB is that the method can be utilized without delay time model (predictive control methods like Smith predictor usually need delay time model). Therefore the method can effectively compensate time delay effect even in the case with time-varying delay. However the method needs a model of controlled system for implementation. Then the robustness on model error of controlled system model is a very important issue for development of the time delay compensation method. In this paper, the robustness on model error is discussed from the perspective of robust stability and steady-state characteristic. At first, robust stability problem is analyzed comparing to that of Smith predictor. Then steady-state characteristic is also studied in the same manner. The validity of analytical results on both robust stability and steady-state characteristics are verified by experimental results.