Improvement in steady-state accuracy of time-delayed control systems with communication disturbance observer by low-frequency model error feedback

This paper proposes a method to improve the steady-state accuracy of time-delayed control systems with a communication disturbance observer (CDOB) by low-frequency model error feedback. The advantageous feature of time delay compensation by the CDOB is that it can be utilized without a delay time model. However, the CDOB needs a model of controlled system, and the model error occurs as the steady-state error. To solve this problem, this paper proposes model error feedback only in the low-frequency area. The proposed method achieves both high robust stability and steady state accuracy.