Online time delay and disturbance compensation for linear non-minimum phase systems

Herein, a disturbance observer is designed for linear non-minimum phase systems. A Smith Predictor is added to the system, using Recursive Least Squares (RLS), with a forgetting factor algorithm. The combination of both approaches, eliminates the restrictive feature of the classical disturbance observer, for non-minimum phase systems and removes the necessity for precise delay measurements, for the Smith Predictor structure. The results show that the proposed design procedure preserves system stability, in the presence of disturbances and time delays.