روشي نوين جهت افزايش مقاومت پيش بيني كننده اسميت در مقابل خطاي مدل

A New Method to Improve the Robustness of Smith Predictor against Model Error

In this paper a new method for compensating time delay is presented to improve the robustness of Smith method relative to the model error. This method is based on the dominant gain concept. In this method by knowing of the maximum error and use of the dominant gain concept for an added function, open loop control system is regulated, so that all of the zeros in the open loop, arising from the delay parameter are located in the left half plane. In this way the non minimum phase characteristic of the open loop will become eliminated. Based on the dominant gain concept, the requirement of the method is that the gain of the added function becomes equal or higher compared to the other gains, at all or a wide high frequency range. The gain of the added function is determined so that the open loop transfer function phase is limited between zero and -180 degrees. This constraint is put to guarantee that no right half plane zero exists in the open loop transfer function.