Analysis of the claimed robustness for PI/PID robust tuning rules

This paper analyzes how recognized robust PI/PID tuning rules accomplish with respect to its robustness specification. A concrete analysis is conducted where the chosen PI/PID controller tuning rules are based on a precise quantitative robustness specification such as the Maximum Sensitivity; Ms; value. It is reported that the claimed robustness specification in most of the cases is not accomplished for some set of plants, on other cases it is accomplished with excessive margin, therefore providing a not satisfactory Robustness/Performance tradeoff. The conclusion drawn from this study is that even if the robustness issue has been incorporated in the new approaches for tuning and design of PI/PID controllers, this does not sufficient. In order to appropriately tackle the Robustness/Performance tradeoff, the achieved robustness level should not only be an integral specification, but its accomplishment should be checked.