Optimized tuning rules for proportional-integral controllers with selected robustness

In this paper, we present tuning rules for PI controllers that represent an effective alternative to the well-known lambda-tuning for the load disturbance rejection task. In particular, the integrated absolute error is minimized subject to a constraint on the maximum sensitivity selected. Suitable formulas are given to relate the proposed tuning with the lambda-tuning, and the improvement obtained is quantified for different process dynamics. Both self-regulating and non self-regulating processes are considered. Simulation results are given to illustrate the methodology.