Maximum sensitivity based robust tuning for two-degree-of-freedom proportional-integral controllers

A tuning method for two-degree-of-freedom (2-DoF) proportional-integral (PI) controllers for first-order-plus-dead-time (FOPDT) models is presented. It allows the designer to deal with the closed-loop control system performance-robustness trade-off specifying the lowest robustness level allowed by selecting a maximum sensitivity in the 1.4-2.0 range. In addition, a smooth performance is obtained by forcing the regulatory and servo-control closed-loop transfer functions to perform as close as possible to a target nonoscillatory dynamics. Controller tuning rules are provided for FOPDT models with normalized dead-times from 0.1 to 2.0. Comparative examples show the effectiveness of the proposed tuning method. © 2010 American Chemical Society.