PID Tuning: Analytical approach based on the weighted Sensitivity problem

• Main Authors: R. Vilanova, S. Alcántara, C. Pedret
• Format: Article
• Language: Spanish
• Published: Universitat Politecnica de Valencia 2021-09-01
• Series: Revista Iberoamericana de Automática e Informática Industrial RIAI
• Subjects: pid; control de procesos; análisis de robustez; rechazo de perturbaciones; seguimiento
• Online Access: https://polipapers.upv.es/index.php/RIAI/article/view/15422

The PID controller is the most common option in the realm of control applications and is dominant in the process control industry. Among the related analytical methods, Internal Model Control (IMC) has gained remarkable industrial acceptance due to its robust nature and good set-point responses. However, the traditional application of IMC results in poor load disturbance rejection for lag-dominant and integrating plants. This work presents an IMC-like design method which avoids this common pitfall and is devised to work well for plants of modest complexity, for which analytical PID tuning is plausible. For simplicity, the design only focuses on the closed-loop sensitivity function. The approach provides model-based tuning of single-loop PID controllers in terms of the robustness/performance and servo/regulator trade-offs. Although the robustness/performance compromise is commonly considered, it is not so common to also take into account, for example, the conflict between input and output disturbances, referred also as the servo/regulator trade-off. As interested in providing a unified tuning approach, it is shown how the proposed methodology allows to deal with different process dynamics in a unified way.