Automated Two-Degree-of-Freedom Model Predictive Control Tuning

Abstract

This work considers the automated tuning of a two-degree-of-freedom model predictive controller (MPC) for single-input, single-output industrial processes with model uncertainties. The objective of the tuning algorithm is to automatically determine the MPC tuning parameters such that (1) the robust stability can be guaranteed, (2) the worst-case overshoot is controlled, (3) the oscillations in process outputs are attenuated, and (4) the worst-case settling time is minimized. A rigorous robust stability analysis is first conducted based on the connection between parametric uncertainties and unstructured uncertainties, and a tight robust stability condition is derived. As the specification on process output variation is not easily made by the end users, two alternative methods are proposed to automatically determine the tolerable total variation, which lead to two automatic tuning algorithms that achieve the tuning objectives. The proposed results are tested and verified through examples extracted from industrial processes in the pulp and paper industry, and comparisons are made with other existing results.