LP methods in MPC of large-scale systems: Application to paper-machine CD control

An application of a linear-programming based model-predictive control strategy to the paper-machine cross-direction (CD) control problem is presented. The objective of CD control is to maintain flat profiles of variables of interest by minimizing worst-case deviations from setpoints (defects). These control problems can have as many as 200 actuators (inputs) and 400 sensor measurements (outputs). This large size coupled with the stringent real-time requirement of computing a control move in a few seconds poses a very challenging control problem. The LP-based strategy is particularly well suited for solving such classes of control problems. This strategy has demonstrated its ability to solve large-scale control problems (over 100 inputs and 100 outputs) in real time and exhibits robustness to model uncertainty.