Designing MPC controllers by reverse-engineering existing LTI controllers

This technical report presents a method for designing a constrained output-feedback model predictive controller (MPC) that behaves in the same way as an existing baseline stabilising linear time invariant output-feedback controller when constraints are inactive. The baseline controller is cast into an observer-compensator form and an inverse-optimal cost function is used as the basis of the MPC controller. The available degrees of design freedom are explored, and some guidelines provided for the selection of an appropriate observer-compensator realisation that will best allow exploitation of the constraint-handling and redundancy management capabilities of MPC. Consideration is given to output setpoint tracking, and the method is demonstrated with three different multivariable plants of varying complexity. A paper based on the work presented in this technical report has been submitted to IEEE Transactions on Automatic Control on 12/09/2011 as a regular paper under the title “Designing output-feedback predictive controllers by reverse-engineering existing LTI controllers”. ∗[email protected] †[email protected] REFERENCE: CUED/F-INFENG/TR.671 DATE: 13/09/2011 ISSUE: 1 PAGE: 2 of 56 REFERENCE: CUED/F-INFENG/TR.671 DATE: 13/09/2011 ISSUE: 1 PAGE: 3 of 56