A stabilizing gradient-based economic MPC for unstable processes: toward the enlargement of the domain of attraction

This work proposes a stabilizing gradient-based economic MPC with enlargement of the domain of attraction, based on the novel combination of three ingredients: terminal equality constraints solely on open-loop non-stable states, an admissible articial steady-state, and a terminal cost. A further enlargement of the domain of attraction is achieved by including slack variables to soften the bound constraints of states, without affecting the stabilizing propertiesor capacity to drive the closed-loop system toward the economic target. Finally, a case study based on an unstable reactor is used to demonstrate the properties of the proposed strategy.

GPC with Structured Perturbations: The Influence of Prefiltering and Terminal Equality Constraints

It is widely accepted that in order to improve the robust stability of generalized predictive control (GPC), the use of a prefilter and terminal equality constraints plays a fundamental role. In this work it is shown with straightforward counterexamples how, in the presence of structured uncertainties, neither the prefilter nor the equality constraints guarantee that the robust stability is improved. In fact, it can even worsen compared with “conventional” GPC.