Tube-based robust contractive economic model predictive control

This paper proposes a novel tube-based economic model predictive control (EMPC) framework for constrained systems subject to unknown but bounded disturbances. To account for the influence of disturbances on system performance, an error system between the actual plant and the nominal model as well as its robust invariant set is first derived. A nominal economic optimization problem is then formulated using a specially designed integrated economic cost function and tightened constraint sets, where a contractive constraint is constructed online to guarantee convergence of the nominal system states. Based on the solution of the nominal optimization problem, a state-feedback control law is applied to keep the actual trajectories within a robust invariant tube around the nominal trajectories. The recursive feasibility and robust stability are rigorously analyzed. Simulation results demonstrate the effectiveness of the proposed strategy.