An Improved Dual-mode EMPC Scheme via Scheduling Terminal Sets

Abstract

The paper presents an improved dual-mode economic model predictive control (EMPC) scheme of constrained input-affine nonlinear systems via scheduling terminal sets. The concept of the equilibrium surface of nonlinear systems is used to pick up a set of transitional equilibrium points of the EMPC scheme. For each equilibrium point, some local controllers with some free-parameters are designed by control Lyapunov functions, as well as maximum terminal invariant sets. It is guaranteed that not only the terminal invariant sets are overlapped each other but also the equilibrium points are in the invariant sets corresponding to the next equilibrium point. Then an improved dual-mode EMPC algorithm is formulated for the nonlinear system with enlarging domain of attraction. Recursive feasibility and stability of the closed-loop system are achieved. The example of the isothermal continuous stirred tank reactor (CSTR) is used to demonstrate the advantages of the presented scheme.