New formulation of robust MPC by incorporating off-line approach with on-line optimization

Abstract

This article addresses robust model predictive control (MPC) for systems with polytopic description. An existing off-line robust MPC enables the on-line computation as simple as searching a state feedback gain among the look-up table. We consider enlarging the region of attraction of the off-line MPC by incorporating free perturbation items. First, a larger ellipsoidal region of attraction is off-line constructed, in which a simple optimization problem is solved on-line. Then, outside of this larger ellipsoid, a standard robust MPC is solved on-line such that the overall region of attraction can be rendered as a much larger nonellipsoidal one. The proposed approach possesses all the merits of the off-line MPC and greatly enlarges the region of attraction. A simulation example is given to demonstrate the effectiveness.