Robust Funnel MPC for nonlinear systems with relative degree one

Abstract

We propose a novel Model Predictive Control scheme for robust output reference tracking with prescribed performance for nonlinear multi-input multi-output systems of relative degree one with stable internal dynamics. Combining funnel MPC with the model-free adaptive funnel controller, the new robust funnel MPC algorithm guarantees output tracking of reference signals within predefined boundaries even in the presence of unknown disturbances and a structural model-plant mismatch. Initial and recursive feasibility of the control scheme is shown without imposing terminal conditions or requirements on the length of the prediction horizon. To this end, we propose a proper initialization strategy; and to ensure that the feedback controller does not contribute unnecessarily much, we introduce an activation function for the latter.