Constraint Enforcement via Tube-Based MPC Exploiting Switching Restrictions

Dwell-time restrictions are critical to overcoming infeasibility caused by arbitrary switches in constrained time-dependent switched systems, especially when the system equilibrium is mode dependent. However, existing approaches to enforce constraints are not applicable in presence of disturbances. In this letter, a recursively feasible switched tube-based MPC (TMPC) is designed for constrained linear modes subject to polytopic-bounded additive disturbances. Control-invariant sets that are robust to mode switches and disturbances are proposed to select terminal constraints and identify feasible initial states. The method is distinguished by the admission of mode-dependent equilibria, user-specified prediction horizons, non-reliance on a preview of the switching signal, and online computations equal to that of a non-switched TMPC.