Multi-rate model predictive control algorithm for systems with fast-slow dynamics

This study proposes a novel multi-rate model predictive control (MPC) scheme for linear discrete-time systems subject to input constraints. The proposed scheme consists of two control layers, acting at two different timescales. At a slow timescale, the outputs associated with the slow dynamics are steered to their reference values while at a fast timescale, a shrinking horizon MPC regulator is designed to refine the control action computed at the slow timescale. The proposed control scheme shows to be particularly useful, not only to control systems with different open-loop dynamics but also in cases when the controlled variables are required to have different responsiveness in a closed loop. Simulation results on a fire tube boiler example are reported, which indeed show that different dynamics can be efficiently imposed on the controlled variables, i.e. the boiler pressure and the water level, in the presence of variations of the disturbance represented by the steam output flow rate.<?show [AQ ID=Q2]?