Time-varying triggering conditions for the robust control of freeway systems

The definition of a control scheme for freeway traffic systems based on Model Predictive Control (MPC) techniques is the objective of the paper. The basic idea in the proposed approach is to switch between control laws computed offline on the basis of a nominal system model and a standard MPC scheme. Then, an offline computed control law is applied to the system until it maintains a suitable performance. This is verified by evaluating the property of natural robustness of the system by means of time-varying conditions depending on the system state and on the amplitude of exogenous perturbations. If the system behaviour, that is characterized by uncertainties, is evolving far from the nominal one, a classical MPC regulator is applied. In the paper, the control scheme is described and its effectiveness is evaluated through a numerical example.