Hierarchical Coordinated Freeway On-Ramp Metering Using Switching System Theory

This paper deals with the problem of freeway traffic control through ramp metering to enhance their efficiency. The traffic is often modeled by a nonlinear hyperbolic conservation laws that may develop and propagate shock waves. The Cell Transmission model (CTM) developed in (Daganzo [1994]), (C. F. Daganzo [1995]) is taken in this work since linear control tools can be used for analysis and control design. This model is extended with parametric uncertainties. A hierarchical control scheme with two levels is considered. The first level gives the optimal densities to apply on the freeway. The second level is charged for compensating local parametric uncertainties and disturbances (on-ramp demands, boundary conditions). These controllers are designed using switching control theory. A real-data based simulation is used to validate the effectiveness of the proposed control approach.