State reconstructor for real-time freeway ramp metering

The work presented in this paper aims to solve the problem of isolated ramp metering in the case of unavailable (not measured) traffic state variables (density and mean speed). A state reconstructor is then proposed and a systematic approach is developed for real time freeway ramp metering. The state reconstructor is developed using a second order sliding mode observer, while the control algorithm is based on the concept of differential flatness. Numerical simulations demonstrate the relevance of the provided algorithm for both state reconstructor and control of freeway networks.