A linear-quadratic-integral regulator for local ramp metering in the case of distant downstream bottlenecks

Abstract

This work develops and investigates the performance of a new control law, specifically a Linear-Quadratic Regulator augmented with integral action (LQI), for the local ramp metering control problem when bottlenecks are located many kilometers (up to 5 km) downstream of the metered on-ramp. LQI makes use of measurements all along the stretch extending from the controllable on-ramp to the bottleneck location, being therefore capable to improve the stability and robustness properties of the control loop, compared to alternative approaches (PI regulators) that employ measurements only from the bottleneck location. Simulation results reveal that: i) the proposed methodology handles efficiently the local ramp metering task in case of very distant downstream bottlenecks; and, ii) LQI is much less sensitive compared to other previously proposed control strategies.