ADRC based freeway traffic density control via ramp metering

Based on the idea of the active disturbance rejection control (ADRC), a novel freeway traffic density control scheme is developed via ramp metering. By the designed tracking differentiator (TD) of ADRC, we can arrange a transition process to avoid system overshoot, and by designing an extended state observer (ESO) of ADRC, the state variables and comprehensive disturbances can be estimated and compensated. As a result, the ADRC can produce the on-ramp entering traffic flow to realize the desired traffic density without requring any information about the freeway traffic model. Furthermore, the capability and feasibility of the proposed ADRC is tested by some simulations.