Control strategy for the optimization of mixed traffic flow with autonomous vehicles

The paper proposes an optimization strategy for the coordination of controlled freeway ramps and autonomous vehicle speed profiles. The objective of the optimization problem is to guarantee the maximum traffic flow, which contains both autonomous and human-driven vehicles. A control-oriented modeling of the mixed traffic flow dynamics is presented, which is based on the law of conservation and the fundamental relationship. As a novelty, the formulation of the fundamental relationship includes the ratio of the autonomous vehicles. Then the constrained optimal task of the coordination strategy is developed based on the minimax principle. In the strategy the inflows of the controlled ramps, traffic density and the ratio of the autonomous vehicles are taken into consideration. The efficiency of the coordination strategy is examined through a simulation example using the VisSim traffic simulator. It is illustrated that the proposed coordination strategy is able to guarantee the maximum outflow performance of the freeway at mixed traffic.