Double-Layer Optimal Control Method for On-Ramp Merging

Congestion often occurs in the merging scene of an on-ramp, which reduces traffic efficiency and increases the risk of collision. This paper proposes a double-layer optimal control method designed for on-ramp merging. The upper layer uses the shortest path algorithm to determine the optimal merging sequence and allocates the initial time for vehicles to reach the merging zone, which minimizes the travel delay and the difference in average speed between two lanes. The lower layer first conducts trajectory planning according to Pontryagin’s maximum principle, and then the time optimization algorithm for arriving at the merging zone is used to ensure that all vehicles meet the speed constraints. The simulation experiment verifies the effectiveness of the proposed method and compares it with the first-in-first-out and no-control methods, and it improves traffic efficiency, fuel economy, and traffic fairness.