  In this paper, we address the problem of coordinating platoons of connected
and automated vehicles at signal-free intersections. We present a
decentralized, two-level optimal framework to coordinate the platoons with the
objective to minimize travel delay and fuel consumption of every platoon
crossing the intersection. In the upper-level, each platoon derives an optimal
schedule to enter the intersection. In the low-level, the platoons derive their
optimal control input (acceleration/deceleration) for the optimal schedule
derived in the upper-level. We validate the effectiveness of the proposed
framework in simulation and show significant improvements both in travel delay
and fuel consumption compared to the baseline scenario with fixed time traffic
signals at the intersection.
