Reducing Time Headway for Platoons of Connected Vehicles via Multiple-Predecessor Following

In a platoon of connected vehicles, a lower time headway can reduce the inter-vehicle distance, thus leading to higher traffic capacity. This paper discusses an approach to reduce time headway for string stable platoons via multiple-predecessor following (MPF). First, the platoon system is formulated using a third-order linear model and a linear feedback controller under the MPF topology. Then, we introduce a new definition of desired inter-vehicle distances using the constant time headway (CTH) policy, which avoids inconsistency in inter-vehicle distances. Under the proposed definition, we present a sufficient condition to guarantee string stability by analyzing the feasible region of feedback gains. It is proved that there exist string stable feedback gains if the time headway is lower bounded. The result indicates that increasing the number of predecessors can reduce the time headway for string stability, which in turn increases the road capacity. Numerical simulations validate the theoretical results.