Reducing time headway in platoons under the MPF topology when using sensors and wireless communications

Abstract

In platoons under the multiple-predecessor following (MPF) topology, the exchange of information is usually assumed to be via Vehicle-to-Vehicle (V2V) communication links. Communication delays, however, deteriorate internal and string stability and, as a consequence, to guarantee stability of the platoon the time headway between vehicles should be increased. Autonomous vehicles are nowadays equipped with a multitude of sensors, the three primary being radar, lidar and camera. The combination of such sensors allows a vehicle, among others, to detect the distance and speed of nearby objects. In this paper, we incorporate the available sensors of vehicles to anticipate the communication delays vehicles experience with their preceding vehicles, thus improving the stability conditions and subsequently reducing the time headway. More specifically, by incorporating sensors we alleviate the communication delays between neighboring vehicles. We demonstrate that (i) the system is internally stable irrespective of the size of the communication delays, and (ii) the time headway can be reduced, by deriving a sufficient condition which provides a lower bound on the time headway that guarantees string stability. With this new lower bound on the time headway, platoons do not need to massively increase the time headway in order to compensate for the effects of communications delays. Simulations demonstrate the effectiveness of the proposed lower bound.