Fault Tolerance of Cooperative Vehicle Platoons Subject to Communication Delay

Cooperative Adaptive Cruise Control (CACC) employs wireless intervehicle communication to allow for automatic vehicle following at small intervehicle distances while guaranteeing string stability. Inherent to the CACC concept, however, is its vulnerability to communication impairments, among which latency of the wireless link, which compromise string stability and, hence, safety. To investigate the sensitivity of the string stability property with respect to communication latency, two controllers are developed by means of H8 controller synthesis, employing a one-vehicle look-ahead and a two-vehicle look-ahead communication topology, respectively. The string stability properties of the controlled vehicle platoon are investigated, based on which it is proposed to switch from one-to two-vehicle look-ahead when the latency exceeds a certain threshold, thereby creating robustness against increasing communication delay by retaining string stability at the lowest possible time gap.