Moment-based plant and string stability analysis of connected cruise control with stochastic delays

In this paper we investigate the concept of connected cruise control (CCC) where vehicles rely on ad-hoc wireless vehicle-to-vehicle (V2V) communication to control their longitudinal motion. While V2V communication potentially allows vehicles to build detailed knowledge about the traffic environment, intermittencies and packet drops introduce stochastic delays into the communication channels that make control very challenging. We derive the mean and covariance dynamics for the corresponding stochastic system and analyze the effects of stochastic delays on vehicular strings. We also provide conditions for plant and string stability using the mean and the covariance. Moreover, we demonstrate that how the stable regimes shrink when the sampling time or the packet drop ratio increases. Our results have important implications regarding safety and efficiency of connected vehicle systems.