Impact of Information Flow Topology on Safety of Tightly-coupled Connected and Automated Vehicle Platoons Utilizing Stochastic Control

Cooperative driving, enabled by Vehicle-to-Everything (V2X) communication, is expected to significantly improve the safety and efficiency of the transportation sys-tem. Cooperative Adaptive Cruise Control (CACC), a major cooperative driving application, has been the subject of many studies in recent years. The primary motivation behind using CACC is to reduce traffic congestion and improve traffic flow, traffic throughput, and highway capacity. Since the information flow between cooperative vehicles can significantly affect the dynamics of a platoon, the design and performance of con-trol components are tightly dependent on the communication component performance. In addition, the choice of Information Flow Topology (IFT) can affect certain platoon's properties such as stability and scalability. Although cooperative vehicles' per-ception can be expanded to multiple predecessors' information by using V2X communication, the communication technologies still suffer from random loss. Therefore, cooperative vehicles are required to predict each other's behavior to compensate for the effects of non-ideal communication. The notion of Model-Based Communication (MBC) was proposed to enhance cooperative vehicle's perception under non-ideal communication by introducing a new flexible content structure for broadcasting joint vehicle's dynamic/driver's behavior models. By utilizing a non-parametric (Bayesian) modeling scheme, i.e., Gaussian Process Regression (GPR), and the MBC concept, this paper develops a discrete hybrid stochastic model predictive control approach and examines the impact of communication losses and different information flow topologies on the performance and safety of the platoon. The results demonstrate an improvement in response time and safety using more vehicles' information, validating the potential of cooperation to attenuate disturbances and improve traffic flow and safety.