Operational Concepts for Truck Maneuvers with Cooperative Adaptive Cruise Control

Cooperative adaptive cruise control (CACC) has been loosely defined in recent literature to represent a wide variety of vehicle-following control concepts, and when trucks are discussed, CACC is often used synonymously with platooning. This paper discusses the similarities and differences between CACC and platooning and provides a more precise functional description of CACC operations for trucks. CACC operations include not only the steady state cruising mode but also the maneuvers needed to join vehicles together and separate them when a vehicle needs to leave a CACC string or when the string is interrupted by a cut-in maneuver by a noncooperative vehicle. Activity diagrams are used to describe the CACC maneuvers; the diagrams specify the sequence of actions that need to be taken by each driver and each vehicle (and its CACC software) and the information that needs to be exchanged between them. These precise definitions can be used to specify the vehicle-to-vehicle messages that need to be exchanged between vehicles to implement CACC and the driver vehicle interface displays and controls that are needed. The paper also addresses practical considerations in CACC operation, such as maximum lengths for strings of CACC trucks, strategies for sequencing the trucks in CACC strings, and higher-level strategies for clustering CACC-capable trucks; these strategies range from ad hoc to local and global coordination.