Cooperative Adaptive Cruise Control

Abstract

Cooperative adaptive cruise control (CACC) includes multiple concepts of communication-enabled vehicle following and speed control. Definitions and classifications are presented to help clarify the distinctions between types of automated vehicle-following control that are often conflated with each other. A distinction is made between vehicle-to-vehicle (V2V) CACC, based on vehicle–vehicle cooperation, and infrastructure-to-vehicle CACC, in which the infrastructure provides information or guidance to the CACC system (such as the target set speed value). In V2V CACC, communication provides enhanced information so that vehicles can follow their predecessors with higher accuracy, faster response, and shorter gaps; the result would be enhanced traffic flow stability and possibly improved safety. A further distinction is made between CACC, which uses constant-time-gap vehicle following (forming CACC strings), and automated platooning, which uses tightly coupled, constant-clearance, vehicle-following strategies. Although adaptive cruise control (ACC) and CACC are examples of Level 1 automation as defined by both SAE and NHTSA, the vehicle-following performance that can be achieved under each scenario is representative of the performance that should be expected at higher levels of automation. Implementation of CACC in practice will also require consideration of more than the lowest level of vehicle-following and speed regulation performance. Because CACC requires interactions between adjacent equipped vehicles, strategies are needed such as ad hoc, local, or global coordination to cluster CACC vehicles. Some of the challenges that must be overcome to implement the clustering strategies are discussed as well as strategies for separating CACC clusters as they approach their destinations, as potential traffic improvements from CACC will be negated if the vehicles cannot disperse effectively.

Approach of Coordinated Control Method for Over-Actuated Vehicle Platoon based on Reference Vector Field

“…At this point, the particle has two degrees of freedom in the plane, including the longitudinal direction and lateral direction. Since the acceleration of the vehicle is limited by road adhesion, the control variable u(t) of the vehicle particle dynamics model is selected as acceleration, and the particle dynamics model can be simplified, as shown in formula (1), where x G and v G are 2-D vectors.…”

“…Vehicle platoon enables multiple vehicles to drive in a formation by automatically adjusting the spacing between the cars. By maintaining a reasonable distance and yaw angle between the adjacent cars, the "traction effect" in aerodynamics can effectively save energy and reduce pollutant emissions [1]. Besides, platoon control can increase traffic capacity and reduce the probability of traffic accidents, which was demonstrated in many studies [2][3][4].…”

A hierarchical approach for splitting truck platoons near network discontinuities

“…Automated driving systems have attracted considerable attention in the recent years, because of the fundamental changes they bring to transportation systems and new services enabled by them. Literature has shown that the individual automation can hardly enhance traffic operations while it is commonly agreed that connected/cooperative automated vehicles (CAVs) possess great potential in increasing roadway capacity and traffic flow stability [13,21,23,24,28]. Vehicle platooning is one of multiple applications that stands out in the domain, characterized by a string of CAVs respecting a specified equilibrium spacing policy [3,15,22,24].…”

Strategic and Tactical Guidance for the Connected and Autonomous Vehicle Future

“…Also, ACC systems, like traditional human driving, may not exhibit string instability, i.e., due to higher response time, fluctuations in traffic flow induced by accelerating and braking of vehicles can be amplified upstream, resulting in phantom traffic jams. CACC systems, on the other hand, have been shown to overcome this limitation by adding V2V communication to ACC (Shladover, Nowakowski, Lu, & Ferlis, 2015;Milanés et al, 2014). Thus, CACC equipped vehicles can get information from similarly equipped vehicles ahead of them downstream and use this information to make decisions related to their own speed and acceleration.…”