On the Progressive Introduction of Heterogeneous CACC Capabilities

Abstract

Can we introduce Cooperative Adaptive Cruise Control (CACC) technologies on the road without separated infrastructures? This simple question is often latent in works dealing with cooperative driving, especially in critical feasibility analysis of cooperative driving. As of today, the question has indeed received no definitive answer in the literature because it is hard to model analytically heterogeneous systems or to experiment with them. This work helps understanding how vehicles interact among each others when they do not run a single, a-priory defined, CACC algorithm, but rather each vehicle adopt its own one. We introduce the concept of mixed platoon, i.e., a string of vehicles where more than one CACC algorithm is used, and we experiment with mixed platoons in silico to study how the mixture of CACC algorithms affects efficiency and safety. For instance we analyze large-scale scenarios where we progressively introduce homogeneous and mixed platoons among standard Adaptive Cruise Control (ACC) vehicles, quantifying the positive or negative effects on traffic efficiency and safety induced by the introduction of CACC technologies as a function of their penetration rate. The obtained results encourage additional research on the topic, starting from theoretical analysis of mixed platoons down to performance evaluations of actual implementations.

Cooperative driving: A comprehensive perspective, the role of communications, and its potential development

“…Only recently we find studies that define new stability properties for the analysis of heterogeneous platoons [76,77]. We also look into the problem empirically in [78] by studying the safety and the efficiency of mixtures of CACCs. We report here some preliminary results.…”

“…For comparison the graph shows also the theoretical free-flow and the baseline throughput, the latter obtained in all ACC-driven vehicles in the simulation. Besides showing Figure 6: Acceleration and distance deviation for a 4-vehicle platoon using a mixture of PATH [63] and Ploeg [69] controllers (pictures adapted from [78]). [63] and Ploeg [69] controllers, for different market penetration rates.…”

“…The figure also shows the theoretical maximum (free-flow) throughput and the baseline throughput (only ACC-driven vehicles). The picture is adapted from [78].…”

“…The analysis in [78] relates to measurable safety performance, which is still an open issue. The standard approach for guaranteeing safety in CACC literature is to prove basic properties such as string-stability, i.e., guaranteeing that errors occurring at the head will not be amplified towards the tail.…”