The design of Cooperative Adaptive Cruise Control (CACC) algorithms for vehicle platooning has been extensively investigated, leading to a wide range of approaches with different requirements and performance. Most existing studies evaluate these algorithms under the assumption of homogeneous platoons, i.e., when all platoon members adopt the same CACC. However, market competition is likely to result in vehicles from different manufacturers implementing distinct CACCs. This raises fundamental questions about whether heterogeneous vehicles can safely cooperate within a platoon and what performance can be achieved. To date, these questions have received little attention, as heterogeneous platoons are difficult to model and analyze. In this work, we introduce the concept of mixed platoons, i.e., platoons made of vehicles running heterogeneous CACCs, and we study their performance through simulation-based experiments. We consider mixtures of three well-established CACCs from the literature. In the first part of the paper, we study a single mixed platoon in isolation to understand the microscopic effects on safety: we evaluate the performance of various CACC-mixtures across speed change and emergency braking scenarios. In the second part, we examine a high-density ring-road scenario to assess macroscopic impacts on safety, comfort, and traffic throughput, especially comparing throughput results with those obtained from vehicles controlled by a standard Adaptive Cruise Control (ACC) or by human drivers. Our findings highlight that some combinations of CACCs can operate robustly and safely, while others exhibit critical limitations in safety, comfort, or efficiency. These results emphasize the need for careful system design and the development of theoretical frameworks for modeling heterogeneous platoons.

翻译：针对车辆编队的协同自适应巡航控制（CACC）算法设计已得到广泛研究，产生了多种具有不同要求和性能的方法。现有研究大多在假设编队为同质性的前提下评估这些算法，即所有编队成员采用相同的CACC。然而，市场竞争可能导致不同制造商生产的车辆搭载不同的CACC系统。这引发了根本性问题：异构车辆能否在编队中安全协同运行？以及能达到何种性能水平？迄今为止，这些问题鲜少受到关注，因为异构编队难以建模和分析。本研究引入了混合编队概念，即由运行异构CACC系统的车辆组成的编队，并通过基于仿真的实验研究其性能。我们选取文献中三种成熟的CACC系统进行混合配置。论文第一部分通过孤立单混合编队研究微观安全效应：在变速和紧急制动场景下评估不同CACC混合配置的性能。第二部分通过高密度环道场景评估宏观层面对安全性、舒适性和交通吞吐量的影响，特别将吞吐量结果与标准自适应巡航控制（ACC）及人工驾驶控制的车辆进行对比。研究结果表明，部分CACC组合能够稳健安全地运行，而其他组合则在安全性、舒适性或效率方面存在明显局限。这些发现凸显了审慎系统设计及建立异构编队建模理论框架的必要性。