Are Commercially Implemented Adaptive Cruise Control Systems String Stable

In this article, we assess the string stability of seven 2018 model year adaptive cruise control (ACC) equipped vehicles that are widely available in the US market. Seven distinct vehicle models from two different vehicle makes are analyzed using data collected from more than 1,200 miles of driving in car-following experiments with ACC engaged by the follower vehicle. The resulting dataset is used to identify the parameters of a linear second order delay differential equation model that approximates the behavior of the black box ACC systems. Thestring stability of the data-fitted model associated with each vehicle is assessed, and the main finding is that all seven vehicle models have string unstable ACC systems. For one commonly available vehicle model that offers ACC as a standard feature on all trim levels, we validate the string stability finding with a multi-vehicle homogeneous platoon experiment in which all vehicles are the same year, make, and model. In this test, an initial disturbance of 6 mph is amplified to a 25 mph disturbance, at which point the last vehicle in the platoon is observed to disengage the ACC. The data collected in the driving experiments is made available, representing the largest publicly available comparative driving dataset on ACC equipped vehicles.

本文对七款2018年型在美国市场广泛销售的具备自适应巡航控制（ACC）功能的车辆进行了字符串稳定性的评估。通过对来自超过1,200英里驾驶实验中跟随车辆开启ACC所收集的数据进行分析，考察了来自两种不同制造商的七种不同车型。所得到的数据集被用于确定一个线性二阶延迟微分方程模型的参数，该模型近似描述了黑盒ACC系统的行为。评估了与每款车型相关的数据拟合模型的字符串稳定性，主要发现是所有七款车型均具备字符串不稳定的ACC系统。对于一款普遍提供的、在所有车型级别上均提供ACC作为标准配置的车型，我们通过一项多车辆同型编队实验验证了字符串稳定性的发现。在此次实验中，初始扰动从6英里每小时放大至25英里每小时，此时编队中的最后一辆车观察到ACC系统已断开。驾驶实验收集到的数据已对外公开，这代表了公开可用的关于配备ACC车辆的最大比较驾驶数据集。