本SAE推荐实施规程描述了持续执行部分或全部动态驾驶任务（DDT）的机动车驾驶自动化系统。它提供了一个分类法，详细定义了六个级别的驾驶自动化，从非驾驶自动化（0级）到完全驾驶自动化（5级），涉及机动车辆（以下也称为“车辆”或“车辆”）及其在道路上的运行。这些级别定义以及本文提供的其他支持性术语和定义可用于以功能一致和连贯的方式描述机动车上配备的全系列驾驶自动化功能。 “道路上”指的是公共可进入的道路（包括允许公共进入的停车场和私人校园），它们共同服务于所有级别和驾驶自动化水平（包括无驾驶自动化）的车辆用户，以及摩托车手、脚踏自行车手和行人。这些级别适用于装备车辆在道路上运行的任何给定实例中使用的驾驶自动化功能。因此，尽管给定车辆可能配备了能够提供多个在不同级别上执行的驾驶自动化功能的驾驶自动化系统，但在任何给定情况下展示的驾驶自动化水平由所使用的功能决定。 本文件还提到了驾驶中的三个主要参与者:（人类）用户、驾驶自动化系统以及其他车辆系统和部件。这些其他车辆系统和部件（或通用术语中的车辆）不包括本车型中的驾驶自动化系统，尽管实际上，驾驶自动化系统可能与其他车辆系统共享硬件和软件部件，例如处理模块或操作代码。驾驶自动化水平是根据三个主要参与者在滴滴涕和/或滴滴涕应急行动中各自发挥的具体作用来确定的。 在本文中，“角色”指的是给定主要参与者的预期角色，基于相关驾驶自动化系统的设计，而不一定是给定主要参与者的实际表现。例如，在1级自适应巡航控制（ACC）系统启用期间未能监控道路的驾驶员仍然扮演驾驶员的角色，即使他/她忽略了这一角色。主动安全系统（如电子稳定控制和自动紧急制动）以及某些类型的驾驶员辅助系统（如车道保持辅助系统）不在本驾驶自动化分类的范围内，因为它们不会持续执行部分或全部DDT，而是，在潜在危险情况下，仅提供短暂干预。 由于主动安全系统动作的瞬时性，其干预不会改变或消除驾驶员在执行部分或全部DDT时的作用，因此不被视为驾驶自动化。然而，应注意的是，配备任何级别的驾驶自动化系统的车辆中都可能包括防撞功能，包括干预型主动安全系统。对于执行完整DDT的自动驾驶系统（ADS）功能（即3-5级），防撞能力是ADS功能的一部分。

This SAE Recommended Practice describes motor vehicle driving automation systems that perform part or all of the dynamic driving task (DDT) on a sustained basis. It provides a taxonomy with detailed definitions for six levels of driving automation, ranging from no driving automation (level 0) to full driving automation (level 5), in the context of motor vehicles (hereafter also referred to as “vehicle” or “vehicles”) and their operation on roadways. These level definitions, along with additional supporting terms and definitions provided herein, can be used to describe the full range of driving automation features equipped on motor vehicles in a functionally consistent and coherent manner. “On-road” refers to publicly accessible roadways (including parking areas and private campuses that permit public access) that collectively serve users of vehicles of all classes and driving automation levels (including no driving automation), as well as motorcyclists, pedal cyclists, and pedestrians.The levels apply to the driving automation feature(s) that are engaged in any given instance of on-road operation of an equipped vehicle. As such, although a given vehicle may be equipped with a driving automation system that is capable of delivering multiple driving automation features that perform at different levels, the level of driving automation exhibited in any given instance is determined by the feature(s) that are engaged.This document also refers to three primary actors in driving: the (human) user, the driving automation system, and other vehicle systems and components. These other vehicle systems and components (or the vehicle in general terms) do not include the driving automation system in this model, even though as a practical matter a driving automation system may actually share hardware and software components with other vehicle systems, such as a processing module(s) or operating code.The levels of driving automation are defined by reference to the specific role played by each of the three primary actors in performance of the DDT and/or DDT fallback. “Role” in this context refers to the expected role of a given primary actor, based on the design of the driving automation system in question and not necessarily to the actual performance of a given primary actor. For example, a driver who fails to monitor the roadway during engagement of a level 1 adaptive cruise control (ACC) system still has the role of driver, even while s/he is neglecting it.Active safety systems, such as electronic stability control and automated emergency braking, and certain types of driver assistance systems, such as lane keeping assistance, are excluded from the scope of this driving automation taxonomy because they do not perform part or all of the DDT on a sustained basis and, rather, merely provide momentary intervention during potentially hazardous situations. Due to the momentary nature of the actions of active safety systems, their intervention does not change or eliminate the role of the driver in performing part or all of the DDT, and thus are not considered to be driving automation.It should, however, be noted that crash avoidance features, including intervention-type active safety systems, may be included in vehicles equipped with driving automation systems at any level. For Automated Driving System (ADS) features (i.e., levels 3-5) that perform the complete DDT, crash avoidance capability is part of ADS functionality.