Definitions relating to automated driving systems and details on the SAE levels of driving automation can be found in SAE J 3016-2021: Taxonomy And Definitions For Terms Related To Driving Automation Systems For On-Road Motor Vehicles.
The Emergence of Automated Driving Systems
As technology consistently follows a pattern of upward progression, concepts once unique to science fiction are manifesting in reality. One formerly-fictional concept now emerging in the automotive industry is automated driving.
Automated driving systems in vehicles are often called one of several interchangeable names, either in their sci-fi origins or in modern colloquial usage, including “self-driving cars,” “driverless cars,” or “automated vehicles.” These terms have burgeoned in usage in recent years due to numerous industry leaders and pioneers exploring the possibility of realistically implementing them in the near future.
However, these endeavors unearth uncertainty. Companies are trying to find where to begin and what factors to consider. Fortunately, standardization has long helped members of any industry to move forward with minimized risk. For driverless cars, standardization is making the concept a little easier to tackle. We have discussed this issue several times in the past, most notably with a discussion on the IEEE Global Initiative for Ethical Considerations in Artificial Intelligence and Autonomous systems in our guest post by Konstantinos Karachalios, Managing Director of IEEE.
Integral to guiding the automotive industry in developing, testing, and eventually mass-producing self-driving cars is the concept’s associated terminology, which can help shape the industry’s path.
Standard Terminology in SAE J 3016-2021
By setting forth the taxonomy and outlining the accepted definitions surrounding driving automation in its descriptive and informative format (as opposed to normative), SAE J 3016-2021 provides a welcome level of clarity, successfully stabilizing the topic of driving automation and saving considerable time and effort.
Furthermore, SAE J 3016-2021 clarifies the role of the human driver during driving automation system engagement, provides a useful framework for driving automation specifications, and answers questions and concerns that may aid in developing laws, policies, regulations, and standards.
Specifically, SAE J 3016-2021 describes motor vehicle driving automation systems that perform part or all of the dynamic driving task (DDT) on a sustained basis and features three primary actors in driving: the human user, the driving automation system, and other vehicle systems and components.
The word choices surrounding automotive driving systems serve to best position the automotive industry. For example, SAE J 3016-2021 does not use the terms “self-driving car” or “driverless car.” In fact, it is carefully worded to refer to the automation as a part of the vehicle’s systems and not that of the vehicle itself. Classification refers to the automation features, which there can be several of in a single vehicle.
SAE J 3016-2021 identifies “autonomous vehicles” as deprecated because, while some might be highly independent and self-sufficient, they will depend on communication and cooperation with outside entities for their functionality. “Robotic vehicles” is misleading for these same reasons, along with “robotic” being a vague term often slapped onto advanced technologies.
As for “self-driving,” “driverless,” or “unmanned,” there is a clear misunderstanding of the different SAE levels through their usage. “Driver” is a term that can have any meanings, and it is not necessarily specific to a human individual turning a steering wheel. Therefore, these terms can confuse rather than clarify.
Ultimately, the official correct terminology for referring to vehicles with these systems, according to SAE J 3016-2021, is “motor vehicles with automated driving systems.”
Understanding Terms from SAE J 3016-2021
Comprehending relevant terms is a necessity for understanding the automation levels. SAE J 3016-2021 defines dynamic driving task (DDT) as
“all of the real-time operational and tactical functions required to operate a vehicle in on-road traffic.”
This differs from driving because it includes tactile and functional effort but excludes strategic effort. DDT may not even involve the vehicle being in motion.
Next is the operational design domain (ODD):
“the specific conditions under which a given driving automation system or feature thereof is designed to function, including, but not limited to, driving modes.”
This can incorporate a variety of limitations, such as those from geography, traffic, speed, and roadways.
Lastly, automated driving system (ADS) is defined as:
“the hardware and software that are collectively capable of performing the entire DDT on a sustained basis, regardless of whether it is limited to a specific operational design domain (ODD).”
This is used to describe the the higher driving automation system levels.
SAE Levels of Driving Automation
The distinction between automation as part of a vehicle’s systems and the vehicle itself is crucial in how SAE J 3016-2021 characterizes the various levels of driving automation. Now considered the SAE levels of driving automation and adopted by the US Department of Transportation (DOT), as covered in SAE J 3016-2021, there are six levels, ranging from 0 to 5:
Level 0 (No Driving Automation)
Level 1 (Driver Assistance)
Level 2 (Partial Driving Automation)
Level 3 (Conditional Driving Automation)
Level 4 (High Driving Automation)
Level 5 (Full Driving Automation)
More driving tasks become the responsibility of the automation systems as you go higher in SAE Levels, with Level 0 being found in a conventional automobile that doesn’t make use of these technologies, and Level 5 being in an automobile in which the primary user is a passenger and not a driver. As previously noted, these levels are mutually exclusive, so a system cannot be classified within multiple levels. Under this gradient of automation, certain vehicle systems falling under Level 1 or Level 2 have been in existence for some time.
The basis of these categories derives from a variety of factors related to the DDT, including the importance of the driving automation system in performing longitudinal or lateral vehicle motion control, fallback, and object and event detection and response (OEDR). The limitations brought on by an ODD also affect this, with Level 5 systems having an unlimited domain.
According to the US Department of Transportation, automobiles using systems at SAE Levels 3-5 are called “highly automated vehicles (HAV).” Similarly, SAE J 3016-2021 refers to vehicles designed to be operated exclusively by a Level 4 or Level 5 ADS for all trips as “ADS-dedicated vehicles.”
You can learn more in our post SAE Levels of Driving Automation.
SAE J 3016-2021: Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles is available on the ANSI Webstore.