Self-driving car
A self-driving car, also known as an autonomous car, driverless car, robotic car or robo-car, is a car that is capable of operating with reduced or no human input. They are sometimes called robotaxis, though this term refers specifically to self-driving cars operated for a ridesharing company.
, the term "self-driving" lacks an agreed standard definition and is also subject to commercial advertising and branding considerations. In 2020, Waymo was the first to offer rides in driverless taxis in the operational design domain of limited geographic areas, but, no system has achieved full autonomy in all domains - sometimes referred to as "Level 5" on a scale of 0 to 5 levels of automation defined by the global standards organisation SAE International, or simply "no driver" as given by the classification system proposed by Mobileye in the US.
Following a history of experimentation and development of advanced driver assistance systems after WWII, two main technologies are now primarily used: LiDAR, and visual sensors which capture images and video like human eyes. These are combined with systems such as GPS, neural networks, artificial intelligence, and established ADAS engineering to deliver levels of driving autonomy.
With more self-driving cars on public roads, an increasing number of safety incidents, collisions and even deaths have been recorded around the world. The primary obstacle to self-driving is the advanced software and mapping required to make them work safely across the wide variety of conditions that drivers experience. Other issues include security of over-the-air updates, legal and regulatory issues, ethics and consumer confidence. Methods of testing and monitoring the reliability of cars have evolved in parallel with the deployment of cars with self-driving capabilities, with various standards for this being proposed. Should autonomous cars gain mass adoption, wider implications for urban infrastructure and the economy have also been discussed.
Public perception and acceptance of autonomous cars has been found to be mixed. A 2014 telephone poll in the US found 31.7% would not continue to drive once an automated car was available to them, while a survey in 2022 found only a quarter of the world's population would feel safe in one.
History
Definitions
Organizations such as the global standards body SAE International have proposed terminology to describe technical capabilities. However, most terms have no standard definition and are employed variously by vendors and others. Proposals to adopt aviation automation terminology for cars has also not prevailed.The first consideration is the operational design domain.
Vendors have taken a variety of approaches to the self-driving problem. Tesla's approach is to allow their "full self-driving" system to be used in all ODDs as a Level 2 ADAS. Waymo picked specific ODDs for their Level 5 robotaxi service. Mercedes Benz offers Level 3 service in Las Vegas in highway traffic jams at speeds up to. Mobileye's SuperVision system offers hands-off/eyes-on driving on all road types at speeds up to. GM's hands-free Super Cruise operates on specific roads in specific conditions, stopping or returning control to the driver when ODD changes. In 2024 the company announced plans to expand road coverage from 400,000 miles to. Ford's BlueCruise hands-off system operates on of US divided highways.
Names such as AutonoDrive, PilotAssist, "Full-Self Driving" or DrivePilot are used even though the products offer an assortment of features that may not match the names. Despite offering a system dubbed Full Self-Driving, Tesla stated that its system did not autonomously handle all driving tasks. In the United Kingdom, a fully self-driving car is defined as a car so registered, rather than one that supports a specific feature set. The Association of British Insurers claimed that the usage of the word autonomous in marketing was dangerous because car ads make motorists think "autonomous" and "autopilot" imply that the driver can rely on the car to control itself, even though they do not.
Concepts
The following are useful in understanding the various definitions and criteria in use for self-driving cars.Driving systems
automate specific driving features such as Forward Collision Warning, Automatic Emergency Braking, Lane Departure Warning, Lane Keeping Assistance or Blind Spot Warning. An ADAS requires a human driver to handle tasks that the ADAS does not support.ADAS contrasts to an automated driving system, which would be classified by SAE J3016 as Level 3 or higher.
Autonomy versus automation
Autonomy implies that an automation system is under the control of the vehicle rather than a driver. Automation is function-specific, handling issues such as speed control, but leaves broader decision-making to the driver.The European car safety performance assessment programme Euro NCAP defines "autonomous" as "the system acts independently of the driver to avoid or mitigate the accident".
In Europe, the words automated and autonomous can be used together. For instance, under Regulation 2019/2144:
- "automated vehicle" means a vehicle that can move without continuous driver supervision, but that driver intervention is still expected or required in the operational design domains ;
- "fully automated vehicle" means a vehicle that can move entirely without driver supervision;
Cooperative system
According to SAE J3016,
Self-driving
The Union of Concerned Scientists defined self-driving as "cars or trucks in which human drivers are never required to take control to safely operate the vehicle. Also known as autonomous or 'driverless' cars, they combine sensors and software to control, navigate, and drive the vehicle."The British Automated and Electric Vehicles Act 2018 defines a vehicle as "driving itself" if the vehicle is "not being controlled, and does not need to be monitored, by an individual".
Another British government definition stated, "Self-driving vehicles are vehicles that can safely and lawfully drive themselves".
British definitions
In British English, the word "automated" has several meanings, such as in the sentence: "Thatcham also found that the automated lane keeping systems could only meet two out of the twelve principles required to guarantee safety, going on to say they cannot, therefore, be classed as 'automated driving', preferring 'assisted driving'". The first occurrence of the "automated" word refers to a UNECE automated system, while the second refers to the British legal definition of an automated vehicle. British law interprets the meaning of "automated vehicle" based on the interpretation section related to a vehicle "driving itself" and an insured vehicle.In November 2023 the British Government introduced the Automated Vehicles Bill. It proposed definitions for related terms:
- Self-driving: "A vehicle 'satisfies the self-driving test' if it is designed or adapted with the intention that a feature of the vehicle will allow it to travel autonomously, and it is capable of doing so, by means of that feature, safely and legally."
- Autonomy: A vehicle travels "autonomously" if it is controlled by the vehicle, and neither the vehicle nor its surroundings are monitored by a person who can intervene.
- Control: control of vehicle motion.
- Safe: a vehicle that conforms to an acceptably safe standard.
- Legal: a vehicle that offers an acceptably low risk of committing a traffic infraction.
SAE classification
The system was adopted by the United Nations Economic Commission for Europe in the form of UN Regulation No. 157, which came into force in January 2021, and used in over 50 countries. After SAE updated its classification in 2016,, the US National Highway Traffic Safety Administration adopted the SAE standard.
The classification is a topic of debate, having been criticized for its technological focus, with various revisions proposed. It has been argued that the structure of the levels suggests that automation increases linearly and that more automation is better, which may not be the case. SAE Levels also do not account for changes that may be required to infrastructure and road user behavior.
Automation levels
The SAE classification of Levels is based on the role of the driver, rather than the vehicle's capabilities, although these are related in the form of a "driving mode". The mode is determined by both an operational design domain and a "dyanmic driving requirement." The ODD is the circumstance in which the car is driving, and the driving requirement is what the system must do while remaining safe within the boundaries of that ODD. These two things define the SAE Level.Cars may therefore switch levels according to the driving mode. A human analogy might be a mode in which you can stand unassisted on one leg if you are on the ground, but would need support when standing on a tightrope.
Above Level 1, level differences are related to how responsibility for safe movement is divided/shared between the advanced driver-assistance system and driver, rather than specific driving features. A car might therefore have Level 3 capability for lane management up to 100km/h, but Level 2 at speeds faster than that. Or it might have Level 4 for driverless navigation on designated highways, but Level 2 on urban side roads.
ADAS that are considered Level 1 are adaptive cruise control, emergency brake assist, automatic emergency brake assist, lane-keeping, and lane centering. ADAS that are considered Level 2 are: highway assist, autonomous obstacle avoidance, and autonomous parking. At Level 3 and above, if a car is driving and the ODD changes - for instance, a clear highway becomes a construction zone with hand-signals from a worker - the system must recognize that it is exiting its ODD and fall back accordingly, including asking for driver intervention if necessary.
A fully self-driving car would therefore stay at Level 5 for all dynamic driving requirements in all circumstances, while a car with no ADAS controlling the driving requirements would rely on the human driver for that, and stay at Level 0 regardless of the domain.