Autonomous Driving Levels Compared: from 0 to 511 min read08/11/2019
Autopilot levels classification has been around for only 5 years. In 2014, the Society of Automotive Engineers, also known as SAE International, published an official document called Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles arranging autonomous driving levels by the amount of driver attention and intervention required to ensure a safe trip from point A to point B. The less driver participation needed, the higher a level of driving automation is. SAE autonomous driving levels are the only system currently used all over the globe to classify vehicle autopilots.
Autopilot is an inherent part of self-driving cars that can communicate by sharing important road condition data wirelessly. Their number is continuously growing, and the worldwide market size of fully autonomous vehicles will reach the value of 6 billion U.S. dollars in 2025, according to Statista. Nevertheless, such cars currently seem to be the far future whereas partially autonomous vehicles equipped with various driver assistance systems are our present. They will form a $36 billion worth market in only 6 years. Both fully autonomous and partially autonomous vehicles refer to the same SAE classification system.
How many levels of autonomous driving cars exist?
What level is Tesla autopilot?
- ADS – Automated Driving System. This term refers to an in-car computer system that perceives data through such sensors as a LIDAR, sonar, and radar, processes road conditions, and automatically makes driving decisions by enabling car safety features and systems like braking, steering, and adaptive cruise control (ACC).
- DDT – Dynamic Driving Task. The meaning of this term points out tactical and operational driver effort to reach a destination point. In other words, DDT means the overall driving process involving acceleration, braking, and steering, excluding a strategic aspect: whether, where and when to go.
- OEDR – Object and Event Detection and Response. This term involves the capability of ADS to scan the environment, detect various objects like obstacles, other vehicles, road signs, and pedestrians as well as distinguish them to make proper driving decisions.
- Minimal risk condition. It’s a condition under which a risk of a car crash is minimal when a current trip can’t or shouldn’t be continued.
- DDT fallback. The dynamic driving task fallback means the response of the driver or automated driving system to an unexpected road situation or system failure, resulting in achieving a minimal risk condition. In other words, when the in-car autopilot can no longer drive a vehicle safely because of the dangerous maneuvers of other cars, poor visibility, car accidents, or other reasons, it either transfers vehicle control to a driver or activates automatic braking, reduces speed, or applies other car accident prevention measures.
- ODD – Operational Design Domain. The definition of this term refers to a set of specific conditions a particular ADS is developed to work under. These conditions can include but not limited to an exact location, weather conditions, the quality of road marking, speed limit, and time period.
To easily determine a level of autonomous driving in a particular car, you can take the following short quiz compiled in a form of a flow diagram.
Perform none of the DDT or DDT fallback?
Perform either longitudinal or lateral vehicle motion control (on a sustained basis), but not complete OEDR?
Perform both longitudinal and lateral vehicle motion control (on a sustained basis), but not complete OEDR?
Perform the complete DDT, but not DDT fallback, within a limited ODD?
Perform the complete DDT and DDT fallback within a limited ODD?
Perform the complete DDT and DDT fallback without ODD limitation ?
Share your Results:
SAE International defines different levels of autonomous driving by reference to the expected role played by a driver and ADS in performance of the DDT. To be more specific, an autopilot category depends on what the automated driving system can do and what a human driver should do when in the car enabled with a specific autopilot level. For example, in the case where a driver doesn’t monitor the highway while driving a vehicle with the adaptive cruise control system enabled still, he still has the role of a driver, even though he ignores it.
Level 0: No automation
The SAE autonomous driving levels document classifies the autopilot category 0 as no driving automation. That is to say, this is a driver who performs a dynamic driving task (DDT), namely makes all driving decisions. Enabled with an autopilot level 0, a car can, however, help a driver control a car with such active safety systems as lane departure warning, cruise control, blind spot detection, road sign recognition, camera-based driver monitoring, night vision system, anti-lock braking system, electronic stability control, and parking sensors.
Examples of vehicles with autopilot level 0:
- Kia Ceed
- Honda Civic
- Toyota Corolla
- Volkswagen Golf
- Ford Fiesta
Modern cars equipped with an ADS of an autonomous driving level 0 can also have a pedestrian detection system (PDS) capable of activating emergency braking when a person or even animal suddenly appears in front of a bumper. These systems, however, require a driver to constantly monitor the road conditions and be ready to timely react since they provide no 100% guarantee. The study conducted by the U.S. Insurance Institute for Highway Safety (IIHS) shows that PDS is imperfect and can work passably only under specific conditions like clear weather and dry roads. This technology is still in its infancy. It’s rather an assistant and can’t be considered as a panacea to rely on.
Level 1: Driver assistance
Level 1 autopilot vehicles can perform a part of the dynamic driving task by executing either the lateral or longitudinal car motion control within the limited operational design domain. In other words, those vehicles enabled with the first autonomous driving level can either turn or accelerate and activate braking under specific conditions, for example, clear road marking. Such cars assist the driving process requiring a driver to supervise the ADS and be ready to intervene at any moment to ensure the safe operation of a car.
Examples of vehicles with autopilot level 1:
- Hyundai Tucson
- Honda Accord
- Toyota Camry
- Volkswagen Passat
- Ford Edge
With a car equipped with an autonomous driving level 1, this is a driver who performs the main part of the DDT while relying on the ADS in typical simple vehicle motion control scenarios like parking and driving a car on a highway without changing gears and lanes. Those vehicles enabled with a driving automation system of the 1st level have adaptive cruise control, next-generation parking assistant, which can automatically park a car without driver intervention, or lane-keeping assist system, which, unlike a lane departure warning system, also can automatically steer when a driver drifts out of the lane.
Level 2: Partial automation
Unlike, an autonomous driving level 1, cars with the second autopilot level can perform a part of the DDT and execute both longitudinal and lateral vehicle motion control simultaneously. That is to say, an autopilot level 2 refers to the automated driving system that can control car motion without a driver within a specific operation design domain, namely, during stop-and-start situations and on highways, demanding, however, him to be ready to intervene and take a DDT under his full control.
That’s why such automated driving systems may require a driver to keep his hands on a steering wheel. Otherwise, the ADS will switch off the autopilot mode and transfer control to a driver. For example, when the 2018 Volvo XC90 pilot assist system displays a notification requiring to apply steering and a driver ignores the demand, the ADS disengages the autonomous driving mode showing the “Canceled” message, thus making a driver control car motion on his own. Autopilot level 2 vehicles can’t ensure a 100% safe trip even on highways.
Examples of vehicles with autopilot level 2:
- Volvo XC90
- Tesla Model S
- Nissan Rogue 2018
- Audi A8 2019
- Cadillac CT6
Taking into account the official SAE classification, Tesla autonomous driving level is 2. It refers to all Tesla models including Model S, Model 3, Model X, and even the upcoming Cybertruck pickup truck to be presented on November 21 in Los Angeles. As a representative example of what autopilot level 2 cars can, Tesla’s Navigate on Autopilot feature can guide a car from “on-ramp to off-ramp” by making lane changes to overtake slow vehicles on the road or make turns, navigating highway interchanges, and properly taking exits.
Level 3: Conditional automation
The SAE classifies the autopilot level 3 as the ADS that can perform the entire DDT within a limited ODD, for example, in low speed. In other words, this level of autonomous driving implies an automated system to be able to make all driving decisions under specific conditions. During a trip, a car enabled with such ADS requires no driver intervention unless an unexpected situation occurs, for example, a system failure, car accident or road works ahead. That’s why a driver becomes a DDT fallback-ready user, that is to say, he should be ready to take control over the car whenever the ADS requires it.
List of cars with autopilot level 3:
- Audi A8 (under development)
- Honda Legend 2020 or Acura RLX 2020 (under development)
- Mercedes-Benz S-Class 2020 (under development)
With the autonomous driving level 3, a driver still should ensure a minimal risk condition. He can watch movies, text, or read a book during a trip while also being prepared to intervene in the cases where ADS issues may not activate the request for driving participation. These situations refer to vehicle malfunctions unrelated to its automated driving system, for example, worn brake pads, flat tire, or broken suspension.
As for now, there exist no publically available cars enabled with an autopilot level 3. Although, such automakers as Honda and Mercedes-Benz have already revealed their plans to present ones in 2020. They have been testing the autopilot mode technology in vehicles (Honda Legend offered as Acura RLX in the U.S and Mercedes-Benz S-Class).
Level 4: High automation
The autopilot level 4 can perform the entire DDT within a limited operational domain design without the need for participation of a driver under any conditions. It means that the ADS can safely drive a car in an autonomous mode within a specific area regardless of road conditions. Unlike an autonomous driving level 3, a driver doesn’t need to be a DDT fallback-ready user, that is to say, he hasn’t to be ready to intervene. since the vehicle can ensure a minimal risk condition if a driver isn’t ready to take manual control over a car.
In other words, a driver plays the role of a passenger when the ADS is engaged. If an expected situation occurs, for example, an ADS failure of other vehicles, the car equipped with the autonomous driving category 4 may request driver participation and when he fails, it can activate emergency braking and then continue a trip or safely park a car without driver intervention in the case where the ADS no longer can complete the DDT.
List of vehicles with autopilot level 4:
- Waymo (under development)
- Daimler Trucks Freightliner Cascadia (under development)
- Volkswagen eGolf 2025 (under development)
- Honda Legend 2025 or Acura RLX 2025 (under development)
- Toyota LQ (a concept car)
A driver can completely disengage the autopilot level 4 mode and take full control over the vehicle, thus driving it as a conventional car. Nevertheless, the ADS may delay user-requested disengagement until it achieves a minimal risk condition and ensures the situation where a driver can safely continue performing the DDT.
Level 5: Full automation
The first 5 levels of autonomous driving cars have a set of conditions under which a vehicle cannot perform a DDT and either requires a driver to intervene or simply stops a trip whereas the last autopilot category implies full automation regardless of conditions. That is to say, whatever happens, the ADS can make driving decisions on its own that’s why it’s called “steering wheel optional” – it just does not need it. The ADS even needs no person inside of a car to complete a trip from start to end.
List of vehicles with autopilot level 5:
- Ford Fusion by Lyft (under development)
- Chrysler Pacifica by Lyft (under development)
- Chevrolet Bolt EV by Cruise Automation (under development)
- Volvo XC90 by Uber ATG (under development)
- Volvo 360c (a concept car)
The only conditions that can make a trip in an autonomous mode impossible are the same that wouldn’t allow a human driver to perform a DDT. They include but not limited to a snowstorm, blocked road, and glare ice. An autopilot level 5 can drive a car on any type of road regardless of location and time of the day, and a driver doesn’t need to supervise the ADS at all.
Why don’t we have cars with the autonomous driving level 3, 4, or 5? The technology is only gaining momentum, and vendors need another numerous testing hours to make it mature enough. While the autopilot level 5 is rather a long-term prospect currently hardly imagined, categories 3 and 4 are under intensive development in R&D’s of such companies as Google, Uber, Daimler, Honda, and Toyota.
While auto giants like Mercedes-Benz and Volkswagen promise to provide partially automated products by 2025, Elon Musk, Tesla’s CEO, claims to reveal a fully autonomous driving system of a level 5 in 2020. Despite this statement seems too optimistic, we will definitely become witnesses of the tremendous changes in the automotive industry in the next decade.