Levels of autonomous driving

What are the 5 levels of autonomous driving?

The development stages up to the autonomous vehicle are divided into five levels. What does this classification look like and how are the individual levels of autonomous driving characterized?

Most recently updated on 30-11-2021

From driver to passenger

Autonomous driving is at the heart of all discussions about the mobility of the future. The prospect of having self-driving cars zooming around in perfect harmony excites everyone. Many discussions focus on when we will get to live out this vision of full autonomy, but the question of which steps we need to get there is just as interesting. Autonomous driving is not about going from 0 to 100, i.e. from manual driving to complete autonomy. It is rather a step-by-step development towards automation.

This development is divided into five stages or levels of autonomous driving. How are these levels of autonomous driving defined? And which ones are already on the road? What do people mean when they talk about  ‘modes’ of autonomous vehicles? Let’s find out:

Gradual development of autonomous driving functions

The classification of the development stages up to the self-driving vehicle comes from the Society of Automotive Engineers (SAE) and describes the extent to which the vehicle can and may take over the tasks of the driver.

The levels of autonomous driving range from 0 with no assistance systems at all to Level 5, which describes fully autonomous driving.

Five Levels of autonomous driving

What are the different levels of Autonomous Driving?

Level 0 Autonomous Driving – manual driving

Anyone who obtained their driving license before the 1990s probably still learned to drive a completely manual vehicle – without ESP, parking assistance, or any other kind of assistance system. According to the classification of the SAE, these vehicles belong to level 0 autonomous driving.

Level 1 Autonomous Driving – driver assistance

New vehicles without any assistance systems are hardly to be found today; the majority of cars are equipped with New vehicles without any assistance systems are hardly to be found today; the majority of cars are equipped with assistance functions that correspond to Level 1. Examples include cruise control, lane departure warning, and emergency brake assistance. They support the driver, increase safety and driving convenience, but in no way replace his or her skills. The driver still steers the vehicle completely independently, has to be alert at all times and keep a constant eye on the traffic.

Level 2 Autonomous Driving – partial automation

Level 2, as expected, goes one step further. Here, several assistance systems are often combined with one another so that the vehicle can independently perform individual driving manoeuvres, such as parking or navigating stop-and-go traffic. The driver can hand over control of the vehicle during these manoeuvres, but must remain alert and be able to intervene at any time if something does not work as intended. The same applies to assistance functions such as lane departure warning or distance warning.  Level 1 and 2, when combined, form the current ADAS (Advanced Driver Assistance System) technology.

Current vehicle models are often categorized as Level 2, and even if the functions are sometimes very impressive, it must be made clear that these are by no means actual self-driving functions that allow drivers to divert their attention from the road.

Level 3 Autonomous Driving – conditional automation

With the step from Level 2 to Level 3, things begin to get more exciting: While Level 2 autonomous driving is all about assistance systems, in Level 3 the car actually drives autonomously under certain conditions. Drivers may temporarily turn their attention towards other activities and even take their hands off the wheel. With Level 3, you enter the world of highly automated driving!

The added value of automating certain scenarios can be seen particularly clearly in highway driving. For instance, driving straight ahead for long periods is boring and relatively straightforward compared with navigating city traffic. Accordingly, a possible development towards Level 3 could be that vehicles on highways drive independently and drivers can devote themselves to other tasks during this time. When the highway exit is approaching or some complicated scenarios pop-up, such as road work or diversions, the vehicle hands control back to the driver.

However, this handover poses a number of challenges. Which activities may the driver perform while the car is steering itself? How long in advance must the vehicle alert about the change of control? These questions need to be clarified, as does the technological assurance that the vehicle will correctly recognize when a traffic situation exceeds its capabilities.

There is an interesting debate on how the companies in the autonomous driving market are shaping up to make the leap from Level 2 autonomy (ADAS) to level 3 and above. We have discussed this in detail in this blog post titled ‘ADAS or Autonomous Driving – Evolution or Intelligent Design?

Level 4 Autonomous Driving – high automation

The next step after the initial automation of certain driving situations is the automation of all driving situations, i.e. fully automated driving on Level 4, where the vehicle controls complete journeys on the highway as well as in city traffic predominantly independently. Drivers can also devote themselves to other activities for longer periods of time, such as working, keeping the children in the back seat busy, or even sleeping.

Those who see their own driving pleasure endangered by autonomous driving functions do not need to worry: At Level 4 the driver can always take back control of the vehicle at any time. In some cases the vehicle may even hand over control to the driver if the system is no longer able to guarantee complete safety. If the driver does not react in this situation, the vehicle will come to a safe stop.

Level 5 Autonomous Driving – full automation

With Level 5 we have arrived at fully autonomous driving: Unlike the previous levels of autonomous driving, neither driving ability nor a driving license are required to use the vehicle.

The driver becomes a pure passenger.

This is why prototypes of fully autonomous vehicles have neither a steering wheel nor pedals, since they are capable of driving completely independently and require no human input. The user merely determines the pick-up location and the destination.

This opens up completely new possibilities for low-cost individual transport, because robo-taxi fleets consisting of fully automated vehicles can be operated very economically and efficiently. In addition, they generate enormous advantages for people without a driving license or their own vehicle, such as children or senior citizens, and offer great added value, especially in rural areas. Thus, autonomous vehicles will not only change the functional spectrum of the car in general, but also the concept of mobility itself from the ground up.

What are the ‘3 Modes’ of Autonomous Driving?

For a long time, the SAE standard of 5 levels of autonomous driving has been the norm. While the levels are very elaborate and comprehensive, it is still important to question whether the distinction between them makes sense. To make the discussion about autonomous driving technology more straightforward, Germany’s Federal Highway Research Institute (Bundesanstalt für Straßenwesen oder BASt) recently presented an alternative. They suggested switching from 5 levels to 3 modes, which would help to simplify the discussion around autonomous vehicles

The graphic below shows the ‘3 Modes of Autonomous Driving.’

3 modes of autonomous driving

The first mode combines SAE levels 1 and 2 of the “assisted mode,” where the driver is supported by the vehicle but must remain alert and ready to intervene at all times.

The second mode would incorporate SAE’s level 3 and would be called “automated mode.’’ The driver temporarily hands over the steering wheel to the computer and can perform other activities for a more extended period.

Last but not least, the “autonomous mode” combines the SAE levels 4 and 5, and as illustrated in the graphic above, gives complete driving authority to the vehicle.

Interestingly, Level 0 is not considered for the new terminology, and the level describes fully analog driving without any accompanying assistance system.

The new BASt designation is a welcome change, as it promises to simplify the terminologies while remaining compatible with the SAE system. This means that the SAE levels of autonomous driving can still be used within more specialist and technical circles. At the same time, general conversation and policy discussions can be easily conducted using these higher modes.

Autonomous driving will only be possible with reliable environment detection

The crucial step into the higher levels of autonomous driving is largely determined by the development of perception technology, i.e. sensor technology. Automated driving functions from Level 3 upwards are only possible if vehicles are able to reliably detect their entire environment and derive instructions for action accordingly. Such vehicles will make use of a wide range of sensors, such as ultrasonic sensors, radar, and cameras, with the LiDAR sensor at the center, thanks to its high resolution and reliable 3D measurement capabilities.

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