Driverless Mobility

The Autonomous Future

Levels Of Automony
In the previous months issue, we tried to introduce all your “temporary drivers” to what self driving cars really are and we journeyed through time, encompassing developments from Udina’s Self Driving Chariot in 1925 to present day Autonomous Shuttles.
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Udina’s Self Driving Chariot (left) and Autonomous Shuttles in Urban Areas (right)
Today we will dig deep into how different types of self driving car systems are categorized based on the features incorporated in them.

The standards are continuously evolving but for the purposes of our classification, we will use the decomposition suggested by the Society of Automotive Engineers (SAE) which basically divides the different automated driving systems in “6 levels of autonomy”, right from level 0 to level 5.

This so called Taxonomy of Driving automation describes the respective roles of the (human) user and the driving automation system in relation to each other. Because changes in the functionality of a driving automation system changes the role of the (human) user, they provide a basis for categorizing such system features. 


The two main types of controls involved in controlling any vehicle are: Longitudinal Control and Lateral Control
Longitudinal Control i.e. control in X direction mainly by varying acceleration and braking pedals. 

Lateral Control i.e. control in Y direction achieved by varying the steering angle of the vehicle.

Along with that, with the advent of latest sensing technologies and development of modern machine learning algorithms, the vehicle is able to accurately sense its environment and provide control commands to control the vehicle in its lateral and longitudinal directions.

So, in this context, driving automation systems are (SAE) categorized into 6 levels:

Level 0 : No Automation
Level 1 : Driver Assistance
Level 2 : Partial Automation
Level 3 : Conditional Automation
Level 4 : High Automation
Level 5 : Full Automation

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Categorization Of Levels Based On:

A. Whether the driving automation system performs either the longitudinal OR the lateral vehicle motion control.

B. Whether the driving automation system performs both the longitudinal AND lateral vehicle motion control simultaneously.

C. Whether the driving automation system also performs the object and event detection and produces a necessary reaction.
D. Whether the driving automation system also performs fallback to the human driver in case of confusing situations.

E. Whether the driving automation system is limited by an Operational design domain (ODD) i.e. an environment in which the autonomous vehicle is designed to perform or not.


Let us explore each level in more detail:
Level 0 In this level, there is absolutely no driving automation involved and the driver has to perform all the dynamic driving task. Only advent here is that the system can provide additional features like automatic emergency braking, lane departure warning, blind spot warning etc. which are mainly features related to warnings and momentary assistance. 

Level 1 Such systems provide Driver assistance by either implementing lateral control OR longitudinal control. So, the driver has to be involved all the time and monitor the situation and intervene whenever necessary. Example features will be lane maintaining system (steering control) OR adaptive cruise control (acceleration and braking control). 
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Level 2 In this level, the automated driving system provides partial automation by implementing both, lateral AND longitudinal control. But here too the driver needs to be in control of the vehicle all the time and takeover the control whenever necessary.

So, example features for such an automated driving system would be both lane maintenance system as well as Adaptive cruise control.


Level 3 Such an automated driving system not only implements longitudinal and lateral control, but also can perform Object and event detection and provide the necessary reaction.

So even though the driver is present, there should be no need for him to stay attentive or drive the vehicle all the time.

The system itself fallbacks to the driver in case of emergency situations. Example features include all the features in above levels in addition with vehicle detection and tracking, pedestrian detection and tracking, lane lines detection etc.
Level 4 In level 4 automated driving system, all the features included in above levels are present and the vehicle can be autonomously driven without any interference from driver but only for a well defined ODD. So beyond that ODD, the vehicle cannot be necessarily driven autonomously without a driver's assistance. 

It is possible for the vehicle to not have any steering wheel or acceleration and brake pedal at all. Majority of current self driving cars are categorized in either level 3 or level 4 automated systems.


Level 5 systems can be categorized as an automated driving system which is capable to drive the vehicle completely in autonomous mode just like level 4 systems, but they are not limited by the ODD and hence can be driven ideally anywhere in the world.

Presently, this level of automated driving is still at a research stage and many companies like Lyft, Waymo, Uber etc are continuously striving to reach this level.
So to conclude, these are the different levels of autonomy as stated by the SAE. Continuous efforts are being made to achieve higher levels of autonomy by companies all over the world working on related technologies like sensing systems, smart cities, better perception systems, better processing capabilities, etc.

Although level 5 is still far away, the advantages of having even level 1 vehicles on our streets is hard to ignore and will have huge impact on our lives. The autonomous future is surely promising!
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Ebrahim
Mechatronics Engineer, Mumbai, India