Levels of Driving Automation Systems

Though Self driving era has already begun, its capabilities are subject to conditions which decide whether it is fully autonomous or semi autonomous. How are they classified? How do i trust semi autonomous systems? When should i take back its control?

This post is to demystify various levels of driving automation systems with reference taken from Society of Automotive Engineers (SAE) recommended practice J3016.

Self driving cars are one of the recent fascinating terms we hear often. If you are a follower of Elon Musk’s Tesla, the obvious thing that comes to mind is “Auto Pilot” mode. It is one of the least available on-road features that lets you to sit and relax while the vehicle drives on its own to your destination. While Auto Pilot mode allows the vehicle to self drive, they are not fully autonomous. Of course you can sit and relax but not from the seat other than driver seat. It still needs a driver to be present to monitor the environment and warnings thrown by the vehicle. Waymo (formerly Google Self Driving Car) has gone beyond Auto Pilot mode. They provide Robotaxi Service through their App that allows users to set pick up and drop points. Once set and ready, you could see a Driverless car coming to your way to pick you up. On May 2019 they partnered with Lyft to introduce Waymo vehicles to Lyft users, while Lyft already provides its own commercial Robotaxi Service using self driving cars made by tech company Aptiv.

So how do i know the level of automation of my vehicle? How many of us really go through vehicle manuals when we buy a car. It is a must to read them if you are going to drive any automated systems. Before that, you should be knowing various automation levels and its terms and conditions.

Picture showing lateral and longitudinal axis of the vehicle

Let us see a set of driving tasks a conventional driver performs. Consider a vehicle moving towards North with North <> South as X axis and East <> West as Y axis. Longitudinal Control adjusts the vehicle in X axis (Accelerate / Brake) and Lateral Control adjusts the vehicle in Y axis (Steering). Whenever an obstacle is detected in front, preventive action has to be taken to avoid collision. In case collision cannot be avoided, multiple controls are put in place to minimize the severity (Environment monitoring, Object and Event Detection and Response – OEDR). Well skilled driver can handle all these controls without much effort, irrespective of whether he is in fast moving highway lane or a slow moving congested road. Now we expect all said controls to be done by a machine. Many cars are able to perform lateral and longitudinal controls smoothly but find it difficult to perform OEDR because of various limitations. So the levels are:

Level 0 – No Automation: All driving tasks are performed by driver.

Level 1 – Driver Assistance: Lateral OR Longitudinal control alone can be performed by the vehicle, still driver attention is required to monitor the environment. Best example of longitudinal control is Adaptive Cruise Control, where you can set desired speed and distance you want to maintain from front vehicle if any. After set, your vehicle drives on its own at set speed if no other vehicle is detected in front. If any vehicle is detected, ACC automatically adjusts speed to maintain your set distance.

Level 2 – Partial Automation: Both Lateral AND Longitudinal control can be performed by the vehicle, still driver attention is required to monitor the environment. When ACC is combined with Lane Centering system, your vehicle can steer to maintain your centricity. Tesla’s Auto Pilot lies here.

Level 3 – Conditional Automation: In addition to level 2, vehicle takes care of monitoring the environment. In case of any failure or obstacle detection, vehicle requests the driver to intervene. It does NOT take preventive action on its own and hence driver support is still required. This is where most of the people assume their attention is not required while its not the case. That is why OEMs recommend to go through vehicle manuals before engaging them. Audi Traffic Jam Pilot is best example for this level.

Level 4 – High Automation: Same as level 3 except the machine itself takes preventive action to reach minimal risk condition. But it puts limitation on the conditions the vehicle can take those actions (eg: only in highways and if weather is good with enough driving condition). Waymo are already at level 4 where they have limited their automation within Phoenix, Arizona.

Level 5 – Full Automation: Same as level 4 but without any limitation on the conditions. It is the ideal expectation we have from a Self Driving / Autonomous Car, it should perform everything a expert driver can do with great precision and accuracy.

Having said about the levels of automation a vehicle can have, it becomes obvious that there is still a long way to reach Full Automation. With advent of AI and Machine learning, experts believe it can be reached without much hustle. But challenges will always prevail wherever a machine tries to replace humans.

Self-driving cars are the natural extension of Active Safety and obviously something we should do.

– Elon Musk
SAE J3016 document can be downloaded at free of cost from their website.

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