Society of Automotive Engineers, SAE Automation Levels for cars

Society of Automotive Engineers, SAE Automation Levels were established as a classification system for self-driving cars in January 2014. The grouping provides a common classification and definitions for driverless vehicles. SAE classification system on driverless cars was accepted by the U.S. National Highway Traffic Safety Administration in later half of the same year.

In order to bring transparency to this situation, two regulatory bodies covering the United States have defined very analogous levels of vehicle automation, with the second bringing better clarity and now used as the standard classification tool.

The primary body to define levels was the US Department of Transportation’s National Highway Traffic Safety Administration (NHTSA). However, its definition of the most automated level of driving was found to be too extensive, and so the SAE International (initially established as the Society of Automotive Engineers) levels were established, building on the earlier NHTSA work.

NHTSA established a policy on automated vehicles in May 2013 that defined automation Levels 0 to 4, with automation growing from Level 0 up to a fully automated vehicle at Level 4.

The SAE levels that were out of date as per the NHTSA levels in October 2016 defined Levels 0 to 5. For both sets of automation definitions, the Levels 0 to 3 were particularly similar. But what the SAE definitions do is sub-divide the fully automated NHTSA Level 4 into SAE Level 4 and Level 5.

Germany Federal Highway Research Institute (BASt) has also issued levels of Autonomy, the levels are Driver Only, Assisted, Partially Automated, Highly Automated, and Fully Automated.

SAE J3016 issued on 2014-01 details all modes of Automation in Cars and is free to download here: LINK

NHTSA Official Page for Autonomous Cars : LINK

This article details all automation levels and is inspired from the standards from SAE and NHTSA.

SAE LEVELS

SAE Level 0 Automation:

At Level 0, cars have no autonomous vehicle controls – but driving can be improved by warning or interference systems like blind spot pointers. At level 0, the human driver does all is just driving.

Steering system: Fully Controlled by Driver.

Throttle Pedal: Fully Controlled by Driver.

Braking: Fully Controlled by Driver.

Perception of Environment: Fully Perceived by Driver.

Interception by Vehicle Intelligence: None.

Failsafe responsibility: Driver.

SAE Level 1 Automation

With Level 1 automation, human drivers control the acute driving tasks – but may get slight technological aid. The car might comprise of a system that functions steering. Or the car may be able to aid with acceleration/deceleration in definite scenarios. Level 1 cars usually never take over both functions. All the cars on the market today are classified as Level 1 vehicles because Stability Control was required for 2012 models. Cruise control (acceleration/deceleration) or lane correction technology (steering) also qualify as Level 1 technologies.

Steering system: Fully Controlled by Driver.

Throttle Pedal: Fully Controlled by Driver.

Braking: Fully Controlled by Driver.

Perception of Environment: Fully Perceived by Driver.

Interception by Vehicle Intelligence: Very Minimal.

Failsafe responsibility: Driver.

Functional Safety Requirements for Automation: None

SAE Level 2 Automation

Level 2 automation vehicles take over both steering and acceleration/deceleration capabilities in fixed situations. Even though level 2 vehicles can take over certain “driving modes” or tasks, the driver is still in control of the vehicle at all times. Tesla’s Enhanced Autopilot or Volvo’s Pilot Assist II are Level 2 automation features. They can support a driver to stay in their lane and even slow down to avoid cars in traffic. Self-park features also benefit a driver with certain utilities. Many of these systems may work in SAE level 3 category, but to cut the regulation strictness and Functional Compliance these vehicle manufacturers still define their systems as level 2.

Steering system: Fully Controlled by Driver.

Throttle Pedal: Minimal Automation.

Braking: Fully Controlled by Driver.

Perception of Environment: Radar’s & Camera’s are used to perceive objects around the car with preloaded maps.

Interception by Vehicle Intelligence: Limited Scenario’s/Defined Modes.

Failsafe responsibility: Driver.

Functional Safety Requirements for Automation: Minimum.

From LEVEL 3 onwards Vehicles are meant to have Good Intelligence, Perception capabilities and Functional Safety requirements.

SAE Level 3 Automation

At level 3 automation, cars securely control all features of driving in a mapped environment. Human drivers still need to be on board monitoring and handling variations in road environments or unexpected situations. To date, no Level 3 cars are being sold to consumers. Level 3 technology has encouraged controversy, with some industry players saying it’s not convincing to expect a driver to remain as attentive as needed, if they’re only inactively monitoring driving functions.

Steering system: Conditional Automation.

Throttle Pedal: Conditional Automation.

Braking: Conditional Automation.

Perception of Environment: Radar’s, Lidar & Camera’s maybe used to perceive objects around the car with HDmaps.

Interception by Vehicle Intelligence: Limited Scenario’s/Defined Modes.

Failsafe responsibility: Driver.

Functional Safety Requirements for Automation: Moderate.

SAE Level 4 Automation

In level 4 vehicles, no driver interaction is required. A level 4 car can stop itself if the systems flop. These cars will be able to handle driving from point A to point B in most use-cases. Nevertheless, the cars will include functional driving device, like wheels, brakes and gas pedals.  So humans can physically drive when conditions confuse predefined use cases (i.e., off-roading,) or when humans feel like actually driving.

Steering system: Maximum Automation.

Throttle Pedal: Maximum Automation.

Braking: Maximum Automation.

Perception of Environment: Radar’s, Lidar & Camera’s are to be used to perceive objects around the car with HDmaps.

Interception by Vehicle Intelligence: Limited Scenario’s/Defined Modes(Most of the City Driving).

Failsafe responsibility: System.

Functional Safety Requirements for Automation: HIGH.

SAE Level 5 Automation

Level 5 cars are completely autonomous. Besides controlling the destination, humans have no other involvement in driving a level 5 car – nor can they intervene. Prototypes of level 5 vehicles look nothing like the cars that we drive today. There are no steering wheels, gas or brake pedals. Instead, the interiors of level 5 vehicles are designed around and productivity of its passengers, with features such as offices or entertainment lounges.

Steering system: Maximum Automation.

Throttle Pedal: Maximum Automation.

Braking: Maximum Automation.

Perception of Environment: Radar’s, Lidar & Camera’s are to be used to perceive objects around the car with HDmaps, V2V, V2X.

Interception by Vehicle Intelligence: Complete Interception(No Intervention of Driver needed).

Failsafe responsibility: System.

Functional Safety Requirements for Automation: HIGH.

Current Trends:

A mixture of two or more advanced driver assistance systems (ADAS), where these systems occasionally help control either the braking, acceleration, or steering, is well-defined as a Level 2 vehicle. There are many altered names and acronyms used by the different automakers to describe these ADAS systems, but examples include:

  • Adaptive Cruise Control: The driver can leave the gas pedal alone and the vehicle will travel at a continuous speed, and it will detect a vehicle in front and slow down to uphold a set gap.
  • Lane-Keeping Assist: Controls the vehicle steering to help inhibit the driver from accidentally travelling out of their lane on the highway.
  • Automatic Emergency Braking: The vehicle senses a forthcoming crash and applies the brakes to avoid, or limit the harshness, of the collision.

More and more vehicles now have Level 2 competence, particularly top-of-the-range models. In order for the vehicle to securely carry out some of the driving tasks, sensor suites are essential that are similar to that which is needed for Level 3 and Level 4 driving. With Level 2 vehicles, however, the driver must stay in control of the vehicle at all times.

Even though Level 2 vehicles can give the impersonations that they are doing all of the driving in definite conditions, such as in congestion with “Traffic Jam Assist” or on highways using “Autopilot,” it is critical that the driver remain watchful at all times. Unfortunately, human nature means that some drivers trust these systems too much and assume them to operate outside their stated capability.

SAE Level 3 vehicles are significantly more advanced than Level 2 vehicles, as they are actually skilled of taking full accountability for the driving task on some particular parts of a journey.

When a Level 3 vehicle touches the point where it is no longer proficient of carrying out the driving duties, it will direct a driver that she/he must take back control in a small amount of time, typically tens of seconds or less. If this driver re-engagement does not happen in the stated time, then the vehicle will subject to warnings more convincingly to gain the driver’s attention. If these warnings also flop, then the system will bring the vehicle to a safe stop, most possibly by the side of the road.

The first example of a Level 3 vehicle that we can expect to see on the roads is one that can drive itself from on-ramp to off-ramp on a freeway. Presently, there is no only one Audi A8 Level 3 Car in market, but Tesla’s CEO Elon Must has declared that Tesla’s  functionality beyond Enhanced Autopilot, moving towards self-driving ability, will definitely be available by July 2019 with existing Vehicle Infrastructure.

Vehicles with SAE Level 4 capability are proficient in driving for an entire journey, in fact driving unmanned. Nevertheless, their operation will be reserved in some way, such as detailed below.

  • Restricted to a geo-fenced area, such as paved streets in a definite area of town.
  • Restricted by hostile weather, such as falling snow, snow-packed roads, strong rain, dense fog, etc.
  • Restricted to a maximum speed, e.g., vehicles restricted to 35 mph may be able to travel on most streets, but not on roads mentioned at 40 mph and above.

Several low-speed, Level 4 shuttle demonstrations have taken place around the world, and several pilot projects have been started to regulate the possibility of this technology.

Unmanned, unrestricted operation describes SAE Level 5 vehicles. They will not have operational restrictions like the Level 4 vehicles, and will be able to go at anyplace at any time.

Some believe that vehicles with this level of ability may never exist. Some say that they will take a very extended time. Many believe that vehicles that would drive themselves to your day and take you places would be 50+ years away.

Dr. Gill Pratt of the Toyota Research Institute trusts that no one is even close to Level 5 now, but that will have such vehicles at some point of time in near future.

The key point in moving from Level 2 to Level 3 autonomy is that Level 3 assumes that the user only has to interfere whenever the car is not able to handle a condition and asks for the user to take over. The vehicle for its part must be able to accomplish all activities related to driving the vehicle at other times.

But, Audi’s solution has certain limitations. For one it is only meant to be activated in comparatively slow moving traffic (upto 60 km/hr) and only on divided roads where a physical barrier splits vehicles driving in the opposite direction.

Audi’s solution is the first of its kind to involve absolutely no monitoring of the vehicle as long as the driver is accessible to take over when the vehicle asks him/her to. While the vehicle is driving itself, the customer is free to do anything else. Note the laws across many countries/regions may still involve the user to pay attention but the car itself is able to handle the driving tasks all by itself. This is what makes it the first production vehicle to potentially attain Level 3 autonomy.

Tesla’s Autopilot also needs the user to keep their hands on the steering wheel and asks the user to observe the actions of the car. This marks it an SAE Level 2 solution at best. They have a long way to go in reaching Level 3 and also take care of functional requirements which they dont want to get involved in.

General Motors (GM) made a big declaration that its forthcoming CT6 sedan will be the first production vehicle to back hands-free autonomous driving. GM uses a minor infrared camera to observe the driver’s head position and make sure he/she is paying attention to the road. Indeed the user does not have to keep their hands on the steering wheel but they still need to observe the car’s behaviour at all time. This again makes it an SAE Level 2 solution.

This article was written by  Eeshan Bashir and Vineet Chatterjee, if you wish to take this article to perfecion or write a guest article email us at contact@automotivelectronics.com

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