Self-driving cars explained: how autonomous is my car?

As safety body Thatcham Research calls for greater clarity around the effectiveness of self-driving systems, we expain what the different levels of autonomy mean...

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Darren Moss
12 June 2018

Drivers are being misled over the extent to which new cars can drive themselves. That's the call from Thatcham Research – which conducts safety tests on behalf of Euro NCAP in the UK – and the Association of British Insurers, which has pointed to a rise in car accidents occuring as a result of drivers expecting their cars to take preventative measures.

Part of the confusion is over naming, with brand names including ProPilot, Pilot Assist and Autopilot making drivers think their cars can effectively drive themselves in any situation. In reality, most semi-autonomous systems act only as a safety back-up or assistance for motorway driving.

Thatcham Research is calling for more clarity from manufacturers over the capabilities of their systems, with head of research Matthew Avery saying: "We're starting to see real-life examples of the hazardous situations that occur when motorists expect the car to drive and function on its own.

"Fully automated vehicles that can own the driving task from A to B, with no need for driver involvement whatsoever, won’t be available for many years to come. Until then, drivers remain criminally liable for the safe use of their cars and, as such, the capability of current road vehicle technologies must not be oversold."

Thatcham's own testing procedures will also include semi-autonomous driving systems from this summer, beginning with six cars fitted with the latest driver assistance aids. These tests will include how clearly the systems are named in promotional material, how easy they are for drivers to activate and operate and what happens when drivers are required to take back control.

The results of the tests, which are expected to be available from this autumn, are likely to be used by insurers to help rate the effectiveness of semi-autonomous technology.

So, what can you expect from a truly driverless car? Autonomy can be broken down into six levels, and below we explain what each one involves.

Autonomous cars – what do the different levels mean?

Level 0

In Level 0 driving, the driver is completely in control of the car, in both speed and steering, with only warnings and alerts assisting the driver in extreme circumstances. Today, such cars are rare and almost invariably extreme, low-volume performance cars; the lack of driver assistance is said to create a 'purer' performance car.

Example: Noble M600. No assistance systems fitted; the driver is in full control of the car at all times.

Self-driving cars explained: how autonomous is my car?

Level 1

Level 1 is the first of the ‘assisted driving’ levels, where the car can ‘support’ driving functions, meaning it has a small level of control in the journey.

Most modern cars can be considered to be of this level because systems such as adaptive-speed steering, speed limiters, traction control and ABS have the car controlling certain elements of travel in spite of the driver’s command. Very little control is given to the car and the control that is given is often unnoticed by the driver.

Example: Skoda Fabia. Traction control: when the car loses traction under acceleration, the car cuts the amount of power delivered to the wheels to stop them from spinning.

Self-driving cars explained: how autonomous is my car?

Level 2

The second level of ‘assisted driving’ as set out by government rules involves the car being able to ‘control lateral or longitudinal movement’. Examples of this are adaptive cruise control, which changes the speed of the car based upon the speed of the car in front, and lane-keeping assist, which adjusts the steering if the car senses danger caused by you drifting out of your lane accidentally.

At no point is the driver not paying attention to the road, nor are they taking their hands off the steering wheel. And in the case of adaptive cruise control, the driver needs to keep the pedals covered in case of an emergency.

Example: Lexus NX. Adaptive cruise control: the car controls the speed at which it is travelling, but the driver controls everything else and must maintain focus on the road.

Self-driving cars explained: how autonomous is my car?

Level 3

Level 3 driving involves near-equal input from driver and car. An example of this type of car is a traffic jam assist system, which will operate the accelerator, brakes and steering in slow-moving traffic.

Despite the car’s control in these situations, the driver must focus on the road and take control when necessary, making it a theoretical ‘hands-off’ system but not an ‘eyes-off’ one.

Example: Seat Ateca. Traffic jam assist: controls all of the driving functions of the car, but you must keep your hands on the wheel and eyes on the road.

Self-driving cars explained: how autonomous is my car?

Level 4

The first of the ‘automated driving’ categories is also the first ‘eyes-off’ and ‘hands-off’ category. There isn't yet a car on the market that fits Level 4, but with the Government’s intention to make the UK a leader in autonomous car development, it shouldn’t be long.

The Government describes this style of driving as “the driver is only responsible and exercises control when the system is not in use”. The car can be in charge of all driving functions without the driver’s intervention, attention or input. The systems can be turned off when the driver chooses and then normal driving resumes.

Example: None available yet, but the first self-driving cars are expected to appear before the end of this year.

Self-driving cars explained: how autonomous is my car?

Level 5

Level 5 is the highest point of automated driving, wherein the car can control its speed and direction fully, without any need for driver intervention. Although the Government's guide does not specify it, this type of autonomous driving would allow the car to drive on its own without an occupant – similar to the ‘summon’ feature on Tesla cars, which allows the driver to summon the car to them remotely. Level 5 vehicles are often referred to as ‘fully autonomous’.

Example: None available yet, but the first fully autonomous cars are expected to appear in around 2025.

Self-driving cars explained: how autonomous is my car?

Self-driving car glossary

AutonomousCars on the upper three levels are often described as ‘autonomous’ because the term can be applied to any car that can drive itself. This is why the word is interchangeable with the terms ‘driverless’, ‘self-driving’, ‘piloted driving’ and others.

Connected carConnected car technology is another widely used term in modern motoring. It applies to technologies that allow cars to communicate with other cars and, when the technology becomes available, to a central information database. The communication will allow cars to update each other with changes in road terrain, safety hazards and other information that will allow them to become fully autonomous safely.

Eyes-offWhen a car can drive itself proficiently enough that the driver no longer needs to pay attention to the road, the term ‘eyes-off’ is used.

Hands-offWhen a car can take over functions of driving proficiently enough that the driver doesn’t have to have their hands on the wheel or their feet on the pedals, the term ‘hands-off’ is used.

Internet of ThingsThe ‘Internet of Things’ is a term that applies to the use of the internet to connect more everyday objects, such as cars, mobile phones and even household appliances, to the internet, allowing them to communicate with one another. In the context of cars, it will eventually allow the remote summoning of cars, as well as access to different functions of the car, such as the climate control and security features, from afar.

Semi-autonomousCars with autonomous systems that aren't active when the driver chooses them not to be, such as lane-keeping assist, are widely regarded and often referred to as ‘semi-autonomous’.

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