HOD in the Spotlight

How hands on/off detection helps comply with assisted/automated driving system regulations

ADAS – friend or foe?

The United Nations have initiated a couple of vehicle regulation activities related to assisted and automated driving systems in recent years. Two items were of key concern: ensure that the systems are safe AND that they are used in a safe way. Special focus was given to the role of the driver when using such systems.

Advanced Driver Assistance Systems (ADAS) hold undeniably numerous advantages, but there is also a risk they might be misused, depending on how their Human-Machine-Interface is implemented and the driver’s behaviour. The social media abound of videos in which drivers take their hands off the steering wheel, execute side tasks, or even leave the driver seat as if their cars were self-driving and fully autonomous. Those vehicles, however, are only equipped with driver assistance systems (often referred to as “Level 2” systems) that require the driver to keep the hands on the steering wheel and to actively be engaged in the traffic. Drivers misusing their ADAS are a known issue, and the consequences can be dire. Crashes investigated by NTSB (National Transportation Safety Board) in the United States clearly confirm that the lack of driver engagement played a key role.

Automated systems – Where clear communication interface is vital

When it comes to vehicles with automated driving capabilities (“Level 3”), the challenge is to make sure the driver understands which driving mode the vehicle is in: is the driver or the vehicle in control of the driving task? Also, how to ensure a safe transition between the driving modes? The “role change” involved when switching from automated to manual (or assisted) mode is critical for safety reasons: The task to monitor the traffic environment goes from the vehicle back to the driver. Therefore, before the control is returned to the driver, it must be clear to both driver and vehicle that it is the driver who is “back in the loop” This is also important from a liability point of view in case it is the vehicle that causes the crash: was the vehicle responsible (Level 3), or the driver (Level 2)?

Evolving technologies & safe drive – A regulatory affair

Two key regulations have been adopted to address the challenges mentioned above.

The UN Regulation 79 refers to Lane Keeping Assist Systems and includes a “hands off” detection requirement. If the driver removes hands from the steering wheel, an optical warning must be triggered after maximum 15 seconds, enhanced by further escalations such as acoustic warnings latest after 30 seconds. Should the driver still not grab the steering wheel, an emergency signal is triggered after 60 seconds and the lane keeping function is deactivated. New vehicle models on the European market with a Lane Keeping Assist System must comply with this hands-off detection requirement since April 2018.

Vehicles with automated driving capabilities entering the market these days legally allow the driver to take the hands off the steering wheel and the eyes off the road under certain conditions: On the highway only, with a maximum operational speed of 60 km/h. Such vehicles will have to comply to the UN Regulation 157 on Automated Lane Keeping Systems (ALKS), applicable since January 2021. The regulation mandates a “driver availability” function checking whether the driver is present in the driver seat and not sleeping. This is imperative to ensure that the driver is quickly available in case the vehicle would initiate a transition demand asking the driver to take back the control. On top, a full transition from automated back to manual driving requires a confirmation that the driver holds the steering wheel and that the eyes are directed on the road. If the confirmation does not take place, the vehicle would have to execute a minimum risk manoeuvre, ultimately bringing the vehicle to a halt.

HOD – The solution for a safe and smooth driving transition

Fast and reliable hands on/hands off detection can be ensured with our capacitive HOD sensor that entered that market already in 2013, as our lead customer recognized early on the need for securing driver engagement, long before any regulatory requirement. HOD, our in-house made sensing technology built on extensive expertise and quality checks, won the prestigious PACE award in 2018 – a sort of “Oscar” equivalent in the automotive supplier world.

The initial sensor was designed to identify the hands on/off status. Since then, we have constantly researched and upgraded it, so that today we bring its performance to the next level. Our latest multizone sensor is now capable to also classify the degree of driver control. Thus, it indicates whether the driver merely touches the steering wheel or whether he/she firmly grabs it. This brings a better view on how safely a driver is in control of the steering wheel.

In such sensitive and safety-critical situations as a driving mode change towards the driver, it is imperative to distinguish whether the driver has a safe grip of the steering. HOD therefore plays a key role in advanced driving functionalities and supports vehicle manufacturers in being compliant with the regulatory demands supporting safe driving as we evolve into the future.