Active safety functions: driver assist systems of the future

Experts understand “active safety” to mean all elements and functions of a vehicle that can help to avoid an accident.¹ “Aside from suspension, tires, brake system and lighting technology, these also include assist functions² that advise of potential hazards early on, issue a warning in the event of acute danger and, if the driver does not react in time, also automatically apply the emergency brakes or take evasive action,” explains Roland Kallweit, Head of Development Active Safety Functions at AUDI AG. His team of 20 employees looks after three main areas: The first involves “warning, braking and swerving” the vehicle. The second focuses on proactive occupant protection functions and the third on the Car2X systems.³ All three areas have the same objective: “We want to use these functions to improve safety on the road for all road users – both for our Audi customers and vehicle occupants as well as for all other road users such as cyclists and motorcyclists.”

The driver maneuvers her Audi down a one-way street at just under 40 km/h. A cyclist is riding very unsteadily on the right and a little too far over in the lane. The system calculates and analyzes the situation: a collision would arise if the Audi were to remain on its course.

“In the situation described, an Audi would already intervene thanks to our swerve assist function and help the driver to take evasive action by optimizing her steering.² Yet our advanced system can do more: with Automatic Emergency Steering, the Audi independently avoids the cyclist if the driver does not react,” explains technology expert Christoph Liebelt. “The vehicle decides in a split second, faster than a human.” Many years of development work have gone into the system. “The Automatic Emergency Steering function has enormous potential to help avoid accidents and therefore save lives.”²

The Audi developers faced many challenges in the course of developing these technologies: “The vehicle’s maneuvers are subject to legally anchored requirements. Whereas swerve assist provides support if the driver leaves their lane, Automatic Emergency Steering means that the Audi practically maneuvers independently in its own lane, unless and until the driver intervenes.² With both systems, however, the driver always remains in control of the vehicle, since even not intervening constitutes a decision. The driver can therefore override the assist system at any time,” explains Christoph Liebelt. A further challenge the development team faced in bringing the technologies to market maturity was to reach agreement on the intensity of the automatic steering intervention. This required a great deal of sensitivity. “It was important to us that driver and passengers feel safe and never feel that they are not in control. Nonetheless, our steering interventions need to be an effective call to action, since ultimately we are aiming to avoid an accident.”

It is already dark and past 11 p.m. The temporary traffic light is red and the Audi is the second and last vehicle in the line. Oncoming traffic is making its way through the single-lane roadworks. The Audi driver glances briefly in the rearview mirror. Headlights are approaching from behind. A second glance – the light beams are getting larger unusually quickly. Suddenly the seat belt tightens, the side window goes up and the hazard warning lights start flashing rapidly in bright orange.

What the driver is experiencing at this moment is the activation of the proactive occupant protection system,² which initiates protective measures for the occupants as soon as it detects an impending rear-end collision.² Audi has been using such preventive systems for more than a decade to help make the roads safer. And they are improved with each vehicle generation. “In the early days, these systems only assessed the traffic conditions in the area in front of the vehicle. Today, sensors monitor a 360 degree area around the vehicle so that the proactive occupant protection system is also activated when danger approaches from the side or from behind,” explains Thomas Bleier, an expert in pre-crash functions in the Active Safety Functions development team.

“We use functions like electrical tightening of the seat belts to minimize forward or sideways displacement of the car’s occupants, closing windows to the greatest extent possible and issuing visual warnings to other road users so that we can proactively increase the safety of the vehicle occupants,” says Thomas Bleier. “To do this, an Audi uses data from sensors installed at the front, side and rear of the vehicle to calculate the probability of an accident.”²

The system initiates a number of proactive protective measures if it detects a risk of collision or in critical driving situations – such as emergency or hazard braking or when handling at the limits – even before a collision or impact occurs.² Proactive occupant protection is activated if there is a high probability of impact. Thomas Bleier: “We carry out a “reality check” in Northern Europe each winter with pre-series vehicles, for example, to test how the systems react and what the potential impact would be on the vehicle occupants.” This is done on closed-off test tracks on frozen lakes and with obstacles. “We simulate the seconds before an accident in numerous scenarios, maneuver the vehicles constantly at the limit and optimize the systems – so that they later provide the best possible protection for all road users.” 

Long sweeping bends stretch across gentle hills. 7:34 a.m. A light fog hangs over the valleys. It’s rush-hour traffic on the rural highway and the speed limit is 100 km/h. The Audi driver reduces her speed to 60 km/h. She does not let herself get flustered by the car behind her flashing its headlights. Its driver will see in a few hundred meters why she is reducing her speed. Around a blind left-hand bend, a vehicle is halfway across the road, having collided with a deer.

It was not because of psychic abilities or any sixth sense that the Audi driver knew that there was a critical situation ahead. Her Audi warned her acoustically and visually on the instrument cluster. This standard online service⁴ is called “hazard alerts.” It is based on swarm data and provides information about events on the predefined route, such as breakdowns, accidents, limited visibility and slippery conditions,” explains Audi developer Mamoon Nomaan. Nomaan is the team’s expert in communication between the vehicle and its surroundings (Car2X³). “The hazard alerts function allows us to meet the challenge posed by a vehicle’s sensors only being able to capture what is visually or acoustically perceptible in the immediate vicinity. By networking our Audi vehicles with their surroundings, it is possible to also capture what is not yet visible and warn the driver in good time.”

The Audi developer differentiates in this context between two forms of communication: direct communication and backend communication.⁴ In the case of the latter, hazard alerts are sent in good time from a server to other road users and hazards detected by the vehicle are made available additionally to the service provider. With direct communication, the vehicles in close proximity can communicate directly with each other, for example via Wi-Fi or the cell phone network. “A lot will happen in the area of Car2X in the future, especially in terms of direct communication between vehicles. Customers will be provided with more and precise hazard alerts from their immediate vicinity. We are convinced that this will allow traffic safety to be improved further,” says Mamoon Nomaan. “Ever since 2019, our experience with this technology on the Chinese market has been positive. The transmission standards have already been defined in North America, while they are still being discussed in Europe at present. But one thing is certain: the greater the swarm of vehicles and the more data we process on current traffic conditions, the simpler it will be to issue warnings about specific hazards and to improve road safety overall.”

Audi is one of the world’s leading brands in automotive lighting technology. It is at the heart of the Audi DNA and helps to increase road safety not only by ensuring good illumination of the road.

“Audi vehicles of the future will use a communication light to share safety-related information with their surroundings,” explains Roland Kallweit: “For decades there were only hazard warning lights. Now, thanks to digital OLED technology, we can use our rear lights like exterior displays on which we can also display safety information.” For example, the OLED rear lights on the current Audi Q6 e-tron display a warning symbol in critical traffic situations. Drivers of vehicles behind understand this to mean that they are approaching a danger spot. The communication light can even alleviate more complex hazard scenarios. “Take our exit warning system,” says safety expert Mamoon Nomaan. “If a cyclist is approaching an Audi from behind, for example, the sensors will detect them. If a vehicle occupant then tries to open one of the doors, the cyclist is warned by a light signal.”² At the same time, the vehicle occupants are alerted on opening the door by visual and acoustic warnings and a “door-lock” delays the opening of the door.²

Issuing a light warning to cyclists may seem simplistic, but its relevance can be seen by casting a glance at the accident statistics:⁵ in Berlin alone, almost two accidents⁶ on average are reported to the police every day, involving cyclists crashing as a result of car doors being opened and in many cases sustaining serious injuries. “Through our technologies, we support the Vision Zero road safety strategy in many countries around the world, which is based on the belief that no death or serious injury is acceptable on roads,” says Roland Kallweit.