Vehicle lighting used to be about seeing and being seen, but Audi has much larger ambitions for automotive illumination. New LED and digital control technologies are moving the humble headlamp into a much wider function of providing vehicle information and piloting guidance. And though the new tech is an obvious darling for designers and branding endeavors, digitized lighting’s potential vehicle-to-everything (V2X) communication abilities could prove crucial for autonomous vehicles (AVs).
This is a large shift for vehicle lighting, which only 20 years ago was comprised almost entirely of cleverly engineered but inefficient incandescent bulbs. In the two decades since, it’s evolved through halogen and xenon bulbs to markedly more efficient LED tech. “The bulb was a wear-and-tear part,” explained Stephan Berlitz, head of lighting development at Audi. “Today's LEDs last the lifetime of the car, so those days of having to replace the bulb are over. And of course, the efficiency of LED technology is also clearly a different ballgame.”
The LED revolution
Audi has been a notable forerunner in advanced lighting technology and began using LED lighting in its production vehicles in 2004, appearing first as daytime running light (DRLs) on the A8 W12. Most in the industry will recall the more prosaic “string of pearls” DRL application in the 2007 A4. Full LED headlights appeared at Audi in 2008 on the R8, a feature now available across its entire model range.
The Ingolstadt, Germany-based brand introduced laser high beams in 2013 on the A8, doubling high-beam throw distances. Audi debuted organic light-emitting diode (OLED) tech in 2016 in the taillamps of the TT RS, and a digital version debuted in July 2020 for the Q5. Digital micro-mirror devices (DMDs) – known to most via TV projection technology pioneered by Texas Instruments and its digital light-processing (DLP) chips – started as 100-pixel devices embedded in the 2013 A8 as an adaptive high-beam system. The latest-generation Digital Matrix LED (DML) units are composed of 1.3 million mirrors, turning each headlight in Audi’s e-tron electric vehicles (EVs) into its own monochromatic HD projector.
LED drawbacks are few, though a lack of heat creates new challenges in colder climates. “We've got less dissipating heat up front. And in the winter, you want to de-ice and have a warm headlight,” Berlitz noted. A solution was derived via extensive calculations from Audi’s CFD simulation department to get the dissipating heat from the LED and transport it to the front of the enclosure, so it defrosts and defogs quickly.
Lighting goes digital
In terms of hardware, LED has been the watershed technology. Digitizing the lighting control is what will alter the visible landscape. As flexible and addressable OLED “lighting surfaces” begin to make inroads, instead of a single lamp or light source to leverage, each component presents its own display, able to convey information via its integration with vehicle systems.
“The key really is digitization, bringing the digital metrics to life when we brought the digital OLED to market,” Berlitz said. “At the end of the day if you look at digitization, it's like a shift of perspective. Until now light was something for the driver, but now light becomes more of a visual communication tool for other traffic participants and pedestrians.”
“Digitization for us is a completely new era,” explained Michael Kruppa, head of rear lamp and OLED development at Audi AG. “Although OLED started back in 2016, now thanks to digitization it has taken this next leap forward. We can make it better to look at, but we can also increase the safety. OLED is exactly what you need on the rear. It's an area light, not like an LED that I have to fit into the rear with a complicated optical element that distributes light to have this area light.”
According to Kruppa, shifting from a single-point source to a homogenous area lets engineers and designers move into the next step of segmenting it. “Digitization here is very important. Separation of the area into little segments means I can activate all of these segments individually, have them at different intensities. We think this is a revolution on the car because now suddenly you can have more than just one rear light.”
“Digitization and networking is vitally important and it's interplay becomes ever more important in our work,” said César Muntada, head of lighting design at Audi AG. “It's not just a matter of looking at light objects. We are developing what we would call a ‘light language’ for communication. Thanks to digitization, we can bring movement in our various signatures and scenarios. Digitization will also enable us to give customers the possibility to develop their own light signals or personalize them.”
The ability to choose the shape of the light signature and animate it is what elevates the new lighting systems. “Moving lights are much better perceived by the human eye. Our eye is actually capable of taking in a host and a wealth of information very, very quickly, but if the light is moving it helps even more,” Muntada explained. “Digitization has allowed us to make this possible and increases safety because the movement of light, the speed, the rhythm can be perfectly tuned to create different characters for the various scenarios.”
The upshot of efficient LED lighting – digitally addressable and integrated with a vehicle’s subsystems – is a new form of V2X communications. Upcoming EVs and AVs will use lighting systems to telegraph intent to other road users. Berlitz noted Audi’s dynamic turn signals, which sweep in the direction of the intended turn, are its first implementation, part of what Audi labels an anthropocentric (human-centric) approach.
“Thanks to digitization, we have completely new means available to increase that safety communication. It's not just nice to look at, but it's also a very clear indication of where the car is going,” Berlitz said. “Even if you don't see the car at a specific angle, you will instantly understand what is meant with this swoosh.”
Another current example is Audi’s available lane illumination feature, which paints a brighter box of light into the lane in front of the vehicle. “It is communication because I'm showing somebody else, ‘Look, this is my lane.’" Berlitz explained. “We actually have planned to take it even further because we want to project elements onto the road. But you've got to be careful [because of] what is allowed by the legislative environment. Traffic signs are only permitted to be positioned by authorities.”
According to Berlitz, he has been approached during meetings with U.N. regulators who noted if properly implemented, displaying symbols onto the roadway could be beneficial. “When we went to Geneva, to the United Nations and presented this,” Berlitz recalled, “this German representative said, ‘Hey, this could be good. For example, if you drive and you want to turn right in 100 yards and your light will tell the cyclist next to you, ‘Careful, that Audi e-tron will actually head to the right in a minute.’”
“The great advantage is you now have digital information and can use it with the light technology to communicate to the outside, and that's the special element,” Kruppa claimed. “For example, with proximity detection, the car knows somebody is coming up close and the car will react by having all the OLED elements on the rear being activated. The moment that rear traffic participant leaves that two-meter area, it goes back to the original signature.”
“So for the first time you find that a car which is nothing but a sheet-metal object for the observer, reacts to you, reacts optically,” Kruppa continued. “This has opened up the door to light communication, emit a warning and maybe even to move on to more complex warning symbols to really make a huge contribution towards extra safety on the road.”
“We are trying to develop a light language that is intuitively understood by everybody. For this, we don't use letters, or words or figures. We use symbols and icons that are accepted and understood worldwide,” Muntada said. “With cars, it’s important to make it crystal clear what we're trying to communicate. We hope that authorities and the legislative environment will also move forward and will help us to bring extra safety to the road.”Continue reading »