Automotive Enlightenment

By Motoring Channel Staff - 8/12/2004

Over 80 percent of all road traffic accidents occur in darkness and bad weather, according German automaker Opel – which was a compelling enough reason for its engineers to put their efforts into developing the next generation of intelligent lighting systems.

The aim is to improve visibility for the driver and so achieve a significant increase in road safety and driving comfort.

Further motivation for the up-and-coming German brand is the fact that human eyesight continually deteriorates with age.

From the age of 45, everyone experiences reduced visual acuity in poor light conditions – and around 25 million drivers license holders in Germany, or more than half of all the country's drivers, are older than 40.

Today, Opel (General Motor's German operation) is a leader in the field of car lighting technology and isn't sitting on its laurels: in 2003, Opel was the first car manufacturer to bring dynamic curve lights and the 90-degree cornering light to the mid-size segment with its Adaptive Forward Lighting (AFL).

The Vectra and Signum (a Vectra wagon) are still the only cars to offer Bi-Xenon headlamps, which combine both these functions in the headlamp assembly.

Engineers at the International Technical Development Center (ITDC) in Rüsselsheim are currently developing the next-generation Adaptive Forward Lighting (AFL).

Country light, highway light, city light and bad weather light are additional functions whose legal basis for installation in cars is expected to be established from 2007 by a new ECE norm. Looking towards the future, experts in the field are conducting the first practical tests of an even more advanced system at the Opel test center in Dudenhofen, and one that caters to different driving scenarios, not just rounding corners.

With the next-generation AFL that Opel is working on, the headlamps' light distribution automatically orients itself to the prevailing road and visibility conditions. When travelling quickly in a straight line, for instance on the highway, a far-reaching beam of light is needed.

The requirements in an urban environment are quite different: here, the broadest possible blanket of light brings sources of danger and important signals on the car's periphery into the driver's field of vision. Thanks to an additional mirror/lens system, on country roads the road ahead and bends are illuminated even more consistently and accurately than with today's AFL system.

And if you thought that was using technology to improve safety, the developers are even considering linking the light controls with satellite navigation systems. When provided with this more exact road information, the system would be able to adapt to bends or hilltops accurately and in good time.

The bad weather light also ensures that the driver sees more in rain, snow or fog without, for example, being disturbed by light reflecting off the road surface. This is achieved by reducing the strength of the central illuminated area in favour of two cones of light, which have a middle-distance range and point towards the edges of the road.

Opel's lighting technology specialists' main objective is to achieve the best possible visibility for drivers in all conditions while eliminating glare for oncoming traffic.

Ingolf Schneider, head of lighting technology development at the ITDC in Rüsselsheim, quotes further priorities from the specification book for the next-generation AFL: "To meet all requirements in terms of aerodynamics, design and space efficiency, we have to incorporate the additional functions into the smallest possible space.

"We achieve this by the intelligent multiple-usage and inter-linking of individual function groups. Moreover, future multi-functional swivel-headlamps should cost the customer roughly the same as today's AFL systems," stated Schneider.

The core elements of Opel's next-generation AFL are both horizontally and vertically swivelling Bi-Xenon headlamp units, with moveable reflector elements and variable filters mounted in the path of the beam. In a fraction of a second, electric step motors adjust these components to adapt accordingly to the prevailing situation.

The so-called 'actuators' receive their commands continually from a microcomputer that is integrated into the vehicle's electronic data network. This assumes control of the AFL system dependently of sensor-recorded parameters such as speed, front-wheel lock angle, body tilt, load and ambient light.

The market potential of such high-tech solutions is shown by the number of orders placed for the current AFL generation. This year, around 28 percent of Signum buyers in Germany opted for the steering-linked headlamps. As of August (model year 2005), Opel has offered this high-tech feature in Germany as part of the comfort package and since then, almost half (45%) of the Signum customers and nearly a quarter (23%) of the Vectra buyers have ordered their car with AFL. In the new Astra for instance, the AFL curve light is fitted as standard to the top-shelf version, the 2.0-litre 147kW (200hp) Turbo.

A study by Darmstadt Technical University drew similar conclusions. By measuring drivers' eye movements while driving, scientists proved for the first time that curve visibility on night journeys with steering-linked Xenon headlamps nearly reaches the level under normal daylight conditions.

More than 50 people were tested with an eye tracking system based on a highly sensitive infrared video camera. Participants ranged from the 18-year old holding a fresh driver's license to professional drivers and experienced seniors up to 68 years of age.

Video imaging and mirroring of two infrared beams aimed at the pupils showed the following results: Curve visibility on night journeys with dynamic curve light based on Xenon technology reaches a visibility of 36 meters, which is almost the ideal 38 meters in normal daylight conditions. In comparison, nocturnal visibility with halogen curve lights is only 27 meters, with static halogen headlamps 24 meters.

Like other safety-based technologies in the past that were once the afforded to only the most prestigious vehicles, such as ABS, power steering and satellite navigation and tracking, the technology that powers adaptive front lights will become cheaper to produce over time and will one day be standard on almost all cars.

And if regions such as Europe decide to make it illegal for cars to be sold without adaptive front lights (rumoured to be slated for 2007) as a safety issue, they could be illuminating dark roads on even entry-level compact cars much sooner than expected.