Engineers at General Motors' German subsidiary had the idea to control the light by the direction of the driver's look already two years ago. In the beginning, they used a simple webcam to track distinctive features like nose and eyes to determine the viewing direction. These data were turned into instructions for the actuators. Though this approach yielded quite promising results, it turned out that the huge amounts of data could not be processed fast enough, and the webcam's frame rate was too low to meet real-time traffic requirements.
In the mean time, the engineering team successfully optimized the camera parameters and the adapted the eye-tracking algorithm for better real-time behaviour. In twilight and darkness, the fast camera used now scans the eyes of the driver more than 50 times per second, using infrared sensors at the margins and with photo diodes in the centre of the image field. Thanks to much faster data forwarding and processing the headlight actuators now react virtually in real-time, horizontally as well as vertically.
However, one problem remains: the human eye unknowingly "jumps" around all the time- Would the system reflect these movements, the cone of light would move hectically. "For this reason, we developed sophisticated delay algorithms that cause the cone of light to move smoothly", says Ingolf Schneider, manager lighting technology for Opel. There is no need to constantly re-calibrate the eye tracker, also the body height of the driver is not relevant.
The eye-tracking technology however will only be introduced in the future. Current-generation vehicles are equipped with the AFL+ adaptive headlight system, which already offers up to ten lighting functions controlled by a frontal camera. For example, the light cone of a xenon headlamp is automatically adapted to different traffic situations as well as road and weather conditions - with variable light distribution within urban areas and country roads.