Adaptive Front Lighting

Basic Description

Adaptive front lighting systems adjust the illumination from a vehicle's headlamps to compensate for various driving situations. Most adaptive front lighting systems have one or more of the following features:

• The aim of the headlamps is adjusted to follow curves in the road.
• The beam pattern is altered at intersections depending on the intended direction
• High-beam/low-beam changes are made automatically is response to rain, fog, oncoming traffic, etc...

Most systems use stepper motors to physically adjust the aim of the headlights. Some systems illuminate new sources of light at different focal points of the headlamp reflector to adjust the beam.

Cornering Lights

Adaptive front headlamp systems use cornering lights to increase the horizontal area that is illuminated by vehicle headlights when turning a corner. There are static cornering lights and dynamic cornering lights. Static cornering lights employ additional light sources or additional reflectors in the headlamp to direct light to the vehicle's turning direction.

Diagram of vehicle turning to the right with cornering lights. Additional reflector or additional light source shines light in turning direction.

With dynamic cornering lights, the entire headlamp component swivels horizontally when the car goes around a corner. The speed and angle of swiveling is determined by an electronic control unit that gathers information from the vehicle speed sensor, steering wheel position sensor, and yaw rate sensor.

Left: Vehicle with no cornering lights. Right: Vehicle with dynamic cornering lights.

Automatic Headlamp Leveling Control

Automatic headlamp leveling control adds another degree of freedom to front adaptive headlamp systems. Sometimes vertical leveling is needed for the headlamps when weight is distributed unevenly in the car, when the vehicle is accelerating/braking, or when traveling across bumpy terrain. An automatic headlamp leveling control provides appropriate lighting for these situations using stepper motors attached to the headlamp assembly. There are static and dynamic systems.

Static systems only correct for the weight distribution in a vehicle. It calculates the vehicle tilt angle using information provided by vehicle axle sensors and adjusts the headlamp to match the vehicle tilt angle.

Left: Low beam with evenly distributed weight. Right: Low beam adjusted when center of gravity moves to rear of vehicle.

Dynamic systems account for both weight distribution and accelerating/braking changes.

Low beam adjusted for vehicle acceleration.

Light Camera

Some adaptive front lighting systems employ a CMOS color camera that detects the position of light sources and an ECU that determines the types of light sources detected. Light sources determined to originate from an approaching vehicle will switch your vehicle headlamps to low beam as the approaching vehicle passes and then switch the headlamps back to the high beam position. This reduces glare for the other driver and creates a safer driving environment for both drivers. The color camera also detects when a vehicle merges in front of your lane and switches the headlamps to low beam position. As the other car speeds up, your headlamps are appropriately adjusted until the full high beam position is reached. The color camera can also detect fog and tunnels and adjust the headlamps accordingly. This camera is typically mounted under the windshield above the rearview mirror.

Sensors

Vehicle speed sensor, environment lighting sensor, rain sensor, steering wheel position sensor, image sensor, yaw rate sensor

Actuators

Motors, relays

Data Communications

Typically CAN or LIN

Manufacturers

Continental (Intelligent Headlamp Control), Denso (Adaptive Front Lighting System), Hella (DynaView), Valeo (Intelligent Lighting Systems), Visteon (Advanced Front Lighting Systems)

For More Information

[1] Headlamp: Wikipedia

[2] AFS ABCs, Motor Vehicle Lighting Council Website

[3] Ford's Adaptive Front Lighting System Car Body Design, Jan. 2006.

[4] Intelligent Lighting Video, Valeo

[5] How Adaptive Headlights Work, Ed Grabianowski, howstuffworks.com, Nov. 26, 2007.

---