HERE’S HOW ADAPTIVE HEADLIGHTS WORK
Technology has advanced radically, and this is how these systems work
At one time, virtually all car headlights pointed straight ahead. You had to turn them on and off, and operate the high-beam headlamps all by yourself.
Now automatic headlamps are commonplace, and even many entry-level models can switch off the high-beams automatically when oncoming traffic is detected. In many premium models, you’ll find headlights that “bend” when you’re turning, so you can see around the corner.
None of these ideas are new, of course. General Motors offered automatic high-beam headlights, called Autronic Eye, in the early 1950s. Even earlier, a couple of cars had headlights that swivelled when turning, including the experimental and ill-fated Tucker. But in addition to being a lot more common, these modern systems depend on far more sophisticated technology.
Today’s automatic headlamps come on whenever the switch is in the “auto” position and it’s dark enough to require them. They use a photoelectric sensor that’s usually mounted on top of the dash, or on the windshield near the rear-view mirror. On some vehicles, the owner’s manual may warn you not to place items such as papers on the dash because doing so can block the sensor and prevent the lights from working.
Most automatic headlights are set by the manufacturer, although some allow drivers to change the light sensitivity to how dark it must be before they’ll come on.
Most don’t activate when it’s relatively bright but your lights should be on, such as when it’s raining, so be sure to switch them on manually in these situations. Your daytime running lights will be on, of course, but very few of them also illuminate the rear lights that other drivers need to see you in rain or snow.
Automatic high-beam headlights help solve two issues. They shut off the brighter lights as needed to avoid blinding occupants of oncoming vehicles. And because they turn the highbeams on when the road ahead is dark, they can also help drivers who don’t always think to switch them on even when they can provide more illumination down the road.
Like automatic headlights, the system is driver-selectable. Most commonly, the driver leaves the high-beam switch on all the time and activates a second button for the automatic function. The system uses a forward-facing camera, usually mounted in or near the rear-view mirror. The camera detects not just oncoming headlights but also the tail lights of vehicles ahead, as well as street lights or other illumination that indicates the driver is in the city and doesn’t need high beams. As soon as other lights are detected, the system turns the high-beam headlights off, and then switches them back on again once the light disappears.
This automatic system is mostly for driving on rural roads or unlit highways where people often “overdrive” their headlights — travelling too fast for how far their lowbeams illuminate the road ahead, so they can’t stop in time if something beyond their illuminated field of vision is on the road, such as an animal.
That’s also the basic idea behind adaptive headlights, which swivel from side to side, or up and down, to adjust for curves or elevation changes.
Without adaptive headlights, the road ahead isn’t fully illuminated until you’ve turned the corner and you’re travelling straight again. Because adaptive headlights swivel in the direction you’re turning, you have a better view of what’s ahead and can see things — such as a stalled car or someone trying to cross the road — before regular headlights would have revealed them.
The few old cars that had swivelling headlights used a mechanical connection to the steering gear to turn them. On modern cars they’re moved by small electric motors, which react to information provided by sensors that determine how fast the vehicle is going and how far the driver has turned the wheel.
On some vehicles, supplementary cornering lights might come on to add extra lighting to the side of the road. The motors may also react to sensors that determine if the vehicle is going up an incline or into a dip, and move the lights up or down to keep the beams level with the road surface.
Of course, technology is always forging ahead, and one of the goals with lighting is to eliminate as many moving parts as possible. Audi has computer-controlled LED headlights (not yet available in North America, because of to our lighting regulations) that can selectively extinguish part of the lights, pinpointing the beams so accurately that the driver can have the benefit of high-beam headlights, but aimed so that they don’t affect other drivers.
Other companies are also improving their headlights. For example, Hyundai is working on adaptive lights with pixels that form horizontal beams; sections of these can be lit or shut off to produce the “bending” effect of adaptive headlights without physically moving the lamps. These improvements will be important even when cars drive themselves.
Self-driving cars use beacons and sensors and won’t have to see each other, but they’ll still have to be visible to pedestrians. High-tech or otherwise, headlights are sticking around.