ELI5 How do automatic high beams work?

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My 2017 Toyota has a feature I’ve recently discovered that doesn’t just automatically turn my headlights on at night, but it will turn high beams on if I’m the only one on the road and will automatically turn them off when a car approaches – or even if I suddenly get behind another car. After observing for a bit, I’ve realized it’s scary accurate. How does this work?

Note: it doesn’t even turn them on if it’s just street lights, it seems to differentiate between street lights and headlights on cars.

In: Engineering

Maybe sensors that detect other vehicles or mass bodies of metal??

There is a camera mounted behind the windscreen that is programmed to detect headlights. When the camera locks on to what it thinks are headlights, it will either dim a section of lights or all the headlights, depending on how complex the setup is.

The reason the your headlights aren’t triggered by the street lights is because, both high and low beam, are programmed with minimum light levels, and the street lights put out an amount of light over the high beam threshold.

Auto high beam requires that one uses either radar or image data to detect on coming traffic and its distance to EGO (your vehicle) car. Upon detection of object and measurement of distance the headlamps can be placed in right state.

BTW with new headlamps with LEDs you can actually steer the headlamp beam based on recognition of environment e.g shine them on street sign in a dark alley