Automatic light

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Evaluation electronics of a light / rain sensor (without optics)

The automatic light control is the colloquial term for a partially automated driving light switch in motor vehicles . In this case, an accepts control electronics set switching of the lighting of the vehicle by evaluation of the connected sensor .

construction

When using automatic driving light control, the vehicle lighting is no longer operated directly by the driver , but by an electronic control unit. Sensors for checking the external conditions of the vehicle are connected to this control unit (or integrated directly). Depending on the situation, individual or multiple elements of the vehicle lighting are switched.

The sensors used are a light sensor (usually attached behind the upper part of the windshield ) and in many cases a rain sensor (which is also able to control the windscreen wipers ). By networking with other control units in the vehicle, additional data can be evaluated to implement more complex switching functions.

functionality

The automatic switching on and off of the low beam depends on the following conditions:

In order to avoid brief switching on and off, which could be perceived as flickering by the driver or other road users, a hysteresis is added to the control algorithm in border areas with the help of a time component .

However, the driver can take control of the lighting at any time. In any case, it is always possible for him to switch on the low beam himself. The driver can only switch off the lights by switching off the automatic system.

Further comfort features

Depending on the version of the control unit, the automatic light system can control the interior lighting in addition to the low beam . The interior lighting can only be activated when it is dark. Likewise, after switching off the engine, the dipped headlights can remain on for some time in the dark ( coming home function ) so that the vehicle remains more visible (source of danger: passengers getting out) or so that the occupants can better perceive their surroundings (e.g .: Garage with no light). A leaving home function can also be implemented in which orientation lighting is switched on for a certain time after the vehicle has been unlocked.

Advantages and disadvantages

Advantages:

  • The driver can (mostly) rely on the automatic system and there is (especially in twilight and rain ) a higher level of road safety, as the vehicle can be seen better.
  • As long as there is no manual control, it cannot happen that the car battery is discharged when the dipped headlights are switched on, as the automatic light system works with a specially designed reserve memory.

Disadvantages: The biggest disadvantage of an automatic light system is the habituation effect :

  • The driver relies on the automatic system and no longer takes care of the lighting himself. This can lead to the fact that when the low beam is activated manually, switching off is forgotten, which in turn can lead to the car battery being discharged .
  • Since the driver no longer observes the external conditions with regard to the use of the low beam, this can lead to the fact that he forgets to switch on the lights while driving a car without (or with switched off) the automatic light (especially at dusk and in heavy rain ). This reduces the current road safety of the vehicle.
  • There are also situations in which the automatic system does not consider it necessary to switch on, while driving with the lights on would increase safety (beginning of twilight , onset of rain , fog , snowfall ). The driver then still has to take over the control of the lighting, which is often forgotten due to the habituation effect and can lead to considerable traffic hazard.

Spread and outlook

Many newer vehicle types can be equipped with an automatic light system (usually in combination with an automatic rain system) (at an additional cost). Since this technology has been used, the parameters of the control have also been continuously improved so that the automatic system has become more and more reliable. In the meantime, there is also an automatic control of the high beam ( high beam assistant ), which continuously analyzes the situation in front of the vehicle and switches the high beam on or off accordingly.

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