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​automatic headlamp leveling system 

overview

        the automatic headlamp leveling system (als/ahl), also known as the dynamic headlamp leveling system (dhl), is an intelligent light adjustment system. by sensing information such as driver’s operation, vehicle travel status, road surface changes, etc., afs automatically controls the headlights to adjust the lighting angles in real time to provide the driver with the best illumination height/distance.

 

 

        hid gas discharge lamps have been widely used in automotive forward illumination. due to the high brightness of hid gas discharge lamps, the requirements for vehicle illumination height/distance adjustment systems are increasing. the original manual adjustment method can no longer meet the needs of driving safety.

        the vehicle component regulations established by ece require that vehicles equipped with hid discharge lamps must be automatically dimmed. the relevant domestic mandatory regulations gb4785 2007 have also been implemented, requiring that the headlight source with a luminous flux exceeding 2000 lm must be equipped with an automatic dimming system.

        as a leading supplier of automatic headlamp leveling systems, hirain technologies has successfully cooperated with well-known domestic lighting manufacturers, providing the als to many domestic and foreign customers, including gm, shanghai general motors (sgm), gac, faw, saic and changan.

 

functionality

• static dimming: automatically adjusts the lighting height according to static load changes (occupant number / position / trunk load);
• dynamic dimming: change the pitch angle of the headlamp according to the vehicle speed and the dynamic change of the vehicle height during the driving process (quick acceleration, sudden deceleration, up and down slope, etc.) to ensure a reasonable irradiation distance;
• pavement identification: under various bumpy roads and short-term road impacts (deceleration roadblocks), the headlamp irradiation distance will not be adjusted frequently to prevent the driver's eyes from fatigue;
• dashboard fault indication: diagnose system faults and alert the driver through the dashboard when the system fails to work properly. in addition to the can bus fault alarm, an output can be provided to drive the fault indicator in the instrument panel.

 

 

system composition

        for als, hirain technologies has developed two mature system solutions after years of development.

• solution one

        solution one consists of a main controller unit, a left/right dimming actuator, a front/rear car body height sensor, and a left/right hid ballast that is responsible for illuminating the light source. the main controller obtains the required input through the high-speed can bus and the vehicle height sensor, and sends the control command to the dimming actuator unit through the private lin bus to realize the automatic leveling function of the headlight.

        solution one uses the lin bus, which effectively reduces the need for wire harnesses, is more integrated, modular, and has better scalability. solution one has successfully supported a number of domestic and foreign customers including general motors (gm), shanghai general motors (sgm), great wall motor (gwm), gac, and faw.

 

 

 

• solution two

        solution two consists of a main controller unit, a left/right dimming motor, and a front/rear car body height sensor. the main controller obtains the required input through the high-speed can bus and the vehicle height sensor, and directly drives the dimming motor to realize the automatic leveling function of the headlight.

        solution two integrates the drive control of the motor into the main control unit, so the system cost is significantly reduced, but the wiring harness between the main controller and the dimming motor is increased. solution two has successfully supported a number of domestic and foreign customers including saic and changan.