Horizontal Adjusting Control for Automotive Headlight System

A well-designed headlamp system should allow enough illumination to road conditions and less glare to an oncoming vehicle for night-time driving or in darkness. However, loads and body motions of a running vehicle can affect the beam direction of a headlamp. Besides, car braking and acceleration also cause vehicle pitching and then change beam direction. Change of beam direction due to the above factors results in insufficient illumination in front of a car and glaring to the oncoming vehicles. To solve the above problems, one solution is to equip a vehicle with a horizontal adjustable headlight system for night-time driving or in darkness. However, some road conditions, such as speed breaker or pavement with pot-hole, can cause high frequency vehicle vibrations, which will cause high frequency headlight adjustments if the headlamp is adjustable. These unnecessary high-frequency adjustments might also cause safety problems to drivers. To solve the dilemma, this paper simulated several vehicle motions under different road conditions for different vehicle speeds. Results showed that an active horizontal adjustable headlight system should not respond to some road conditions which cause high frequency vehicle motions. A low-pass filter was proposed for headlight control system to keep the headlight horizontal adjustment appropriate under different driving conditions.