Design Of Adaptive Front Lighting Controller

Adaptive Front Lighting system(AFS) is a new technology for improving the driving safety at night. It can make the vehicle lighting in the best light effect at night or poor light illumination effect environment. The main function of the AFS is automatically adjust turn angle of the headlamps in horizontal direction according to the speed of the vehicle, the turn angle of the steering wheel and other external factors. The AFS can decide whether to adjust irradiation optical axis at a curve or other road conditions to make the driver get the best view range.The AFS designed in this thesis is based on the existing technology of AFS. It have three important parts, namely, the module of sensor signal acquisition of steering wheel angle, the module of headlamps turn angle control and the module of headlamps steering control central. The three modules realize the communication by CAN bus. The module of headlamps steering control central receive the signal from the module of sensor signal acquisition of steering wheel angle and calculates the turn angle of headlamps, then packing the calculated results into a CAN message and transmitting it to the module of headlamps steering control central, finally, the module of headlamps steering control central will control headlamps angle and complete the turning of headlamps.Compared with other AFS system, this thesis adopt Embedded Linux System as the running platform for the main program of the AFS, making this system get the excellent performance, and providing adequate performance and scalability for the research of AFS system.This thesis mainly include the basic structure and algorithm of adaptive front lighting system, finishing the driving circuit of rotary encoder and realizing the simulation of steering wheel angle signal acquisition, finishing the driving circuit of stepping motor and realizing the accurate control of the headlamps steering intelligently, finishing the CAN bus communication network to realize the communication between each function module, build the embedded Linux platform for the running of main control program, programming for each module to realize the function of each module.The experimental results shown that, Linux system can work stably on the ARM hardware platform, the stepping motor can run smoothly, CAN bus network can transmite data reliably, the system response time did not exceed 400 ms, angle error of this system can be controlled in 0.5 degree, the range of the inner headlight turn angle is 15 degree, the range of the outside headlight turn angle is 7 degree.