| The history of automobile headlamp can be traced back to 1899.People first used kerosene lamps,and then acetylene lamps,incandescent lamps,halogen lamps and xenon headlights appeared successively,but they all have the disadvantage of low brightness.In modern times,LED(light emitting diode)is used as the mainstream lamp of automobile because of its strong luminescence and long service life.Some of the high-configuration cars have used matrix LED headlights as high beams,and several luxury models(such as Audi)are even supplemented by matrix laser headlights with longer irradiation distance.On the other hand,with the increasing number of vehicles in cities,how to ensure the safety of driving in the nighttime is becoming an inevitable focus.The adaptive driving beam(ADB)system automatically turns on or off the high beam according to the light intensity of the current environment,and with the help of the intelligent frontview sensor,it can avoid dazzling to the drivers in other vehicles through the grouping opening and closing control of the matrix LED lamp group,so as to eliminate the hidden dangers of driving at night greatly and reduce the occurrence of dangerous situations on the traffic road.Based on the actual demand of the adaptive opening function of high beam during driving at night,an intelligent driving beam control system based on S32K14 x series controller is proposed in this paper.The specific research contents are as follows:Firstly,this paper introduces the core control algorithm of ADB system,which completes the mapping from the target vehicle’s position to the angle of high beam’s shielding area through coordinate transformation.The on-board intelligent camera captures the position information of the target vehicle in the spherical coordinate with the lens center as the origin,and then converts the coordinate into the spherical coordinate with the high beam of the vehicle as the center through calibration parameters and coordinate transformation,so as to calculate the azimuth and Euclidean distance of the target vehicle relative to the high beam.Next,the on-and off-state of each LED lamp group are determined according to the mapping relationship between the matrix LED lamp group and the illumination angle in the high beam.In order to improve the stability of ADB system,a filtering algorithm and a delay fault-tolerant mechanism are designed in this paper,and the latter makes delay and gradient settings for the time of LED on and off respectively to avoid frequent flashing of high beam.In addition,this paper briefly introduces some characteristics of ISO standardized CAN protocol,and analyzes the message instructions and the specific implementation of CAN communication in MLC(matrix LED controller)based on the characteristics of CAN message frame.Secondly,this paper introduces the hardware system design of S32K148 microcontroller and the system diagram of ADB,and designs the PCB circuit board.This paper systematically analyzes the function of each hardware module,and presents the model selection of main components and specific circuit structure.In terms of software,this paper systematically expounds the workflow of ADB,and designs and debugs the functions of CAN and SPI bus in the serial data communication part.In this paper,the three CANs integrated in S32K148 are used as ADAS(advanced driving assistance system)CAN,high beam private CAN and IFC(intelligent front camera)CAN respectively,and CAN＿PAL is basically configured.This paper shows the CAN bus initialization,the message sending and receiving and the buffer configuration of CAN bus,and applies the callback function to enhance the flexibility of the program.Additionally,the ADB program needs extra CAN bus to control the high beams.Therefore,this paper also designs the program of converting SPI bus to CAN bus based on its functional protocol.Finally,this paper calibrate and test the real vehicle with the designed system.In the static calibration,various kinds of working conditions are set in this design,and the target vehicle is tested in every working condition in turn.And in the dynamic calibration,this paper sets up the following and meeting conditions,and make the vehicle driven at different speeds and tested.In order to make the results more reliable,we also test the target vehicles with different models and colors,and the final measured results are in line with the expected assumption.To sum up,this paper introduces the algorithm principle of adaptive driving beam ADB,designs the hardware system based on S32K148,and tests and calibrates the functions of each part of ADB successively.The related work in this paper has important practical significance for the application of adaptive high beam technology in the field of automobile intelligent driving. |
