Development Of Calibration System For Automotive Electronics Applications

With the rapid development of automotive electronics technology,the number of electronically-controlled ECU is increasing dramatically,objects of control have also become numerous and diversified,and the difficulty of control has increased significantly.On the one hand,the effect of control depends on the design of control algorithm,on the other hand,it depends more on calibration and test.Therefore,developing a calibration tool for automotive electronics applications has important engineering significance.On the basis of consulting domestic and international relevant calibration software documents,this paper has analyzed the ASAM MCD standard model,CCP protocol,CAN bus protocol and so on.A calibration framework system was constructed,including PC-end calibration software,ECU-end calibration firmware and USB CAN interface card.From the perspective of developing a universal calibration software for automotive electronics application,a overall scheme was designed: CCP protocol as an interactive protocol,the CAN bus for data transmission,and the A2 L file as the database of calibration and measurement.PC-end calibration software was developed based on MATLAB GUI platform.A2 L file parsing module,calibration module,measurement module,post-processing module and so on were designed by the method of modular division.This paper realized the functions of parsing A2 L file,updating the ECU address of measurement and calibration signal,drawing and dynamic display,real-time digital display,saving the data of measurement,calibrating data online or offline,uploading calibration value and showing,processing and analysis and so on.Moreover,a ECU firmware was developed by the method of hierarchical structure design.The firmware was divided into three parts,including bottom driver layer,service layer and application layer.Bottom driver functions were developed,such as CAN driver and EEPROM driver.The task scheduling mechanism was structed,including periodic tasks controlled by RTI timing and event tasks controlled by interrupt.CCP protocol command functions were wrote to parse PC-end commands.The power-off storage of calibration data was designed by the RAM-EEPROM related link list.The DAQ function was designed to upload measurement data periodically after accomplishing the DAQ configuration.The control mechanism of a commercial vehicle was refitted to meet the requirement of autonomous drive.A controller was developed with ECU-end calibration software to form a system with functions of calibration and measurement.With the aid of calibration software,we accomplished the steering,speed,gear and other objects‘ control.The experiments verified that the calibration software can meet the requirement of the application of automotive electronics.