Design And Realization Of On-line Fault Diagnosis System For Vehicles Based On 4G Network And CAN Bus

With the rapid development of the automobile industry and the Internet of Things,as a necessary means of transportation for people to travel,automobiles will certainly be integrated into the trend of the Internet of Things.At present,more and more electronic control systems are installed in the vehicle,and the vehicle control terminal monitors the overall situation of the vehicle through a series of sensors and CAN bus,which greatly improves the performance of the vehicle,However,at the same time,the electronic control structure and circuit of the vehicle are becoming more and more complex.The increase of some electronic components makes the probability of automobile failure relatively increased,and some of the causes of failure are difficult to analyze due to lack of data.The wireless communication technology can transmit real-time data of the vehicle to the remote server,and provide historical and real-time data of the corresponding components for the vehicle fault information,thereby realizing remote monitoring and online fault diagnosis functions of the vehicle.This design combines CAN bus technology,4G communication data transmission technology,GB/T32960 standard protocol and automobile fault diagnosis protocol to complete the research work of automobile online fault diagnosis system.Firstly,this paper analyses the functional requirements of the system,completes the overall structure design,then designs the scheme for the key functions including data acquisition,remote communication and server architecture,and formulates the communication protocol and vehicle fault diagnosis protocol for the remote data transmission in this design based on the existing protocols.For the encryption method used in transmission and the data analysis model of server-side fault early warning,this paper optimizes the implementation process by modifying the algorithm and tests its practicability by simulation.After completing the scheme design,the hardware and software of the system are designed.The hardware part is mainly the vehicle terminal installed in the vehicle.The 32-bit processor LPC1758 chip based on Cortex-M3 core is used as the main control core of each module,and the CAN message of the controller of different parts of the vehicle is received and parsed with the PCA82C250 module,and stored in the SD card according to the date.GPS information acquisition and wireless data transmission are carried out by using SIM7600 CE module of 4G.The software design includes the vehicle terminal and the remote server terminal,and the vehicle terminal is equipped with the ?C/OS-II real-time operating system to properly schedule multiple tasks and complete the vehicle terminal function.The server side uses Python-based Django as the back-end development framework.AdminLTE acts as the front-end interface,which can effectively receive and parse the data of the vehicle terminal,and provide a concise and friendly interactive interface to display the data and fault codes of various parts of the vehicle to users,as well as to warn the hidden faults of the vehicle through historical data analysis.According to the overall scheme of the system,the design is completed.After functional verification and analysis in the simulated and real vehicle environment,the design can collect,store and send CAN data through the vehicle terminal according to the requirements.The server can receive,store and display the data smoothly.According to the results of data analysis,an early warning is given to the hidden fault of the vehicle.The test results show that the system basically achieves the expected effect.