Design And Implementation Of Remote Vehicle Diagnostic System Based On K/CAN Bus

With the development of economy,car has entered millions of households,bringing great convenience to people's travel.China's car ownership increased from 10.4 million in 1995 to 194 million in 2016,with an average of 36 private cars owned by a hundred households nationwide.China has entered the automobile society.As the number of vehicles on the road increases,it is crucial for the vehicle owner to have real-time information about the internal status of the vehicle.In addition,with the development of automotive electronic technology,the types of vehicle failure are more and more complicated.Combined with the increase of the vehicle base,it makes the number of vehicle failure become more and more,which brings a higher request for the garage and the stuffs.Based on the above background,this paper develops a remote vehicle diagnosis system which can meet the desire of the vehicle owner to monitor the internal state of the vehicle in real time,and can greatly improve the efficiency of the auto repair shops.It has broad application prospects.First of all,this article chooses a technical framework which meets the needs of the system and is more economical,through comparison and argument.The framework divides the system into four functional modules: the diagnostic module,the smartphone APP module,the remote server module,the Web front-end module.This thesis is mainly responsible for the research and development of the diagnostic module and the remote server module.Secondly,this article studies and introduces the techniques that system used.Through further study of automobile communications technology,the paper summs up the funtction and role of various types of communications protocols,and proposes a diagnostic communications protocol framework based on this.This framework regulates and unifies a large number of on-board diagnostic communications protocols,processes the communication procedure,provides a unified communication services.The framework has a quite good openness and extensibility,can reduce the costs of maintainning diagnostic communications software and improve efficiency of development.The two typical integrated communication lines based on K-Line and CAN BUS are further selected to be studied,and the series of protocol ISO11898-1,ISO11898-2,ISO15765-2,ISO15765-4,ISO14230-1,ISO14230-2,ISO14230-4,and ISO15013-5 relied by these two lines are concretely analyzed,compared,summarized the differences and connections between them.As following is the introduction of the technology that is applied during the development of the server.Subsequently,the thesis is based on core controller LPC1549JBD48 to build the diagnostic hardware circuit,and on this basis by using of LPCXpresso IDE to develop diagnostic software.Diagnostic software builds the diagnostic communication framework and application,and completes development of the above two sets of communication lines in the framework.Diagnostic communication framework greatly facilitates the subsequent maintenance and upgradation of the diagnostic protocol communication software.Last but not least,this paper chooses the Pyhton programming language,based on the Flask lightweight framework,to adopt the layered software design concept to design and realize the remote server;then deploys the services to the Internet by putting it into the cloud using Nginx and uWSGI and test the service.The server proposes the concept of DB Proxy(Database Proxy),which provides network database services for the third-party applications.By accessing specific URLs,databases and data tables can be created,deleted,updated and queried without using native SQL codes,which improves the efficiency during developing third-party applications.DB Proxy can create virtual tables for the third-party applications,that is,the third-party applications can create and query a custom table doesn't exist in the database tables,the actual data is from data items splicing of multiple database tables in database,with a greater flexibility.In this paper,the inner vehicle electronic control unit as the object,based on the K-Line and CAN BUS related technology of communication in OBD-? standard,Bluetooth communication technology,http/https communication technology and Python programming language altogether research and develop a vehicle remote diagnotic system.The system not only meets the need of market,but also has good compatibility,maintainability and scalability,further combining with big data,artificial intelligence and other technology fields,you can excavate a great application value.