Study And Development On Remote Fault Diagnostic Of Automotive Based On Smartphone

Vehicle electronics are getting more and more complex with the increasing proba-bility of failure in electronic control systems, so it is getting hard to judge the failure causes and failure parts. Therefore, a vehicle fault diagnosis system plays an essen-tial role during vehicle diagnosis process. And researchers also have made great ef-forts on the research of developing the vehicle fault diagnosis systems based on OBD (On-Board Diagnostics) system. This paper analyses the deficiency of current vehicle fault diagnosis system, and develops a remote vehicle fault diagnosis system based on the smartphone platform, aiming at meeting the demands for a remote, networked, and intelligent fault diagnosis system in the future.After the study of the OBD protocol KWP2000is done, a remote fault diagnosis system is proposed based on a layered architectural model of OSI, which is an assem-blage of a VCI (Vehicle Communication Interface), smartphone and a remote server. This primary work in this paper is focused on developing the hardware and software of the VCI system, designing the smartphone diagnostics software, and setting up the remote server.First, the paper deliberates the hardware and software of a VCI, and built an em-bedded system applying of16-bit MCU, according to requirements of physical and link layer in diagnostic protocol KWP2000. The building work is constructed by two parts. In the first part, it designs a K-Line interface circuit and a CAN bus to realize the data communication with VCI and in-vehicle networks. In the second part, it inte-grates a Bluetooth module to realize the data communication with VCI and Smartphone. At the same time, a single chip micro-computer monitoring program is designed to control the communication links and business logic.Second, referring to the hierarchical structure model, the smartphone diagnostics software is developed based on. Net Compact Framework by using the c#-language, and divided into four layers including a presentation layer, a business logic layer, a data-access layer, and a layer for data storage and management. Therefore, the paper investigates the theory and the implementation of each layer, especially the commu- nication mechanism of the system, aiming at reducing negative effects caused by a delay of Bluetooth communication.Third, the remote fault diagnosis server is built up based on mobile communication network and the Internet by setting up the server on the Internet. Once the smartphone makes a primary request to remote server, the remote server will respond to this re-quest. In the process of diagnosis, it is based on interactions between the requests for diagnostic service and the information on the site. Hence, an effective remote com-munication program is proposed and performed to fulfill the remote fault diagnosis. In addition, a further study for the synchronization display between remote server and smartphone is done by elaborating the implementation principle and framework of the associated software.Finally this paper verifies the system by testing the VCI communication link, sys-tem communications mechanism, smartphone diagnosis software, PC data manage-ment system software and remote diagnostics. Test results indicate that the system can meet the actual functional and performance requirements.