Research And Implementation Of Vehicle Wireless Diagnosis System Based On Bluetooth Technology

Auto self-diagnosis technology can carry out effective fault self-diagnosis for vehicle ECU.Based on this technology,the car manufacturers have developed dedicated fault diagnosis equipment for vehicle diagnosis.However,there are drawbacks in both features and user experience.The traditional fault diagnosis equipment uses a dedicated hardware equipment for vehicle local diagnosis,the cost of hardware is high,and the versatility is poor.With the development of Internet technology and vehicle electronics technology,the application of Internet technology to vehicle fault diagnosis will gradually become a trend.In this thesis,combined with existing vehicle diagnostic functions,a wireless diagnosis system based on Bluetooth technology is researched and implemented on the basis of traditional vehicle diagnostic system architecture.The system includes the mobile diagnostic subsystem,remote diagnostic subsystem,and faulty vehicle.The system supports local diagnosis and remote diagnosis.In order not to change the original vehicle fault diagnosis method,this thesis studies the communication protocol between the mobile diagnostic subsystem and the Bluetooth diagnostic interface module,and defines the data interactive message format.Considering that the Bluetooth diagnostic interface module only forwards the diagnostic message,and the vehicle ECU diagnostic communication is strict with the diagnostic protocol time parameter,therefore,the application of ISO 15765 mechanism in Bluetooth communication is put forward.The data packet format and data transmission mechanism of the core protocol of Bluetooth protocol stack are analyzed.Then it comes to the communication delay requirement that the ISO 15765 diagnostic message must meet in the Bluetooth protocol stack according to single frame and multi-frame transmission respectively.In addition,in the process of remote diagnosis,the communication protocol between the mobile diagnostic subsystem and the remote diagnosis subsystem is studied and the data interactive message format is defined,considering that the Internet data transmission delay is not controllable.Finally,functional implementation of wireless diagnosis system based on Bluetooth technology is completed in this thesis.The application shows that system in this thesis is well qualified to the requirements of vehicle fault diagnosis,and it can timely,accurately get the feedback of the diagnosis information.Due to the use of the vehicle's Bluetooth diagnostic interface for message forwarding,the system does not need a dedicated hardware device to connect to the vehicle besides mobile diagnostic subsystem,which reduces the system development costs and improves the system diagnostic efficiency.