| The Electronic Pneumatic Shift(EPS) system has changed the traditional shift of mechanical transmission. It makes the position of control crank and shift much more flexible, comfortable and accurate and it eventually actualizes the passenger car gear-shift's car-like . However, with the development and application of EPS system, some requirements of its stability, security and reliability have increased, and, as a result, bring about the diagnostic system of EPS.Through the analysis of several control programs which have existed and under the premise of without affecting the system's function, we designed a multi-function on-board diagnostic apparatus based on bus-EPS system. The diagnostic apparatus mainly consists of main control unit, display unit and communication unit. In this apparatus, main control unit and display unit are separately controlled by their own MCU. Main control unit is mainly responsible for collecting some quantitative data of EPS system through RS232, and then it analyses, deals with and storages these data. What's more, the main control unit would send the fault message of EPS system and some important vehicle's information to the display unit. Display unit would display these information in the form of pictures and texts through M100 and TFT-LCD touch screen. Communication unit uses not only USB, RS232 and SD card to communicate with upper computer, but also CAN bus to exchange data with other electronic modules. The diagnostic apparatus can provide real-time and accurate information of passenger car for drivers, and it can reduce clutch wear and increase smoothness during gearshift process in order to save energy.This paper mainly discusses system solutions of diagnostic apparatus and some technical principles of diagnosing EPS system. It also completes the hardware and software designs of the master and salves control modules as well as structural appearance. What's more, it makes more detailed analysis on some key components. |
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