Research On Data Sampling System For Auto Braking Tester Based On CAN Bus

The testing of the automotive brake performance is one of important parts in vehicle safety inspecting. With the amount of the automotive increasing rapidly in our country, the brake performance of automotive has the relation with the safety of people. Therefore, it is necessary to find best methods and tools of testing automotive brake performances quickly and accurately.As being the bridge of data transmission, the reliability of communication network directly affect the reliability of the system. CAN bus is a technology which efficiently supports distributed system and real-time control with a very high level of security. It attracted attention with a very high level of capability and a very high level of security and a very better of anti-jampping and a very fast of communication speed and a very low of maintenance cost and a particular design. It was regarded a fieldbus with expansibility. With rapid development of fieldbus technology, the traditional instrument will be affected, and it will be replaced with the instrument based on fieldbus.It is realistic meaning to research and develop instrument based on fieldbus.The paper analyzes the current state of vehicle safety inspecting worldwide and conducts research in the following aspect:Firstly, the paper make a summary of the basic structure of the auto brake system, then the criterions of assessing brake performance was analyzed, and give a brief introduction about the machine of the tester referring to the paper, these are the theory base of data processing(DP).Secondly, the overall plan of the system is introduced in detail, and the CAN bus protocol and the correlative developing tool is discussed.Thirdly, it has been designed that the Data Acquisition System (DAS) based on PIC18F458 microcomputer; the software design of firmware update program and CAN bus communication part is analyzed in detail.Finally, the programs has been developed for the IPC computer used for data managements, and then researched the method of making braking performance curve smooth.By experiment of this instrument, it is proved that stability and real-time and precision of instrument based on CAN bus are better than traditional instrument. The error-delaying and data-switching and system-managing and anti-jamming of test system based on CAN bus instruments are better than the system based on traditional instruments.