Research And Design Of Vehicle Network Control System Based On Can Bus

With the rapid development of automobile electronic technology, the current car is nolonger a simple way of transport. More and more intelligent functions have been mergedinto automobile, which making the car has more and more electronic control units. If westill taking the traditional connection mode which was a point to point electrical system,Inevitably, the limited space of car would case the arrangement of wire becoming more andmore complex, at the same time, which would also reduce reliability of car, and increasedifficulties of maintenance and cost rise, body weight increase and many other issues,Apparently, which was unable to satisfy the communication needs for today’s "electric car".To deal with the problems, CAN bus technology was proposesed by BOSCH group, whichprovides an effective solution for electronic control unit for networked.This thesis studies the vehicle network control system based on CAN bus technology.First of all, from the perspective of vehicle network, designed the overall scheme of controlsystem. The CAN bus network architecture was composed of two subnetworks: high-speednetwork and low-speed network, the communication rate of high-speed network is 500 kbps,including engine node and so on, the communication rate of low-speed network is 125 kbps,including lights, instrument panel, central control unit and so on. The two subnetworks wasconnected by the gateway node.Furthermore, researched and analyzed the CAN bus protocol and application layerprotocol-SAE J1939. Based on the network architecture which has been designed, from theaspects of network node definition, message signal priority allocation, data field definitionand so on, refer to SAE J1939 protocol, established the CAN application layer protocolwhich had a good extensibility. In addition, the software and hardware of node controlmodules were designed, select Freescale 16-bit controller MC9S12XS128 as maincontroller node, the integration of MSCAN module and CAN drive MC33388 module torealize the CAN send and receive message function.The design of software using modularprogramming ideas, mainly includes MSCAN initialization program, CAN messagesending and receiving process and so on.Finally, using the bus network development tool CANoe to verify the design ofnetwork structure and the feasibility of the formulation of CAN application layer protocol.And by means of the physical node send message to virtual bus to verify the hardware andsoftware of the control module which were designed. In the CANoe environment we buildbus network simulation platform, including establishing CANdb++ database, by means ofthe pannel editor to creat the interface, writing the node CAPL program, etc. In the CANoe,we analyzed and tested the total simulation network and residual simulation network forthe whole control system, and at the end, evaluated the network performance from twoaspects: the network busload rate and the real-time property.Through the analysis of the testing results, we can come to a conclusion that: theapplication communication protocol of CAN bus and the vehicle network control systemincluded software and hardware which had been designed satisfy the control requirements,and also has a good real-time and reliability performance. Therefor, the research has a greatvalue in engineering application.