Research Of Electric Vehicle’s Scheduling Strategy Based On CAN Network

With the development of automotive electronics technology and people demand the function of new cars, automotive electronic control unit and increasing the wire harness constitute a huge system, occupies a large number of cars in the first space, and the maintenance difficulty increases, reliability and real time also can not be guaranteed. So the network has become the main development direction of the vehicle network. And can bus is one of fieldbus, because of their high reliability and real-time of the data communication, It is widely used in vehicle network system, but using the CAN bus arbitration mechanism is with collision avoidance of carrier sense multiple access (Carrier Sense Multiple Access with collision avoidance, CSMA/CA), resulting in inability to guarantee the real-time performance of the low priority packets. TTCAN protocol is a kind of high level protocol based on CAN protocol, which has been improved and the real-time performance has been improved greatly, which meets the requirement of real-time performance and the increasing demand of high load.The advantages and disadvantages of TTCAN is introduced in this paper.. Based on the analysis of TTCAN protocol, the arbitration of TTCAN protocol still uses CAN bus protocol of CSMA/Ca mechanism, the mechanism in high load situations cannot guarantee the real-time character of the low priority node, even if it is a high priority information, if there is a higher priority nodes in transmitting cycle and produce information, actually cannot be guaranteed. In view of this situation, this paper improves the TTCAN protocol, and changes the original arbitration mode to mode of short data frame and data frame classification. That takes into account both the high priority nodes in real time and can be sent in a unit of time as much as possible the information, so that the system as much as possible response of multi node, which improved the real-time performance of the system bus on the whole. In order to verify the performance of the improved TTCAN protocol, Finally, simulation was made through the simulation software CANoe and CANcard, we build a simulation platform for a TTCAN.Through several experiments of before improvement and analysis of improved data, simulation experiment results well verify the improved TTCAN protocol in real time and bandwidth utilization rate of advantage, effectively improve the TTCAN system flexibility in practical application, for TTCAN protocol in real time provides an important theoretical basis and reference value.