Research And Implementation Of Scheduling Method In The Static Segment Of Automotive FlexRay Bus

With the growing number of the car ECU, the vehicle communication network has become an inevitable trend. Compared with the traditional CAN bus, FlexRay bus in transmission efficiency, reliability and flexibility has great advantages. It can meet the requirements of future car ECU network communication, and it is recognized as a new generation of automotive network standard. At the same time, as a typical safety critical systems, network real-time scheduling methods is one of the key issues to ensure the real-time and reliable communication.This topic based on the national natural science fund. For the deficiency of FlexRay static segment fixed slot allocation mechanism, a message scheduling mechanism of static slot dynamic allocation (SDAS) is proposed, which gives the state transition model and running algorithms of the scheduler, and analyzed the worst-case response time for each message quantitatively. On the basis of FlexRay frame design, with the minimum time debris for the target, a configuration method for the relevant network parameters is established under the constraints of message response time and communication cycle range. Furthermore, based on Freescale MC9S12XF512chips and TJA1080transceiver, software and hardware architecture and implementation of SDAS mechanism is researched and designed, including SDAS scheduler and related modules. At last, a complete semi-physical simulation platform is built based on the CANoe. FlexRay. The design scheme can be proved from the schedulability of message, real-time, bandwidth and slot utilization after the design of virtual node. The simulation results show that SDAS mechanism can effectively improve message real-time and bandwidth utilization, which is compared with the fixed allocation time slot. Improving application FlexRay bus vehicle system reliability and real-time performance has important theory value and practical significance.