Message Scheduling And Optimal Design For Dynamic Segment Of Automotive FlexRay Network

Aiming at meeting the growing needs of automotive safety, reliability and comfort,more and more electronic devices are applied to the automobile. These electroniccontrol units exchange huge amount of information among each other, the requirementsof which is hard to meet by the traditional automotive electronic control system.Automotive network technology has born and developed to solve this problem. LIN,CAN, MOST and FlexRay has become the key part of the automotive networks, amongwhich the FlexRay bus is becoming the next generation of automotive bus standard withits advantages of high bandwidth, high fault tolerance, reliability and flexibility etc.,which is especially suitable for automotive safety critical systems such as x-by-wire,power and chassis.This thesis is supported by National Nature Science Fund. By consulting andcollecting domestic and forein related research, the communication scheduling andoptimal design problem of FlexRay dynamic segment is studied. Considering theschedulability of messages transmitted in FlexRay dynamic segment under FTDMAmechanism can not be guaranteed in all cases, a two-layer message schedulingmechanism of FlexRay dynamic segment is put forward based on polling servers. Byanalyzing how the parameters of polling servers and network affect the performance ofFlexRay network, such as schedulability, transmission efficiency and real time, anoptimal design model based on BNIP is constructed in order to find the best parametersincluding FlexRay cycle length, dynamic segment length, and parameters of the serverssuch as period, offset, frame ID and message group. This optimal design method is forthe purpose of guaranteeing the schedulability and obtaining the maximum bandwidthand relative minimum delay of messages in dynamic segment. Thehalf-semi-half-physical experiment system of FlexRay network based on the platform ofCANoe is built, which is used to verify the feasibility and the improvement of thenetwork performance such as schedulability, transmission efficiency and real-time ofFlexRay dynamic segment. The research of this thesis have certain theoretical andengineering value for improving the reliability and real-time of FlexRay application.