基于总线占用率的FlexRay消息时隙分配方法研究

Research on FlexRay Message Slot Distribution Methods Based on Bus Occupancy Rate

消息时隙分配问题是FlexRay汽车网络设计的关键问题之一。在分析FlexRay消息帧格式和消息物理层传输规则的基础上,推导出了FlexRay消息传输时间片长度和总线占用率计算公式,给出了影响总线占用率的主要因素;以最小总线占用率为目标,提出了将静态段最长消息帧分配到动态段的时隙分配方法。实验表明,该消息时隙分配方法可有效地降低总线占用率,提高网络使用的效率。

Message slot distribution method is one of the key problems of design of FlexRay vehicle bus.On the basis of analyzing characteristics of FlexRay and its frame of format and physical layer transmission features,methods of calculating message frame slots and bus occupation rate were obtained,factors that influenced on bus occupation were given herein.With the goal of minimal bus occupation rate,a message frame slot distribution method was proposed which assigned the longest static message frame to the dynamic segment.By example validation,the proposed message frame slot method is proved to be feasible,it reduces bus occupation rate effectively,and increases efficiency of the network.