一种FlexRay总线优化方法研究

RESEARCH ON A FLEXRAY BUS OPTIMISATION METHOD

为了提高FlexRay车载网络带宽利用率,减小消息帧的最坏响应时间,对FlexRay总线配置问题进行研究。针对FlexRay协议中静态段负载长度相等,静态消息的长度不等的情况,找到最优静态段负载长度,提高带宽利用率。基于静态段的优化之上,综合分析静态段、动态段消息的最坏响应时间,得到最优总线周期长度。实验结果表明,在得到最优负载的条件下,带宽利用率提高22%,并且在周期长度为982μs时,总线消息帧的最坏响应时间最小,保证了消息传输的实时性、可靠性。

In order to improve the utilisation of FlexRay in-vehicle networks bandwidth and to reduce worst-case response time of message frames, we study the FlexRay bus configuration issue. For the circumstances of FlexRay protocol that in static segment the payload length is equal but the static message length is not, we find the optimal static segment payload length to improve the bandwidth utilisation. Based on the static segment optimisation, we comprehensively analyse the messages worst-case response times in both static segment and dynamic segment, and get the optimal bus cycle length. Experimental results show that the bandwidth utilisation ratio increased by 22% under the condition of acquiring the optimal payload length. Furthermore, in the case of the cycle length being 982 microseconds, the worst-case response time of FlexRay bus is minimum, and this ensures the real-time performance and reliability of message transmission.