基于FlexRay线控转向系统的传输延时算法

Transmission delay algorithm based on FlexRay steering-by-wire system

为确保汽车转向系统的实时性,对影响时钟同步的因素——传输延时进行研究,主要针对传输延时的不确定性。通过节点互发同步报文,本地节点动作点获取相应时间戳,并在同步报文发送的负载端里传输时间戳信息,根据时间戳及相应的FlexRay节点计算得到传输延时的算法。此算法可以应用于在分布式系统启动时,通过同步报文的传输计算出节点间传播延时和解码消耗后,然后进行配置节点,提高时钟同步精度的同时又不浪费带宽资源。将该算法导入FlexRay线控转向系统,并通过MATLAB仿真平台对系统进行仿真,得出该算法在对非同步节点进行计算修正之后,使其时钟得到有效调整,提高了系统整体的实时性及可靠性,对汽车技术的发展具有一定意义。

In order to ensure the real‐time performance of vehicle steering system ,the transmission delay which is an important factor of clock synchronization is researched in this paper ,especially uncertainty of transmission delay .With the nodes send message with each other ,action point of local node could get corresponding timestamp message which is sent by the load segment of synchronous message ,and the algorithm could be concluded with the timestamp and the corresponding FlexRay nodes .This algorithm could be applied to the startup of distributed system ,with transmission of synchronization message ,transmission delay and decoding consumption could be calculated ,then configuring node ,and the clock synchronization accuracy of the system could be improved and the bandwidth resources also couldn ’ t be wasted .According to the simulation of FlexRay steering‐by‐wire system which the algorithm has been embedded ,after correction of transmission delay ,the asynchronous nodes could be adjusted effectively .the algorithm improve the overall real‐time and reliability ,which is of certain significance to the development of automobile technology .