汽车CAN系统精确时钟同步机制研究

Research on precise clock synchronization mechanism of car CAN system

高可靠、高精度的时钟同步机制对于汽车CAN网络安全运行有着重要影响。针对分布式汽车网络同步问题,引入4种特殊的报文帧,定量研究了同步帧传输的网络时延,给出了即时偏差与网络延时的测算方法;在此基础上,结合基于最小"相对即时偏差和"的主时钟协商选择方法,建立了支持主时钟选择的精确时钟同步机制。实验结果表明,该机制不仅具有较高的同步精度和可靠性,而且有效降低了同步网络开销,能够满足当今汽车的高实时性要求。

High reliability and high precision clock synchronization mechanism has an important impact on the safe operation of automotive CAN network. Aiming at the problem of the synchronization in distributed automotive net- work, four special message frames are introduced, the network delay of synchronization frame transmission quantita- tively is studied, and the measurement method of instant deviation and network delay are given. On this basis, com- bined with the master clock consultation selection method based on the minimum relative instant deviation sum, a precise clock synchronization mechanism supporting master clock selection is established. The experiment results show that this mechanism achieves a high synchronization precision and reliability,and reduces the synchronization network overhead effectively. Therefore it can meet the high real-time requirement of today＇s cars.