时间触发CAN总线实时性分析及评估方法

针对目前时间触发控制器局域网(CAN,Controller Area Network)总线缺乏统一评估方法的现状,提出了一套系统建立与评估方案.采用均匀装载算法建立系统调度矩阵,实现了周期信息的实时传输.结合CAN总线的传输机制与时间触发的特点,改进了时间触发系统中非周期信息最坏延迟的计算方法.在此基础上针对不满足系统实时性要求的信息提出了计算其失效概率的方法,建立了时间触发CAN总线系统的设计与评估流程,提出了系统参数调整方案.评估方案能够提高设计效率,利用信息失效概率以及最坏延迟对系统实时性进行分析,使分析结果更加精确、实用.

Real-time analysis and assessment method of time-triggered CAN-bus

To solve the problem that time-triggered CAN (controller area network) bus system lacked a unified real-time performance assessment method, a complete system establishment and assessment scheme was proposed. Time-triggered CAN-bus system scheduling matrix was established by using average-loading algorithm and periodic messages were guaranteed to transmit without delay by distributing them independent transmission windows within the system matrix. While considering the traditional CAN-bus transmission mechanism and the time-triggeredness feature, a calculation method was improved to calculate the worst-case delay of event-triggered messages in time-triggered CAN-bus system. The failure probability was calculated for event-triggered messages whose worst-case delay exceeded their deadlines. System design and assessment process was established for CAN-bus transmission system and parameter adjustment was proposed to optimize system real-time performance. This assessment method could improve the design efficiency and the final analysis result is more accurate and practical by considering the effects of the event-triggered messages worst-case delay and failure probability.