TTCAN非周期信息概率延时分析及改进

Study and Improvement on Probability of TTCAN Aperiodic Message Delay

时间触发控制器局域网(TTCAN)总线保证了周期信息的实时性,但低优先级节点的非周期信息在高负载下延时未得到改善,甚至与CAN相比,其延时将增大。文中运用概率论分析了TTCAN非周期信息的延时及计算方法。提出在TTCAN的独占窗时间段插入非周期信息仲裁时隙,以提高非周期信息实时性。分析了改进后TTCAN非周期信息概率延时的计算方法,并给出了改进后周期信息延时分析。仿真计算说明文中提出的改进方法在满足周期信息实时性要求的情况下,有效提高了非周期信息的实时性。

The period messages of time-triggered CAN （TTCAN） bus system possess highly real-time performance, but the a- periodic message delay of low priority nodes doesn＇ t decrease, and is even more serious compared with CAN under high loads. Probability theory was used to analyze the delay of TTCAN aperiodic message, and the calculation process was given. The method which inserted aperiodic information arbitration time slot between two adjacent exclusive windows was put forward to improve the real-time performance of the TTCAN aperiodic messages. Probabilistic delay of improved TFCAN aperiodic message was calculated, and period message delay was analyzed. The simulation calculation shows that the method proposed effectively reduces the aperiodic message delay and the period messages meet the real-time demand.