时间触发AFDX调度策略设计与实时性分析

Scheduling Strategy Designand Real-time Analysisof Tme-triggered Ai FDX

为了解决航空电子全双工交换式以太网(AFDX,Avionics Full Duplex Switched Ethernet)时间关键消息传输的确定性问题,本文提出一种时间触发AFDX(Time-Triggered AFDX,TTAFDX)网络的体系结构,同时设计了基于周期优先的端系统时间触发虚拟链路调度算法。通过网络演算方法对比了TTAFDX与采用FIFO调度算法的AFDX网络的实时性能。计算结果表明:TTAFDX中的时间触发虚拟链路的延迟主要由固定延迟部分组成,而且速率限制虚拟链路的实时性也较AFDX有所提高。证明了TTAFDX体系结构和调度算法在兼容AFDX的同时能够改善网络的时间确定性,并适用于具有硬实时传输要求的航空电子系统。

To solve the temporal determinism problem of time-critical message transmission in Avionics Full Duplex Switched Ethernet（AFDX）, this paper proposed the network architecture of Time-triggered AFDX（TTAFDX） and designed the scheduling algorithm of time-triggered virtual link based on cycle-prior end system to contrast the real-time performance between TTAFDX and AFDX by the method of network calculus. The results showed that the delay of time-triggered virtual link in TTAFDX mainly consisted of fixed part and the real-time of the rate constraint virtual link was higher than AFDX. At the same time, TTAFDX architecture was compatible to AFDX and could enhance temporal determinism to be suitable for the avionics with hard real-time transmission requirement.