基于AFDX的航空电子系统可调度性分析

航空电子全双工交换式以太网(AFDX,Avionics Full Duplex Switched Ethernet)是新一代大型飞机机载网络的首选方案,构建其上的航空电子系统应保证强实时应用在时限内完成.针对现有AFDX实时性研究仅给出网络延迟上界的不足,综合考虑了任务的响应时间以及实时消息在AFDX网络中的传输延迟.建立了使用AFDX网络的航空电子系统模型,分析了分布式任务序列的整体时间需求.应用全局分析思想,给出任务序列的最坏情况响应时间,为系统实时性的评价和优化提供了理论依据.仿真结果表明该分析给出了紧凑的任务序列响应时间上界.

Schedulability analysis for AFDX-based avionics systems

Avionics full duplex switched ethernet (AFDX) is designed for on-board communications in the new generation large aircraft. AFDX-based avionics systems are required to guarantee that hard real-time applications can be completed within their dead-lines. While current researches on real-time performance of AFDX only give the delay upper bound of frames,both the response-time of tasks in each processor and the delivery delay of hard real-time messages in AFDX networks were consided. The AFDX-based avionics system model was built, and the timing requirement of distributed task sequences was analyzed. Then, the worst case response time of task sequences was derived by using the holistic analysis. The proposed schedulability analysis provided a theoretical means to evaluate and optimize system real-time performance. Simulation results manifest that this analysis can give the tight upper bound for response time of task sequences.