A Study Of Reliability Modeling And Evaluation On IMA Airborne Network

Avionics airborne network is a safety-critical system that has strict requirements in security and real-time performance. In recent years, Integrated Modular Avionics(IMA) has gradually replaced the joint avionics system with the advantages of flexibility, sharing, and interoperability. It has become a major research on IMA system framework and availability of software and hardware, but the method of reliability analysis and performance evaluation is rare. In response to this phenomenon, this paper studies the centralized IMA airborne network, and analyzes the mechanism of its transmission reliability, real-time reliability and service reliability, establishing the performance evaluation models in multiple dimensions.Avionics Full Duplex Switched Ethernet(AFDX) is a communication network for IMA. It solved a lot of uncertainty and reliability issues by enhancing certainty and fault tolerance mechanisms on the basis of traditional Ethernet. First of all, this paper analyzes the failure modes and failure mechanism of AFDX, and then establishes a dynamic fault tree to describe the system failure. Based on the above, for limitations of dynamic fault tree analysis based on Markov chain and modular dynamic fault tree analysis, a dynamic fault tree analysis based on multi-valued binary decision diagrams is studied to ease the problem of state space explosion and lower the solving complexity of the dynamic fault tree for AFDX, and obtain connectivity reliability parameters.Secondly, this paper analyzes the scheduling mechanism of centralized IMA, and establishes models of periodic tasks, aperiodic tasks as well as a variety of system resources taking advantages of deterministic and stochastic Petri nets having diversified transitions, and designs the model of task scheduling algorithm based on different priorities. It can be done to compare and analyze the task delay between independent resources scheduling and shared resources scheduling, as well as the task throughput between priority task scheduling algorithm and FIFO task scheduling algorithm based on shared resources. The results verifies that priority-based scheduling algorithm based on shared resources performs better in the real-time reliability and service reliability on centralized IMA.Resource allocation and load balancing on shared resources is another reliability issue that cannot be ignored in scheduling for centralized IMA. Finally, this paper introduces several commonly used load balancing algorithms, and studies load balancing algorithm under the centralized IMA scheduling mechanism. Combined with Petri net, the model of load balancing algorithm is designed to compare the performance of priority-based least task load balancing algorithm and least task load balancing algorithm. By the evaluation parameters of throughput and response time, it is verified that priority-based least task load balancing algorithm ensures the service reliability of high-priority tasks in centralized IMA better.