The integrated modular avionics (IMA) has been widely deployed on the new designed aircraft to replace the traditional federated avionics. Hosted in different partitions which are isolated by the virtual boundaries, different functions are able to share the common resources in the IMA system. The IMA system can dynamically reconfigure the common resources to perform the hosted functions when some modules fail, which makes the system more robust. Meanwhile, the reliability of the reconfigurable integrated modular avionics becomes more complicated. In this paper, we firstly model the IMA as a joint (m,k)-failure tolerant system with the consideration of its reconfigurable capability. Secondly, the continuous-time Markov chains are introduced to analyze the reliability of the IMA system. Thirdly, we take the comprehensive display function hosted in the IMA system as an example to show the practical use of the proposed reliability analysis model. Through the parameter sensitivity analysis, different failure rate λ and priority order of different modules are chosen to analyze their impact on system reliability, which can provide guidance to improve the reliability of the IMA system during a dynamic reconstruction process and optimize resource allocation.

The reconfiguration technology, which is the significant feature of the newly designed Integrated Modular Avionics (IMA) system, enables the transfer of avionics functions from the failed module to the residual normal module, thereby enhancing the robustness of the whole system. The basic target of the IMA reconfiguration is to ensure the safe flight and correct execution of the mission. To solve the problem of lack of effective management mechanism for the IMA system development and safety assessment, a safety analysis method based on STAMP/STPA and UPPAAL for IMA reconfiguration is proposed. The method focuses mainly on system characteristics and multiparty interactions. On the basis of this approach, some studies and analyses have been carried out. Firstly, the STAMP/STPA principle is studied and used to identify unsafe control actions in the reconfiguration process. Secondly, a formal model of IMA reconfiguration is developed using UPPAAL. Finally, the accessibility analysis of the formal model is used to analyze UCAs and the corresponding loss scenarios. The method enables a detailed description of the interactions between the components and a rigorous mathematical analysis of the system, thereby diluting the effect of human factors while ensuring the accuracy and reliability of the safety constraints.

Worst-case delay analysis is important for avionics full duplex switched Ethernet (AFDX) standardised as ARINC 664. The flow model of virtual link (VL) in the worst-case delay analysis of AFDX is inaccurate, which depends only on the parameters of VL and ignores the impact from the network, so it makes the worst-case delay analysis of AFDX impractical. A worst-case flow model of VL, which takes the worst impact from the network into account, is proposed to mend the worst-case delay analysis of AFDX. This worst-case flow model of VL is applied in one of the main theoretical approaches for worst-case delay analysis, the network calculus approach. It assists the network calculus approach to get the real upper bound of delay for VL.Introduction: Avionics full duplex switched Ethernet (AFDX) [1] is an upgrade from Ethernet for avionics demand. It is a time-critical network for aerospace applications, and worst-case delay analysis is significant for this network. The way to perform the worst-case delay analysis of AFDX is to calculate the upper bound of delay for virtual link (VL) by theoretical calculation. The main approaches for worst-case delay analysis include the trajectory approach [2], the network calculus approach [3] and so on. The network calculus approach is the most mature one, which was first proposed in [3] and applied to AFDX in [2,4,5].The flow model of VL in the worst-case delay analysis of AFDX is constructed according to the parameters of VL. This flow model ignores the impact from the network, so it cannot represent the worst situation of flow, and the worst-case delay analysis of AFDX cannot be rigorous. To overcome this problem, a worst-case flow model of VL is proposed in this Letter, which takes the worst impact from the network into account. This worst-case flow model of VL is applied to the network calculus approach. With this assistance, the network calculus approach can get the real upper bound of delay for VL.

Worst-case end-to-end delay analysis is important for real-time applications of switched Ethernet network. The Trajectory approach is one of the mature tools for worst-case delay analysis to calculate the upper bound of delay. The delay analysis based on the Trajectory approach as well as the packet serialisation of such networks is presented. An optimisation of packet serialisation is proposed in order to improve the Trajectory approach. A case study is illustrated to compare the improved Trajectory approach with the classical one, and the result shows that the improved Trajectory approach can get tighter upper bound of end-to-end delay.

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