Modelling and simulation of integrated modular avionics systems

Abstract

Integrated Modular Avionics (IMA) has now been fully developed, and installed in practically every new airplane model that are in service today. IMA approach allows mixed criticality real-time applications to be merged into integrated system. These integrated real-time applications must meet their own timing requirements and be protected from other malfunctioning applications, while physically sharing resources such as processors and communication networks. To guarantee timing constraints and dependability of each application, an IMA-based system must be equipped with strong partitioning schemes. Based on ARINC IMA standards, we refer a model as strongly partitioned distributed real-time system which composed of three major parts that are Avionics Subsystem, End System and Avionics Full Duplex Switched Ethernet (AFDX) Communication System. We build the two-level scheduling hierarchy architecture model of Avionics Subsystem to provide spatial and temporal partitioning for real-time applications. End system provides communication interface for Avionics Subsystem and AFDX Communication system. AFDX Communication system provides reliable message transmission among applications. To evaluate the performance of an IMA-based system, simulation tool based on the discrete event system simulation method has been developed. The simulation captures additional characteristics of the system with respect to the analytical study, which is basically used to evaluate worst cases and deterministic guarantees. The tool is designed to help platform designer, applications developer and system integrator to describe and evaluate different implementation choices.