Managing the Challenges of Integrated Modular Avionics
A summary of the technical whitepaper “Aircraft IMA Integration Bench—Managing the Challenges of Integrated Modular Avionics” is presented below. The full whitepaper in .pdf format can be found here.
Integrated Modular Avionics (IMA) is forever changing commercial and military avionics systems. IMA, and its early adopters have rewritten the rules of integration, verification, and certification for modern avionics systems.
The Airbus A380 and the Boeing 787, are two highly advanced aircraft programs embracing an IMA platform architecture. Both Boeing and Airbus are banking on IMA to improve their competitiveness. The Airbus A350XWB as well as a collection of yet-to-be-announced aircraft programs are committed to IMA.
After decades of methodical, evolutionary changes, the top aerospace competitors, under intense market pressures, have retired the status quo. Multidisciplinary optimization efforts are yielding major changes in aircraft design and technology. Along with composite materials, advanced propulsion systems, novel airfoil designs, etc., IMA is a major technological undertaking designed to improve efficiency and maintainability on multiple levels. Unsurprisingly, IMA is making a significant impact on R&D, which must rise to the challenge.
IMA includes the following key elements:
- A distributed architecture where avionics functions are split into centrally computed software applications and remotely located End Systems
- An “IMA Platform” providing shared computational resource to execute avionics application software
- A shared, dual-redundant ARINC-664/AFDX network
Integrating and Verifying IMA Aircraft Systems
End Systems and their Avionics Application
With few exceptions, having aircraft system suppliers develop software applications for a shared, third-party airborne computer system is a big departure from past practices. But this is exactly what IMA requires.
The figure above shows the IMA Platform with four applications, each from a different supplier, each executed on shared computational resources, and each communicating with its respective End System on a shared network.
As aircraft systems’ dependence on software, electronics, and data sharing with other systems increases, so has the challenge of integration and verification. In an IMA-based aircraft this task is suddenly far more challenging. Today’s program schedules are more aggressive than ever. To support these short schedules, system integration and verification depends on Model Based Systems Engineering (MBSE) techniques. MBSE supports an agile development approach where simulation is used to integrate and verify systems well ahead of access to representative airborne equipment and flightworthy software.
MBSE Techniques for IMA Integration
It is standard practice to use real-time, hardware and pilot-in-the-loop integration and verification facilities for major aircraft development programs. Common aircraft MBSE facilities include Avionics Integration, Iron Bird, and engineering cockpit simulation.
IMA-based programs introduce a new role: The IMA Manager. The IMA Manager, or management team takes responsibility for the allocation of the IMA’s shared resources. The IMA Platform (ARINC-653 in particular) and the ARINC-664 network rely heavily on XML to specify shared-resource configurations. Some uses for XML configuration tables are:
- ARINC-653 inter-application communication specification
- ARINC-653 partition and module specification
- Allocation of applications on ARINC-653 partitions
- ARINC-664 switch configuration
The IMA Management team is responsible for:
- Allocating IMA platform resources
- Managing IMA platform configuration tables
- Performing verification testing on the integrated platform
- Qualifying the module configuration
The IMA management team does integration testing at multiple levels including:
- Desktop software testing of the application
- Application testing on a representative hardware platform
- Functional verification on the real IMA platform
- Integration of all applications with an IMA integration facility
- Functional verification of individual systems within the IMA Platform
- Integration and verification of all systems together
This work demands a new category of hardware-in-the-loop (HIL) simulation testing facilities: The IMA Integration Bench.
An Avionic Integration Facility includes a full flight deck, avionics suite, electrical loads, and most electronic system found in the aircraft, while the IMA Integration Bench is limited to the IMA Platform, the ARINC-664 network, and the electronic units connected to the network; remaining systems are simulated.
The IMA Integration Bench
Applied Dynamics works closely with airframers, avionics and other sub-system suppliers to support their adoption of IMA technology and to supply IMA Integration Bench systems for integration, verification, and certification of IMA aircraft. The figure below illustrates a Four Node IMA Integration Bench.
The ADI IMA Integration Bench is a high-performance, distributed, real-time simulation system that covers every requirement of IMA integration, verification, and certification. ADI’s ADvantage Framework gives users the perfect set of tools for every phase and every level needed to perform interactive and automated integration and verification testing.
Distributed System Architecture
Performing HIL simulation with dozens of IMA End Systems requires tremendous computational power. It is common to use four or five interconnected, high-performance real-time simulation computers to meet the computational needs of an IMA Integration Bench. The figure below shows the Target Processor / Core Usage view within ADvantageDE showing the assignment of models and devices in a five node real-time simulation project.
Data acquisition from IMA Integration Bench tests is a crucial capability. During test case execution, data will be collected and record test case stimuli and their effect on signals of importance. The data collected will typically vary between test cases and reconfiguration must be quick and easy.
Working with Databus and Serial Interfaces
A very challenging aspect of IMA Integration testing is working with dozens to hundreds of serial and databus network communication channels. Signals moving across this dense network must serve as inputs to simulation models; and model outputs need to be sent to the network; all in a real-time deterministic manner. Network channel definitions will typically change over the course of an aircraft development program as the design of each End System evolves. Correctly and quickly defining the configuration, e.g. message packing, Virtual Links, BAG, SDI, SSM, etc., of each network channel across a range of network types is key.
The ADvantage Framework includes the ADvantageDB tool for working with aircraft network communication. ADvantageDB makes it easy to define, apply, redefine, and reapply test-specific network definitions to IMA Integration Bench projects. ADvantageDB uses XML data files, which are preferred for revision control and change tracking. ADvantageDB features Python scripting for the analysis and automation that the aircraft network definition effort requires. The figure above illustrates databus and serial network configuration and test implementation tasks.
ADvantageDB builds a Reference Database representing the golden standard definition of an aircraft’s complete network. Reference Objects applied to a Framework Database assigns bus definitions to bus interface channels linked with specific IMA Integration Bench project configurations.
Essential aspects of the IMA Integration Bench include:
- Distributed system architecture with multiple nodes and multi-core processors
- Data dictionary of simulation models, signal interfaces, and aircraft network traffic satisfying Interface Control Documentation (ICD) needs
- Test-case-specific data acquisition
- Flexible aircraft network channel configuration and implementation
- Automated aircraft power distribution
- A comprehensive test language
Read the full whitepaper: Aircraft IMA Integration Bench – Managing the Challenges of Integrated Modular Avionics
Learn more about how a technology partnership with Applied Dynamics can successfully drive your organization’s adoption of IMA systems. Speak with an application engineer today.