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New Solutions for Avionics Testing

Jacob Perrin, Applications Engineer, dSPACE Inc.

September 12, 2016: Avionic software testing is among the most stringently mandated of all the domains within the embedded systems industry. As electrification and newer requirements for distance and comfort increase, the complexity of the aircraft increases. Consequently, the complexity of testing the related components increases tremendously.

Among the various methods of validating avionics software, hardware-in-the-loop (HIL) is generally recognized as the standard for reliable, flexible, and cost-efficient development. HIL is now commonplace for testing embedded systems across the industries, including the aerospace, automotive, and commercial vehicle industries.

dSPACE has built systems from the ground up to become the leader in providing high-performance simulators for these industries. The latest system created by dSPACE, known as SCALEXIO, is the most configurable, flexible, and extendible platform in this space, yet.

The SCALEXIO hardware platform is augmented by a strong suite of modeling, experimentation, test automation and management software. In addition to providing support for Simulink and FMI, this platform also provides an open interface to integrate third-party models for real-time execution. An illustration of the capabilities of this platform is the ability to integrate third-party software and hardware. One such example of a third-party model which has been successfully integrated onto a SCALEXIO system is Presagis’ FlightSIM.

A High-Fidelity, Real-Time Testing System

Within the context of HIL simulation, it is imperative to have a plant model that is both high fidelity and real-time. The burden of this requirement is shared between the platform and simulation model. Presagis has created flight simulator software which flexibly allows designers to model aircraft components in an environment which, when combined with a SCALEXIO platform, composes a powerful system aimed to meet the demanding requirements of the aerospace industry.

The SCALEXIO HIL simulator provides highly flexible channels for use with a wide variety of test domains.

The dSPACE SCALEXIO system is a versatile HIL simulator intended to be as extendable and configurable as possible. It includes features like graphical channel configuration, virtual ECU capability, and FMI support, the real-time platform covers all test domains.

For its part, Presagis FlightSIM is an end-to-end software development solution that allows you to rapidly prototype aircraft systems and support your embedded development through the integration of simulation and HIL. FlightSIM’s open modular architecture allows users to freely combine out-of-the-box software system simulation, Mathworks MATLAB / Simulink system simulation, and HIL. This enables users to simulate accurate and precise conditions in its model. These tests can be targeted at early development stages, and thus, shorten time to market.

A System with the Flexibility to Meet Full Development Cycle Needs

As HIL teams expand and tasks are being distributed across a group, the ability to test at both a component and system level becomes more critical and more difficult. Each mechanical system model must be developed in a unique environment respective to its domain, yet the models have to be combined together on the real-time simulation platform for validation and verification of the embedded software.

In addition, the developers may require the ability to decouple the embedded controller from the plant model and distribute computation and change conditions. The SCALEXIO platform, combined with a simulation environment such as FlightSIM, composes a system that can meet these requirements.

Flight hardware can be interfaced to the HIL simulator using an appropriate communication protocol. Then, in FlightSIM, the related default flight simulator components can be replaced with custom components, which interface to the flight hardware under test. Changes to the FlightSIM flight environment model parameters are as easy as changing curves, readily allowing users to customize the performance of the selected fixed-wing aircraft. The controller and plant can be set apart from one another, and processing can be distributed across simulation platforms.

The flight instrumentation library can be substituted for actual flight hardware, in which case CDNG would serve to modify hardware controller inputs and monitor and record outputs. This interfacing to the hardware can be done via the requisite communication protocol – whether that be ARINC 429, MIL-STD-1553, etc.

Parameters such as stick pitch, roll, and yaw are relayed from the dSPACE controller to the database editor (DE), which influences the FlightSIM simulation model at a rate which ensures real-time execution at the selected simulation step. The flight simulator output is then visualized back on the host PC using Presagis VegaPrime 3D Simulation Software.

This setup serves to introduce a small subset of the capabilities of the SCALEXIO platform, when paired with a powerful environment model such as Presagis FlightSIM.

ControlDesk is used to control the pilot inputs in this demo. ControlDesk provides libraries for users to quickly build instrumentation layouts. Steering controllers are one such instrument which is used to interface to a joystick for this demo.

Presagis VegaPrime is a comprehensive visualization toolkit used to visualize the simulation environment for this demo.

An Exemplary Testing System

The SCALEXIO platform provides users the features necessary to accomplish some of the most complex HIL tasks. The openness of the SCALEXIO simulator, when combined with an open, configurable, high fidelity, real-time model such as Presagis FlightSIM, allows for boundless possibility in the context of verification and validation of embedded software.

This flexibility means that the integration of third-party software and hardware can be accomplished with relative ease. With the immense potential of this platform, the question seems to become, “What would you like to do with it?” Most often, user requirements can be met and projects can be realized through the use the SCALEXIO simulation platform.

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