Proven technology for aircraft test systems
In markets with strict regulations such as the aerospace industry there are specific requirements, which are evident throughout the entire value chain. One of the specific features is the longevity of applications - respectively of their components such as electronics and mechanics. Hendrik Thiel, HEITEC AG, international sales manager business unit electronics, tells us more
O
nce the choice of components is made, it is about being able to support these technologies in the long term due to the consequences that may follow from failures. For example, small changes in the system may have serious consequences and may result in comprehensive testing and requalification activities, which tie up resources and cost time and money. It can be very advantageous to keep the cost as low as possible by working with a reliable supplier who is able to guarantee the longevity and to share responsibility for necessary redesigns. Another significant criterion is the selection of the architecture. A commonly encountered bus system in military technology is the VMEbus (Versa Module Eurocard Bus), which is ideal for use in harsh environments due to its robustness and reliability. It resists shock, vibration and high/low ambient temperatures better than other computer technologies. Due to its asynchronous multi-master capability it offers an excellent and energy- efficient basis for I/O-intensive applications and for high data streams with time-critical data processing. Finally, its flexibility has to be mentioned; currently available VME systems support almost all processor architectures and interfaces on the market, which allows not only long-lasting security for operation and investment, partly for decades, but also offers modularity and expandability for use in various extensive and heterogeneous applications. It is these considerations which do facilitate standardisation over a long period. Frequently used criteria in military applications, such as large amounts of data, ease of implementation, redundancy, high precision and inspection depth, are not only high performance requirements for the electronics, but also for each part of the system, including the mechanics. Quality and reliability are a must, because the quality of the final result depends on each individual element and there may be high risks, even for human life. Classification according to EN/AS9100, for example, is important for use in military applications. Defects in material and production failures can result in economic disadvantages for the manufacturers. In regulatory applications, it is especially vital that evidence of tests can be provided in each design phase, proving that prototypes are absolutely error-free before they are approved for production and that the final products are constantly monitored.
The application
The test system AIDASS (Advanced Integrated Data Acquisition and Stimulation System) consists of a modular real-time system for the testing and integration of safety-critical products, like those used in the "flying systems" Airbus A320 to A350, Eurocopter, Eurofighter or unmanned flying objects. The system is used in very different sectors: in development, in maintenance and for training purposes. Typical application areas are the testing of software modules for aircraft equipment, virtual system integration for the testing of simulated environments - for instance, when it comes to imitate extreme situations which cannot be implemented in real. Further fields of application are SW/HW integration, e.g. testing of the software functionality, the integration of aircraft flight control systems or on-aircraft tests such as checking the avionics, sensors, hydraulics or landing gears. The system scalability, based on user requests, is an outstanding feature of AIDASS. It offers comprehensive application opportunities and software functionality and supports a wide range of hardware. AIDASS can not only generate, but also collect, edit, simulate and visualise data and provide offline analysis. The control and automation of tests are programmable and
enable the provision of complete test environments. AIDASS can always be easily adapted to existing user’s environments thanks to its programmable software interface and its tools for adaptation to existing software environments as well as its open HW interface for addressing the project- related hardware. The system can support each stage of a flying system, from the pre-design phase, integration, qualification and current operation up to necessary upgrades. On the hardware side, the system supports both, classic Windows architectures as well as PCI and VME-based real-time systems in different designs. Because it is not tied to any specific microprocessor technology, the VMEbus architecture is particularly suitable to easily adapt to any desired application size.
The housing and systems engineering When Airbus decided to switch from VME32 to VME64 systems to extend the connectivity options, HEITEC became a cooperation partner, since new VME system platforms had to be defined and new 3.3V power supplies had to be implemented. HEITEC presented the best offer for these adjustments, and was also convincing by its conservative conception of the longevity specifications. Since then, chassis, power supplies, fans and backplane are supplied with a so-called "Certificate of Conformance". In the second step Airbus equips the system platform with boards, firmware, software including multiple interfaces and the internally developed control application and also performs the final tests. Standard elements are used as far as possible. HEITEC’s choice of cabinets offer plenty of space for a variety of interfaces and modules for analog or discrete functionality, Ethernet, optical or GPS connectivity and multiple system and simulation CPUs. One VME slot is needed for the interconnection of the VME systems. The standard rack is ideal for simulation tests or for use in integration tests for air traffic control systems or avionics. A double bottom ensures adequate climate control, and, utilising the physical conditions, ventilation is directed from bottom to top. In addition an optional installation of air conditioning is also possible. The I/O connection is located on the back, while the complex wiring runs under the board to the back plane. The ventilation and power supply solution adapts to the particular circumstances, too. To ensure modularity, "plug and play" was a key issue and it was explicitly ensured that the cards are easily accessible at any time.
Conclusion In areas with strict certifications, such as the aeronautical industry, product lifecycles can last for several decades. Therefore, it must be guaranteed that applications can be supported in the long term. And often it’s not only the products and technologies that change, but sometimes it’s the overall conditions, regulations and standards, which require to modify not only the system itself but also add-on products and peripherals. Here, an external partner may be advantageous. The experience and knowledge of how a system can be designed effectively and how it can be assembled quickly and economically according to the idea of “Design for Manufacturability”, as well as including all further steps into the design, can be the key factors for serviceability and upgradeability.
http://www.heitec-electronic.com 8 CIE Aerospace/Military/Defence Supplement July/August 2016
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