Open systems avionics network to replace MIL-STD-1553

This paper is a proposal for a future method of avionics data communication. The need for this proposal results from the shortcomings in the current avionics architecture, video distribution network, and in the MIL-STD-1553 data communication system. The separately wired video and data communication systems can be combined to save weight, which is especially critical for rotorcraft. Aircraft, once fielded, have limited capacity for modification and improvement due to fixed computer throughput and processing performance, network bandwidth, and space available in the avionics equipment bays. The changes proposed by this paper are to be made in conjunction with the replacement of the redundant computer boxes with open system avionics functions on industry standard circuit cards. This open architecture approach was developed over the last ten years and is now being implemented in many aircraft applications including the F-22 and the RAH-66 programs. The V-22 rotorcraft, which although just entering production, is being modified for joint service customers where modern computer performance and expanded data network bandwidth is needed. The changes of this proposal will fill this need, reduce the weight of upcoming production models, and provide growth or spare capability so that additional video and data components can be added with minimal effect on existing components. This paper examines the current V-22 avionics video and data communication hardware and wiring and propose a new implementation of open system architecture standards with integrated digital video and data communication based on ANSI standard copper fibre channel     

COTS based open systems for military avionics

The DoD has many acquisition programs that are aggressively implementing open architecture principles in new avionics systems. Since “open” is an unclear attribute, projects eventually give in to a point solution that has no flexibility to cost effectively keep up with rapid changes in technology. The Open Systems Development Initiative (OSDI) project utilized COTS products to study the feasibility of building an open system that has plug-and-play capabilities. Lessons learned from the AV-8B Open Systems Core Avionics Requirements (OSCAR) and the F/A-18 Advanced Mission Computers and Displays (AMC&D) programs clearly indicated that understanding the underlying interfaces is crucial to keeping the system as open as possible to take advantage of the rapid changes in technology. A matrix of Key Open Standard Interfaces (KOSI), called the KOSI matrix, was developed and an applicable standard was identified for each interface. A list of non-conforming interfaces was also identified and the use of extensions or wrappers was investigated in an attempt to comply with standards. Standardization, rather than optimization of such interfaces, was considered more beneficial. It became evident that, with the exception of ruggedization, there is no difference in the use of COTS products for either commercial or military systems. Performing a KOSI analysis helped identify the key interfaces and standards, thus enabling the OSDI system to be scalable, portable and interoperable. A good KOSI matrix provides a vehicle for clear communication and helps systems integration and technology insertion to be less painful than what it is today. It helps reduce time-to-market and provides guidance to systems engineers and vendors to keep the system open     

Design for testability for future digital avionics systems

The authors describe an integrated testing approach called the Maintenance and Diagnostic System (MADS), which was developed for digital avionics systems using VHSIC and semicustom devices. Mission/operational requirements dictate high availability with capability to detect 98% of all faults and isolate 90% of these faults to a line replacement module (LRM) or 95% of the faults to two LRMs. MADS achieves these goals by defining a module maintenance node (MMN) chip set for each LRM in the system and the design for testability concepts for hardware. The MMN aids parallel, high-speed testing of LRMs, isolating the fault(s) to a module/chip level while incurring less than 10% overhead. It uses the concepts of scan set design, pseudorandom test vector generation, output response compression, and separate scan set loops to test the SSI-MSI logic on the LRM. It also stores interim test results and run-time fault information to isolate the hard-to-reproduce failures and performs verification of interchip and intermodule wiring     

Using LabVIEW to provide rapid prototyping environment for theteaching of avionics systems

This paper describes a simulation environment which has been used to teach the fundamental principles of Avionics Systems to students of Systems Engineering at Loughborough University of Technology. A versatile model of a Radar System is detailed as an example and its attributes from a teaching perspective are highlighted. The generic nature of the environment is also described, as is its position within the systems life cycle     

Open systems architecture solutions for military avionics testing

Raytheon makes extensive use of open systems architecture methods in developing special test equipment (STE) for testing military avionics equipment. Such use has resulted in significant cost and schedule savings in the development of production test equipment for radar and infrared systems. With open systems architectures, a test system can be assembled using COTS products. This brings economies of scale to test equipment, which is normally built in very low quantities. Therefore, the potential cost savings due to COTS usage is proportionately greater in STE than in the higher volume avionics systems that are tested. A second major benefit of using COTS products is that test system development schedule cycle time is greatly reduced. This paper describes the application of Open Systems Architectures (OSA) to avionics testing. The following major architectures are surveyed: VME bus, VXI bus, IEEE GPIB, IEEE 1149.1 JTAG test bus, 1553 Military Bus, Fibre Channel, and COTS Test Applications Software. We describe how the benefits of OSA have been extended at Raytheon into achieving vertical test commonalities. The flexibility of OSA can be exploited to provide an overall optimum test solution, taking all levels of test into account. For example, test systems can be tailored with COTS products to provide integrated methods for avionics tests at the module, unit, and system levels. Test systems can be configured to maximize the reuse of COTS hardware over all test levels. Test software can also be programmed to optimize such reuse over levels of test. Additional test verticality synergies derived from such OSA usage are described, including: test false alarm avoidance; test cones of tolerance optimization; and efficient test of field returns     

Hardware reconfiguration algorithm in multiprocessor systems of integrated modular avionics

Reconfiguration of multiprocessor systems makes it possible to improve their failure-resistance that is especially important for the integrated modular avionics systems. The algorithm considered in this paper allows minimizing the reservation and providing the better safety level and more effective flight completion or even its further execution in the case of failures of airborne equipment.     

Integrating VISA, IVI and ATEasy to migrate legacy test systems

New software technologies, such as VISA and IVI, continue to bring the industry toward greater standardization. The benefit to the integrator is reduced costs through reuse of the same hardware and software. The benefit to the customer end-user is lower costs by reducing modification and support through the life-cycle to the test station. However, while we position ourselves for the future with PXI and these software technologies, we must still provide support for VXI, GPIB, and instrument drivers that use current software technologies. Using a number of additional tools such as National Instrument's Measurement and Automation Explorer and Geotest's ATEasy, we can have the power of these tools today while waiting for wider acceptance and support of the newer VISA and IVI technologies. We are just now seeing the development of IVI drivers and the ink is still wet on the VISA specification for PXI. ATEasy provided the structure necessary to use these technologies with the current technology. This paper explores the process of implementing and integrating the system driver and instrument drivers for a PXI-based test station for the TOW2 optical sight sensor.     

Hybrid partition-and network-level scheduling design for distributed integrated modular avionics systems

Distributed Integrated Modular Avionics(DIMA) develops from Integrated Modular Avionics(IMA) and realizes distributed integration of multiple sub-function areas. Timetriggered network provides effective support for time synchronization and information coordination in DIMA systems. However, inconsistency between processing resources and communication network destroys the time determinism benefiting from partitions and time-triggered mechanism.To ensure such time determinism and achieve guaranteed real-time performance, system design should collectively provide a global communication scheme for messages in network domain and a corresponding execution scheme for partitions in processing domain. This paper firstly establishes a general DIMA model which coordinates partitioned processing and time-triggered communication, and then proposes a hybrid scheduling algorithm using Mixed Integer Programming to produce feasible system schemes. Furthermore, incrementally integrating new functions causes upgrades or reconfigurations of DIMA systems and will generate integration cost. To control such cost, this paper further develops an optimization algorithm based on Maximum Satisfiability Problem and guarantees that the scheduling design for upgraded DIMA systems inherit their original schemes as much as possible. Finally, two typical cases, including a simple fully connected DIMA system case and an industrial DIMA system case, are constructed to illustrate our DIMA model and validate the effectiveness of our hybrid scheduling algorithms.     

High-performance front-end converter for avionics applications [aircraft power systems]

The distributed power systems of future commercial aircraft will adopt variable frequency generation (360 to 800 Hz). Front-end converters in the system will be required to have a high efficiency and a low total harmonic distortion (THD) of the input current. This paper explains the design of a zero-voltage-switching (ZVS) active-clamped isolated low-harmonic SEPIC rectifier for such applications. Utilization of the transformer leakage inductance for ZVS and a single-layer transformer design contribute to a high efficiency. An accurate averaged switch model has been developed, which shows that the control-to-input-current transfer function of this converter does not exhibit resonances observed in the conventional SEPIC. As a result, for closed-loop operation using average current control, damping of the coupling capacitor is not required. Operating at a switching frequency of 200 kHz, an experimental 100 W, 28 V output rectifier achieves a THD of 3-4% and efficiency exceeding 90% over the entire line frequency range.     

An environment for the integration and test of the Space Stationdistributed avionics systems

An approach is described to supplying an environment for the integration and test of the Space Station distributed avionics systems. Background is included on the development of this concept including the lessons learned from Space Shuttle experience. The environment's relationship to the process flow of the Space-Station verification, from systems development to on-orbit verification, is presented. The uses of the environment's hardware implementation, called Data Management System (DMS) kits, are covered. It is explained how these DMS kits provide a development version of the Space-Station operational environment and how this environment allows system developers to verify their systems performance, fault detection, and recovery capability. Conclusions on how the use of the DMS kits, in support of this concept, will ensure adequate on-orbit test capability are included     

Sustainment of legacy automatic test systems: lessons learned on TPS transportability

Sustainment of legacy automatic test systems (ATS) saves cost through the re-use of software and hardware. The ATS consists of the automatic test equipment (ATE), the test program sets (TPSs), and associated software. The associated software includes the architecture the TPSs run on, known as the control software or test station test executive. In some cases, to sustain the legacy ATS, it is more practical to develop a replacement ATE with the latest instrumentation, often in the form of commercial off-the-shelf (COTS) hardware and software. The existing TPSs, including their hardware and test programs, then need to be transported, or translated, to the new test station. In order to understand how to sustain a legacy ATS by translating TPSs, one must realize the full architecture of the legacy ATS to be replaced. It must be understood that TPS transportability does not only include translating the original TPS from an existing language (such as ATLAS) to a new language (such as "C") to run on a new test station, but includes transporting the run-time environment created by the legacy ATS. This paper examines the similarities and differences of legacy ATE and modern COTS ATE architectures, how the ATS testing philosophy impacts the ease of TPS transportability from legacy ATE to modern-day platforms, and what SEI has done to address the issues that arise out of TPS transportability.     

The Flight 2000 avionics suite: paving the way to free flight

The FAA's Flight 2000 project is an innovative initiative to implement and validate selected operational improvements leading to Free Flight. It integrates new avionics, new ground systems, new procedures, avionics certification, and operational approval. Approximately 2000 aircraft operating in Alaska, Hawaii, and Oceanic airspace will be equipped with new capabilities enabling benefits such as improved situational awareness, increased flexibility, and efficiency gains. By developing and fielding these operational improvements, the actual benefits of new procedures and capabilities will be validated and risks associated with national implementation will be reduced     

Improving the productivity of complex electronic systems design byutilizing applied design methodologies

The design process of complex electronic systems consists of four traditional main stages, which are system design, electronic design, mechanical design, and design for manufacturing. Even today when many integrated computer aided design environments are in use for electronic systems design, we still seem to accept that the design process really has to follow this path of four individual design stages. It is common that we are dealing with data transfer problems between different types of CAE-applications. However, there is a possibility to avoid the disadvantages due to integration problems between the design stages if we decide to develop the design methodology itself instead of developing those independent software applications. One effective way to improve the productivity of complex electronic systems design is to tune the so-called systematic design approach by adding special aspects of electronic systems design into the questionnaires used for collecting the requirement lists for further mechanical design and DFM. Another important tool is the carefully made manufacturability analysis. The deep interaction of mechanical and electronic design, extended by manufacturability analysis can also lead to innovative solutions as presented previously by the author. In the article entitled “Manufacturability Analysis-A Useful Subset of Systems Engineering” we were able to show that the number of iteration cycles during the different design and manufacturing stages could be reduced by 50% compared to the conventional design methodology. In this paper, we illustrate additional tools to continue this promising development work     

Correspondence [Errata to "Military digital avionics fiber-optic network design for maintainability and supportability", Sep 06]

Readers provide commentary about previous articles from the IEEE Aerospace and Electronic Systems Magazine.     

Real-time parameter identification applied to flight simulation

In-flight simulations are normally accomplished using model-following control laws which depend on accurate knowledge of the stability derivatives of the host aircraft. Degraded simulation results if the stability derivatives deviate considerably from their presumed values. Gain scheduling is often used to compensate for plant parameter variations, but this form of open-loop compensation usually requires extensive flight testing for proper fine tuning. An adaptive, fast-sampling control law to compensate for changing aircraft parameters is described. The step-response matrix required for implementation is identified recursively using a technique which does not need special test signals, and which automatically discounts old data depending on the input excitation detected. Tracking fidelity is maintained despite parameter changes which occur abruptly or slowly, and actuator position and rate limiting are discussed. The performance of the resulting system is excellent and demonstrates the relative advantages of adaptive controllers for in-flight simulation     

A robust exponential mixture detector applied to radar

Exponential mixture probability density functions (pdfs) are shown to be useful models of radar sea clutter. The variability of certain parameters leads to estimation error and degradation in the performance of detection algorithms derived from this model. Robust implementations are introduced by assuming that parameters are known within certain intervals and selecting values to prevent an excessive number of false alarms. An empirical study demonstrates an average 6-9 dB gain in comparison with a constant false-alarm rate (CFAR) processor