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SOFTWARE DEVELOPMENT AND AVIONICS SYSTEM INTEGRATION TECHNOLOGY

Modern (and even more so advanced) airborne computer systems (ACS) are basically complex engineering systems comprising a fairly large number of stand-alone airborne digital computers or computer modules differing in architecture, composition and component interaction, as well as a large volume of complex airborne software. ACS development is basically a time-consuming and labor- and capital-intensive process. In this context the cost and feasibility of proposed technical solutions become critical development factors. To meet the tight schedule and budget constraints ACS developers should use state-of-the-art information technologies. These technologies assure high design flexibility, while minimizing the cost of architecture options analysis and the introduction of necessary changes, and allow keeping within specified cost limits while providing the high quality of development. In this context modern airborne software design and development technologies are of key importance. These technologies should provide an aircraft efficiency throughout its service life. It means that a special attention should be given to open system architecture that allows efficient system upgrade and replacement of obsolete software components with the new ones.

An open architecture concept allows the use of general principles of software development based on a limited set of common modules and standard interfaces, which can be expanded if necessary. Common module approach, supported by modular software and assembling programming principles, along with the possibility of commercial module use at early stages allow to reduce dramatically ACS development time and cost.

By way of example let us consider the issues of computer process management for airborne weapon delivery missions.

Within the framework of an airborne digital control system with the use of sufficiently powerful airborne digital computers (ADC) the following missions were accomplished:

  • Airborne weapon delivery based on both missile launch envelope and weapon ballistic parameters;

  • Aircraft control signal generation for precision weapon delivery;

  • Calculation of airborne weapon launch envelope;

  • Aircraft control management during airborne weapon delivery;

  • Aiming data generation in the process of manual, director and automatic aircraft control during airborne weapon delivery;

  • Relevant data generation and display to aircrew during ground target attack to avoid weapon fragment dispersion zone;

  • Launch of unguided airborne weapons against mobile and stationary surface targets during level flight, dive and climb attack;

  • Single-shot and serial bombing;

  • Navigation bombing;

  • Airborne weapon ballistic characteristics entry in accordance with the Inter-service resolution on the introduction of a standardized air-delivered munitions coding system for entry into aiming systems of 1987;

  • Use of airborne rockets against mobile and stationary surface targets;

  • Use of internal gun against surface targets.

For weapon delivery missions a common software development pattern was accepted. In combat missions a common scheduler provides successive execution of software modules, comprising the core of specific task set. Core programs are basically different for various airborne weapon types. After the execution of main weapon delivery calculation modules (core) the common scheduler runs the standardized programs, providing the calculation of aircraft control parameters and fragment dispersion zone avoidance. In the process of aircraft aiming and guidance the software generates and displays the relevant information. The module of fragment dispersion zone warning generates signals warning about possible aircraft entry into a fragment dispersion zone depending on chosen weapon type and aircraft trajectory parameters.

At FGUP GosNIIAS modern airborne software development is carried out in compliance with GOST R 51904-2002 Embedded systems software. Requirements for content and execution of documents (Russian DO-178B analogue), that indicates specific features of modern requirements for life cycle processes of high quality real-time embedded system software as applied to aerospace and transport systems. This standard focuses on software quality and functional safety assurance.

The first step involves system concept definition, in this case avionics system core. At this stage the simulation environment is generated, which comprises an aircraft, its information systems and external environment models, etc.

The second step involves software implementation, i.e. coding and testing. For this purpose programming and software debugging system is created that includes programmer workstations and a target ADC, connected into a local area network.

In the third stage a hardware-in-the-loop system is used, allowing onboard equipment integration including flight test maintenance.

Programming and software debugging system is designed for software and accompanying documentation development, verification, maintenance, protection, and archiving.

During airborne software development software life cycle processes are maintained and interrelated with software and a system as a whole verification process in line with GOST R 51904 requirements. Verification is a process of testing if current development state achieved in the current stage meets this stage requirements. Software verification process includes module testing in development environment, integration testing in development environment and in ADC, qualification software testing in ADC, review and analysis of various level requirements, a source code and integration process output.

This airborne software development technology allows to reduce dramatically development time and maintenance costs and to improve significantly software quality and reliability.

 


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