As an architectural model, behavioral specifications are not part of the core AADL semantics, but are spread across the core and multiple non-overlapping AADL annexes, including the Error Modeling Annex (EMV2) and the Behavior Annex (BA). One such analysis gap is in behavioral modeling and specification, which has proven challenging using AADL. This methodology has been useful at detecting errors including system scheduling, real-time performance, and safety at design time and is now being evaluated and matured for Army Aviation and potentially for Future Vertical Lift (FVL) for the results it can produce in cost efficiencies and safer, more secure cyber physical systems.ĭespite these successes, virtual integration is still a developing technique, with significant gaps in analysis capabilities. These subcomponent models can then be virtually integrated into a common architectural model for formal analysis. In ACVIP, hardware and software components are specified as AADL models with semantics that include interfaces, connections, and real-time performance details. The Architecture-Centric Virtual Integration Process (ACVIP) using the Architecture Analysis and Design Language (AADL) provides a model based system engineering methodology to detect errors early in the development process and reduce the costs associated with late stage rework. Because of the difficulty detecting behavioral error, hidden in the specification, these errors are only detected at integration time, contributing significantly to cost overruns. Specifications often contain subtle errors and unstated assumptions regarding the overall behavior, error handling, and interaction of subcomponents that are challenging to detect because of the multiple formalisms used to express behavior. These specifications use multiple formalisms, such as state machines, first order logic, and fault propagations to express multiple views of behavior. ![]() To address these issues, software component developers use high level functional requirements and design specifications to guide their work. These standards provide a framework for common operating environment for software components and define the channels of interaction, but do not currently address the behavior of these components. To a large degree the software based standards and frameworks like FACE and JCA encourage reuse and portability across systems to reduce cost however, with the reuse of the software across various systems the resulting component interactions and behavior must be known and analyzed else failures that have been seen in complex safety critical systems may result (e.g., THERAC-25, Ariane 5 rocket, Mars Polar Lander failure, V-22 Osprey ). In avionics systems, this modular approach is being enhanced by open architectures and standards such as Joint Communications Architecture (JCA), Open Mission Systems (OMS), Hardware Open System Technologies (HOST), Vehicular Integration for C4ISR/EW Interoperability (VICTORY), and Future Airborne Capabilities Environment (FACE). Due to their complexity, these systems are required to be modular, with different subcomponents developed by teams or subcontractors working largely with minimal interaction. ![]() ![]() The development of these systems must support nominal interaction behavior and be resilient to errors with the ability to safely switch to fault tolerant recovery modes. ![]() Aviation systems, in particular, demonstrate significant complexity given complex patterns of real-time interaction between mission system software components interacting across complex hardware architectures with safety and cybersecurity critical operation. OBJECTIVE: Develop unified behavior formalisms and tools for virtual integration of architectural models and tools from segmented behavior specifications of embedded computing systems using multiple formalisms.ĭESCRIPTION: Cost overruns are a persistent problem with complex cyber-physical systems such as modern aircraft, automobiles, and medical devices.
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