MBSE with CORE 100821

Static Representations, Dynamic Systems: The Problem

The systems that we develop are usually dynamic. The system specification should be dynamically consistent and executable at the system level. • Can it be achieved by confirming that the individual subsystems are executable? • No – modern control theory shows that having a set of individually executable subsystems does not result in an executable system • Can we use simulation of the design? • Yes – but common dynamic verification simulators are not exact representations of the system being specified • If not executable, what happens? • Achievement of dynamic consistency is left to integration and test teams, or • The system fails to meet dynamic needs

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How is it Classically Handled?

• Give the software and test/simulation team a copy of the preliminary system specification • They interpret it and build software and simulators • If the delivered software and simulator results seem reasonable, it is accepted • Question: Does the simulator team ever return a simulator that does not run? (answer: not in our experience) • Developers “debug” the simulation until it runs and gives reasonable answers • Debugging simulator code often modifies the system concept by accident • Results?

• We dynamically verified a system that is different than specified • Integration and test team must finish the systems engineering

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MBSE with CORE