In the context of systems health management, simulations serve many uses. For one, the underlying physical models can be used by model-based health management tools to develop diagnostic and prognostic models. These simulations should incorporate both nominal and faulty behavior with the ability to inject various faults into the system. Such simulations can therefore be used for operator training, as well as for developing and prototyping health management algorithms.

CryoSim consists of a physics-based simulation model of a cryogenic fluid test bed, along with supporting code to provide control, presentation, and recording of the simulation output. A set of physics-based component libraries was developed for cryogenic fluid, pneumatics, and control systems. A system model was created using the component libraries and then combined with simulation framework code to provide operator, message bus, and data file interfaces. Each component model includes a set of user-selectable fault modes that modify the component’s behavior such that the effect of a given fault will propagate through the system model.

The user can independently select the fidelity of the cryogenic fluid and pneumatics subsystems within the model on a run-by-run basis. This allows the user to trade model fidelity for increased simulation speed, depending on the simulation objectives. CryoSim uses MATLAB/Simulink, Java, and Ice commercial or open-source software.

This work was done by John Barber and Kyle Johnston of Kennedy Space Center, and Matthew Daigle of Ames Research Center. KSC-13847

NASA Tech Briefs Magazine

This article first appeared in the February, 2015 issue of NASA Tech Briefs Magazine.

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