A Finite State Automata-Based Description of Device States for Function Modeling of Multi-State Technical Devices
Chowdhury, Ahmed Mohammed Sobhan
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Many modern and innovative design problems require multi-modal, reconfigurable solutions. Function modeling (FM) is a common tool used to explore solutions in early stages of mechanical engineering design. Currently, function structure representations do not abet the modeling of formally-defined reconfigurable function models as graph-based function models used in early-stage systems design usually represent only one operational mode of the system. Currently there is a need, but no rigorous formalism to model multiple possible modes in the model and logically predict the behavior of the system as it transitions between the modes. Additionally, function modeling representations will benefit from dynamically capturing the effects of state change of a flow property on the operating mode of the system. This thesis presents a formal representation (1) of operational modes and states of technical devices and systems based on automata theory for both discrete and continuous state transitions and a formal representation (2) to capture the duality of specific functions through four verbs that shift from one mode of operation to its logical and topological opposite, based on the existence of, or the value of a signal from, an input flow. It then presents formal definitions of three signal-processing verbs that actuate or regulate energy flows: Actuate_E, Regulate_E_Discrete, and Regulate_E_Continuous. Additionally, three conjugate verbs: CEnergize_M, CStore_E, CDistribute_M, CTypeChange_E are also presented alongside an approach to extend these functions to function features using the example of conjugate features: CHandover_E and CConvergize_EM in order to support physics-based reasoning on the interactions between flows. The graphical templates, definitions, and application of each verb in modeling is illustrated. Lastly, FSAs are integrated with an existing software for concept modeling and system-level models are used to illustrate the verbs’ modeling and reasoning ability, in terms of cause-and-effect propagation. Finally, the representation is shown to the demonstrate the ability to support reasoning on operating modes of systems, provide quantitative reasoning on the efficiency of those modes, and offer modeling efficacy to the designers.