Common Functionality Across Engineering Domains Through Transfer Functions and Bond Graphs

Functional Modeling allows a direct, and sometimes abstract, method for depicting a product. Through this method, product architecture, concept generation and physical modeling can be used to obtain repeatable and more meaningful results. The Functional Basis approach of engineering design, as taught to engineering design students, provides the vocabulary to produce a uniform approach to function structures with functions (verbs) and flows (nouns). This paper suggests that the flows, particularly the “signal” flows, can be correlated to additional domains domain through transfer functions common in controls engineering. Controls engineering employs transfer functions to mathematically represent the physical or digital functions of a system or product using block diagrams to show the individual steps. The research herein suggests the correlations between the mathematical representations of transfer functions and the functional basis of engineering design through the actions performed upon “signal” flows. Specifically, the methodologies employed by controls engineering can relate to engineering design by 1) Schematic similarities, 2) Quantifiable performance metric inputs/outputs, 3) Mathematical representations of the flows, and 4) isomorphic matching of the schematics. Controls systems use block diagrams to represent the sequential steps of the system, These block diagrams parallel the functions structures of engineering design. Performance metrics between the two domains can be complimentary when decomposed down to non-dimensional engineering units. Mathematical Functions of the actions in a controls systems can resemble the functional basis functions through the use if bond graphs by identifying characteristic behavior of the functions on the flows. Isomorphic matching using the schematic diagrams can be used to find analogies based upon similar functionality and target performance metrics. When these four similarities are performed, parallels between the engineering domain and the controls engineering can be establish. Examples of cross-domain matching via transfer functions and controls systems are provided as contextualization for the concepts proposed. Pathways forward for this preliminary research are additionally suggested.