Structure And Use Of A Library For Physical Systems Models

The availability of reusable and sharable models of physical systems will be a major advance in Computer Aided Engineering. Therefore, a generic framework for storing and retrieving public and private model data is needed. Our thesis is that such a framework must be based on a differentiation between three different levels of abstraction, which we define as engineering components, conceptual descriptions in terms of physical processes, and mathematical relations. Our approach is centered around the bond graph language, which provides the conceptual link between components and mathematical relations, a.o., in the field of mechatronics. When constructing a model, a system is decomposed down to an appropriate level of granularity. Each component is associated with one of a number of alternative conceptual descriptions (bond graphs), one of which is to be selected. Concepts (i.e. bond graph elements) in turn are further specified by selection from a number of alternative mathematical rela..

Exploring validity frames in practice

ABSTRACT: Model-Based Systems Engineering (MBSE) provides workflows, methods, techniques and tools for optimal simulation-based design and realization of complex Software-Intensive, Cyber-Physical Systems. One of the key benefits of this approach is that the behavior of the realized system can be reasoned about and predicted in-silico, before any prototype has been developed. Design models are increasingly used after the system has been realized as well. For example, a (design) digital twin can be used for runtime monitoring to detect and diagnose discrepancies between the simulated and realized system. Inconsistencies may arise, however, because models were used at design time that are not valid within the operating context of the realized system. It is often left to the domain expert to ensure that the models used are valid with respect to their realized counterpart. Due to system complexity and automated Design-Space Exploration (DSE), it is increasingly difficult for a human to reason about model validity. We propose validity frames as an explicit model of the contexts in which a model is a valid representation of a system to rule out invalid designs at design time. We explain the essential and conceptual, yet practical, structure of validity frames and a process for building them using an electrical resistor in the optimal design of a high-pass filter as a running example. We indicate how validity frames can be used in a DSE process, as well as for runtime monitoring

Control: A perspective

Feedback is an ancient idea, but feedback control is a young field. Nature long ago discovered feedback since it is essential for homeostasis and life. It was the key for harnessing power in the industrial revolution and is today found everywhere around us. Its development as a field involved contributions from engineers, mathematicians, economists and physicists. It is the first systems discipline; it represented a paradigm shift because it cut across the traditional engineering disciplines of aeronautical, chemical, civil, electrical and mechanical engineering, as well as economics and operations research. The scope of control makes it the quintessential multidisciplinary field. Its complex story of evolution is fascinating, and a perspective on its growth is presented in this paper. The interplay of industry, applications, technology, theory and research is discussed