Construction and analysis of causally dynamic hybrid bond graphs

Engineering systems are frequently abstracted to models with discontinuous behaviour (such as a switch or contact), and a hybrid model is one which contains continuous and discontinuous behaviours. Bond graphs are an established physical modelling method, but there are several methods for constructing switched or ‘hybrid’ bond graphs, developed for either qualitative ‘structural’ analysis or efficient numerical simulation of engineering systems. This article proposes a general hybrid bond graph suitable for both. The controlled junction is adopted as an intuitive way of modelling a discontinuity in the model structure. This element gives rise to ‘dynamic causality’ that is facilitated by a new bond graph notation. From this model, the junction structure and state equations are derived and compared to those obtained by existing methods. The proposed model includes all possible modes of operation and can be represented by a single set of equations. The controlled junctions manifest as Boolean variables in the matrices of coefficients. The method is more compact and intuitive than existing methods and dispenses with the need to derive various modes of operation from a given reference representation. Hence, a method has been developed, which can reach common usage and form a platform for further study

Modelling and analysis of traffic networks based on graph transformation

This is an electronic version of the paper presented at the Symposium on Formal Methods for Automation and Safety in Railway and Automotive Systems, FORMS/FORMATS 2004 , held in Braunschweig on 2004We present the formal definition of a domain specific visual language (Traffic) for the area of traffic networks. The syntax has been specified by means of meta-modelling. For the semantics, two approaches have been followed. In the first one, graph transformation is used to specify an operational semantics. In the second one we include timing information and a denotational semantics is defined in terms of Timed Transition Petri Nets (TTPN). The transformation from the Traffic formalism into TTPN was also defined by graph transformation. Both approaches have been used for the analysis of Traffic models. The ideas have been implemented in the AToM3 tool and are illustrated with examples.Juan de Lara’s work has been partially sponsored by a grant from the E.U. SEGRAVIS research network (HPRN-CT-2002-00) and the Spanish Ministry of Science and Technology (TIC2002-01948). Hans Vangheluwe gratefully acknowledges partial support for this work by a National Sciences and Engineering Research Council of Canada (NSERC) Individual Research Grant

The landscape of nonlinear structural dynamics: an introduction.

Nonlinear behaviour is ever-present in vibrations and other dynamical motions of engineering structures. Manifestations of nonlinearity include amplitude-dependent natural frequencies, buzz, squeak and rattle, self-excited oscillation and non-repeatability. This article primarily serves as an extended introduction to a theme issue in which such nonlinear phenomena are highlighted through diverse case studies. More ambitiously though, there is another goal. Both the engineering context and the mathematical techniques that can be used to identify, analyse, control or exploit these phenomena in practice are placed in the context of a mind-map, which has been created through expert elicitation. This map, which is available in software through the electronic supplementary material, attempts to provide a practitioner's guide to what hitherto might seem like a vast and complex research landscape.This project has arisen from a collaboration between the five UK universities and eight industrial collaborators on the EPSRC ‘Engineering Nonlinearity’ Programme Grant (EPSRC grant no. EP/K003836/1). T.B. is funded by an RAEng/EPSRC Research Fellowship.This is the final version of the article. It was first available from Royal Society Publishing via http://dx.doi.org/10.1098/rsta.2014.040

Meta-modelling hybrid formalisms

Proceedigns of 2004 IEEE International Symposium on Computer Aided Control Systems DesignPersonal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. S. Lacoste-Julien, H. Vangheluwe J. de Lara, and P. J. Mosterman, "Meta-modelling hybrid formalisms", 2004 IEEE International Symposium on Computer Aided Control Systems Design, Taipei, China, 2004, pp. 65-70This article demonstrates how meta-modelling can simplify the construction of domain-and formalism-specific modelling environments. Using AToM3 (a tool for multi-formalism and meta-modelling developed at McGill University), a model is constructed of a hybrid formalism, HS, that combines event scheduling constructs with ordinary differential equations. From this specification, an HS-specific visual modelling environment is synthesized. For the purpose of this demonstration, a simple hybrid model of a bouncing ball is modelled in this environment. It is envisioned that the future of modelling and simulation in general, and more specifically in hybrid dynamic systems design lies in domain-specific computer automated multi-paradigm modelling (CAMPaM) which combines multi-abstraction, multi-formalism, and meta-modelling. The small example presented in this article demonstrates the feasibility of this approac

Combined Global and Local Search for the Falsification of Hybrid Systems

In this paper we solve the problem of finding a trajectory that shows that a given hybrid dynamical system with deterministic evolution leaves a given set of states considered to be safe. The algorithm combines local with global search for achieving both efficiency and global convergence. In local search, it exploits derivatives for efficient computation. Unlike other methods for falsification of hybrid systems with deterministic evolution, we do not restrict our search to trajectories of a certain bounded length but search for error trajectories of arbitrary length

Abstracting modelling languages: A reutilization approach

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-31095-9_9Proceedings of 24th International Conference, CAiSE 2012, Gdansk, Poland, June 25-29, 2012Model-Driven Engineering automates the development of information systems. This approach is based on the use of Domain-Specific Modelling Languages (DSMLs) for the description of the relevant aspects of the systems to be built. The increasing complexity of the target systems has raised the need for abstraction techniques able to produce simpler versions of the models, but retaining certain properties of interest. However, developing such abstractions for each DSML from scratch is a time and resource consuming activity. Our solution to this situation is a number of techniques to build reusable abstractions that are defined once and can be reused over families of modelling languages sharing certain requirements. As a proof of concept, we present a catalogue of reusable abstractions, together with an implementation in the MetaDepth multi-level meta-modelling tool.Work funded by the Spanish Ministry of Economy and Competitivity (TIN2011-24139), and the R&D programme of Madrid Region (S2009/TIC-1650)