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Discrete event simulation of hybrid systems
 SIAM Journal on Scientific Computing
, 2004
"... Abstract. This paper describes the quantization–based integration methods and extends their use to the simulation ofhybrid systems. Using the fact that these methods approximate ordinary differential equations (ODEs) and differential algebraic equations (DAEs) by discrete event systems, it is shown ..."
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Cited by 38 (13 self)
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Abstract. This paper describes the quantization–based integration methods and extends their use to the simulation ofhybrid systems. Using the fact that these methods approximate ordinary differential equations (ODEs) and differential algebraic equations (DAEs) by discrete event systems, it is shown how hybrid systems can be approximated by pure discrete event simulation models (within the DEVS formalism framework). In this way, the treatment and detection of events representing discontinuities –which constitute an important problem for classic ODE solvers – is notably simplified. It can be also seen that the main advantages ofquantization–based methods (error control, reduction ofcomputational costs, possibilities ofparallelization, sparsity exploitation, etc.) are still verified in the presence ofdiscontinuities. Finally, some examples which illustrate the use and the advantages ofthe methodology in hybrid systems are discussed.
Modelica  a language for physical system modeling, visualization and interaction
 In 1999 IEEE Symposium on ComputerAided Control System Design
, 1999
"... Modelica is an objectoriented language for modeling of large, complex and heterogeneous physical systems. It is suited for multidomain modeling, for example for modeling of mechatronics including cars, aircrafts and industrial robots which typically consist of mechanical, electrical and hydraulic ..."
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Cited by 27 (3 self)
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Modelica is an objectoriented language for modeling of large, complex and heterogeneous physical systems. It is suited for multidomain modeling, for example for modeling of mechatronics including cars, aircrafts and industrial robots which typically consist of mechanical, electrical and hydraulic subsystems as well as control systems. General equations are used for modeling of the physical phenomena. No particular variable needs to be solved for manually. A Modelica tool will have enough information to do that automatically. The language has been designed to allow tools to generate efficient code automatically. The modeling effort is thus reduced considerably since model components can be reused and tedious and errorprone manual manipulations are not needed. The principles of objectoriented modeling and the details of the Modelica language as well as several examples are presented. 1.
Modeling of Multibody Systems with the ObjectOriented Modeling Language Dymola
"... The objectoriented modeling language Dymola allows the physical modeling of large interconnected systems based on model components from different engineering domains. It generates symbolic code for different target simulators. In this paper, a Dymola class library for the efficient generation of t ..."
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Cited by 24 (7 self)
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The objectoriented modeling language Dymola allows the physical modeling of large interconnected systems based on model components from different engineering domains. It generates symbolic code for different target simulators. In this paper, a Dymola class library for the efficient generation of the equations of motion for multibody systems is presented. The library is based on an O(n) algorithm which is reformulated in an objectoriented way. This feature can also be interpreted as a bond graph oriented modeling of multibody systems. Furthermore a new algorithm for a certain class of variable structure multibody systems, such as systems with Coulomb friction, is presented, which allows the generation of efficient symbolic code.
Toward a Modeling Language Standard for Hybrid Dynamical Systems
 Proc. 32nd ieee Conference on Decision and Control
, 1993
"... 1 A rigorous means for modeling and evaluating hybrid systems is needed for the efficient and costeffective development of embedded realtime software for a wide variety of applications (weapons, manufacturing, intelligent vehicles, process control, . . . ). The development of a standard hybrid sys ..."
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Cited by 18 (6 self)
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1 A rigorous means for modeling and evaluating hybrid systems is needed for the efficient and costeffective development of embedded realtime software for a wide variety of applications (weapons, manufacturing, intelligent vehicles, process control, . . . ). The development of a standard hybrid systems modeling language (SHSML) and corresponding rigorous simulation environments represent important contributions to fulfilling this requirement. 1. Introduction A standard hybrid systems modeling language called SHSML is under development, to serve five purposes: ffl to define formally what is meant by the term "hybrid system", ffl to provide a modeling language that matches recent advances in mathematical formalisms for hybrid systems [1], and thus permits their rigorous evaluation, ffl to define an architectural description language for hybrid systems, in support of domainspecific / referencearchitecturebased approaches to hybrid systems development [2], ffl to provide the bas...
Modelica  The New ObjectOriented Modeling Language
 IN PROCEEDINGS OF THE 12TH EUROPEAN SIMULATION MULTICONFERENCE
, 1998
"... A standardized language for reuse and exchange of models is needed. An international design group has designed such a language called Modelica. Modelica is a modern language built on noncausal modeling with mathematical equations and objectoriented constructs to facilitate reuse of modeling knowle ..."
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Cited by 17 (0 self)
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A standardized language for reuse and exchange of models is needed. An international design group has designed such a language called Modelica. Modelica is a modern language built on noncausal modeling with mathematical equations and objectoriented constructs to facilitate reuse of modeling knowledge.
Structural Analysis utilizing MSS Sets with Application to a Paper Plant
, 2002
"... When designing modelbased faultdiagnosis systems, the use of consistency relations (also called e.g. parity relations)is a common choice. Different subsets are sensitive to different subsets of faults, and thereby isolation can be achieved. This paper presents an algorithm for finding a small set ..."
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Cited by 12 (5 self)
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When designing modelbased faultdiagnosis systems, the use of consistency relations (also called e.g. parity relations)is a common choice. Different subsets are sensitive to different subsets of faults, and thereby isolation can be achieved. This paper presents an algorithm for finding a small set of submodels that can be used to derive consistency relations with highest possible diagnosis capability. The algorithm handles differentialalgebraic models and is based on graph theoretical reasoning about the structure of the model. An important step, towards finding these submodels and therefore also towards finding consistency relations, is to find all minimal structurally singular (MSS) sets of equations. These sets characterize the fault diagnosability. The algorithm is applied to a large nonlinear industrial example, a part of a paper plant. In spite of the complexity of this process, a small set of consistency relations with high diagnosis capability is successfully derived.
Bond Graph Modeling Of Variable Structure Systems
 Proc. ICBGM'95 (Second International Conference on Bond Graph Modeling and Simulation), Las Vegas
, 1995
"... The problem of describing variable structure models in a compact, objectoriented fashion is revisited and analyzed from the perspective of bond graph modeling. Traditionally, bond graphs have always been used to describe continuous time physical processes with a fixed structure. Yet, this paper ..."
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Cited by 11 (1 self)
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The problem of describing variable structure models in a compact, objectoriented fashion is revisited and analyzed from the perspective of bond graph modeling. Traditionally, bond graphs have always been used to describe continuous time physical processes with a fixed structure. Yet, this paper shall demonstrate that bond graphs are equally suitable to describe variable structure models as fixed structure models. Moreover, a bond graph description of variable structure models can teach us a lot about the essential properties of variable structure models, properties that are not easily visible when other modeling approaches are taken. The paper discusses issues related to causality reassignment and conditional index changes as a consequence of switching in a physical system. Keywords: Bond graphs, variable structure system, computational causality, conditional index change, switching, objectoriented modeling, Dymola. INTRODUCTION When the causality strokes were added to the forme...
Quantization–Based Simulation of Differential Algebraic Equation Systems
 Simulation
"... This paper studies the use of first and second order Quantized State Systems methods (QSS and QSS2) in the simulation of Differential Algebraic Equation (DAE) systems. A general methodology to obtain the QSS and the QSS2 approximations of a generic DAE of index 1 is provided and their corresponding ..."
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Cited by 10 (5 self)
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This paper studies the use of first and second order Quantized State Systems methods (QSS and QSS2) in the simulation of Differential Algebraic Equation (DAE) systems. A general methodology to obtain the QSS and the QSS2 approximations of a generic DAE of index 1 is provided and their corresponding DEVS implementations are developed. Further, an alternative method is given based on the block–by–block translation from Block Diagrams containing algebraic loops into coupled DEVS representations of the corresponding QSS and QSS2 approximations. We show that the main advantages provided by the quantization–based methods in the simulation of Ordinary Differential Equations (ODE) –stability properties, reduction of computational costs, sparsity exploitation, etc. – are still verified in DAEs. These advantages are illustrated and discussed in the simulation of two examples which show the main features of the methodology. Keywords:
A Modeling Language for Hybrid Systems
 Proc. ieee/ifac Symposium on ComputerAided Control System Design
, 1994
"... 1 The general hybrid systems modeling language (HSML) described here will serve two purposes: to define formally what is meant by the term "hybrid system", and to provide the basis for languagebased "front ends" for hybrid system simulation environments. Features of HSML include: hierarchical, modu ..."
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Cited by 9 (6 self)
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1 The general hybrid systems modeling language (HSML) described here will serve two purposes: to define formally what is meant by the term "hybrid system", and to provide the basis for languagebased "front ends" for hybrid system simulation environments. Features of HSML include: hierarchical, modular construction of models; consistent yet distinctive definition of continuoustime, discretetime and logicbased components; prioritized scheduling of discretetime components; mechanisms for stateevent handling; approaches for dealing with vectorfield conflicts and changing order and structure; rigorous type and range checking; and a strict semantic basis that permits extensive checking and validation of the model. Keywords: Modeling languages; hybrid systems; dynamical systems; integration methods; discontinuity handling; modeling and simulation. 1 Introduction The language described below is being designed to support a broad definition of a hybrid system (within the context of intel...