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object-oriented modelling for spacecraft dynamics: Tools and applications

SIMULATION modelling PRACTICE AND THEORY 2010年第1期18卷 63-86页

作者： Pulecchi, T. Casella, F. Lovera, M. Politecn Milan Dipartimento Elettron & Informaz I-20133 Milan Italy

The development process for spacecraft control systems relies heavily on modelling and simulation tools for spacecraft dynamics. For this reason, there is an increasing need for adequate design tools in order to cope efficiently with tightening budgets for space missions. The paper discusses the main issues related to the modelling and simulation of satellite dynamics for control purposes, and then presents an object-oriented modelling framework, implemented as a Modelica library. The proposed approach allows a unified approach to a range of problems spanning from initial mission design and actuator sizing phases, down to detailed closed-loop simulation of the control system, including realistic models of sensors and actuators. It also promotes the reuse of modelling knowledge among similar missions, thus minimizing the design effort for any new project. The proposed framework and the Modelica library are demonstrated by several illustrative case studies. (C) 2009 Elsevier B.V. All rights reserved.

关键词： object-oriented modelling Spacecraft dynamics Orbital control Attitude control

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object-oriented modelling and simulation for the ALFRED dynamics

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PROGRESS IN NUCLEAR ENERGY 2014年 71卷 15-29页

作者： Ponciroli, Roberto Bigoni, Andrea Cammi, Antonio Lorenzi, Stefano Luzzi, Lelio Politecn Milan Dept Energy CeSNEF Enrico Fermi Ctr Nucl Studies I-20133 Milan Italy

In this paper, a control-oriented modelling and simulation tool for the study of the Advanced Lead-cooled Fast Reactor European Demonstrator (ALFRED) plant dynamics is presented. It has been developed in order to perform design-basis transient analyses aimed at providing essential feedbacks for the system design finalization. The simulator has been meant to be modular, open and efficient. In this perspective, an object-oriented modelling approach has been adopted, by employing the reliable, tested and well-documented Modelica language. Simulation of core behaviour is based on point kinetics for neutronics and one-dimensional heat transfer models for thermal-hydraulics, coherently with ALFRED specifications. An effort has been spent to model the bayonet-tube Steam Generator (SG) foreseen to be installed within the reactor vessel. The primary loop model has been built by connecting the above-mentioned components (taking into account suitable time delays) and by incorporating the cold pool, which has revealed to be fundamental for an accurate definition of the time constants characteristic of the system because of its large thermal inertia. The description of the overall plant has been finalized by connecting standard turbine, condenser and other components of the balance of plant. Afterwards, the reactor responses to three typical transient initiators have been simulated (i.e., reduction of feedwater mass flow rate, variation of the turbine admission valve coefficient and transient of overpower). Simulation outcomes confirm the strong coupling between core and SG, besides showing the characteristic time constants of the various component responses. Results of the present study constitute a starting point in the definition of plant control strategies, laying the basis for investigation and development of a model-based control-system design. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Lead Fast Reactor ALFRED (Advanced Lead-cooled Fast Reactor European Demonstrator) Dynamics object-oriented modelling Control-oriented modelling

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object-oriented modelling of material flow controls

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JOURNAL OF MATERIALS PROCESSING TECHNOLOGY 1998年第1-3期76卷 227-232页

作者： Wache, I Univ Rostock Inst Fabr Syst & Logist D-18119 Rostock Germany

For a number of years, software design has featured methods of software engineering. object-oriented modelling (OOM) is a new and very promising method for the professional production of software. This paper aims to contribute to the application of the OOM in planning and deals with the implementation of controls for flexible automated material flow systems. The method of application of the OOM to the design of automatic systems is systematically approached. The introduction provides an overview of the planning process and the history of modelling methods. This is followed by a demonstration of how OOM and its components, 'object-oriented analysis', 'design' and 'programming', can contribute to the handling of the complex demands of a flexible material flow system (I. Wache, Selbstorganisierende Materialflusssteuerung fur die flexible Fertigung, in: Tagungsband The International Workshop on Machine Dynamics and Production Automation, April 20-22, 1995 Szcecin, Poland, 18 S;H.-J. Warnecke, Revolution der Unternehmenskultur: Das Fraktale Unternehmen, Springer, Berlin, 1993, 282 S.) The example of a control for the flow of material in an automated pallet transportation system proves the feasibility of the methodology. The pallet transportation system is described in detail in I. Wache, Das Materialflusssystem 'Kugelpalette' fur die flexible Fertigung, in: Wissenschaftliche Zeitschrift des Instituts fur Fabriksysteme und Logistik, Universitat Rostock, Institut fur Fabriksysteme und Logistik, 1994, 11 S. (C) 1998 Elsevier Science S.A. All rights reserved.

关键词： object-oriented modelling controls material flow flexible automated system

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object-oriented modelling of virtual-labs for education in chemical process control

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COMPUTERS & CHEMICAL ENGINEERING 2008年第12期32卷 3176-3186页

作者： Martin-Villalba, Carla Urquia, Alfonso Dormido, Sebastian Univ Nacl Educ Distancia Dept Informat & Automat Madrid 28040 Spain

Easy Java Simulations (Ejs) and Sysquake are two software tools specifically intended for implementation of virtual-labs. They allow easy definition of the virtual-lab view (i.e., the model-to-user interface). However, the model definition capabilities and the numerical solvers provided by these tools are not the state-of-the-art. On the other hand, the use of the object-oriented modelling language Modelica reduces considerably the modelling effort and permits better reuse of the models. Modelica is supported by the state-of-the-art simulation environment Dymola. Nevertheless, Modelica does not provide the interactive capabilities required for virtual-lab implementation. The approach proposed in this manuscript is to combine the best features of each tool. Ejs and Sysquake capability for building interactive user-interfaces composed of graphical elements, whose properties are linked to the model variables. Modelica capability for physical modelling and Dymola capability for simulating DAE-hybrid models. This novel approach has been successfully applied to set up virtual-labs for control education. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Control education Virtual laboratory Interactive simulation Chemical process control object-oriented modelling Modelica

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object-oriented modelling and Control in Buildings 18

Object-Oriented Modelling and Control in Buildings

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Combined IMACS World Congress/modelling and Simulation Society-of-Australia-and-New-Zealand (MSSANZ)/18th Biennial Conference on modelling and Simulation

作者： Zupancic, B. Sodja, A. Univ Ljubljana Fac Elect Engn Lab Modelling Simulat & Control Ljubljana 61000 Slovenia

ISBN: (纸本)9780975840078

This paper deals with some of the important aspects of the harmonisation of thermal and radiation flows in buildings using an object-oriented multi-domain modelling approach. The traditional modelling approach is based on block-oriented schemes in which causal relations play an important role. However, this causality is artificially generated in order to fulfil the appropriate conditions for a simulation on conventional sequential computers. Fortunately, new concepts based on object-oriented approaches, use physically oriented connections and algebraic manipulations to enable the so-called acausal modelling. Here, all these basic concepts are described and the advantages of the new concepts in comparison with traditional approaches are briefly discussed. We have developed a mathematical model that gives the dependence of the external temperature, the solar radiation, the artificial heating and the roller-blind positioning on the internal room temperature. The approach was a combination of theoretical and experimental modelling. The heat dynamics is caused by the heat conduction, the convection and the solar radiation. In the latter case the transfer of the sun's rays through a glass window was studied, and in many cases simplifications were introduced. Some of the model's constants were determined experimentally, comparing the experimental and simulation results. However, only some basic equations are presented (one can find them in the appropriate references) as the emphasis here is on the object-oriented simulator paradigm. The simulator was originally developed in the Matlab-Simulink environment. However, the main drawback of such a conventional modelling approach soon became apparent - the simulator could only be used for the developed configuration. Almost every structural change demanded a new development from scratch. We were not able to establish a library of reusable sub-models for the walls, windows, etc. For this reason we decided to implement the model i

关键词： object-oriented modelling Simulation Acausal modelling Thermal flows Intelligent building

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Symbolic manipulation techniques for model simplification in object-oriented modelling of large scale continuous systems

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MATHEMATICS AND COMPUTERS IN SIMULATION 1998年第2期48卷 133-150页

作者： Carpanzano, E Maffezzoni, C Politecn Milan Dipartimento Elettron Informaz I-20133 Milan Italy

In the present work, techniques for the symbolic manipulation of general nonlinear differential algebraic equation (DAE) systems are presented, and used for model simplification purposes, to support efficient simulation of large scale continuous systems in an object-oriented modelling environment. The specific problems addressed are efficient elimination of trivial equations by means of substitution, system block lower triangular (BLT) partitioning, and tearing, i.e. hiding of algebraic variables. Moreover, the weakening heuristic criterion for decoupling of large systems, via dynamic approximation, is studied. All these techniques have been successfully implemented and tested in MOSES (modular object-oriented software environment for simulation), in order to define a complete model simplification process. The results achieved by applying the discussed algorithms and criteria on serial multibody systems are illustrated. A brief overview on further known symbolic manipulation techniques is also given, comparing them with the proposed ones, throughout the paper. (C) 1998 IMACS/Elsevier Science B.V.

关键词： object-oriented modelling nonlinear DAE systems symbolic manipulation algorithms model simplification multibody systems

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object-oriented modelling and simulation of a motorcycle

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MATHEMATICAL AND COMPUTER modelling OF DYNAMICAL SYSTEMS 2008年第2期14卷 79-100页

作者： Donida, F. Ferretti, G. Savaresi, M. Tanelli, M. Politecn Milan Dipartimento Elettron & Informaz I-20133 Milan Italy

The design of a control oriented motorcycle model for the simulation of two-wheeled vehicles is widely recognized to be a very challenging task, as a complete analytical model is not directly available, due to its complexity and its high sensitivity to parameters' variations. Accordingly, a reliable model should be based on multibody modelling tools endowed with automated symbolic manipulation capabilities. This paper presents a simulation model for the dynamic behaviour of a motorcycle based on the object-oriented modelling paradigm developed in Modelica, within the Dymola environment. Specifically, we illustrate the modular approach to motorcycle modelling and discuss the tire-road interaction model, which is the crucial part of the proposed model. The validity of the proposed simulation model is assessed on real data, measured on an instrumented test vehicle. Further, to perform the verification phase a virtual driver model has been implemented, which allows to track both a roll angle and a target speed profile during different maneuvers. In particular, the behaviour of the driver is modelled as an inverse pendulum, with a rotational degree of freedom along the forward axis. This allows accounting for the driver lean angle, which is necessary to fully capture the real driving behaviour and its effects on the overall vehicle dynamics.

关键词： motorcycle dynamics simulation physical modelling object-oriented modelling tire-road interaction verification by experiments

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Bond graphs and object-oriented modelling - a comparison

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART I-JOURNAL OF SYSTEMS AND CONTROL ENGINEERING 2002年第I1期216卷 21-33页

作者： Borutzky, W Bonn Rhein Sieg Univ Appl Sci D-53754 St Augustin Germany

Bond graph modelling was devised by Professor Paynter at the Massachusetts Institute of Technology in 1959 and subsequently developed into a methodology for modelling multidisciplinary systems at a time when nobody was speaking of object-oriented modelling. On the other hand, so-called object-oriented modelling has become increasingly popular during the last few years. By relating the characteristics of both approaches, it is shown that bond graph modelling, although much older, may be viewed as a special form of object-oriented modelling. For that purpose the new object-oriented modelling language Modelica is used as a working language which aims at supporting multiple formalisms. Although it turns out that bond graph models can be described rather easily, it is obvious that Modelica started from generalized networks and was not designed to support bond graphs. The description of bond graph models in Modelica is illustrated by means of a hydraulic drive. Since VHDL-AMS as an important language standardized and supported by IEEE has been extended to support also modelling of non-electrical systems, it is briefly investigated as to whether it can be used for description of bond graphs. It turns out that currently it does not seem to be suitable.

关键词： bond-graph-based physical systems modelling object-oriented modelling textual model description languages model exchange

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object-oriented modelling of Active Systems

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IFAC Proceedings Volumes 1994年第4期27卷 129-133页

作者： Kaj A. Jørgensen Ole Madsen Aalborg University Department of Production Fibigerstraede 16 DK-9220 Aalborg Denmark

Active systems, e.g. computer based systems for manufacturing control, require some mechanisms for synchronisation of its processes. This paper addresses the application of the object-oriented paradigm to key issues on modelling of active systems. The active components of such an object-oriented model are regarded as clients and servers which are interacting with each other concurrently. In order to prepare the components for such situations, a proposal for a simple description of the conditions for synchronisation mechanisms is presented. In line with object-orientation, the description is data-driven in contradiction to the traditional process-driven approaches. As a result, comprehensive development tools can be constructed in order to assist the designer in the modelling process and to generated the specific implementation. Furthermore, there are better opportunities for automatic control of queuing and scheduling as well as detection of deadlock problems.

关键词： object-oriented modelling active systems client-server architecture concurrent processes synchronisation mechanisms shared data mutual exclusion synchronisation conditions automatic scheduling deadlock detection reusability reliability extendibility

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object-oriented modelling of Power Plants: a Structured Approach

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IFAC Proceedings Volumes 2009年第9期42卷 249-254页

作者： Francesco Casella Politecnico di Milano Dipartimento di Elettronica e Informazione 20133 Milano ITALY

object-oriented modelling languages have become in recent years a very attractive choice for the control-oriented, dynamic modelling of power plants, due to their ease of development, flexibility, and reusability features. The paper describes a hierarchical modelling framework for thermal power plants, based on the Modelica language and on an existing library of elementary models, with particular emphasis on combined-cycle plants. The design criteria of the framework are discussed, and demonstrated by examples. The implications for the modelling of advanced power plants of the future, such as IGCC plants, integrated fuel-cell and combined cycle plants, and plants with CO 2 capture capabilities are finally discussed.

关键词： Power plant modelling object-oriented modelling computer-aided control system design

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