EOOLT 2007 – Proceedings of the 1st International Workshop on Equation-Based Object-Oriented Languages and Tools

Computer aided modeling and simulation of complex systems, using components from multiple application domains, such as electrical, mechanical, hydraulic, control, etc., have in recent years witness0065d a significant growth of interest. In the last decade, novel equation-based object-oriented (EOO) modeling languages, (e.g. Mode- lica, gPROMS, and VHDL-AMS) based on acausal modeling using equations have appeared. Using such languages, it has become possible to model complex systems covering multiple application domains at a high level of abstraction through reusable model components. The interest in EOO languages and tools is rapidly growing in the industry because of their increasing importance in modeling, simulation, and specification of complex systems. There exist several different EOO language communities today that grew out of different application areas (multi-body system dynamics, electronic circuit simula- tion, chemical process engineering). The members of these disparate communities rarely talk to each other in spite of the similarities of their modeling and simulation needs. The EOOLT workshop series aims at bringing these different communities together to discuss their common needs and goals as well as the algorithms and tools that best support them. Despite the short deadlines and the fact that this is a new not very established workshop series, there was a good response to the call-for-papers. Thirteen papers and one presentation were accepted to the workshop program. All papers were subject to reviews by the program committee, and are present in these electronic proceedings. The workshop program started with a welcome and introduction to the area of equa- tion-based object-oriented languages, followed by paper presentations and discussion sessions after presentations of each set of related papers. On behalf of the program committee, the Program Chairmen would like to thank all those who submitted papers to EOOLT'2007. Special thanks go to David Broman who created the web page and helped with organization of the workshop. Many thanks to the program committee for reviewing the papers. EOOLT'2007 was hosted by the Technical University of Berlin, in conjunction with the ECOOP'2007 conference

Interfacing Functional Mock-Up Units in Modelica

Different simulation tools often have their own definition of how a model is represented. This causes complications when modeling in one tool and trying to simulate in another, or if one wants to verify simulation results in another tool. This thesis focuses on a way of interfacing the Functional Mock-up Interface (FMI) into Modelica models. Modelica is an open standard modeling language for modeling physicals model, such as electrical circuits, drive trains etc. The Functional Mock-up Interface is an interface which provides tool independent C-functions for execution of models. In this thesis we make use of the FMI specification and Modelica's external function interface to generate a complete Modelica model. The results shows that the implementation works quite well, but with some decrease of performance

A Stand–Alone Quantized State System Solver for Continuous System Simulation

This article introduces a stand-alone implementation of the quantized state system (QSS) integration methods for continuous and hybrid system simulation. QSS methods replace the time discretization of classic numerical integration by the quantization of the state variables. These algorithms lead to discrete event approximations of the original continuous systems and show some advantages over classic numerical integration schemes. For simplicity, most implementations of QSS methods were confined to discrete event simulation engines. The problem is that they were not fully efficient, as they wasted much of the computational load in the discrete event simulation mechanism. The stand-alone QSS solver presented here overcomes this problem, improving in more than one order of magnitude the computation times of the previous discrete event implementations. Besides describing the solver structure and functionality, the article analyzes four different models and compares the performance of the new solver with that of the discrete event implementation, and with that of different classic solvers.Fil: Kofman, Ernesto Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y Sistemas; ArgentinaFil: Fernandez, Joaquin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y Sistemas; Argentin

Mallinnus- ja Simulointikäytännöt Ohjausjärjestelmien Ohjelmistokehityksessä

Software development represents a significant portion of the total work effort in control system development, which is why improving the efficiency of the software development process is important. Modeling and simulation tools can be used for design and verification of parts of the control system. Model-based design is a development methodology, that presents models as a central concept in the development process. This thesis explores the opportunities model-based design presents for improving the efficiency of the control system development process. Specifically, the possibility of using automatic production code generation to generate program code representations of design models is of interest. This thesis presents a selection of the tools available for model-based design and explores their capabilities through a design example. The tools presented are Simulink and OpenModelica. The benefits and challenges of model-based design are discussed with regards to the software development process. Tools and methods for achieving the benefits and addressing the challenges are explored. Analysis of the tools concluded that Simulink is suitable for model-based design and enables automatic program code generation. OpenModelica was used for basic modeling and simulation work, but the development environment was not mature enough for production use and the tool lacked production code generation capabilities. Methods for supporting the use of modeling practices in control system development were presesented. A draft of a modeling guidelines collection was created and a template for the hierarchical structure of Simulink models was specified. Methods for implementing traceability and documenting models are also presented. Lastly, the reliability and performance of the Simulink code generator was addressed. Based on existing research, it could be deduced that the code generator was reliable and predictable. In terms of performance, the program code generated by the code generator was found to be comparable to code written by a programmer

Systems engineering languages for modeling and analyzing supervisory control structures in cyber-physical systems

In today’s world, a new generation of high-tech cyber-physical systems are becoming an integral part of our societies and their impact is only going to increase within the next years. Because of their importance, the companies that develop these systems use proper systems engineering modeling tools to help with the design and development of these types of systems and to accelerate the whole development process. In this thesis, 4 very popular modeling tools/languages are being tested and evaluated in terms of their capabilities for model-based systems engineering. These tools are Simulink&Stateflow from MATLAB, Modelica, MechatronicUML and SysML. In order to do that, a proper introduction of the systems engineering process is presented to set the criteria in which the different tools/lan- guages will be evaluated. To support the evaluation process, a case study is presented with the CIF3 language that will be attempted with all the other languages/tools. Each modeling lan- guage/tool has been evaluated individually at first and then together with the others in the end. In addition to the first evaluation, a proper basic introduction of all the modeling concepts that each tool uses for modeling cyber-physical systems is provided and the building of the case study as well. After that, in the second evaluation, the languages are extensively compared against each other in terms of all the criteria set previously to see exactly the scope of capabilities that each tools has. As a result from the two evaluations, a definitive review for each language/tool is presented addressing their overall scope of capabilities, main strong features, main uses, possible ways of improving and future development.Outgoin

Reliability modelling of PEM fuel cells with hybrid Petri nets

In this paper, a novel model for dynamic reliability analysis of a PEM fuel cell system is developed using Modelica language in order to account for multi-state dynamics and aging. The modelling approach constitutes the combination of physical and stochastic sub-models with shared variables. The physical model consist of deterministic calculations of the system state described by variables such as temperature, pressure, mass flow rates and voltage output. Additionally, estimated component degradation rates are also taken into account. The non-deterministic model, on the other hand, is implemented with stochastic Petri nets which represent different events that can occur at random times during fuel cell lifetime. A case study of effects of a cooling system on fuel cell performance was investigated. Monte Carlo simulations of the process resulted in a distribution of system parameters, thus providing an estimate of best and worst scenarios of a fuel cell lifetime

Languages and Tools for Optimization of Large-Scale Systems

Modeling and simulation are established techniques for solving design problems in a wide range of engineering disciplines today. Dedicated computer languages, such as Modelica, and efficient software tools are available. In this thesis, an extension of Modelica, Optimica, targeted at dynamic optimization of Modelica models is proposed. In order to demonstrate the Optimica extension, supporting software has been developed. This includes a modularly extensible Modelica compiler, the JModelica compiler, and an extension that supports also Optimica. A Modelica library for paper machine dryer section modeling, DryLib, has been developed. The classes in the library enable structured and hierarchical modeling of dryer sections at the application user level, while offering extensibility for the expert user. Based on DryLib, a parameter optimization problem, a model reduction problem, and an optimization-based control problem have been formulated and solved. A start-up optimization problem for a plate reactor has been formulated in Optimica, and solved by means of the Optimica compiler. In addition, the robustness properties of the start-up trajectories have been evaluated by means of Monte-Carlo simulation. In many control systems, it is necessary to consider interaction with a user. In this thesis, a manual control scheme for an unstable inverted pendulum system, where the inputs are bounded, is presented. The proposed controller is based on the notion of reachability sets and guarantees semi global stability for all references. An inverted pendulum on a two wheels robot has been developed. A distributed control system, including sensor processing algorithms and a stabilizing control scheme has been implemented on three on-board embedded processors

Using Modelica for advanced Multi-Body modelling in 3D graphical robotic simulators

This paper describes a framework to extend the 3D robotic simulation environment Gazebo, and similar ones, with enhanced, tailor-made, multi-body dynamics specified in the Modelica language. The body-to-body interaction models are written in Modelica, but they use the sophisticated collision detection capabilities of the Gazebo engine. This contribution is a first step toward the simulation of complex robotics systems integrating detailed physics modelling and realistic sensors such as lidar and cameras. A proof-of-concept implementation is described in the paper integrating Gazebo collider and the Modelica MultiBody library, and the results obtained when simulating the interaction of an elastic sphere with a rigid plane are shown