The OpenModelica integrated environment for modeling, simulation, and model-based development

OpenModelica is a unique large-scale integrated open-source Modelica- and FMI-based modeling, simulation, optimization, model-based analysis and development environment. Moreover, the OpenModelica environment provides a number of facilities such as debugging; optimization; visualization and 3D animation; web-based model editing and simulation; scripting from Modelica, Python, Julia, and Matlab; efficient simulation and co-simulation of FMI-based models; compilation for embedded systems; Modelica- UML integration; requirement verification; and generation of parallel code for multi-core architectures. The environment is based on the equation-based object-oriented Modelica language and currently uses the MetaModelica extended version of Modelica for its model compiler implementation. This overview paper gives an up-to-date description of the capabilities of the system, short overviews of used open source symbolic and numeric algorithms with pointers to published literature, tool integration aspects, some lessons learned, and the main vision behind its development.Fil: Fritzson, Peter. Linköping University; SueciaFil: Pop, Adrian. Linköping University; SueciaFil: Abdelhak, Karim. Fachhochschule Bielefeld; AlemaniaFil: Asghar, Adeel. Linköping University; SueciaFil: Bachmann, Bernhard. Fachhochschule Bielefeld; AlemaniaFil: Braun, Willi. Fachhochschule Bielefeld; AlemaniaFil: Bouskela, Daniel. Electricité de France; FranciaFil: Braun, Robert. Linköping University; SueciaFil: Buffoni, Lena. Linköping University; SueciaFil: Casella, Francesco. Politecnico di Milano; ItaliaFil: Castro, Rodrigo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigación en Ciencias de la Computación. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigación en Ciencias de la Computación; ArgentinaFil: Franke, Rüdiger. Abb Group; AlemaniaFil: Fritzson, Dag. Linköping University; SueciaFil: Gebremedhin, Mahder. Linköping University; SueciaFil: Heuermann, Andreas. Linköping University; SueciaFil: Lie, Bernt. University of South-Eastern Norway; NoruegaFil: Mengist, Alachew. Linköping University; SueciaFil: Mikelsons, Lars. Linköping University; SueciaFil: Moudgalya, Kannan. Indian Institute Of Technology Bombay; IndiaFil: Ochel, Lennart. Linköping University; SueciaFil: Palanisamy, Arunkumar. Linköping University; SueciaFil: Ruge, Vitalij. Fachhochschule Bielefeld; AlemaniaFil: Schamai, Wladimir. Danfoss Power Solutions GmbH & Co; AlemaniaFil: Sjolund, Martin. Linköping University; SueciaFil: Thiele, Bernhard. Linköping University; SueciaFil: Tinnerholm, John. Linköping University; SueciaFil: Ostlund, Per. Linköping University; Sueci

Methods and Tools for Efficient Model-Based Development of Cyber-Physical Systems with Emphasis on Model and Tool Integration

Model-based tools and methods are playing important roles in the design and analysis of cyber-physical systems before building and testing physical prototypes. The development of increasingly complex CPSs requires the use of multiple tools for different phases of the development lifecycle, which in turn depends on the ability of the supporting tools to interoperate. However, currently no vendor provides comprehensive end-to-end systems engineering tool support across the entire product lifecycle, and no mature solution currently exists for integrating different system modeling and simulation languages, tools and algorithms in the CPSs design process. Thus, modeling and simulation tools are still used separately in industry. The unique challenges in integration of CPSs are a result of the increasing heterogeneity of components and their interactions, increasing size of systems, and essential design requirements from various stakeholders. The corresponding system development involves several specialists in different domains, often using different modeling languages and tools. In order to address the challenges of CPSs and facilitate design of system architecture and design integration of different models, significant progress needs to be made towards model-based integration of multiple design tools, languages, and algorithms into a single integrated modeling and simulation environment. In this thesis we present the need for methods and tools with the aim of developing techniques for numerically stable co-simulation, advanced simulation model analysis, simulation-based optimization, and traceability capability, and making them more accessible to the model-based cyber physical product development process, leading to more efficient simulation. In particular, the contributions of this thesis are as follows: 1) development of a model-based dynamic optimization approach by integrating optimization into the model development process; 2) development of a graphical co-modeling editor and co-simulation framework for modeling, connecting, and unified system simulation of several different modeling tools using the TLM technique; 3) development of a tool-supported method for multidisciplinary collaborative modeling and traceability support throughout the development process for CPSs; 4) development of an advanced simulation modeling analysis tool for more efficient simulation

Model‐Based Tool Integration and Ontology‐Driven Traceability in Model‐Based Development Environments

The landscape of tools available for model-based development of Cyber-Physical Systems (CPSs) is vast, encompassing numerous specialized tools designed to support models at the component-level. In reality, the different parts of the system represented by these component-level models are often physically tightly coupled and interdependent, and the models themselves are subject to change and evolve over time. However, due to the lack of interoperability between tools it is often challenging to integrate component-level models into larger system simulations and to support model evolution across the entire product lifecycle. In order to streamline the system development process and allow for seamless integration of models and a variety of development tools, a comprehensive integrated model-based development environment is required. To address these challenges, this thesis contributes a model-based tool integration approach and an ontology-driven automated traceability method that utilizes a standardized integration convention, language-neutral model transformation technology, and co-simulation technique to integrate several tools for CPSs development as well as to automatically establish and maintain traceability between heterogeneous artifacts created throughout the product development lifecycle. The applicability, validity, and usefulness of these approaches and the developed prototypes are demonstrated through industrial-relevant use case examples. In particular, the main contributions presented in this thesis are summarized as follows: Design, development, and validation of an ontology-driven approach for multidisciplinary collaborative modeling and traceability support throughout the development process for CPSs; Design, development, and validation of a general approach for modeling a composite model containing several tool-specific simulation component-level models which can be integrated, connected, and simulated using the Transmission Line Modeling (TLM) co-simulation technique; Design, development, and validation of a model-based dynamic optimization approach by enabling the reuse of simulation models for optimization; Design, development, and validation of advanced simulation analysis and post processing of results support in model-based development environments. Funding agencies: The research presented in this thesis has been supported by Vinnova in the ITEA2 MODRIO, OPENCPS, and EMPHYSIS projects, by EU in the H2020 INTO-CPS project and, by the CleanSky Joint Undertaking project PyModSimA (JTI-CS-2013-2- SGO-02-064). Support from the Swedish Government has also been received from the ELLIIT project, and the Swedish Strategic Research Foundation (SSF) in the Proviking EDOP project. The Open Source Modelica Consortium supports the continuous development of the OpenModelica framework.</p

Template Based XML and Modelica Unparser in OpenModelica

In many areas modeling and simulation plays an important role. Currently, an equation-based object oriented modeling and simulation languages, such as Modelica, are used for multi-domain modeling, and the OpenModelica Compiler (OMC) is Modelica-based platform for modeling, compilation and simulation. In this thesis, we address two issues relevant to OMC. The first issue deals with translation from the internal equation-based model representation in OpenModelica to an Extensible Markup Language (XML) form which can be imported in to the CasADi open source toolkit, in order to enable integrated dynamic modeling and optimization. To achieve this, we have implemented a new template based XML code generator module in OMC based on an XML standard defined in OPENPROD EU project for representation of flattened Modelica model. The second issue deals with transformation of OpenModelica Abstract Syntax Tree (AST) into Modelica text (Unparser). With regard to this issue, we have implemented a new template based Modelica Unparser from OpenModelica AST into Modelica text

An Integrated Framework for Traceability and Impact Analysis in Requirements Verification of Cyber-Physical Systems

In the field of model-based design of Cyber-Physical Systems (CPS), seamless traceability of the process, from requirements to models to simulation results, is becoming increasingly important. It can be used to support several activities such as variant handling, impact analysis, component reuse, software maintenance and evolution, verification, and validation. Despite the fact that the relevance of traceability in the model-based design of CPSs is well known, current tools that support traceability management are inadequate in practice. The lack of comprehensive whole-lifecycle systems engineering support in a single tool is one of the main causes of such ineffective traceability management, where traceability relationships between artifacts are still manually generated and maintained. This paper aims at presenting an approach and a prototype for automatically generating and maintaining the appropriate traceability links between heterogeneous artifacts ranging from requirement models, through design models, down to simulation and verification results throughout the product life cycle in model-based design of CPSs. A use case study is presented to validate and illustrate the proposed method and prototype.Funding Agencies|Swedish Government; European Union in the H2020 INTO-CPS project; Vinnova in the ITEA OPENCPSVinnova; EMBRACE project; Open Source Modelica Consortium</p

Automatic Regression Testing of Simulation Models and Concept for Simulation of Connected FMUs in PySimulator

The Modelica and FMI tool ecosystem is growing each year with new tools and methods becoming available. The open Modelica standard promises portability but it is important to ensure that a certain model behaves the same in different Modelica tools or in a different version of the same tool. It is also very important (for model evolution) to check that a new version of the same model produces comparable results. Finally, it is desirable to verify that a model exported in FMU form from a Modelica tool gives exactly the same results as the original model. This paper presents a framework for automatic regression testing as part of PySimulator which provides an efficient and concise way of testing if a model or a range of models behaves in the same way in several tools or versions of a tool by checking that the results produced are essentially identical. The FMI standard has been adopted by many tool vendors and is growing in popularity each year. This paper proposes a concept for building and simulating a system made from connected FMUs generated by different tools. The FMUs for Co-Simulation can be connected together using a GUI. The system model built graphically in this way can be saved for later use or simulated directly inside PySimulator. Active development is going on to support simulation of connected FMUs for Model Exchange

OMJulia: An OpenModelica API for Julia-Modelica Interaction

Modelica is an object oriented, acausal equation-based language for describing complex, hybrid dynamic models. About ten Modelica implementations exist, of which most are commercial and two are open source; the implementations have varying levels of tool functionality. Many Modelica implementations have limited support for model analysis. It is therefore of interest to integrate Modelica tools with a powerful scripting and programming language, such as Julia. Julia is a modern and free language for scientific computing. Such integration would facilitate the needed analysis possibilities and can speed up the development of effient simulation models. A number of design choices for interaction between Julia and Modelica tools are discussed. Next, Julia package OMJulia is introduced with an API for interaction between Open-Modelica and Julia. Some discussion of the reasoning behind the OMJulia design is given. The API is based on a new class ModelicaSystem within package OMJulia, with systematic methods which operate on instantiated models. OMJulia supports handling of FMU and Modelica models, setting and getting model values, as well as some model operations. Results are available in Julia for further analysis. OMJulia is a further development of a previous OMPython package; a key advantage of Julia over Python is that Julia has better support for control engineering packages. OMJulia represents a first effort to interface a relatively complete Modelica tool to Julia, giving access to an open source set-up for modeling and analysis, including control synthesis, easily installable from a unified package manager. Some possibilities of OMJulia are illustrated by application to a few simple, yet industrially relevant problems within control design. Keywords: Modelica, FMI, FMU, OpenModelica, Julia, Julia API, OMJulia

An Open-Source Graphical Composite Modeling Editor and Simulation Tool Based on FMI and TLM Co-Simulation

A common situation in industry is that a system model (here a composite model) is composed of several sub-models which may have been developed using different tools. FMI is one important technology for exporting/importing models between tools and/or connecting them via co-simulation. TLM based modeling and co-simulation is another important technique for modeling, connecting, and simulation of especially mechanical systems, which is simple, numerically stable, and efficient. A number of tool-specific simulation models, such as Modelica models, SimuLink models, Adams models, BEAST models, etc., have successfully been connected and simulated using TLM based co-simulation. However, previously there was no general open source tool for creation, graphic editing, and simulation of composite models connected via FMI or TLM based co-simulation. In this paper we present a graphical composite model editor based on OpenModelica which is integrated with the OpenModelica and the SKF TLM co-simulation frameworks to support both FMI and TLM based composite model editing and simulation. The editor supports creating, viewing and editing a composite model both in textual and graphical representation. The system supports simulation of composite models consisting of sub-models created using different tools

The OpenModelica Integrated Environment for Modeling, Simulation, and Model-Based Development

OpenModelica is a unique large-scale integrated open-source Modelica- and FMI-based modeling, simulation, optimization, model-based analysis and development environment. Moreover, the OpenModelica environment provides a number of facilities such as debugging; optimization; visualization and 3D animation; web-based model editing and simulation; scripting from Modelica, Python, Julia, and Matlab; efficient simulation and co-simulation of FMI-based models; compilation for embedded systems; Modelica-UML integration; requirement verification; and generation of parallel code for multi-core architectures. The environment is based on the equation-based object-oriented Modelica language and currently uses the MetaModelica extended version of Modelica for its model compiler implementation. This overview paper gives an up-to-date description of the capabilities of the system, short overviews of used open source symbolic and numeric algorithms with pointers to published literature, tool integration aspects, some lessons learned, and the main vision behind its development.Funding agencies: Vinnova in the ITEA OPENPROD projectVinnova; Vinnova in the ITEA MODRIO projectVinnova; Vinnova in the ITEA OPENCPS projectVinnova; Vinnova in the ITEA EMPHYSIS projectVinnova; Vinnova in the ITEA EMBRACE projectVinnova; Vinnova RTISIM projectVinnova; Vin</p