| 1. |
- Bengtsson, Fredrik, 1989, et al.
(författare)
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Finding feedforward configurations using gramian based interaction measures
- 2021
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Ingår i: Modeling, Identification and Control. - : Norwegian Society of Automatic Control. - 1890-1328 .- 0332-7353. ; 42:1, s. 27-35
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Tidskriftsartikel (refereegranskat)abstract
- A sparse control structure can be seen as a decentralised controller that is expanded to include feedforward or MIMO blocks. Here, use of the gramian based interaction measures to determine a sparse control structure with feedforward is examined. A modification to the method used today is proposed and it is demonstrated that it results in a considerable improvement. Furthermore, recently proposed modifications to scaling gramian based measures are expanded to also cover sparse control structures. We show that the method that yields the best result is when two different scaling methods are combined, using one to design a decentralized controller and another to find feedforward connections.
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| 2. |
- Byström, Johan, et al.
(författare)
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Using generalized Fibonacci sequences for solving the one-dimensional LQR problem and its discrete-time Riccati equation
- 2010
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Ingår i: Modeling, Identification and Control. - : Norwegian Society of Automatic Control. - 0332-7353 .- 1890-1328. ; 31:1, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- In this article we develop a method of solving general one-dimensional Linear Quadratic Regulator (LQR) problems in optimal control theory, using a generalized form of Fibonacci numbers. We find the solution R (k) of the corresponding discrete-time Riccati equation in terms of ratios of generalized Fibonacci numbers. An explicit Binet type formula for R (k) is also found, removing the need for recursively finding the solution at a given timestep. Moreover, we show that it is also possible to express the feedback gain, the penalty functional and the controller state in terms of these ratios. A generalized golden ratio appears in the corresponding in finite horizon problem. Finally, we show the use of the method in a few examples.
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| 3. |
- Fritzson, Dag, et al.
(författare)
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Composite modelling in 3-D mechanics utilizing Transmission Line Modelling (TLM) and Functional Mock-up Interface (FMI)
- 2018
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Ingår i: Modeling, Identification and Control. - : MIC. - 0332-7353 .- 1890-1328. ; 39:3, s. 179-190
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Tidskriftsartikel (refereegranskat)abstract
- Composite modelling and simulation is a solution to utilize investments in models and tools, use the right tool for the right task, increase the accuracy by means of more accurate modelled boundary conditions, switch between levels in model complexity for a specific sub-system, and facilitate co-operation in organizations. With the new Functional Mock-up Interface (FMI) standardization, efforts are increasing to make this happen. SKF BEAST is an advanced dynamic simulation tool for rolling bearings and other mechanical systems with contacts. The tool incorporates a framework for composite modelling and cosimulation, i.e., a Master Simulation Tool (MST). It uses Transmission Line Modelling (TLM) to ensure robust numerical behaviour of the complete composite system model and supports the Functional Mock-up Interface (FMI) for model import, including both model exchange and co-simulation. In this paper, the tools and the techniques for composite modelling are discussed in further detail and application examples are given.
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| 4. |
- Fritzson, Peter, 1952-, et al.
(författare)
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The OpenModelica Integrated Environment for Modeling, Simulation, and Model-Based Development
- 2020
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Ingår i: Modeling, Identification and Control. - Kristiansand, Norway : Norsk Forening for Automatisering. - 0332-7353 .- 1890-1328. ; 41:4, s. 241-295
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Kadhim, Ali, et al.
(författare)
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Dynamic Relative Gain Array Estimation using Local Polynomial Approximation Approach
- 2016
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Ingår i: Modeling, Identification and Control. - : Norwegian Society of Automatic Control. - 0332-7353 .- 1890-1328. ; 37:4, s. 247-259
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a procedure that utilizes the local polynomial approximation approach in the estimation of the Dynamic Relative Gain Array (DRGA) matrix and its uncertainty bounds for weakly nonlinear systems. This procedure offers enhanced frequency resolution and noise reduction when random excitation is used. It also allows separation of nonlinear distortions with shorter measuring time when multisine excitation is imposed. The procedure is illustrated using the well-known quadruple tank process as a case study in simulation and in real life. Besides, a comparison with the pairing results of the static RGA, nonlinear RGA and DRGA based on linearized quadruple tank model for different simulation cases is performed.
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| 6. |
- Kinnander, Åke, et al.
(författare)
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Industrial Evaluation of Integrated Performance Analysis and Equation Model Debugging for Equation-Based Models
- 2016
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Ingår i: Modeling, Identification and Control. - : MIC. - 0332-7353 .- 1890-1328. ; 37:4, s. 225-236
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Tidskriftsartikel (refereegranskat)abstract
- The ease of use and the high abstraction level of equation-based object-oriented (EOO) languages such as Modelica has the drawback that performance problems and modeling errors are often hard to find. To address this problem, we have earlier developed advanced performance analysis and equation model debugging support in the OpenModelica tool. The aim of the work reported in this paper is to perform an independent investigation and evaluation of this equation model performance analysis and debugging methods and tool support on industrial models. The results turned out to be mainly positive. The integrated debugger and performance analyzer locates several kinds of errors such as division by zero, chattering, etc., and greatly facilitates finding the equations that take most of the execution time during simulation. It remains to further evaluate the performance profiler and debugger on even larger industrial models.
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| 7. |
- Ljung, Lennart, 1946-
(författare)
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System Identification in a MIC Perspective
- 1994
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Ingår i: Modeling, Identification and Control. - Linköping : Norwegian Society of Automatic Control. - 0332-7353 .- 1890-1328. ; 15:3, s. 153-159
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes some sibjective aspects on some current research topics in system identification. A 'classical' standpoint is taken regarding complexity models. The need for specific tools for 'semi-physical-modeling' is also pointed out, and a discussion on different disturbance models is also included.
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| 8. |
- Pop, Adrian, et al.
(författare)
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Integrated Debugging of Modelica Models
- 2014
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Ingår i: Modeling, Identification and Control. - : Norwegian Society of Automatic Control. - 1890-1328. ; 35:2, s. 93-107
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Tidskriftsartikel (refereegranskat)abstract
- The high abstraction level of equation-based object-oriented (EOO) languages such as Modelica has the drawback that programming and modeling errors are often hard to find. In this paper we present integrated static and dynamic debugging methods for Modelica models and a debugger prototype that addresses several of those problems. The goal is an integrated debugging framework that combines classical debugging techniques with special techniques for equation-based languages partly based on graph visualization and interaction. To our knowledge, this is the first Modelica debugger that supports both equation-based transformational and algorithmic code debugging in an integrated fashion.
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| 9. |
- Schamai, Wladimir, et al.
(författare)
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An Approach to Automated Model Composition Illustrated in the Context of Design Verification
- 2014
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Ingår i: Modeling, Identification and Control. - : Norwegian Society of Automatic Control. - 1890-1328. ; 35:2, s. 79-91
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Tidskriftsartikel (refereegranskat)abstract
- Building complex systems form models that were developed separately without modifying existing code is a challenging task faced on a regular basis in multiple contexts, for instance, in design verification. To address this issue, this paper presents a new approach for automating the dynamic system model composition. The presented approach aims to maximise information reuse, by defining the minimum set of information that is necessary to the composition process, to maximise decoupling by removing the need for explicit interfaces and to present a methodology with a modular and structured approach to composition. Moreover the presented approach is illustrated in the context of system design verification against requirements using a Modelica environment, and an approach for expressing the information necessary for automating the composition is formalized.
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| 10. |
- Sjölund, Martin, 1984-, et al.
(författare)
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Bootstrapping a Compiler for an Equation-Based Object-Oriented Language
- 2014
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Ingår i: Modeling, Identification and Control. - : Norwegian Society of Automatic Control. - 0332-7353 .- 1890-1328. ; 35:1, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- What does it mean to bootstrap a compiler, and why do it? This paper reports on the first bootstrapping of a full-scale EOO (Equation-based Object-Oriented) modeling language such as Modelica. Bootstrapping means that the compiler of a language can compile itself. However, the usual application area for the Modelica is modeling and simulation of complex physical systems. Fortunately it turns out that with some minor extensions, the Modelica language is well suited for the modeling of language semantics. We use the name MetaModelica for this slightly extended Modelica. This is a prerequisite for bootstrapping which requires that the language can be used to model and/or implement itself. The OpenModelica Compiler (OMC) has been written in this MetaModelica language. It originally supported only the standard Modelica language but has been gradually extended to also cover the MetaModelica language extensions. After substantial work, OMC is able to quickly compile itself and produces an executable with good performance. The benefits include a more extensible and maintainable compiler by introducing improved language constructs and a more powerful runtime that makes it easy to add functionality such as parser generators, debuggers, and profiling tools. Future work includes extracting and restructuring parts of OMC, making the compiler smaller and more modular and extensible. This will also make it easier to interface with OMC, making it possible to create more powerful and user-friendly OpenModelica-based tools. The compiler and its bootstrapping is a major effort -- it is currently about 330 000 lines of code, and the MetaModelica extensions are used routinely by approximately ten developers on a daily basis.
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