liu.seSearch for publications in DiVA
Change search
Refine search result
1234567 151 - 200 of 650
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 151.
    Frisk, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Order of Residual Generators - Bounds and Algorithms2000In: IFAC Fault Detection, Supervision and Safety for Technical Processes,2000, 2000, p. 587-592Conference paper (Refereed)
    Abstract [en]

    This contribution analyses residual generators that perfectly decouples disturbances in linear systems. The analysis focuses on the orders of the residual generators and it is shown how low order, local relationships in the model can be utilized to increase robustness properties. Easily computed bounds on minimum and maximum order residual generators are derived and presented. An upper bound on the minimal row-degree is derived and is given directly by the number of measurements, the number of linearly independent disturbances, and the number of states in the model. A lower bound is given by the minimum observability index of the model. An upper bound for the maximum order is the number of states in the model.

  • 152.
    Frisk, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Residual generation in linear stochastic systems - a polynomial approach2001In: IEEE Conference on Decision and Control,2001, 2001Conference paper (Refereed)
  • 153.
    Frisk, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Residual Generation in Stochastic Systems - A Polynomial Approach2001Report (Other academic)
    Abstract [en]

    This report describes a polynomial design algorithm for linear residual generation for stochastic systems in both continuous and discrete time. It is shown how the two main steps in the design algorithm is extraction of a polynomial basis for the left null-space of a polynomial matrix followed by a J-spectral co-factorization of a para-hermitian polynomial matrix. For both these operations there exists good numerical tools. The design algorithm is successfully demonstrated on a number of non-trivial examples. Full Matlab implementations is also provided.

  • 154.
    Frisk, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Residual Generator Design for Non-linear, Polynomial Systems - A Gröbner Basis Approach2000Conference paper (Refereed)
    Abstract [en]

    Design and analysis of residual generators for polynomial systems is considered. This paper presents a systematic procedure, given an input-output description of system dynamics, to design residual generators for fault diagnosis. The design procedure is based on standard elimination theory. The design procedure is applied in a simulation study on a non-linear system, where it is showed how multiplicative and additive faults are detected and isolated. The example also shows how a fault detectability/isolability analysis can be made during the design.

  • 155.
    Frisk, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Residual Generator Design for Non-linear, Polynomial Systems - A Gröbner Basis Approach2000In: IFAC Fault Detection, Supervision and Safety for Technical Processes,2000, 2000, p. 957-962Conference paper (Refereed)
    Abstract [en]

    Design and analysis of residual generators for polynomial systems is considered. This paper presents a systematic procedure, given an input-output description of system dynamics, to design residual generators for fault diagnosis. The design procedure is based on standard elimination theory. The design procedure is applied in a simulation study on a non-linear system, where it is showed how multiplicative and additive faults are detected and isolated. The example also shows how a fault detectability/isolability analysis can be made during the design.

  • 156.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Bregon, Anibal
    University of Valladolid, Spain .
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Pulido, Belarmino
    University of Valladolid, Spain .
    Biswas, Gautam
    Vanderbilt University, TN 37235 USA Vanderbilt University, TN 37235 USA .
    Diagnosability Analysis Considering Causal Interpretations for Differential Constraints2012In: IEEE transactions on systems, man and cybernetics. Part A. Systems and humans, ISSN 1083-4427, E-ISSN 1558-2426, Vol. 42, no 5, p. 1216-1229Article in journal (Refereed)
    Abstract [en]

    This paper is focused on structural approaches to study diagnosability properties given a system model taking into account, both simultaneously or separately, integral and differential causal interpretations for differential constraints. We develop a model characterization and corresponding algorithms, for studying system diagnosability using a structural decomposition that avoids generating the full set of system analytical redundancy relations. Simultaneous application of integral and differential causal interpretations for differential constraints results in a mixed causality interpretation for the system. The added power of mixed causality is demonstrated using a Reverse Osmosis Subsystem from the Advanced Water Recovery System developed at the NASA Johnson Space Center. Finally, we summarize our work and provide a discussion of the advantages of mixed causality over just derivative or just integral causality.

    Download full text (pdf)
    fulltext
  • 157.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Dustegör, Dilek
    LAIL Universite des Sciences et Technologies de Lille.
    Krysander, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Cocquempot, Vincent
    LAIL Universite des Sciences et Technologies de Lille.
    Improving fault isolability properties by structural analysis of faulty behavior models: application to the DAMADICS benchmark problem2003In: IFAC Safeprocess03,2003, Washington D.C., USA, 2003Conference paper (Refereed)
    Abstract [en]

    Structural analysis is a powerful tool for early determination of detectability/isolability possibilities. It is shown how different levels of knowledge about faults can be incorporated in a structural fault-isolability analysis and how they result in different isolability properties. The results are evaluated on the DAMADICS valve benchmark model. It is also shown how to determine which faults in the benchmark that need further modeling to get desired isolability properties of the diagnosis system.

  • 158.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Gelso, Esteban
    Institut d¿Informatica i Aplicacions Universitat de Girona, Spain.
    Armengol, Joaquim
    Institut d¿Informatica i Aplicacions Universitat de Girona, Spain.
    Robust fault detection using consistency techniques with application to an automotive engine2008In: IFAC World Congress,2008, Seoul, Korea: IFAC , 2008Conference paper (Refereed)
  • 159.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Krysander, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Leakage Detection In a Fuel Evaporative System2008In: IFAC World Congress,2008, Seoul, Korea: IFAC , 2008Conference paper (Refereed)
    Abstract [en]

    On-Board Diagnostics (OBD) regulations require that the fuel system in personal vehicles must be supervised for leakages. Legislative requirement on the smallest leakage size that has to be detected is decreasing and at the same time the requirement on number of leakage checks are increasing. A consequence is that detection must be performed under more and more diverse operating conditions. This paper describes a vacuum-decay based approach for evaporative leak detection. The approach requires no additional hardware such as pumps or pressure regulators, it only utilizes the pressure sensor that is mounted in the fuel tank. A detection algorithm is proposed that detects small leakages under different operating conditions. The method is based on a first principles physical model of the pressure in the fuel tank. Careful statistical analysis of the model and measurement data together with statistical maximum-likelihood estimation methods, results in a systematic design procedure that is easily tuned with few and intuitive parameters. The approach has been successfully evaluated on real data measured in a research laboratory.

  • 160.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, Faculty of Science & Engineering.
    Residual Selection for Consistency Based Diagnosis Using Machine Learning Models2018In: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2018, Vol. 51, no 24, p. 139-146Conference paper (Refereed)
    Abstract [en]

    A common architecture of model-based diagnosis systems is to use a set of residuals to detect and isolate faults. In the paper it is motivated that in many cases there are more possible candidate residuals than needed for detection and single fault isolation and key sources of varying performance in the candidate residuals are model errors and noise. This paper formulates a systematic method of how to select, from a set of candidate residuals, a subset with good diagnosis performance. A key contribution is the combination of a machine learning model, here a random forest model, with diagnosis specific performance specifications to select a high performing subset of residuals. The approach is applied to an industrial use case, an automotive engine, and it is shown how the trade-off between diagnosis performance and the number of residuals easily can be controlled. The number of residuals used are reduced from original 42 to only 12 without losing significant diagnosis performance. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 161.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Krysander, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Sensor placement for maximum fault isolability2007In: 18th International Workshop on Principles of Diagnosis,2007, Nashville, USA, 2007, p. 106-113Conference paper (Refereed)
    Abstract [en]

    An algorithm is developed for computing which sensors to add to obtain maximum fault detectability and fault isolability. The method is based on only the structural information in a model which means that large and non-linear differential-algebraic models can be handled in an efficient manner. The approach is exemplified on a model of an industrial valve where the benefits and properties of the method is clearly shown.

  • 162.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Treatment of accumulative variables in data-driven prognostics of lead-acid batteries2015In: Proceedings of the 9th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes Safeprocess'15, Elsevier, 2015, Vol. 48, no 21, p. 105-112Conference paper (Refereed)
    Abstract [en]

    Problems with starter batteries in heavy-duty trucks can cause costly unplanned stops along the road. Frequent battery changes can increase availability but is expensive and sometimes not necessary since battery degradation is highly dependent on the particular vehicle usage and ambient conditions. The main contribution of this work is case study where prognostic information on remaining useful life of lead-acid batteries in individual Scania heavy-duty trucks is computed. A data-driven approach using random survival forests is used where the prognostic algorithm has access to fleet operational data including 291 variables from $33 603$ vehicles from 5 different European markets. A main implementation aspect that is discussed is the treatment of accumulative variables such as vehicle age in the approach. Battery lifetime predictions are computed and evaluated on recorded data from Scania's fleet-management system and the effect of how accumulative variables are handled is analyzed.

  • 163.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, Faculty of Science & Engineering.
    Jung, Daniel
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A Toolbox for Analysis and Design of Model Based Diagnosis Systems for Large Scale Models2017In: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2017, Vol. 50, no 1, p. 3287-3293Conference paper (Refereed)
    Abstract [en]

    To facilitate the use of advanced fault diagnosis analysis and design techniques to industrial sized systems, there is a need for computer support. This paper describes a Matlab toolbox and evaluates the software on a challenging industrial problem, air-path diagnosis in an automotive engine. The toolbox includes tools for analysis and design of model based diagnosis systems for large-scale differential algebraic models. The software package supports a complete tool-chain from modeling a system to generating C-code for residual generators. Major design steps supported by the tool are modeling, fault diagnosability analysis, sensor selection, residual generator analysis, test selection, and code generation. Structural methods based on efficient graph theoretical algorithms are used in several steps. In the automotive diagnosis example, a diagnosis system is generated and evaluated using measurement data, both in fault-free operation and with faults injected in the control-loop. The results clearly show the benefit of the toolbox in a model-based design of a diagnosis system. Latest version of the toolbox can be downloaded at faultdiagnosistoolbox.github.io. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 164.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Emil
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Data-driven Lead-Acide Battery Prognostics Using Random Survival Forests2014In: PMH 2014. Proceedings of the Annual Conference of The Prognostics and Health Management Society. Fort Worth, Texas, USA / [ed] Mathew J. Daigle and Anibal Bregon, PMH Society , 2014, p. 92-101Conference paper (Refereed)
    Abstract [en]

    Problems with starter batteries in heavy-duty trucks can cause costly unplanned stops along the road. Frequent battery changes can increase availability but is expensive and sometimes not necessary since battery degradation is highly dependent on the particular vehicle usage and ambient conditions. The main contribution of this work is a case-study where prognostic information on remaining useful life of lead-acid batteries in individual Scania heavy-duty trucks is computed. A data-driven approach using random survival forests is proposed where the prognostic algorithm has access to fleet management data including 291 variables from 33 603 vehicles from 5 different European markets. The data is a mix of numerical values such as temperatures and pressures, together with histograms and categorical data such as battery mount point. Implementation aspects are discussed such as how to include histogram data and how to reduce the computational complexity by reducing the number of variables. Finally, battery lifetime predictions are computed and evaluated on recorded data from Scania's fleet-management system.

  • 165.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Krysander, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nyberg, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Åslund, Jan
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    A toolbox for design of diagnosis systems2006In: IFAC Safeprocess06,2006, Beijing, China: IFAC , 2006, p. 703-Conference paper (Refereed)
    Abstract [en]

    Design of diagnosis systems is a complex task that involves many different steps. Full understanding of all different parts of the design procedure requires deep knowledge on theory from a wide variety of subjects. Thus, to encourage the use of results from diagnosis research it is highly desirable to have software support in the design process. This paper describes ongoing work for determining an architecture for such a toolbox. The paper also describes software solutions in the toolbox. In industry as well as in universities, Matlab is probably the most widespread tool used by control engineers. Therefore the toolbox is primarily based upon Matlab but also some computer algebraic tools such as Mathematica and Maple are used.

  • 166.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, Faculty of Science & Engineering.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Analysis and Design of Diagnosis Systems Based on the Structural Differential Index2017In: 20th IFAC World Congress, ELSEVIER SCIENCE BV , 2017, Vol. 50, no 1, p. 12236-12242Conference paper (Refereed)
    Abstract [en]

    Structural approaches have shown to be useful for analyzing and designing diagnosis systems for industrial systems. In simulation and estimation literature, related theories about differential index have been developed and, also there, structural methods have been successfully applied for simulating large-scale differential algebraic models. A main contribution of this paper is to connect those theories and thus making the tools from simulation and estimation literature available for model based diagnosis design. A key step in the unification is an extension of the notion of differential index of exactly determined systems of equations to overdetermined systems of equations. A second main contribution is how differential-index can be used in diagnosability analysis and also in the design stage where an exponentially sized search space is significantly reduced. This allows focusing on residual generators where basic design techniques, such as standard state-observation techniques and sequential residual generation are directly applicable. The developed theory has a direct industrial relevance, which is illustrated with discussions on an automotive engine example. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

  • 167.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Sensor placement for fault isolation in linear differential-algebraic systems2009In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 45, no 2, p. 364-371Article in journal (Refereed)
    Abstract [en]

    An algorithm is proposed for computing which sensor additions make a diagnosis requirement specification regarding fault detectability and isolability attainable for a given linear differential-algebraic model. Restrictions on possible sensor locations can be given, and if the diagnosis specification is not attainable with any available sensor addition, the algorithm provides the solutions that maximize specification fulfillment. Previous approaches with similar objectives have been based on the model structure only. Since the proposed algorithm utilizes the analytical expressions, it can handle models where structural approaches fail.

  • 168.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Robust Residual Generation for Diagnosis Including a Reference Model for Residual Behavior1999In: IFAC World Congress,1999, 1999Conference paper (Refereed)
  • 169.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Robust Residual Generation for Diagnosis Including a Reference Model for Residual Behavior2006In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 42, no 3, p. 437-445Article in journal (Refereed)
  • 170.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nyberg, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    A Minimal Polynomial Basis Approach to Residual Generation for Linear Systems1998In: First Conference on Computer Science and Systems Engineering in Linköping, 1998, p. 223-237Conference paper (Refereed)
  • 171.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nyberg, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    A minimal polynomial basis solution to residual generation for fault diagnosis in linear systems2001In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 37, no 9, p. 1417-1424Article in journal (Refereed)
    Abstract [en]

    A fundamental part of a fault diagnosis system is the residual generator. Here a new method, the minimal polynomial basis approach, for design of residual generators for linear systems, is presented. The residual generation problem is transformed into a problem of finding polynomial bases for null-spaces of polynomial matrices. This is a standard problem in established linear systems theory, which means that numerically efficient computational tools are generally available. It is shown that the minimal polynomial basis approach can find all possible residual generators and explicitly those of minimal order. © 2001 Elsevier Science Ltd. All rights reserved.

  • 172.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nyberg, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Residual Generation for Fault Diagnosis of Systems Described by General Linear Differential-algebraic Equations2002In: IFAC World Congress,2002, 2002Conference paper (Refereed)
  • 173.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Nyberg, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Residual Generation for Fault Diagnosis of Systems Described by General Linear Differential-Algebraic Equations (revised)2005Report (Other academic)
    Abstract [en]

    Linear residual generation for DAE systems has been considered. In all results derived, no distinction between input and output signals is done. A complete characterization and parameterization of all residual generators is presented. Further, a condition for fault detectability in DAE systems is given. Based on the characterization of all residual generators, a design strategy for residual generators for DAE systems is presented. Given that a set of faults are detectable, the design strategy will result in a residual generator sensitive to all the detectable faults. Further the residual generator is guaranteed to be of lowest possible order. Special care has been devoted to assure this property also for non-controllable systems.

    Download full text (pdf)
    Residual Generation for Fault Diagnosis of Systems Described by General Linear Differential-Algebraic Equations (revised)
  • 174.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nyberg, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Using Minimal Polynomial Bases for Fault Diagnosis1999In: European Control Conference,1999, 1999Conference paper (Refereed)
  • 175.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nyberg, Mattias
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Using Minimal Polynomial Bases for Model-Based Fault Diagnosis: A Demonstration Document for PolyX, Ltd1999Report (Other academic)
    Abstract [en]

    This document is a demonstration document, demonstrating the use of the Polynomial Toolbox for Matlab when designing residual generators for fault diagnosis. A brief introduction to the residual generation problem for fault diagnosis in linear systems is given and a solution based on polynomial methods are outlined. Also, a design example, complete with \sc Matlab code illustrates how the Polynomial Toolbox can be used in the design of residual generators.

    Download full text (pdf)
    Using Minimal Polynomial Bases for Model-Based Fault Diagnosis: A Demonstration Document for PolyX, Ltd
  • 176.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nyberg, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    FDI with adaptive residual generation applied to a DC-servo1997In: IFAC Safeprocess,1997, Hull: IFAC , 1997Conference paper (Refereed)
  • 177.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Åslund, Jan
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    An observer for semi-explicit differential-algebraic systems2005In: IFAC World Congress,2005, Prague, Czech Republic: IFAC , 2005Conference paper (Refereed)
  • 178.
    Frisk, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Lowering Orders of Derivatives in Non-linear Consistency Relations: Theory and Simulation Examples2003Report (Other academic)
    Abstract [en]

    Consistency relations are often used to design residual generators based on non-linear process models. A main difficulty is that they generally include time differentiated versions of known or measured signals which are difficult to estimate in a noisy environment, especially higher order derivatives. The main results of this paper show how to lower, or if possible avoid, the need to estimate derivatives of known signals in order to compute the residual. This is achieved by rewriting the problem into an integrability problem using state-space realization theory. An attractive feature of the approach is that general differential algebraic system descriptions can be handled in the same way as for example ordinary differential equations and also that stability of the residual generator is always guaranteed.

    Download full text (pdf)
    Lowering Orders of Derivatives in Non-linear Consistency Relations - Theory and Simulation Examples
  • 179.
    Frisk, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Åslund, Jan
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Lowering Orders of Derivatives in Non-linear Residual Generation using Realization Theory2005In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 41, no 10, p. 1799-1807Article in journal (Refereed)
    Abstract [en]

    Consistency relations are often used to design residual generators based on non-linear process models. A main difficulty is that they generally include time differentiated versions of known signals which are difficult to estimate in a noisy environment. The main results of this paper show how to lower the need to estimate derivatives of known signals in order to compute a residual. Necessary and sufficient conditions for lowering the order of the derivatives one step are presented and a main step in the approach is to obtain a state-space realization of the residual generator. An attractive feature of the approach is that general differential algebraic system descriptions can be handled in the same way as for example ordinary differential equations and also that stability of the residual generator is always guaranteed.

  • 180. Order onlineBuy this publication >>
    Fröberg, Anders
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Efficient Simulation and Optimal Control for Vehicle Propulsion2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Efficient drive cycle simulation of longitudinal vehicle propulsion models is an important aid for design and analysis of power trains. Tools on the market today mainly use two different methods for such simulations, forward dynamic or quasi-static inverse simulation. Here known theory for stable inversion of non linear systems is used in order to combine the fast simulation times of the quasi-static inverse simulation with the ability of including transient dynamics as in the forward dynamic simulation. The stable inversion technique with a new implicit driver model together forms a new concept, inverse dynamic simulation. This technique is demonstrated feasible for vehicle propulsion simulation and specifically on three powertrain applications that include important dynamics that can not be handled using quasi-static inverse simulation. The extensions are engine dynamics, drive line dynamics, and gas flow dynamics for diesel engines, which also are selected to represent important properties such as zero dynamics, resonances, and non-minimum phase systems. It is shown that inverse dynamic simulation is easy to set up, gives short simulation times, and gives consistent results for design space exploration. This makes inverse dynamic simulation a suitable method to use for drive cycle simulation, especially in situations requiring many simulations, such as optimization over design space, powertrain configuration optimization, or development of powertrain control strategies.

    Optimal vehicle propulsion control is developed with special focus on heavy trucks used for long haulage. The power to mass ratio for a typical heavy duty truck makes even moderate road slopes significant in the sense that it is impossible to keep a constant cruising speed. This gives an interesting problem how to control vehicle speed such that fuel consumption is minimized. Todays telematic systems together with three dimensional roadmaps can provide the vehicle control system with information of the road topography. This enables intelligent cruise controllers that utilize this information to control engine fueling and gear shifting such that an optimal speed trajectory is obtained.

    First the optimal control problem is solved numerically by dynamic programming, giving a controller with real time capabilities that can be used on-line in the vehicles control system. Simulations of such a system on authentic road profiles show that it has potential for significant fuel savings. To achieve knowledge about the underlying physics that affects the optimal solution, the optimal control problem is solved in detail and analytical expressions for the conditions of optimality are derived. Those expressions are then used to find optimal solutions on constructed test road profiles. Such test cases point out the typical behavior of an optimal solution and also which parameters that are decisive for the fuel minimization problem, and also how they quantitatively influence the behavior. It is for example shown that small non-linearities in the engine torque characteristics have significant effect on the optimal control strategy. The solutions for the non linear engine model have a smoother character but also require longer prediction horizons. For optimal gear ratio control it is shown that the maximum fueling function is essential for the solution. For example, in the case of a continuously variable transmission it is shown that the gear ratio never is chosen such that engine speed exceeds the speed of maximum engine power. For a discrete step transmission the gear shifting losses are essential for the optimal shift positions, but over all the solutions are close to continuous solutions.

    List of papers
    1. Efficient Drive Cycle Simulation
    Open this publication in new window or tab >>Efficient Drive Cycle Simulation
    2008 (English)In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 57, no 3, p. 1442-1453Article in journal (Refereed) Published
    Abstract [en]

    Drive cycle simulations of longitudinal vehicle models are important aids for the design and analysis of power trains, and tools currently on the market mainly use two different methods for such simulations: the forward dynamic and quasi-static inverse simulations. Here, a known theory for the stable inversion of nonlinear systems is used to combine the fast simulation times of the quasi-static inverse simulation with the ability of the forward dynamic simulation to include transient dynamics. The stable inversion technique and a new implicit driver model together form a new concept: inverse dynamic simulation. This technique is demonstrated to be feasible for vehicle propulsion simulation and specifically for three power train applications that include important dynamics that cannot be handled using quasi-static inverse simulation. The extensions are engine dynamics, driveline dynamics, and gas flow dynamics for diesel engines, which are also selected to represent important properties, such as zero dynamics, resonances, and nonminimum-phase systems. It is shown that inverse dynamic simulation is easy to set up, gives short simulation times, and gives consistent results for design space exploration. This makes inverse dynamic simulation a suitable method to use for drive cycle simulation, particularly in situations requiring many simulations, such as optimization over design space, power train configuration optimization, or the development of power train control strategies.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13142 (URN)10.1109/TVT.2007.907310 (DOI)
    Available from: 2008-05-08 Created: 2008-05-08 Last updated: 2017-12-13
    2. Inverse Dynamic Simulation of Non-Quadratic MIMO Powertrain Models -Application to Hybrid Vehicles
    Open this publication in new window or tab >>Inverse Dynamic Simulation of Non-Quadratic MIMO Powertrain Models -Application to Hybrid Vehicles
    2006 (English)In: IEEE Vehicle Power and Propulsion, 2006, p. 1-6Conference paper, Published paper (Refereed)
    Abstract [en]

    The method for stable inversion of nonlinear systems has earlier been demonstrated as an efficient tool in inverse dynamic vehicle propulsion simulation. However, that method is restricted to quadratic systems, i.e. systems with equally many inputs and outputs. Here that restriction is relaxed for typical vehicle propulsion simulation where the number of inputs, e.g. accelerator pedal and brake pedal, are greater than the number of outputs, e.g. vehicle speed. Also restrictions to states and inputs resulting in time varying system order and relative degree is discussed. A model of a parallel hybrid vehicle is used for demonstration.

    Keywords
    MIMO systems, brakes, electric propulsion, hybrid electric vehicles, nonlinear systems, power transmission (mechanical), time-varying systems, accelerator pedal, brake pedal, hybrid vehicles, inverse dynamic vehicle propulsion simulation, nonlinear systems, nonquadratic MIMO powertrain models, parallel hybrid vehicle, quadratic systems, time varying system, vehicle propulsion simulation
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13143 (URN)10.1109/VPPC.2006.364292 (DOI)1-4244-0158-5 (ISBN)
    Available from: 2008-05-08 Created: 2008-05-08 Last updated: 2009-05-14
    3. Controlling Gear Engagement and disengagement on heavy trucks for minimization of fuel consumption
    Open this publication in new window or tab >>Controlling Gear Engagement and disengagement on heavy trucks for minimization of fuel consumption
    2005 (English)In: Proceedings of the 16th IFAC World Congress, 2005Conference paper, Published paper (Refereed)
    Abstract [en]

    There is a potential to save fuel for heavy trucks by storing kineticenergy in the vehicle when driving downhill, because the speed adds kinetic energyto the vehicle which can be used after the downhill slope to propell the vehicle.This behavior can be even more utilized by disengaging the gear to reduce thefriction in the driveline and thus increase the speed even more. Two differentcontrol strategies to choose when to disengage the gear is presented: One schemethat uses instantaneous inclination and one predictive control scheme that useslook ahead information of the road topology. Simulation results show that geardisengagement in downhills can reduce the fuel consumption about 3%.

    Series
    Keywords
    Driveline Control, Dynamic Programming, Model Predictive Control
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13144 (URN)
    Available from: 2008-05-08 Created: 2008-05-08 Last updated: 2009-05-14
    4. A Real-Time Fuel-Optimal Cruise Controller for Heavy Trucks using Road Topography Information
    Open this publication in new window or tab >>A Real-Time Fuel-Optimal Cruise Controller for Heavy Trucks using Road Topography Information
    2006 (English)In: SAE World Congress, 2006Conference paper, Published paper (Refereed)
    Abstract [en]

    New and exciting possibilities in vehicle control are revealed by the consideration of topography, for example through the combination of GPS and three-dimensional road maps. How information about future road slopes can be utilized in a heavy truck is explored. The aim is set at reducing the fuel consumption over a route without increasing the total travel time.

    A model predictive control (MPC) scheme is used to control the longitudinal behavior of the vehicle, which entails determining accelerator and brake levels and also which gear to engage. The optimization is accomplished through discrete dynamic programming. A cost function that weighs fuel use, negative deviations from the reference velocity, velocity changes, gear shifts and brake use is used to define the optimization criterion.

    Computer simulations back and forth on 127 km of a typical highway route in Sweden show that the fuel consumption in a heavy truck can be reduced 2.5% with a negligible change in travel time.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13145 (URN)
    Available from: 2008-05-08 Created: 2008-05-08
    5. Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topograhic Road Profiles
    Open this publication in new window or tab >>Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topograhic Road Profiles
    2006 (English)In: Electronic Engine Controls, SAE World Congress 2006, 2006Conference paper, Published paper (Refereed)
    Abstract [en]

    The problem addressed is how to drive a heavy truck over various road topographies such that the fuel consumption is minimized. Using a realistic model of a truck powertrain, an optimization problem for minimization of fuel consumption is formulated. Through the solutions of this problem optimal speed profiles are found. An advantage here is that explicit analytical solutions can be found, and this is done for a few constructed test roads. The test roads are constructed to be easy enough to enable analytical solutions but still capture the important properties of real roads. In this way the obtained solutions provide explanations to some behavior obtained by ourselves and others using more elaborate modelling and numeric optimization like dynamic programming.

    The results show that for level road and in small gradients the optimal solution is to drive with constant speed. For large gradients in downhill slopes it is optimal to utilize the kinetic energy of the vehicle to accelerate in order to gain speed. This speed increase is used to lower the speed on other road sections such that the total average speed is kept. Taking account for limitations of top speed the optimal speed profile changes to a strategy that minimizes brake usage. This is done by, e.g., slowing down before steep down gradients where the truck will accelerate even though the engine does not produce any torque.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-13146 (URN)978-0-7680-1738-0 (ISBN)
    Available from: 2008-05-08 Created: 2008-05-08 Last updated: 2009-09-14
    6. Optimal Control Utilizing Analytical Solutions for Heavy Truck Cruise Control
    Open this publication in new window or tab >>Optimal Control Utilizing Analytical Solutions for Heavy Truck Cruise Control
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:liu:diva-13147 (URN)
    Available from: 2008-05-08 Created: 2008-05-08 Last updated: 2010-01-13
    Download full text (pdf)
    FULLTEXT01
    Download (pdf)
    COVER01
  • 181.
    Fröberg, Anders
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Extending the inverse vehicle propulsion simulation concept - to improve simulation performance2005Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Drive cycle simulations of longitudinal vehicle models is an important tool for design and analysis of power trains. On the market today there are several tools for such simulations, and these tools use mainly two different methods of simulation, forward dynamic or quasi-static inverse simulation. Forward dynamic simulation is capable of describing the dynamic behavior of a system to a high level of detail, but suffers from long simulation times. On the other hand, quasi-static inverse simulations are very fast, but lack the ability of describing additional dynamics in a good way. Here known theory for stable inversion of non linear systems is used in order to try to combine the fast simulation times of the quasi-static inverse simulation with the ability of describing the dynamics as in the forward dynamic simulation. The stable inversion technique together with a new implicit driver model forms a new concept, inverse dynamic simulation. Using this technique the need to develop dedicated inverse models is reduced, and it is shown that a large class of models that can be simulated in forward dynamic simulation also can be simulated in inverse dynamic simulation. In this respect, three powertrain applications are used that include important dynamics that can not be handled using quasi-static inverse simulation. The extensions are engine dynamics, drive line dynamics, and gas flow dynamics around diesel engines. These three cases also represent interesting mathematical properties such as zero dynamics, resonances, and non-minimum phase systems, i.e. unstable zero dynamics. The inversion technique is demonstrated on all three examples, and the feasibility of inverse dynamic simulation of these systems is shown. Moreover, using the three examples, inverse dynamic simulation is compared to forward dynamic simulation regarding simulation set-up effort, simulation time, and parameter-result dependency. It is shown that inverse dynamic simulation is easy to set up, gives short simulation times, and gives consistent result for design space exploration. This makes inverse dynamic simulation a suitable method to use for drive cycle simulation, and especially in situations requiring many simulations, such as optimization over design space, powertrain configuration optimization, or development of powertrain control strategies.

  • 182.
    Fröberg, Anders
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Inverse Dynamic Simulation of Non-Quadratic MIMO Powertrain Models -Application to Hybrid Vehicles2006In: IEEE Vehicle Power and Propulsion, 2006, p. 1-6Conference paper (Refereed)
    Abstract [en]

    The method for stable inversion of nonlinear systems has earlier been demonstrated as an efficient tool in inverse dynamic vehicle propulsion simulation. However, that method is restricted to quadratic systems, i.e. systems with equally many inputs and outputs. Here that restriction is relaxed for typical vehicle propulsion simulation where the number of inputs, e.g. accelerator pedal and brake pedal, are greater than the number of outputs, e.g. vehicle speed. Also restrictions to states and inputs resulting in time varying system order and relative degree is discussed. A model of a parallel hybrid vehicle is used for demonstration.

  • 183.
    Fröberg, Anders
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Hellström, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topograhic Road Profiles2006In: Electronic Engine Controls, SAE World Congress 2006, 2006Conference paper (Refereed)
    Abstract [en]

    The problem addressed is how to drive a heavy truck over various road topographies such that the fuel consumption is minimized. Using a realistic model of a truck powertrain, an optimization problem for minimization of fuel consumption is formulated. Through the solutions of this problem optimal speed profiles are found. An advantage here is that explicit analytical solutions can be found, and this is done for a few constructed test roads. The test roads are constructed to be easy enough to enable analytical solutions but still capture the important properties of real roads. In this way the obtained solutions provide explanations to some behavior obtained by ourselves and others using more elaborate modelling and numeric optimization like dynamic programming.

    The results show that for level road and in small gradients the optimal solution is to drive with constant speed. For large gradients in downhill slopes it is optimal to utilize the kinetic energy of the vehicle to accelerate in order to gain speed. This speed increase is used to lower the speed on other road sections such that the total average speed is kept. Taking account for limitations of top speed the optimal speed profile changes to a strategy that minimizes brake usage. This is done by, e.g., slowing down before steep down gradients where the truck will accelerate even though the engine does not produce any torque.

  • 184.
    Fröberg, Anders
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Hellström, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topographic Road Profiles2006In: SAE World Congress 2006,2006, SAE , 2006Conference paper (Refereed)
    Abstract [en]

     The problem addressed is how to drive a heavy truck over various road topographies such that the fuel consumption is minimized. Using a realistic model of a truck powertrain, an optimization problem for minimization of fuel consumption is formulated. Through the solutions of this problem optimal speed profiles are found. An advantage here is that explicit analytical solutions can be found, and this is done for a few constructed test roads. The test roads are constructed to be easy enough to enable analytical solutions but still capture the important properties of real roads. In this way the obtained solutions provide explanations to some behaviour obtained by ourselves and others using more elaborate modeling and numeric optimization like dynamic programming. The results show that for level road and in small gradients the optimal solution is to drive with constant speed. For large gradients in downhill slopes it is optimal to utilize the kinetic energy of the vehicle to accelerate in order to gain speed. This speed increase is used to lower the speed on other road sections such that the total average speed is kept. Taking account for limitations of top speed the optimal speed profile changes to a strategy that minimizes brake usage. This is done by e.g. slowing down before steep down gradients were the truck will accelerate even though the engine does not produce any torque.

  • 185.
    Fröberg, Anders
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    A Method to Extend Inverse Dynamic Simulation of Powertrains with Additional Dyanmics2004Conference paper (Refereed)
    Abstract [en]

    Inverse dynamic powertrain simulation, like in Advisor or the QSS-toolbox, has proven to be an efficient and successful approach to simulate vehicles during drive cycles. The approach is based on back-calculation of accelerations and torques from the prescribed velocities in the drive cycle, and the differentiation requirements in this simulation process limits the possibility to include additional states in the powertrain models. The main objective here is to extend the simulation with additional dynamics like e.g. mean value models of the engine. This is achieved using stable inversion of nonlinear systems that can handle such additional dynamics. Computer algebra can be used to perform the necessary model transformations. A key step in obtaining sufficient differentiation properties is to smooth the drive cycle using a kernel with interpretation as an implicit driver model. The proposed method is demonstrated using Mathematica for model transformation and Matlab for simulation.

  • 186.
    Fröberg, Anders
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Dynamic Vehicle Simulation -Forward, Inverse and New Mixed Possibilities for Optimized Design and Control2004In: Modeling Diesel Engines, Multi-Dimensional Engine, and Vehicle and Engine Systems, 2004Conference paper (Refereed)
    Abstract [en]

    Inverse dynamic simulation is a successful method to make fast simulations of powertrains modeled using vehicle velocity and acceleration. This method is here extended so that additional dynamics can be included, and it is compared to the standard/usual forward dynamic simulation. Simulation results show that extended inverse dynamic simulation is a good method for maintaining speed and increasing accuracy in simulations. This gives the possibility to use the inverse dynamic simulation as a tool for powertrain optimization and control strategy evaluation.

  • 187.
    Fröberg, Anders
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Efficient Drive Cycle Simulation2008In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 57, no 3, p. 1442-1453Article in journal (Refereed)
    Abstract [en]

    Drive cycle simulations of longitudinal vehicle models are important aids for the design and analysis of power trains, and tools currently on the market mainly use two different methods for such simulations: the forward dynamic and quasi-static inverse simulations. Here, a known theory for the stable inversion of nonlinear systems is used to combine the fast simulation times of the quasi-static inverse simulation with the ability of the forward dynamic simulation to include transient dynamics. The stable inversion technique and a new implicit driver model together form a new concept: inverse dynamic simulation. This technique is demonstrated to be feasible for vehicle propulsion simulation and specifically for three power train applications that include important dynamics that cannot be handled using quasi-static inverse simulation. The extensions are engine dynamics, driveline dynamics, and gas flow dynamics for diesel engines, which are also selected to represent important properties, such as zero dynamics, resonances, and nonminimum-phase systems. It is shown that inverse dynamic simulation is easy to set up, gives short simulation times, and gives consistent results for design space exploration. This makes inverse dynamic simulation a suitable method to use for drive cycle simulation, particularly in situations requiring many simulations, such as optimization over design space, power train configuration optimization, or the development of power train control strategies.

  • 188.
    Fröberg, Anders
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Optimal fuel and gear ratio control for heavy trucks with piece wise affine engine characteristics2007In: Fifth IFAC symposium on advances in automotive control,2007, IFAC: IFAC , 2007, p. 335-Conference paper (Refereed)
  • 189.
    Fröberg, Anders
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Hedström, Lars-Gunnar
    Scania, Södertälje, Sweden.
    Pettersson, Magnus
    Scania, Södertälje, Sweden.
    Controlling Gear Engagement and disengagement on heavy trucks for minimization of fuel consumption2005In: Proceedings of the 16th IFAC World Congress, 2005Conference paper (Refereed)
    Abstract [en]

    There is a potential to save fuel for heavy trucks by storing kineticenergy in the vehicle when driving downhill, because the speed adds kinetic energyto the vehicle which can be used after the downhill slope to propell the vehicle.This behavior can be even more utilized by disengaging the gear to reduce thefriction in the driveline and thus increase the speed even more. Two differentcontrol strategies to choose when to disengage the gear is presented: One schemethat uses instantaneous inclination and one predictive control scheme that useslook ahead information of the road topology. Simulation results show that geardisengagement in downhills can reduce the fuel consumption about 3%.

  • 190.
    Fu, Jiali
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Uhlin, Erik
    Volvo Construct Equipment, Sweden.
    A Simulation Framework for Off-road Transport Operations using Electric Construction Vehicles2019In: 2019 IEEE INTELLIGENT TRANSPORTATION SYSTEMS CONFERENCE (ITSC), IEEE , 2019, p. 2539-2544Conference paper (Refereed)
    Abstract [en]

    This paper presents a simulation framework for modeling off-road transport operations at construction worksites using electric construction vehicles. A dynamic model is developed to describe the longitudinal behavior of the electric vehicles, and the outputs from the vehicle dynamic model are fed into a fleet model to evaluate the transport efficiency performance. Discrete event simulation technique is used in the fleet model to represent the logistics of the transport operations and capture the interactions among the vehicles and resources. The simulation framework is applied in a real world quarry operation to study the transport efficiency performance using different number of vehicles. The case study shows that the proposed mechanism can effectively allocate the optimal number of vehicles for the operation and hence serve as an efficient tool in decision-making for construction management.

  • 191.
    Garrido Gálvez, Mario
    et al.
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, Faculty of Science & Engineering.
    Andersson, Rikard
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Qureshi, Fahad
    Tampere University of Technology, Finland.
    Gustafsson, Oscar
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, Faculty of Science & Engineering.
    Multiplierless Unity-Gain SDF FFTs2016In: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 24, no 9, p. 3003-3007Article in journal (Refereed)
    Abstract [en]

    In this brief, we propose a novel approach to implement multiplierless unity-gain single-delay feedback fast Fourier transforms (FFTs). Previous methods achieve unity-gain FFTs by using either complex multipliers or nonunity-gain rotators with additional scaling compensation. Conversely, this brief proposes unity-gain FFTs without compensation circuits, even when using nonunity-gain rotators. This is achieved by a joint design of rotators, so that the entire FFT is scaled by a power of two, which is then shifted to unity. This reduces the amount of hardware resources of the FFT architecture, while having high accuracy in the calculations. The proposed approach can be applied to any FFT size, and various designs for different FFT sizes are presented.

    Download full text (pdf)
    fulltext
  • 192.
    Gerhardsson, Daniel
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Starter Motor Protection2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Starter motors are sensitive for overheating. By estimating the temperature and preventing cranking in time, there is an option to avoid the dangerous temperatures. The truck manufacturer Scania CV AB proposed a master thesis that should evaluate the need of an overheating protection for the starter motor.

    The aim is to evaluate any positive effects of implementing an algorithm that can estimate the brush temperature instead of using the available time constrain, which allows 35 seconds of cranking with a following 2 seconds delay, allowing the crank shaft to stop before a new start attempt is allowed. To achieve high load on the starter motor and high temperature in the brushes, tests were performed under −20o Celsius.

    Initial testing on truck, under normal temperatures, showed that the batteries could not run the starter motor long enough to reach high temperatures in the brushes. This is believed to be caused by the voltage drop between the batteries and the starter motor, causing the starter motor to run in an operating area it is not optimized for. There are several other problems which gives a higher load on the engine, for example oil viscosity, resulting in higher currents, but those are not mentioned in this report.

    Three different models are compared, Two State Model, Single State Model and a Time Constrained Model. Tests and verifications show that the Two State Model is superior when it comes to protecting the starter motor from overheating and at the same time maximizing the cranking time. The major difference between the Two State Model and the Single State Model are the cooling characteristics. In the Single State Model the brush temperature drops quickly to the outside temperature while in the Two State Model the brush temperature drops to a second state  temperature instead of the outside temperature. With the currently implemented time constrain it is possible to overheat the starter motor. The algorithms are optimized under cold conditions, due to problems in reaching high temperatures under warmer conditions.

    Download full text (pdf)
    FULLTEXT01
  • 193.
    Germeys, Jasper
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Supervision of the Air Loop in the Columbus Module of the International Space Station2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Failure detection and isolation (FDI) is essential for reliable operations of complex autonomous systems or other systems where continuous observation or maintenance thereof is either very costly or for any other reason not easily accessible.

    Beneficial for the model based FDI is that there is no need for fault data to detect and isolate a fault in contrary to design by data clustering. However, it is limited by the accuracy and complexity of the model used. As models grow more complex, or have multiple interconnections, problems with the traditional methods for FDI emerge.

    The main objective of this thesis is to utilise the automated methodology presented in [Svärd, 2012] to create a model based FDI system for the Columbus air loop. A small but crucial part of the life support on board the European space laboratory Columbus.

    The process of creating a model based FDI, from creation of the model equations, validation thereof to the design of residuals, test quantities and evaluation logic is handled in this work. Although the latter parts only briefly which leaves room for future work.

    This work indicate that the methodology presented is capable to create quite decent model based FDI systems even with poor sensor placement and limited information of the actual design.

    [] Carl Svärd. Methods for Automated Design of Fault Detection and Isolation Systems with Automotive Applications. PhD thesis, Linköping University, Vehicular Systems, The Institute of Technology, 2012

    Download full text (pdf)
    fulltext
  • 194.
    Green, Rickard
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Development of a 2D Optimal Path Simulation for Ship-to-Shore Cranes: Safe Trajectories within Interchangeable Obstalce Environments2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The most advanced ports as of writing of this report are at least somewhat autonomous. Whether discussing the transporters between crane and stack (temporary storage) or cranes, the ports are shifting into a completely autonomous system. This ultimate goal presents a challenge in regards to unloading and loading cargo ships in the harbour. How do you achieve unloading of a ship without human intervention while still guaranteeing secure trajectories for the containers?

    ABB Ports in collaboration with the Division of Vehicular Systems at Linköping University have developed a simulation that utilises a simple control model to investigate the behaviour, limitations and capabilities of such an autonomous crane. Specifically, this simulation utilises a model of the dynamics of a Ship-to-Shore crane (STS), which has the task of unloading a ship. In order to set the crane model in context of realistic scenarios, some additions to the simulation are needed.

    One of these additions is obstacles. Before this thesis work, the model enjoyed an empty simulation environment to freely optimise how quickly the containers could be transported off of the ship. The addition of obstacles in the form of other containers on the cargo ship as well as the physical presence of the crane’s legs presents new challenges for the optimiser used to solve the optimal control problems formulated through the model in the simulation. The implementation of obstacles is one of the objectives for this thesis. This addition was implemented by modeling the obstacle dimensions and ship limitations by looking at the largest container ships in the world.

    Due to the simulation not containing obstacles previous to this thesis work, the initial guess provided to the solver initialised the solving in an area of convergence that is unfair to the solver, This rendered the simulation useless, as any obstacle presented to the solver would generate an infeasible solution.

    Another functionality needed for the obstacle implementation to be meaningful is a solution for guaranteeing safe trajectories for the containers from ship to shore. The solution utilised to reach this goal was to combine a convex hull and safety conditions where the convex hull covers the obstacles, including some padding to prevent collisions between the container carried (load) and obstacles. The safety conditions however calculates the potential positions of the load when an emergency stop occurs, and therefore can prevent the load from swinging into obstacles if there is an emergency stop.

    These implementations however changes the usefulness and performance of the simulation because of how they shrink the area of convergence for the solver and making some problems non-solvable. When considering both a convex hull and safety conditions, the usability of the simulations is harmed, but can still be utilised to learn about autonomous performance of the simulation. The optimal solutions include some interesting characteristics that can learn crane operators about how the control systems can be utilised.

    Such a simulation would benefit from continuous development in order to investigate further technologies and features that could improve both performance and usability. Areas such as homotopy, modelling ropes, comparison between simple and nuanced model would be truly interesting for future areas of investigation.

    Download full text (pdf)
    ricgr658_MSC_REPORT
  • 195.
    Guardiola, C
    et al.
    University of Politecn Valencia, Spain .
    Pla, B
    University of Politecn Valencia, Spain .
    Blanco-Rodriguez, D
    University of Politecn Valencia, Spain .
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    A computationally efficient Kalman filter based estimator for updating look-up tables applied to NOx estimation in diesel engines2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 11, p. 1455-1468Article in journal (Refereed)
    Abstract [en]

    No-x estimation in diesel engines is an up-to-date problem but still some issues need to be solved. Raw sensor signals are not fast enough for real-time use while control-oriented models suffer from drift and aging. A control-oriented gray box model based on engine maps and calibrated off-line is used as benchmark model for No-x estimation. Calibration effort is important and engine data-dependent. This motivates the use of adaptive look-up tables. In addition to, look-up tables are often used in automotive control systems and there is a need for systematic methods that can estimate or update them on-line. For that purpose, Kalman filter (KF) based methods are explored as having the interesting property of tracking estimation error in a covariance matrix. Nevertheless, when coping with large systems, the computational burden is high, in terms of time and memory, compromising its implementation in commercial electronic control units. However look-up table estimation has a structure, that is here exploited to develop a memory and computationally efficient approximation to the KF, named Simplified Kalman filter (SKF). Convergence and robustness is evaluated in simulation and compared to both a full KF and a minimal steady-state version, that neglects the variance information. SKF is used for the online calibration of an adaptive model for No-x estimation in dynamic engine cycles. Prediction results are compared with the ones of the benchmark model and of the other methods. Furthermore, actual online estimation of No-x is solved by means of the proposed adaptive structure. Results on dynamic tests with a diesel engine and the computational study demonstrate the feasibility and capabilities of the method for an implementation in engine control units.

    Download full text (pdf)
    fulltext
  • 196.
    Gustafsson, Fredrik
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Åslund, Jan
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Frisk, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Krysander, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Nielsen, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    On Threshold Optimization in Fault Tolerant Systems2008In: Proceedings of the 17th IFAC World Congress, 2008, p. 7883-7888Conference paper (Refereed)
    Abstract [en]

    Fault tolerant systems are considered, where a nominal system is monitored by a fault detection algorithm, and the nominal system is switched to a backup system in case of a detected fault. Conventional fault detection is in the classical setting a trade-off between detection probability and false alarm probability. For the considered fault tolerant system, a system failure occurs either when the nominal system gets a fault that is not detected, or when the fault detector signals an alarm and the backup system breaks down. This means that the trade-off for threshold setting is different and depends on the overall conditions, and the characterization and understanding of this trade-off is important. It is shown that the probability of system failure can be expressed in a general form based on the probability of false alarm and detection power, and based on this form the influence ratio is introduced. This ratio includes all information about the supervised system and the backup system that is needed for the threshold optimization problem. It is shown that the influence ratio has a geometrical interpretation as the gradient of the receiver operating characteristics (ROC) curve at the optimal point, and furthermore, it is the threshold for the optimal test quantity in important cases.

  • 197.
    Gustafsson, Mikael
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Crank Angle Based Virtual Cylinder Pressure Sensor in Heavy-Duty Engine Application2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The in-cylinder pressure is an important signal that gives information about the combustion process. To further improve engine performance, this information can be used as a feedback signal in a control system. Usually a pressure sensor is mounted in the cylinder to extract this information. A drawback with pressure sensors is that they are expensive and have issues with aging. This master’s thesis investigates the possibility to create a virtual sensor to estimate in-cylinder pressure based on crank angle degree sensor (CAD-sensor) data and physical models of the heavy-duty engine.

    Instead of using the standard mounted CAD-sensor an optical high-precision sensor measures the elapsed time between equidistant angles. Based on this signal the instantaneous angular acceleration was estimated. Together with the inertia of the crankshaft, connecting rods and pistons, an estimation of the engine torque was calculated. To be able to extract in-cylinder pressure from the estimated torque, knowledge about how the in-cylinder pressure signal propagates in the drivetrain to accelerate the flywheel needs to be known. Two engine models based on the torque balance on the crankshaft are presented. The fundamental difference between them is how the crankshaft is modeled, rigid body or spring-mass-damper system. The latter captures torsional effects of the crankshaft. Comparisons between the estimated torque from sensor data and the two engine models are presented. It is found that torsional effects of the crankshaft is present at normal engine speeds and has a significant influence on the flywheel torque.

    A separation of the gas torque contribution from one cylinder is done with CAD-sensor data together with the rigid body engine model. The in-cylinder pressure is then estimated by using the inverse crank-slider function and a Kalman filter estimator. The estimated pressure captures part of the compression and most of the expansion at engine speeds below 1200 RPM. Due to the crank-slider geometry the pressure signal disappears at TDC. The torsional effects perturb the estimated pressure during the gas exchange cycle.

    Further development must be made if this method is to be used on heavy-duty applications in the future.

    Download full text (pdf)
    fulltext
  • 198.
    Hagelin, Henrik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Detection of Critical Events Using Limited Sensors2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Unfortunately, people die and get injured due to accidents in the traffic. Furthermore, statistics of road accidents is limited and mostly composed of serious accidents, making it difficult to draw conclusions about how to improve the safety in the traffic. Thus, there is an interest in obtaining information about critical events in the traffic, i.e. potential accident situations, since they occur much more frequently.

    One way of detecting critical events is to use sensors, such as accelerometers and gyroscopes. As the usage of cellphones with built-in sensors increases, it would be interesting to examine whether these sensors are good enough to detect critical events. This is where the focus of this thesis lies.

    An application that collects data from the cellphone’s built-in accelerometer, gyroscope and GPS was developed and tested. The data was then analysed and compared to data from accurate sensors, represented by a VBOX coupled to an IMU.

    The conclusions made in this thesis are that the sensors in the cellphone perform almost equivalent results compared to the VBOX. It is possible to use data from the sensors in orderto detect critical events.

    Download full text (pdf)
    main
  • 199.
    Hall, Marcus
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Forsberg, David
    Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Reduced Fuel Consumption of Heavy-Duty Vehicles using Pulse and Glide2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The transport sector always strive towards reduced fuel consumption for heavydutyvehicles. One promising control strategy is to use Pulse and Glide. Themethod works by acceleration to a high speed and then glide in neutral gear to alow speed.Two different control strategies and four different glide options were investigated.The two strategies were either to follow the optimal BSFC-line or using optimalcontrol. For each strategy, different velocity spans between the upper and lowervelocity were tested.The results show that the fuel consumption can be reduced up to 8.1 % comparedto a constant speed driving strategy. The fuel consumption was reduced the mostfor lower velocities and if the difference between the upper and lower velocity forthe Pulse and Glide strategy was kept small. The fuel saving can be explaineddue to increased engine efficiency during the pulse. The results also show thatthe difference between the rule-based and optimization based control strategy issmall. It can be concluded that a near-optimal strategy for a heavy-duty vehicleutilizing Pulse and Glide is to always pulse on the optimal BSFC-line.

    Download full text (pdf)
    fulltext
  • 200.
    Hallqvist, Joakim
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Faster Locking Differential Through Active Brake-Control2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When a vehicle with wheels aligned in pairs turn, the wheel traveling around the outside of the curve has to roll farther than the wheel on the inside. This means that some sort of device must must be used to allow the drive wheels to rotate at different speeds to prevent wear on the tires. This is usually a mechanical device where the input rotation controls the sum of the two output rotations, this is known as a differential. This solution however has some shortcomings, the biggest one is that the total amount of force that can be transferred between the tires and the road surface is limited by the tire with the least traction. In slippery conditions this can be a big problem since it only takes one wheel to lose traction in order to prevent the vehicle from accelerating. In this thesis a locking differential is used to overcome this shortcoming, this gives the driver the option to lock the shafts of the driving wheels together. This is done by pushing two cogwheels, one attached to each shaft, together. The aim of this thesis is to shorten the lock- and unlock-time of the locking differential by aligning the cogwheels using the service brakes and available sensors. The results were evaluated by implementing the software in a truck and doing test runs on Scanias test track. These tests showed that the system greatly improved both lock- and unlock-times but at cost of lower driver comfort. With additional work with some fine tuning of the system, the overall performance could probably be increased even more.

    Download full text (pdf)
    fulltext
1234567 151 - 200 of 650
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf