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  • 151.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Bregon, Anibal
    University of Valladolid, Spain .
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    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 Constraints2012Inngår i: IEEE transactions on systems, man and cybernetics. Part A. Systems and humans, ISSN 1083-4427, E-ISSN 1558-2426, Vol. 42, nr 5, s. 1216-1229Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 152.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Dustegör, Dilek
    LAIL Universite des Sciences et Technologies de Lille.
    Krysander, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    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 problem2003Inngår i: IFAC Safeprocess03,2003, Washington D.C., USA, 2003Konferansepaper (Fagfellevurdert)
    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.

  • 153.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    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 engine2008Inngår i: IFAC World Congress,2008, Seoul, Korea: IFAC , 2008Konferansepaper (Fagfellevurdert)
  • 154.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Krysander, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Leakage Detection In a Fuel Evaporative System2008Inngår i: IFAC World Congress,2008, Seoul, Korea: IFAC , 2008Konferansepaper (Fagfellevurdert)
    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.

  • 155.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Residual Selection for Consistency Based Diagnosis Using Machine Learning Models2018Inngår i: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2018, Vol. 51, nr 24, s. 139-146Konferansepaper (Fagfellevurdert)
    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.

  • 156.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Krysander, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Sensor placement for maximum fault isolability2007Inngår i: 18th International Workshop on Principles of Diagnosis,2007, Nashville, USA, 2007, s. 106-113Konferansepaper (Fagfellevurdert)
    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.

  • 157.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Treatment of accumulative variables in data-driven prognostics of lead-acid batteries2015Inngår i: Proceedings of the 9th IFAC Symposium on Fault Detection, Supervision and Safety of Technical Processes Safeprocess'15, Elsevier, 2015, Vol. 48, nr 21, s. 105-112Konferansepaper (Fagfellevurdert)
    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.

  • 158.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Jung, Daniel
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    A Toolbox for Analysis and Design of Model Based Diagnosis Systems for Large Scale Models2017Inngår i: IFAC PAPERSONLINE, ELSEVIER SCIENCE BV , 2017, Vol. 50, nr 1, s. 3287-3293Konferansepaper (Fagfellevurdert)
    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.

  • 159.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Larsson, Emil
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Data-driven Lead-Acide Battery Prognostics Using Random Survival Forests2014Inngår i: 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, s. 92-101Konferansepaper (Fagfellevurdert)
    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.

  • 160.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Krysander, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nyberg, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    A toolbox for design of diagnosis systems2006Inngår i: IFAC Safeprocess06,2006, Beijing, China: IFAC , 2006, s. 703-Konferansepaper (Fagfellevurdert)
    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.

  • 161.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Analysis and Design of Diagnosis Systems Based on the Structural Differential Index2017Inngår i: 20th IFAC World Congress, ELSEVIER SCIENCE BV , 2017, Vol. 50, nr 1, s. 12236-12242Konferansepaper (Fagfellevurdert)
    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.

  • 162.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Sensor placement for fault isolation in linear differential-algebraic systems2009Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 45, nr 2, s. 364-371Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 163.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Robust Residual Generation for Diagnosis Including a Reference Model for Residual Behavior1999Inngår i: IFAC World Congress,1999, 1999Konferansepaper (Fagfellevurdert)
  • 164.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Robust Residual Generation for Diagnosis Including a Reference Model for Residual Behavior2006Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 42, nr 3, s. 437-445Artikkel i tidsskrift (Fagfellevurdert)
  • 165.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nyberg, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    A Minimal Polynomial Basis Approach to Residual Generation for Linear Systems1998Inngår i: First Conference on Computer Science and Systems Engineering in Linköping, 1998, s. 223-237Konferansepaper (Fagfellevurdert)
  • 166.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nyberg, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik.
    A minimal polynomial basis solution to residual generation for fault diagnosis in linear systems2001Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 37, nr 9, s. 1417-1424Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 167.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nyberg, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Residual Generation for Fault Diagnosis of Systems Described by General Linear Differential-algebraic Equations2002Inngår i: IFAC World Congress,2002, 2002Konferansepaper (Fagfellevurdert)
  • 168.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nyberg, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Residual Generation for Fault Diagnosis of Systems Described by General Linear Differential-Algebraic Equations (revised)2005Rapport (Annet vitenskapelig)
    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.

  • 169.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nyberg, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Using Minimal Polynomial Bases for Fault Diagnosis1999Inngår i: European Control Conference,1999, 1999Konferansepaper (Fagfellevurdert)
  • 170.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Nyberg, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Using Minimal Polynomial Bases for Model-Based Fault Diagnosis: A Demonstration Document for PolyX, Ltd1999Rapport (Annet vitenskapelig)
    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.

  • 171.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nyberg, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    FDI with adaptive residual generation applied to a DC-servo1997Inngår i: IFAC Safeprocess,1997, Hull: IFAC , 1997Konferansepaper (Fagfellevurdert)
  • 172.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    An observer for semi-explicit differential-algebraic systems2005Inngår i: IFAC World Congress,2005, Prague, Czech Republic: IFAC , 2005Konferansepaper (Fagfellevurdert)
  • 173.
    Frisk, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Lowering Orders of Derivatives in Non-linear Consistency Relations: Theory and Simulation Examples2003Rapport (Annet vitenskapelig)
    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.

  • 174.
    Frisk, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Lowering Orders of Derivatives in Non-linear Residual Generation using Realization Theory2005Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 41, nr 10, s. 1799-1807Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 175.
    Fröberg, Anders
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Efficient Simulation and Optimal Control for Vehicle Propulsion2008Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

    Delarbeid
    1. Efficient Drive Cycle Simulation
    Åpne denne publikasjonen i ny fane eller vindu >>Efficient Drive Cycle Simulation
    2008 (engelsk)Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 57, nr 3, s. 1442-1453Artikkel i tidsskrift (Fagfellevurdert) 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.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13142 (URN)10.1109/TVT.2007.907310 (DOI)
    Tilgjengelig fra: 2008-05-08 Laget: 2008-05-08 Sist oppdatert: 2017-12-13
    2. Inverse Dynamic Simulation of Non-Quadratic MIMO Powertrain Models -Application to Hybrid Vehicles
    Åpne denne publikasjonen i ny fane eller vindu >>Inverse Dynamic Simulation of Non-Quadratic MIMO Powertrain Models -Application to Hybrid Vehicles
    2006 (engelsk)Inngår i: IEEE Vehicle Power and Propulsion, 2006, s. 1-6Konferansepaper, Publicerat paper (Fagfellevurdert)
    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.

    Emneord
    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
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13143 (URN)10.1109/VPPC.2006.364292 (DOI)1-4244-0158-5 (ISBN)
    Tilgjengelig fra: 2008-05-08 Laget: 2008-05-08 Sist oppdatert: 2009-05-14
    3. Controlling Gear Engagement and disengagement on heavy trucks for minimization of fuel consumption
    Åpne denne publikasjonen i ny fane eller vindu >>Controlling Gear Engagement and disengagement on heavy trucks for minimization of fuel consumption
    2005 (engelsk)Inngår i: Proceedings of the 16th IFAC World Congress, 2005Konferansepaper, Publicerat paper (Fagfellevurdert)
    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%.

    Serie
    Emneord
    Driveline Control, Dynamic Programming, Model Predictive Control
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13144 (URN)
    Tilgjengelig fra: 2008-05-08 Laget: 2008-05-08 Sist oppdatert: 2009-05-14
    4. A Real-Time Fuel-Optimal Cruise Controller for Heavy Trucks using Road Topography Information
    Åpne denne publikasjonen i ny fane eller vindu >>A Real-Time Fuel-Optimal Cruise Controller for Heavy Trucks using Road Topography Information
    2006 (engelsk)Inngår i: SAE World Congress, 2006Konferansepaper, Publicerat paper (Fagfellevurdert)
    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.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13145 (URN)
    Tilgjengelig fra: 2008-05-08 Laget: 2008-05-08
    5. Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topograhic Road Profiles
    Åpne denne publikasjonen i ny fane eller vindu >>Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topograhic Road Profiles
    2006 (engelsk)Inngår i: Electronic Engine Controls, SAE World Congress 2006, 2006Konferansepaper, Publicerat paper (Fagfellevurdert)
    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.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13146 (URN)978-0-7680-1738-0 (ISBN)
    Tilgjengelig fra: 2008-05-08 Laget: 2008-05-08 Sist oppdatert: 2009-09-14
    6. Optimal Control Utilizing Analytical Solutions for Heavy Truck Cruise Control
    Åpne denne publikasjonen i ny fane eller vindu >>Optimal Control Utilizing Analytical Solutions for Heavy Truck Cruise Control
    Manuskript (Annet vitenskapelig)
    Identifikatorer
    urn:nbn:se:liu:diva-13147 (URN)
    Tilgjengelig fra: 2008-05-08 Laget: 2008-05-08 Sist oppdatert: 2010-01-13
  • 176.
    Fröberg, Anders
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Extending the inverse vehicle propulsion simulation concept - to improve simulation performance2005Licentiatavhandling, monografi (Annet vitenskapelig)
    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.

  • 177.
    Fröberg, Anders
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Inverse Dynamic Simulation of Non-Quadratic MIMO Powertrain Models -Application to Hybrid Vehicles2006Inngår i: IEEE Vehicle Power and Propulsion, 2006, s. 1-6Konferansepaper (Fagfellevurdert)
    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.

  • 178.
    Fröberg, Anders
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Hellström, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topograhic Road Profiles2006Inngår i: Electronic Engine Controls, SAE World Congress 2006, 2006Konferansepaper (Fagfellevurdert)
    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.

  • 179.
    Fröberg, Anders
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Hellström, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Explicit Fuel Optimal Speed Profiles for Heavy Trucks on a Set of Topographic Road Profiles2006Inngår i: SAE World Congress 2006,2006, SAE , 2006Konferansepaper (Fagfellevurdert)
    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.

  • 180.
    Fröberg, Anders
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    A Method to Extend Inverse Dynamic Simulation of Powertrains with Additional Dyanmics2004Konferansepaper (Fagfellevurdert)
    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.

  • 181.
    Fröberg, Anders
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Dynamic Vehicle Simulation -Forward, Inverse and New Mixed Possibilities for Optimized Design and Control2004Inngår i: Modeling Diesel Engines, Multi-Dimensional Engine, and Vehicle and Engine Systems, 2004Konferansepaper (Fagfellevurdert)
    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.

  • 182.
    Fröberg, Anders
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Efficient Drive Cycle Simulation2008Inngår i: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 57, nr 3, s. 1442-1453Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 183.
    Fröberg, Anders
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Optimal fuel and gear ratio control for heavy trucks with piece wise affine engine characteristics2007Inngår i: Fifth IFAC symposium on advances in automotive control,2007, IFAC: IFAC , 2007, s. 335-Konferansepaper (Fagfellevurdert)
  • 184.
    Fröberg, Anders
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Hedström, Lars-Gunnar
    Scania, Södertälje, Sweden.
    Pettersson, Magnus
    Scania, Södertälje, Sweden.
    Controlling Gear Engagement and disengagement on heavy trucks for minimization of fuel consumption2005Inngår i: Proceedings of the 16th IFAC World Congress, 2005Konferansepaper (Fagfellevurdert)
    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%.

  • 185.
    Garrido Gálvez, Mario
    et al.
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Andersson, Rikard
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Qureshi, Fahad
    Tampere University of Technology, Finland.
    Gustafsson, Oscar
    Linköpings universitet, Institutionen för systemteknik, Datorteknik. Linköpings universitet, Tekniska fakulteten.
    Multiplierless Unity-Gain SDF FFTs2016Inngår i: IEEE Transactions on Very Large Scale Integration (vlsi) Systems, ISSN 1063-8210, E-ISSN 1557-9999, Vol. 24, nr 9, s. 3003-3007Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 186.
    Gerhardsson, Daniel
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Starter Motor Protection2010Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    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.

  • 187.
    Germeys, Jasper
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Supervision of the Air Loop in the Columbus Module of the International Space Station2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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

  • 188.
    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
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    A computationally efficient Kalman filter based estimator for updating look-up tables applied to NOx estimation in diesel engines2013Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, nr 11, s. 1455-1468Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 189.
    Gustafsson, Fredrik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Frisk, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Krysander, Mattias
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    On Threshold Optimization in Fault Tolerant Systems2008Inngår i: Proceedings of the 17th IFAC World Congress, 2008, s. 7883-7888Konferansepaper (Fagfellevurdert)
    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.

  • 190.
    Gustafsson, Mikael
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Crank Angle Based Virtual Cylinder Pressure Sensor in Heavy-Duty Engine Application2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

  • 191.
    Hagelin, Henrik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Detection of Critical Events Using Limited Sensors2012Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    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.

  • 192.
    Hall, Marcus
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Forsberg, David
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Reduced Fuel Consumption of Heavy-Duty Vehicles using Pulse and Glide2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

  • 193.
    Hallqvist, Joakim
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska fakulteten.
    Faster Locking Differential Through Active Brake-Control2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    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.

  • 194.
    Hebib, Jasmina
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Dam, Sofie
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Vehicle Dynamic Models for Virtual Testing of Autonomous Trucks2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The simulator in a testing environment for trucks is dependent on accurate vehicle dynamic models. There are multiple models at Volvo, all developed to support the objectives of individual research. A selection of four, named Single Track model (STM), Global Simulation Platform (GSP), One-Track Model with linear slip (OTM) and Volvo Transport Model (VTM), are evaluated to examine the usage of them. Four different scenarios are therefore generated to emulate common situations in traffic. Depending on the results, the models and their corresponding limitsforusagearedescribed. Theevaluationismadebycomparingallmodelsto the best model for each scenario by measuring the normalized error distribution. It is shown that at certain thresholds, other models can perform close enough to the best model. In the end of the report, future improvements for the evaluated models and external models are suggested.

  • 195.
    Heintz, Fredrik
    et al.
    Linköpings universitet, Institutionen för datavetenskap. Linköpings universitet, Tekniska högskolan.
    Krysander, Mattias
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Roll, Jacob
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Frisk, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    FlexDx: A Reconfigurable Diagnosis Framework2008Inngår i: Proceedings of the 19th International Workshop on Principles of Diagnosis (DX), 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Detecting and isolating multiple faults is a computationally intense task which typically consists of computing a set of tests, and then computing the diagnoses based on the test results. This paper describes FlexDx, a reconfigurable diagnosis framework which reduces the computational burden by only running the tests that are currently needed. The method selects tests such that the isolation performance of the diagnostic system is maintained. Special attention is given to the practical issues introduced by a reconfigurable diagnosis framework such as FlexDx. For example, tests are added and removed dynamically, tests are partially performed on historic data, and synchronous and asynchronous processing are combined. To handle these issues FlexDx uses DyKnow, a stream-based knowledge processing middleware framework. The approach is exemplified on a relatively small dynamical system, which still illustrates the computational gain with the proposed approach.

  • 196.
    Hellström, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Look-ahead Control of Heavy Trucks utilizing Road Topography2007Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The power to mass ratio of a heavy truck causes even moderate slopes to have a significant influence on the motion. The velocity will inevitable vary within an interval that is primarily determined by the ratio and the road topography. If further variations are actuated by a controller, there is a potential to lower the fuel consumption by taking the upcoming topography into account. This possibility is explored through theoretical and simulation studies as well as experiments in this work.

    Look-ahead control is a predictive strategy that repeatedly solves an optimization problem online by means of a tailored dynamic programming algorithm. The scenario in this work is a drive mission for a heavy diesel truck where the route is known. It is assumed that there is road data on-board and that the current heading is known. A look-ahead controller is then developed to minimize fuel consumption and trip time.

    The look-ahead control is realized and evaluated in a demonstrator vehicle and further studied in simulations. In the prototype demonstration, information about the road slope ahead is extracted from an on-board database in combination with a GPS unit. The algorithm calculates the optimal velocity trajectory online and feeds the conventional cruise controller with new set points. The results from the experiments and simulations confirm that look-ahead control reduces the fuel consumption without increasing the travel time. Also, the number of gear shifts is reduced. Drivers and passengers that have participated in tests and demonstrations have perceived the vehicle behavior as comfortable and natural.

  • 197.
    Hellström, Erik
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Look-ahead Control of Heavy Vehicles2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Trucks are responsible for the major part of inland freight and so, they are a backbone of the modern economy but they are also a large consumer of energy. In this context, a dominating vehicle is a truck with heavy load on a long trip. The aim with look-ahead control is to reduce the energy consumption of heavy vehicles by utilizing information about future conditions focusing on the road topography ahead of the vehicle.

    The possible gains with look-ahead control are evaluated by performing experiments with a truck on highway. A real-time control system based on receding horizon control (RHC) is set up where the optimization problem is solved repeatedly on-line for a certain horizon ahead of the vehicle. The experimental results show that significant reductions of the fuel consumption are achieved, and that the controller structure, where the algorithm calculates set points fed to lower level controllers, has satisfactory robustness to perform well on-board in a real environment. Moreover, the controller behavior has the preferred property of being intuitive, and the behavior is perceived as comfortable and natural by participating drivers and passengers.

    A well-behaved and efficient algorithm is developed, based on dynamic programing, for the mixed-integer nonlinear minimum-fuel problem. A modeling framework is formulated where special attention is given to properly include gear shifting with physical models. Fuel equivalents are used to reformulate the problem into a tractable form and to construct a residual cost enabling the use of a shorter horizon ahead of the vehicle. Analysis of errors due to discretization of the continuous dynamics and due to interpolation shows that an energy formulation is beneficial for reducing both error sources. The result is an algorithm giving accurate solutions with low computational effort for use in an on-board controller for a fuel-optimal velocity profile and gear selection.

    The prevailing approach for the look-ahead problem is RHC where main topics are the approximation of the residual cost and the choice of the horizon length. These two topics are given a thorough investigation independent of the method of solving the optimal control problem in each time step. The basis for the fuel equivalents and the residual cost is formed from physical intuition as well as mathematical interpretations in terms of the Lagrange multipliers used in optimization theory. Measures for suboptimality are introduced that enables choosing horizon length with the appropriate compromise between fuel consumption and trip time.

    Control of a hybrid electric powertrain is put in the framework together with control of velocity and gear. For an efficient solution of the minimum-fuel problem in this case, more fuel equivalence factors and an energy formulation are employed. An application is demonstrated in a design study where it is shown how the optimal trade-off between size and capacity of the electrical system depends on road characteristics, and also that a modestly sized electrical system achieves most of the gain.

    The contributions develop algorithms, create associated design tools, and carry out experiments. Altogether, a feasible framework is achieved that pave the way for on-board fuel-optimal look-ahead control.

    Delarbeid
    1. Look-ahead control for heavy trucks to minimize trip time and fuel consumption
    Åpne denne publikasjonen i ny fane eller vindu >>Look-ahead control for heavy trucks to minimize trip time and fuel consumption
    2009 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, nr 2, s. 245-254Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The scenario studied is a drive mission for a heavy diesel truck. With aid of an on board road slope database in combination with a GPS unit, information about the road geometry ahead is extracted. This look-ahead information is used in an optimization of the velocity trajectory with respect to a criterion formulation that weighs trip time and fuel consumption. A dynamic programming algorithm is devised and used in a predictive control scheme by constantly feeding the conventional cruise controller with new set points. The algorithm is evaluated with a real truck on a highway, and the experimental results show that the fuel consumption is significantly reduced.

    Emneord
    predictive control, dynamic programming, fuel-optimal control
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-16629 (URN)10.1016/j.conengprac.2008.07.005 (DOI)
    Prosjekter
    CADICS
    Merknad

    Original Publication: Erik Hellström, Maria Ivarsson, Jan Åslund and Lars Nielsen, Look-ahead control for heavy trucks to minimize trip time and fuel consumption, 2009, Control Engineering Practice, (17), 2, 245-254. http://dx.doi.org/10.1016/j.conengprac.2008.07.005 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/

    Tilgjengelig fra: 2009-02-08 Laget: 2009-02-06 Sist oppdatert: 2018-01-13
    2. Design of an efficient algorithm for fuel-optimal look-ahead control
    Åpne denne publikasjonen i ny fane eller vindu >>Design of an efficient algorithm for fuel-optimal look-ahead control
    2010 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 18, nr 11, s. 1318-1327Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    A fuel-optimal control algorithm is developed for a heavy diesel truck that utilizes information about the road topography ahead of the vehicle when the route is known. A prediction model is formulated where special attention is given to properly include gear shifting. The aim is an algorithm with sufficiently low computational complexity. To this end, a dynamic programming algorithm is tailored, and complexity and numerical errors are analyzed. It is shown that it is beneficial to formulate the problem in terms of kinetic energy in order to avoid oscillating solutions and to reduce linear interpolation errors. A residual cost is derived from engine and driveline characteristics. The result is an on-board controller for an optimal velocity profile and gear selection.

    sted, utgiver, år, opplag, sider
    Elsevier, 2010
    Emneord
    automotive control, long haulage truck, dynamic programming, predictive control
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-54917 (URN)10.1016/j.conengprac.2009.12.008 (DOI)000284670800009 ()
    Prosjekter
    CADICS
    Merknad

    Original Publication: Erik Hellström, Jan Åslund and Lars Nielsen, Design of an efficient algorithm for fuel-optimal look-ahead control, 2010, Control Engineering Practice. http://dx.doi.org/10.1016/j.conengprac.2009.12.008 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/

    Tilgjengelig fra: 2010-04-22 Laget: 2010-04-21 Sist oppdatert: 2018-01-12
    3. Horizon length and fuel equivalents for fuel-optimal look-ahead control
    Åpne denne publikasjonen i ny fane eller vindu >>Horizon length and fuel equivalents for fuel-optimal look-ahead control
    2010 (engelsk)Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Recent studies from several authors show that it is possible to lower the fuel consumption for heavy trucks by utilizing information about the road topography ahead of the vehicle. The approach in these studies is receding horizon control where horizon length and residual cost are main topics. To approach these topics, fuel equivalents previously introduced based on physical intuition are given a mathematical interpretation in terms of Lagrange multipliers. Measures for the suboptimality, caused by the truncated horizon and the residual cost approximation, are defined and evaluated for different routes and parameters.

    Emneord
    automotive control, intelligent cruise control, multipliers, predictive control
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-54920 (URN)10.3182/20100712-3-DE-2013.00114 (DOI)978-390266172-2 (ISBN)
    Konferanse
    6th IFAC Symposium Advances in Automatic Control, 12 - 14 July, Munich, Germany
    Merknad

    Original Publication: Erik Hellström, Jan Åslund and Lars Nielsen, Horizon length and fuel equivalents for fuel-optimal look-ahead control, 2010, 6th IFAC Symposium Advances in Automatic Control. Copyright: INTERNATIONAL FEDERATION OF AUTOMATIC CONTROL IFAC.

    Tilgjengelig fra: 2010-04-22 Laget: 2010-04-22 Sist oppdatert: 2018-01-12
    4. Management of kinetic and electric energy in heavy trucks
    Åpne denne publikasjonen i ny fane eller vindu >>Management of kinetic and electric energy in heavy trucks
    2010 (engelsk)Inngår i: Transmission and Driveline, 2010, SAE International , 2010Konferansepaper, Publicerat paper (Fagfellevurdert)
    Abstract [en]

    Hybridization and velocity management are two important techniques for energy efficiency that mainly have been treated separately. Here they are put in a common framework that from the hybridization perspective can be seen as an extension of the equivalence factor idea in the well known strategy ECMS. From the perspective of look-ahead control, the extension is that energy can be stored not only in kinetic energy, but also electrically. The key idea is to introduce more equivalence factors in a way that enables efficient computations, but also so that the equivalence factors have a physical interpretation. The latter fact makes it easy to formulate a good residual cost to be used at the end of the look-ahead horizon. The formulation has different possible uses, but it is here applied on an evaluation of the size of the electrical system. Previous such studies, for e.g. ECMS, have typically used a driving cycle, i.e. a fixed velocity profile, but here the extra freedom to choose an optimal driving pattern is added.

    sted, utgiver, år, opplag, sider
    SAE International, 2010
    Emneord
    automotive control, predictive control, fuel-optimal control, hybrid electric vehicles, energy management
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-54921 (URN)10.4271/2010-01-1314 (DOI)978-0-7680-3425-7 (ISBN)
    Konferanse
    SAE 2010 World Congress & Exhibition, April 2010, Detroit, MI, USA, Session: Transmission and Driveline: Hybrid
    Prosjekter
    CADICS
    Tilgjengelig fra: 2010-04-22 Laget: 2010-04-22 Sist oppdatert: 2018-01-12
  • 198.
    Hellström, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Fröberg, Anders
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    A Real-Time Fuel-Optimal Cruise Controller for Heavy Trucks using Road Topography Information2006Inngår i: SAE World Congress, 2006Konferansepaper (Fagfellevurdert)
    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.

  • 199.
    Hellström, Erik
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Ivarsson, Maria
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Åslund, Jan
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Nielsen, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för systemteknik, Fordonssystem.
    Look-ahead Control for Heavy Trucks to minimize Trip Time and Fuel Consumption2007Inngår i: Fifth IFAC Symposium on Advances in Automotive Control,2007, 2007Konferansepaper (Fagfellevurdert)
  • 200.
    Hellström, Erik
    et al.
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Ivarsson, Maria
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Åslund, Jan
    Linköpings universitet, Institutionen för systemteknik, Fordonssystem. Linköpings universitet, Tekniska högskolan.
    Nielsen, Lars
    Linköpings universitet, Institutionen för systemteknik. Linköpings universitet, Tekniska högskolan.
    Look-ahead control for heavy trucks to minimize trip time and fuel consumption2009Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, nr 2, s. 245-254Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The scenario studied is a drive mission for a heavy diesel truck. With aid of an on board road slope database in combination with a GPS unit, information about the road geometry ahead is extracted. This look-ahead information is used in an optimization of the velocity trajectory with respect to a criterion formulation that weighs trip time and fuel consumption. A dynamic programming algorithm is devised and used in a predictive control scheme by constantly feeding the conventional cruise controller with new set points. The algorithm is evaluated with a real truck on a highway, and the experimental results show that the fuel consumption is significantly reduced.

1234567 151 - 200 of 624
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