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  • 1.
    Alegret, Guillem
    et al.
    MAN Diesel & Turbo, Copenhagen, Denmark.
    Llamas, Xavier
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Vejlgaard-Laursen, Morten
    MAN Diesel & Turbo, Copenhagen, Denmark.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Modeling of a Large Marine Two-Stroke Diesel Engine with Cylinder Bypass Valve and EGR System2015In: 10th IFAC Conference on Manoeuvring and Control of Marine Craft MCMC 2015: Copenhagen, 24–26 August 2015 / [ed] Roberto Galeazzi and Mogens Blanke, IFAC Papers Online, 2015, Vol. 48, p. 273-278Conference paper (Refereed)
    Abstract [en]

    A nonlinear mean value engine model (MVEM) of a two-stroke turbocharged marine diesel engine is developed, parameterized and validated against measurement data. The goal is to have a computationally fast and accurate engine model that captures the main dynamics and can be used in the development of control systems for the newly introduced EGR system. The tuning procedure used is explained, and the result is a six-state MVEM with seven control inputs that capture the main system dynamics.

  • 2.
    Andersson, Ingemar
    et al.
    Chalmers.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    A Parametric Model for Ionization Current in a Four Stroke SI Engine2009In: JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME, ISSN 0022-0434, Vol. 131, no 2, p. 021001-Article in journal (Refereed)
    Abstract [en]

    A model for the thermal part of an ionization signal is presented that connects the ionization current to cylinder pressure and temperature in a spark ignited internal combustion engine. One strength of the model is that, after calibration, it has only two free parameters: burn angle and initial kernel temperature. By fitting the model to a measured ionization signal, it is possible to estimate both cylinder pressure and temperature, where the pressure is estimated with good accuracy. The model approach is validated on engine data. Cylinder pressure and ionization current data were collected on a Saab four-cylinder spark ignited engine for a variation in ignition timing and air-fuel ratio. The main result is that the parametrized ionization current model can be used to estimating combustion properties as pressure, temperature, and content of nitric oxides based on measured ionization currents. The current status of the model is suitable for off-line analysis of ionization currents and cylinder pressure. This ionization current model not only describes the connection between the ionization current and the combustion process, but also offers new possibilities for engine management system to control the internal combustion engine.

  • 3.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Air-to-Cylinder Observer on a Turbocharged SI-Engine with Wastegate2001Conference paper (Refereed)
    Abstract [en]

    Observers for air mass flow to the cylinder is studied on a turbocharged SI-engine with wastegate. A position change of the wastegate influences the residual gas mass and causes the volumetric efficiency to change, which produces a transient in the air mass flow to the cylinder. Two standard methods of estimating air-to-cylinder are investigated. A new nonlinear air-to-cylinder observer is suggested with two states: one for intake manifold pressure and one for the offset in in-cylinder air mass compared to expected through the volumetric efficiency. The observers are validated on intake manifold pressure data from a turbocharged spark ignited production engine with wastegate.

  • 4.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Cylinder Air Charge Estimator in Turbocharged SI-Engines2004Conference paper (Refereed)
  • 5.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Detection of Exhaust Manifold Leaks on a Turbocharged SI-engine with Wastegate2002Conference paper (Refereed)
  • 6.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Exhaust Manifold Pressure Estimation on a Turbocharged SI-engine with Wastegate2001Conference paper (Refereed)
  • 7.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Mean-value Observer for a Turbocharged SI-engine2004Conference paper (Refereed)
  • 8.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Observer Based Feedforward Air-Fuel Control of Turbocharged SI-Engines2005In: Proceedings of 16th Triennial World Congress, Prague, Czech Republic, IFAC Papers Online, 2005, Vol. 38, p. 200-205Conference paper (Refereed)
    Abstract [en]

    Air-fuel control on turbocharged (TC) SI-engines require precise prediction of the cylinder air-charge (CAC). Using an observer it is possible to both estimate the necessary system states and to provide a framework to design the necessary CAC feedforward controller. Here a mean value engine model of a TC SI-engine is used to develop an observer. The output of the observer is fed as an initial condition to a predictor which is used for feedforward of the CAC for air-fuel control. The resulting controller is experimentally validated on a SAAB 2.0 dm3 TC engine using tip-in and tip-out transients. The results show that the excursions in Λ are less than 5%

  • 9.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Three Way Catalyst Control using PI-style Controller with HEGO Sensor Feedback2002Conference paper (Refereed)
  • 10.
    Andersson, Per
    et al.
    Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering.
    Modeling and Architecture Examples of Model Based Engine Control1999Conference paper (Refereed)
  • 11.
    Andersson, Per
    et al.
    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.
    Eriksson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Sensor Selection for Observer Feedback in Turbocharged Spark Ignited Engines2005Conference paper (Refereed)
  • 12.
    Bachmann, Bernhard
    et al.
    Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
    Ochel, Lennart
    Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
    Ruge, Vitalij
    Dept. Mathematics and Engineering, University of Applied Sciences, Bielefeld, Germany.
    Gebremedhin, Mahder
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Fritzson, Peter
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Computer and Information Science, PELAB - Programming Environment Laboratory.
    Nezhadali, Vaheed
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Sivertsson, Martin
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Parallel Multiple-Shooting and Collocation Optimization with OpenModelica2012In: Proceedings of the 9th International MODELICA Conference; September 3-5; 2012; Munich; Germany, Linköping University Electronic Press, 2012, p. 659-668, article id 067Conference paper (Refereed)
    Abstract [en]

    Nonlinear model predictive control (NMPC) has become increasingly important for today’s control engineers during the last decade. In order to apply NMPC a nonlinear optimal control problem (NOCP) must be solved which needs a high computational effort.

    State-of-the-art solution algorithms are based on multiple shooting or collocation algorithms; which are required to solve the underlying dynamic model formulation. This paper describes a general discretization scheme applied to the dynamic model description which can be further concretized to reproduce the mul-tiple shooting or collocation approach. Furthermore; this approach can be refined to represent a total collocation method in order to solve the underlying NOCP much more efficiently. Further speedup of optimization has been achieved by parallelizing the calculation of model specific parts (e.g. constraints; Jacobians; etc.) and is presented in the coming sections.

    The corresponding discretized optimization problem has been solved by the interior optimizer Ipopt. The proposed parallelized algorithms have been tested on different applications. As industrial relevant application an optimal control of a Diesel-Electric power train has been investigated. The modeling and problem description has been done in Optimica and Modelica. The simulation has been performed using OpenModelica. Speedup curves for parallel execution are presented.

  • 13.
    Broomhead, Timothy James
    et al.
    Department of Mechanical Engineering, The University of Melbourne, Australia.
    Manzie, Chris
    Department of Mechanical Engineering, The University of Melbourne, Australia.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Brear, Michael
    Department of Mechanical Engineering, The University of Melbourne, Australia.
    Hield, Peter
    Defence Science and Technology Organisation, Australia.
    A Robust Model Predictive Control Framework for Diesel Generators2014In: Proceedings of 19th IFAC World Congress / [ed] Edward Boje; Xiaohua Xia, International Federation of Automatic Control (IFAC) , 2014, Vol. 47, p. 11848-11853Conference paper (Refereed)
    Abstract [en]

    A constraint tightened linear-time-varying MPC framework is proposed with applications in power tracking for variable and fixed speed generators. Current constraint tightening approaches are extended to allow for practical applications where future system representations are unknown. The resulting control structure is shown to be robustly feasible under given conditions. Knowledge about the geometry of system constraints is exploited to obtain a computationally efficient method of computing tightened sets online. A simulation study is presented demonstrating the ability of the controller to handle modelling error and demonstrate tracking of a commanded power profile.

  • 14.
    Criscuolo, Ivan
    et al.
    Department of Mechanical Engineering, University of Salerno, Fisciano, Italy.
    Leufvén, Oskar
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Thomasson, Andreas
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Model-Based Boost Pressure Control with System Voltage Disturbance Rejection2011In: Proceedings of the 18th IFAC World Congress, 2011 / [ed] Bittanti, Sergio, Cenedese, Angelo, Zampieri, Sandro, International Federation of Automatic Control (IFAC) , 2011, p. 5058-5063Conference paper (Refereed)
    Abstract [en]

    Actuation systems for automotive boost control incorporate a vacuum tank and PWM controlled vacuum valves to increase the boosting system flexibility. Physical models for the actuator system are constructed using measurement data from a dynamometer with an engine having a two stage turbo system. The actuator model is integrated in a complete Mean Value Engine Model and a boost pressure controller is constructed. The developed model is used as basis for a nonlinear compensator, that is capable of rejecting disturbances from system voltage. An IMC based boost pressure controller is developed for the vacuum actuator and engine by using the engine model and then tested on the test cell. The controller performance is quantified and system voltage disturbance rejection is demonstrated.

  • 15.
    Edlund, Simon
    et al.
    Nokia Svenska AB, Linköping, SWEDEN.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Pettersson, Magnus
    SCANIA AB, Södertälje. SWEDEN.
    A Real-Time Platform for Collaboration Projects in Power Train Modeling and Control1999Conference paper (Refereed)
    Abstract [en]

    The requirements on research and development in automotive control are growing fast, and therefore convenient and efficient ways to make prototype experiments and demonstrations are sought for. Collaboration projects put some additional constraints on the experimental system used due to issues of safety and secrecy. These requirements are outlined, a real-time platform is developed, and experiences from some collaboration projects between industry and academia are discussed.

  • 16.
    Eriksson, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Frisk, Erik
    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.
    Analysis and optimization with the Kullback-Leibler divergence for misfire detection using estimated torque2013Report (Other academic)
    Abstract [en]

    Engine misfire detection is an important part of the On-Board Diagnostics (OBDII) legislations to reduce exhaust emissions and avoid damage to the catalytic converters. The flywheel angular velocity signal is analyzed, investigating how to use the signal in order to best detect misfires. An algorithm for engine misfire detection is proposed based on the flywheel angular velocity signal. The flywheel signal is used to estimate the torque at the flywheel and a test quantity is designed by weighting and thresholding the samples of estimated torque related to one combustion. During the development process, the Kullback-Leibler divergence is used to analyze the ability to detect a misfire given a test quantity and how the misfire detectability performance varies depending on, e.g., load and speed. The Kullback-Leibler divergence is also used for parameter optimization to maximize the difference between misfire data and fault-free data. Evaluation shows that the proposed misfire detection algorithm is able to have a low probability of false alarms while having a low probability of missed detections.

  • 17.
    Eriksson, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Frisk, Erik
    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.
    Flywheel angular velocity model for misfire and driveline disturbance simulation2013In: Proceedings of the 7th IFAC Symposium on Advances in Automotive Control, The International Federation of Automatic Control, Elsevier, 2013, Vol. 46, no 21, p. 570-575Conference paper (Refereed)
    Abstract [en]

    A flywheel angular velocity model for misfire and disturbance simulation is presented. Applications of the model are, for example, initial parameter calibration and robustness analysis of misfire detection algorithms. An analytical cylinder pressure model is used to model cylinder torque and a multi-body model with torsional flexibilities is used to model crankshaft and driveline oscillations. Misfires, cylinder variations, changes in auxiliary load, and flywheel manufacturing errors can be injected in the model and the resulting speed variations can be simulated. A qualitative validation of the model shows that simulated angular velocity captures the amplitude and oscillatory behavior of measurement data and the effects of different phenomena, such as misfire and flywheel manufacturing errors.

  • 18.
    Eriksson, Daniel
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Frisk, Erik
    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.
    Flywheel angular velocity model for misfire simulation2013Manuscript (preprint) (Other academic)
    Abstract [en]

    A flywheel angular velocity model for misfire and disturbance simulation is presented. Applications of the model are, for example, initial parameter calibration or robustness analysis of misfire detection algorithms. An analytical model of cylinder pressure is used to model cylinder torque and a multi-body model is used to model crankshaft and driveline oscillations. Different types of disturbances, such as cylinder variations, changes in auxiliary load, and flywheel manufacturing errors can be injected in the model. A qualitative validation of the model shows that simulated angular velocity captures the amplitude and oscillatory behavior of real measurements and the effects of different types of disturbances, e.g. misfire and flywheel manufacturing errors.

  • 19.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    A Real-Time Platform for Spark Advance Control1997Report (Other academic)
    Abstract [en]

    With the aim at spark advance control, a method for estimating the peak pressure position (PPP) from the ionization current has previously been developed and off-line validated. To implement the concept on an engine a real-time platform is needed. A hardware platform, that consists of a PC, an electronic engine control unit (ECU), and a synchronization circuit, is described. The platform synchronizes the data acquisition with the engine and the functionality is validated. Also a refined interpretation algorithm for estimating the PPP is described and validated to give a good estimate. The algorithm is suitable for implementation on the described real-time platform.

  • 20.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    An overview of various control benchmarks with a focus on automotive control2019In: Control Theory and Technology, ISSN 2095-6983, Vol. 17, no 2, p. 121-130Article in journal (Refereed)
    Abstract [en]

    There exists a gap between control theory and control practice, i.e., all control methods suggested by researchers are not implemented in real systems and, on the other hand, many important industrial problems are not studied in the academic research. Benchmark problems can help close this gap and provide many opportunities for members in both the controls theory and application communities. The goal is to survey and give pointers to different general controls and modeling related benchmark problems that can serve as inspiration for future benchmarks and then specifically focus the benchmark coverage on automotive control engineering application. In the paper reflections are given on how different categories of benchmark designers, benchmark solvers and third part users can benefit from providing, solving, and studying benchmark problems. The paper also collects information about several benchmark problems and gives pointers to papers than give more detailed information about different problems that have been presented.

  • 21.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    CHEPP – A Chemical Equilibrium Program Package for Matlab2005In: SAE technical paper series, ISSN 0148-7191, Vol. 4, no 113, p. 730-741Article in journal (Refereed)
    Abstract [en]

    A program package, that calculates chemical equilibrium and thermodynamic properties of reactants and products of a combustion reaction between fuel and air, has been developed and validated. The package consists of the following four parts: 1) A program for calculating chemical equilibrium. 2) A database that contains thermochemical information about the molecules, which comes from the GRI-Mech tables. 3) A GUI that allows the user to easily select fuels, fuel/air ratio for the reaction, and combustion products. 4) A set of functions designed to access the thermochemical database and the chemical equilibrium programs. Results are validated against both the NASA equilibrium program (Gordon and McBride, 1994) and the program developed by Olikara and Borman (1975). It is shown that the new method gives results identical to those well recognized Fortran programs.

  • 22.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Documentation for the Chemical Equilibrium Program Package CHEPP2000Report (Other academic)
    Abstract [en]

    A program package has been developed that calculates chemical equilibrium and thermodynamic properties of reactants and products of a combustion reaction between fuel and air. The package consists of the following four parts: 1) A program for calculating chemical equilibrium. 2) A database that contains thermochemical information about the molecules, which comes from the GRI-Mech tables. 3) A GUI that allows the user to easily select fuels, fuel/air ratio for the reaction, and combustion products. 4) A set of functions designed to access the thermochemical database and the chemical equilibrium programs. The program package is validated with respect to how well it can reproduce results shown in the standard literature. The thermodynamic properties for the individual molecules and the results from the equilibrium calculation all agree with the results shown in the literature. There is almost perfect agreement, between the results produced by the program package and those shown in the book by Heywood, when comparing the thermodynamic properties of the mixture of equilibrium products.

  • 23.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Increasing the Efficiency of SI-Engines by Spark Advance Control and Water Injection1997Report (Other academic)
    Abstract [en]

    By directly measuring in-cylinder parameters and adjusting the spark advance, the engine efficiency can be maximized. A feedback scheme for spark-advance control using the ionization current as sensed variable has earlier been presented. One issue is to verify that the algorithm works when the environmental conditions changes the burn rate. Humidity significantly affects the burn rate and active water injection is used to slow down the combustion giving a peak pressure position (PPP) that occurs too late. The ionization current based feedback-scheme adjusts the spark advance, and moves the PPP back to optimum. An additional result is that the engine efficiency can be increased by combining active supply of water to the combustion and the spark-advance control scheme.

  • 24.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Les rencontres scientifiques d’IFP energies nouvelles RHEVE 2011: International Scientific Conference on Hybrid and Electric Vehicles2013In: Oil & Gas Science and Technology: Revue de l'Institut Français du Pétrole, ISSN 1294-4475, Vol. 68, no 1, p. 9-12Article in journal (Other academic)
  • 25.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Mean Value Models for Exhaust System Temperatures2003In: SAE technical paper series, ISSN 0148-7191, Vol. 111, no 3Article in journal (Refereed)
    Abstract [en]

    Exhaust temperatures are important for turbine and catalyst performance. A set of exhaust temperature models suitable for turbo matching as well as design and analysis of engine control systems are developed and investigated. The models are lumped parameter heat transfer models, that fall within the category of mean value engine models. The model is developed for describing exit temperatures from the exhaust manifold and temperature drops in pipe sections in the exhaust system. The components used to model the exhaust temperature are: engine out temperature, temperature drop in a straight pipe, and a set of heat transfer modes. The model is validated using data from three different engines. It is shown that, for a spark ignited engine operating at MBT and stoichiometric conditions, it is sufficient to model the engine out temperature as a linear function of mass flow. Recommendations for tuning the model are also given. A thorough survey of exhaust heat transfer literature is also made together with a comparative summary of the different heat transfer modes that are present in the exhaust.

  • 26.
    Eriksson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Modeling and Control of Turbocharged SI and DI Engines2007In: Oil & gas science and technology, ISSN 1294-4475, E-ISSN 1953-8189, Vol. 62, no 4, p. 523-538Article in journal (Refereed)
  • 27.
    Eriksson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Modeling and Control of Turbocharged SI and DI Engines2006Conference paper (Refereed)
  • 28.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Requirements for and a Systematic Method for Identifying Heat-Release Model Parameters1998In: SAE technical paper series, ISSN 0148-7191, Vol. 107, p. 898-908Article in journal (Refereed)
    Abstract [en]

    Heat release analysis by using a pressure sensor signal is a well recognized technique for evaluation of the combustion event, and also for combustion diagnostics. The analysis includes tuning of several parameters in order to accurately explain measured data. This work presents and investigates a systematic method for estimating parameters in heat release models and minimizing the arbitrary choices. In order for the procedure to be systematic there are also the requirements on the model, that it includes no inherent ambiguities, like over-parameterization with respect to the parameters and to the information contained in the measurements. The fundamental question is which parameters, in the heat release model, that can be identified by using only cylinder pressure data. The parameter estimation is based on established techniques, that constructs a predictor for the model and then minimizes a least-squares objective function of the prediction error. The study is performed on data measured on a SAAB 2.3 liter, four stroke four cylinder, normally aspirated, gasoline engine.

  • 29.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Spark Advance for Optimal Efficiency1999In: SAE technical paper series, ISSN 0148-7191, Vol. 108, p. 789-798Article in journal (Refereed)
    Abstract [en]

    Most of todays spark-advance controllers operate in open loop but there are several benefits of using feed-back or adaptive schemes based on variables deduced from the cylinder pressure. A systematic study of how different engine conditions change the deduced variables, at optimal ignition timing, is performed. The analysis is performed using a one-zone heat-release model and varying the model parameters. The deduced variables that are studied are: position of the pressure peak, mass fraction burned levels of 30%, 45%, 50%, and 90%, and the pressure ratio. For MBT timing the position for 45% mass fraction burned changed least under a large variety of changes in burn rate. Cycle-to-cycle variations do not have a significant effect and it suffices to evaluate the mean values for the burn rate parameters. The pressure ratio produces values similar to the mass fraction burned and requires no separate treatment.

  • 30.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Andersson, Ingemar
    Chalmers.
    An Analytic Model for Cylinder Pressure in a Four Stroke SI Engine2003In: SAE technical paper series, ISSN 0148-7191, Vol. 111, no 3Article in journal (Refereed)
    Abstract [en]

    An analytic model for cylinder pressures in spark ignited engines is developed and validated. The main result is a model expressed in closed form that describe the in-cylinder pressure development of an SI engine. The method is based on a parameterization of the ideal Otto cycle and takes variations in spark advance and air-to-fuel ratio into account. The model consists of a set of tuning parameters that all have a physical meaning. Experimental validation on two engines show that it is possible to describe the in-cylinder pressure of a spark ignited combustion engine operating close to stoichiometric conditions, as a function of crank angle, manifold pressure, manifold temperature and spark timing.

  • 31.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nezhadali, Vaheed
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Andersson, Conny
    Linköping University.
    Compressor Flow Extrapolation and Library Design for the Modelica Vehicle Propulsion Library - VehProLib2016In: SAE 2016 World Congress and Exhibition, SAE International , 2016, article id 2016-01-1037Conference paper (Refereed)
    Abstract [en]

    Modelbased systems engineering is becoming an important tool when meeting the challenges of developing the complex future vehicles that fulfill the customers and legislators ever increasing demands for reduced pollutants and fuel consumption. To be able to work systematically and efficiently it is desirable to have a library of components that can be adjusted and adapted to each new situation. Turbocharged engines are complex and the compressor model serves as an in-depth example of how a library can be designed, incorporating the basic physics and allowing fine tuning as more information becomes available. A major part of the paper is the summary and compilation of a set of rules of thumb for compressor map extrapolation. The considerations discussed are extrapolation to surge, extrapolation to restriction region, and extrapolation out to choking. Furthermore the compressor diameter is coupled to the maximum performance of the compressor such as maximum speed, mass flow, and pressure ratio. All this is a result of an analysis of a database of more than 300 compressors. The paper uses the compressor modeling to discuss how wishes for extendability and reuse of component performance influences the library design. A Modelica library named Vehicle Propulsion Library VehProLib has been developed to meet these goals by including basic components that give a starting point for modeling and at the same time allows reuse and extendablility.

  • 32.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Ionization Current Interpretation for Ignition Control in Internal Combustion Engines1997In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 5, no 8, p. 1107-1113Article in journal (Refereed)
    Abstract [en]

    Spark advance setting in spark-ignited engines is used to place the in-cylinder pressure curve relative to the top dead center. A feedback scheme, not a calibration scheme, based on ionization current is proposed here. It is thus related to pressure sensor feedback schemes, that have reported good results, but have not yet been proved cost effective, due to the cost of the pressure sensor. The method proposed here is very cost-effective, since it uses exactly the same hardware and instrumentation (already used in production cars) that is used to utilize the spark plug as a sensor to detect misfire and as a sensor for knock control. A key idea in the method is to use parameterized functions to describe the ionization current. These parameterized functions are used to separate out the different phases of the ionization current. Special emphasis is laid on getting a correct description of the pressure development. The results are validated on a SAAB 2.3 l production engine by direct comparison with an in-cylinder pressure sensor (used only for validation, not for control), but also by using a physical model relating the ionization current to the pressure.

  • 33.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Modeling and control of engines and drivelines2014Book (Refereed)
  • 34.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Towards On-Board Engine Calibration with Feedback Control Incorporating Combustion Models and Ion-sense2003In: Automatisierungstechnik, ISSN 0178-2312, Vol. 51, no 5, p. 204-212Article in journal (Refereed)
    Abstract [en]

    Die Technik der Ionenstrommessung dient der Untersuchung des Verbrennungsvorganges im Zylinder. Bei der Ionenstrommessung wird nach der Zündung eine Spannung zwischen der Mittel- und der Massenelektrode der Zündkerze angelegt. Anschliessend wird der Stromfluss zwischen diesen beiden Elektroden gemessen. Das Signal des Ionenstroms ist eine komplexe Funktion, die Informationüber den Zylinderdruck, die Zylindertemperatur und den Verbrennungsvorgang enth ält. Um diese Information zu erhalten, bedient man sich eines einfachen analytischen Ionenstrommodells. Das Modell besteht aus detaillierten Untermodellen zur Analyse des Drucks, der Temperatur, der thermischen Ionisierung und des Ionisierungsstroms innerhalb des Zylinders. Die Kalibrierung der Modellparameter erfolgt on-board durch eine Signalinterpretation. Experimentelle Untersuchungen zeigen eine gute Übereinstimmung mit dem Modell und ebnen damit den Weg hin zu einer Echtzeit-Kalibrierung des Motors. Ion-sense is a technique to probe the in-cylinder combustion by applying, after ignition, a sense voltage across the spark plug gap and measure the current through the gap. This current measurement is a complicated function that contains a lot of information about the in-cylinder pressure, temperature and combustion. To extract this information, a major contribution here is a simple analytical ionization current model that consists of explicit analytical submodels for in-cylinder pressure, temperature, thermal ionization, and ionization current. Since the model is analytical, the on-board signal interpretation is a simple adaptation of some model parameters. Experimental validation shows good agreement, and thus paves the way towards real-time on-board engine calibration.

  • 35.
    Eriksson, Lars
    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.
    Brugard, J.
    Bergstrom, J.
    Pettersson, F.
    Andersson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Modeling of a turbocharged SI engine2002In: Annual Reviews in Control, ISSN 1367-5788, E-ISSN 1872-9088, Vol. 26 I, p. 129-137Article in journal (Refereed)
    Abstract [en]

    Turbocharged SI engines are a major possibility in the current trend of down-sized engines with preserved drivability performance. Considering control and supervision it is favorable to have a mean value model to be used e.g. in observer design. Such models of turbo engines are similar to those of naturally aspirated engines, but there are some special characteristics, e.g. the interconnected gas flows, the intercooler, the difference in relative sizes between the gas volumes (compared to naturally aspirated engines), the turbo, and the waste gate. Here, a model is developed with a strategy to find a model for each engine component (air filter, compressor, after cooler (or intercooler), throttle, engine, turbine, waste gate, and a lumped model for the catalyst and exhaust) as they behave in an engine setting. When investigating agreement with measured data and sensitivity of possible model structures, a number of interesting issues are raised. The experiments and the model validation have been performed on a Saab 2.3 1 production engine.

  • 36.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering.
    Brugård, Jan
    Bergström, Johan
    Pettersson, Fredrik
    Andersson, Per
    Linköping University, Department of Electrical Engineering.
    Modeling and Simulation of a Turbo Charged SI Engine2001Conference paper (Refereed)
  • 37.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering.
    Brugård, Jan
    Bergström, Johan
    Pettersson, Fredrik
    Andersson, Per
    Linköping University, Department of Electrical Engineering.
    Modeling and Simulation of a Turbo Charged SI Engine2002In: Annual Reviews in Control, ISSN 1367-5788, E-ISSN 1872-9088, Vol. 26, p. 129-137Article in journal (Refereed)
  • 38.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Glavenius, Mikael
    Mecel AB.
    Closed Loop Ignition Control by Ionization Current Interpretation1998In: SAE technical paper series, ISSN 0148-7191, Vol. 106, no SAE Technical Paper 970854, p. 1216-1223Article in journal (Refereed)
    Abstract [en]

    The main result of this paper is a real-time closed loop demonstration of spark advance control by interpretation of ionization current signals. The advantages of such a system is quantified. The ionization current, obtained by using the spark plug as a sensor, is rich on information, but the signal is also complex. A key step in our method is to use parameterized functions to describe the ionization current. The results are validated on a SAAB 2.3 l, normally aspirated, production engine, showing that the placement of the pressure trace relative to TDC is controlled using only the ionization current for feedback.

  • 39.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Nytomt, Jan
    Mecel AB.
    Ignition Control by Ionization Current Interpretation1997In: SAE technical paper series, ISSN 0148-7191, Vol. 105, no SAE Technical Paper 960045, p. 165-171Article in journal (Refereed)
    Abstract [en]

    Spark advance setting in spark-ignited engines is used to place the in-cylinder pressure curve relative to the top dead center. It is demonstrated that ionization current interpretation is feasible to use for spark advance control to optimize engine performance. A feedback scheme, not a calibration scheme, based on ionization current is proposed. It is thus related to pressure sensor feedback schemes, that have reported good results, but have not yet proven cost effective due to the cost of the pressure sensor. The method proposed here is very cost effective since it uses exactly the same hardware and instrumentation (already used in production cars) that is used to utilize the spark plug as a sensor to detect misfire and as a sensor for knock control. The only addition for ignition control is further signal interpretation in the electronic engine control unit.</P> A key idea in our method is to use parameterized functions to describe the ionization current. These parameterized functions are used to separate out the different phases of the ionization current. Special emphasis is made to get a correct description of the pressure development. The results are validated on a SAAB 2.3 l production engine by direct comparison with an in-cylinder pressure sensor (used only for validation, not for control), but also by using a physical model relating the ionization current to the pressure.

  • 40.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Norrlöf, Mikael
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, Faculty of Science & Engineering. ABB AB - Robotics, Västerås, Sweden.
    Improved Drive Cycle Following with an ILC Supported Driver Model2015In: 4th IFAC Workshop on Engine and Powertrain Control, Simulation and Modeling ECOSM’15, The International Federation of Automatic Control (IFAC) , 2015, Vol. 48, p. 347-353Conference paper (Refereed)
    Abstract [en]

    Drive cycle following is important for concept comparisons when evaluating vehicle concepts, but it can be time consuming to develop good driver models that can achieve accurate following of a specific velocity profile. Here, a new approach is proposed where a simple driver model based on a PID controller is extended with an Iterative Learning Control (ILC) algorithm. Simulation results using a nonlinear vehicle and control system model show that it is possible to achieve very good cycle following in a few iterations with little tuning effort. It is also possible to utilize the repetitive behavior in the drive cycle to accelerate the convergence of the ILC algorithm even further.

  • 41.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Wahlström, Johan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Klein, Marcus
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Physical Modeling of Turbocharged Engines and Parameter Identification2009In: Automotive Model Predictive Control: Models, Methods and Applications, Springer Verlag , 2009, 1, p. 53-71Chapter in book (Refereed)
    Abstract [en]

    The common theme in this chapter is physical modeling of engines and the subjects touch three topics in nonlinear engine models and parameter identification. First, a modeling methodology is described. It focuses on the gas and energy flows in engines and covers turbocharged engines. Examples are given where the methodology has been successfully applied, covering naturally aspirated engines and both single and dual stage turbocharged engines. Second, the modeling with the emphasis on models for EGR/VGT equipped diesel engine. The aim is to describe models that capture the essential dynamics and nonlinear behaviors and that are relatively small so that they can be utilized in model predictive control algorithms. Special emphasis is on the selection of the states. The third and last topic is related to parameter identification in gray-box models. A common issue is that parameters with physical interpretation often receive values that lie outside their admissible range during the identification. Regularization is discussed as a solution and methods for choosing the regularization parameter are described and highlighted.

  • 42.
    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.

  • 43.
    Hockerdal, Erik
    et al.
    Scania CV AB, Sweden.
    Frisk, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Real-time performance of DAE and ODE based estimators evaluated on a diesel engine2018In: Science China Information Sciences, ISSN 1674-733X, E-ISSN 1869-1919, Vol. 61, no 7, article id 70202Article in journal (Refereed)
    Abstract [en]

    Computation and sampling time requirements for real-time implementation of observers is studied. A common procedure for state estimation and observer design is to have a system model in continuous time that is converted to sampled time with Euler forward method and then the observer is designed and implemented in sampled time in the real time system. When considering state estimation in real time control systems for production there are often limited computational resources. This becomes especially apparent when designing observers for stiff systems since the discretized implementation requires small step lengths to ensure stability. One way to reduce the computational burden, is to reduce the model stiffness by approximating the fast dynamics with instantaneous relations, transforming an ordinary differential equations (ODE) model into a differential algebraic equation (DAE) model. Performance and sampling frequency limitations for extended Kalman filter (EKF)s based on both the original ODE model and the reduced DAE model are here analyzed and compared for an industrial system. Furthermore, the effect of using backward Euler instead of forward Euler when discretizing the continuous time model is also analyzed. The ideas are evaluated using measurement data from a diesel engine. The engine is equipped with throttle, exhaust gas recirculation (EGR), and variable geometry turbines (VGT) and the stiff model dynamics arise as a consequence of the throttle between two control volumes in the air intake system. The process of simplifying and modifying the stiff ODE model to a DAE model is also discussed. The analysis of the computational effort shows that even though the ODE, for each time-update, is less computationally demanding than the resulting DAE, an EKF based on the DAE model achieves better estimation performance than one based on the ODE with less computational effort. The main gain with the DAE based EKF is that it allows increased step lengths without degrading the estimation performance compared to the ODE based EKF.

  • 44.
    Holmbom, Robin
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Liang, Bohan
    Volvo Car Corporation.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Investigation of Performance Differences and Control Synthesis for Servo-Controlled and Vacuum-Actuated Wastegates2017In: SAE Technical Paper 2017-01-0592, SAE International , 2017, article id 2017-01-0592Conference paper (Refereed)
    Abstract [en]

    Turbocharging plays an important role in the downsizing of engines. Model-based approaches for boost control are going to increasing the necessity for controlling the wastegate flow more accurately. In today’s cars, the wastegate is usually only controlled with a duty cycle and without position feedback. Due to nonlinearities and varying disturbances a duty cycle does not correspond to a certain position. Currently the most frequently used feedback controller strategy is to use the boost pressure as the controller reference. This means that there is a large time constant from actuation command to effect in boost pressure, which can impair dynamic performance. In this paper, the performance of an electrically controlled vacuum-actuated waste-gate, subsequently referred to as vacuum wastegate, is compared to an electrical servo-controlled wastegate, also referred to as electric wastegate. Their performance is investigated with the two actuators installed on a turbocharged inline four gasoline engine in an engine test bench. Furthermore, different control synthesis designs for these different actuators are investigated. A state-feedback controller with standard models for the electric wastegate is described and implemented, which gives a position-controlled wastegate. One main difference between vacuum and electric wastegate is that the latter has a position sensor. To make an extended comparison between the solutions, the vacuum wastegate is also equipped with a position sensor and controller using standard controller design methods. The controllers are implemented and compared both in a simulation environment and evaluated in an engine test bench. In addition, for the electric wastegate, both soft-landing and tightening features are also implemented and investigated. Their aim is to improve the lifetime and behavior at or near the closed position.

  • 45.
    Höckerdal, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Eriksson, Lars
    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.
    Air mass-flow measurement and estimation in diesel engines equipped with EGR and VGT2008In: International Journal of Passenger Cars - Electronic and Electrical Systems, ISSN 1946-4622, Vol. 1, no 1, p. 393-402Article in journal (Refereed)
  • 46.
    Höckerdal, Erik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Eriksson, Lars
    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.
    Air mass-flow measurement and estimation in diesel engines equipped with EGR and VGT2008Conference paper (Refereed)
    Abstract [en]

    With stricter emission legislations and customer demands on low fuel consumption, good control strategies are necessary. This may involve control of variables that are hard, or even impossible, to measure with real physical sensors. By applying estimators or observers, these variables can be made available. The quality of a real sensor is determined by e.g. accuracy, drift and aging, but assessing the quality of an estimator is a more subtle task. An estimator is the result of a design work and hence, connected to factors like application, model, control error and robustness.

    The air mass-flow in a diesel engine is a very important quantity that has a direct impact on many control and diagnosis functions. The quality of the air mass-flow sensor in a diesel engine is analyzed with respect to day-to-day variations, aging, and differences in engine configurations. The investigation highlights the necessity of continuous monitoring and adaption of the air mass-flow. One way to do this is to use an estimator. Nine estimators are designed for estimation of the air mass-flow with the aim of assessing different quality measures. In the study of the estimators and quality measures it is evident that model accuracy is important and that special care has to be taken, regarding what quality measure to use, when the estimator performance is evaluated.

  • 47.
    Höckerdal, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Frisk, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Off- and On-Line Identification of Maps Applied to the Gas Path in Diesel Engines2012In: Lecture notes in control and information sciences, ISSN 0170-8643, E-ISSN 1610-7411, Vol. 418, p. 241-256Article in journal (Refereed)
    Abstract [en]

    Maps or look-up tables are frequently used in engine control systems, and can be of dimension one or higher. Their use is often to describe stationary phenomena such as sensor characteristics or engine performance parameters like volumetric efficiency. Aging can slowly change the behavior, which can be manifested as a bias, and it can be necessary to adapt the maps. Methods for bias compensation and on-line map adaptation using extended Kalman filters are investigated and discussed. Key properties of the approach are ways of handling component aging, varying measurement quality, as well as operating point dependent model quality. Handling covariance growth on locally unobservable modes, which is an inherent property of the map adaptation problem, is also important and this is solved for the Kalman filter. The method is applicable to off-line calibration ofmaps where the only requirement of the data is that the entire operating region of the system is covered, i.e. no special calibration cycles are required. Two truck engine applications are evaluated, one where a 1-D air mass-ffow sensoradaptation map is estimated, and one where a 2-D volumetric efficiency map is adapted, both during a European transient cycle. An evaluation on experimental data shows that the method estimates a map, describing the sensor error, on a measurement sequence not specially designed for adaptation.

  • 48.
    Höckerdal, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Frisk, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson , Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Observer design and model augmentation for bias compensation with a truck engine application2009In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, no 3, p. 408-417Article in journal (Refereed)
    Abstract [en]

    A systematic design method for reducing bias in observers is developed. The method utilizes an observable default model of the system together with measurement data from the real system and estimates a model augmentation. The augmented model is then used to design an observer which reduces the estimation bias compared to an observer based on the default model. Three main results are a characterization of possible augmentations from observability perspectives, a parameterization of the augmentations from the method, and a robustness analysis of the proposed augmentation estimation method. The method is applied to a truck engine where the resulting augmented observer reduces the estimation bias by 50% in a European transient cycle.

  • 49.
    Höckerdal, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Frisk, Erik
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Bias Reduction in DAE Estimators by Model Augmentation: Observability Analysis and Experimental EvaluationManuscript (preprint) (Other academic)
    Abstract [en]

    A method for bias compensation in model based estimation utilizing model augmentation is developed. Based on a default model, that suffers from stationary errors, and measurements from the system a low order augmentation is estimated. The method handles models described by differential algebraic equations and the main contributions are necessary and sufficient conditions for the preservation of the observability properties of the default model during the augmentation.

    A characterization of possible augmentations found through the estimation, showing the benefits of adding extra sensors during the design, is included. This enables reduction of estimation errors also in states not used for feedback, which is not possible with for example PI-observers. Beside the estimated augmentation the method handles user provided augmentations, found through e.g. physical knowledge of the system.

    The method is evaluated on a nonlinear engine model where its ability to incorporate information from additional sensors during the augmentation estimationis clearly illustrated. By applying the method the mean relative estimation error for the exhaust manifold pressure is reduced by 55 %.

  • 50.
    Höckerdal, Erik
    et al.
    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.
    Eriksson, Lars
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Bias Reduction in DAE Estimators by Model Augmentation: Observability Analysis and Experimental Evaluation2011In: 50th IEEE Conference on Decision and Control and European Control Conference (CDC-ECC), 2011, Institute of Electrical and Electronics Engineers (IEEE), 2011Conference paper (Refereed)
    Abstract [en]

    A method for bias compensation in model based estimation utilizing model augmentation is developed. Based on a default model, that suffers from stationary errors, and measurements from the system a low order augmentation is estimated. The method handles models described by differential algebraic equations and the main contributions are necessary and sufficient conditions for the preservation of the observability properties of the default model during the augmentation.

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