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  • 1.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Scania CV AB, SE-15187 Södertälje, Sweden.
    Gattami, Ather
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Tomlin, Claire J.
    UC Berkeley.
    Guaranteeing safety for heavy duty vehicle platooning: Safe set computations and experimental evaluations2014In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 24, no 1, p. 33-41Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of finding a safety criteria between neighboring heavy duty vehicles traveling in a platoon. We present a possible framework for analyzing safety aspects of heavy duty vehicle platooning. A nonlinear underlying dynamical model is utilized, where the states of two neighboring vehicles are conveyed through radar information and wireless communication. Numerical safe sets are derived through the framework, under a worst-case scenario, and the minimum safe spacing is studied for heterogenous platoons. Real life experimental results are presented in an attempt to validate the theoretical results in practice. The findings show that a minimum relative distance of 1.2 m at maximum legal velocity on Swedish highways can be maintained for two identical vehicles without endangering a collision. The main conclusion is that the relative distance utilized in commercial applications today can be reduced significantly with a suitable automatic control system.

  • 2.
    Alam, Assad
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Experimental evaluation of decentralized cooperative cruise control for heavy-duty vehicle platooning2015In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 38, p. 11-25Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the problem of finding decentralized controllers for heavy-duty vehicle (HDV) platooning by establishing empiric results for a qualitative verification of a control design methodology. We present a linear quadratic control framework for the design of a high-level cooperative platooning controller suitable for modern HDVs. A nonlinear low-level dynamical model is utilized, where realistic response delays in certain modes of operation are considered. The controller performance is evaluated through numerical and experimental studies. It is concluded that the proposed controller behaves well in the sense that experiments show that it allows for short time headways to achieve fuel efficiency, without compromising safety. Simulation results indicate that the model mimics real life behavior. Experiment results show that the dynamic behavior of the platooning vehicles depends strongly on the gear switching logic, which is confirmed by the simulation model. Both simulation and experiment results show that the third vehicle never displays a bigger undershoot than its preceding vehicle. The spacing errors stay bounded within 6.8. m in the simulation results and 7.2. m in the experiment results for varying transient responses. Furthermore, a minimum spacing of -0.6. m and -1.9. m during braking is observed in simulations and experiments, respectively. The results indicate that HDV platooning can be conducted at close spacings with standardized sensors and control units that are already present on commercial HDVs today.

  • 3.
    Alexis, Kostas
    et al.
    Department of Electrical and Computer Engineering, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Tzes, Anthony
    Department of Electrical and Computer Engineering, University of Patras.
    Switching model predictive attitude control for a quadrotor helicopter subject to atmospheric disturbances2011In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 19, no 10, p. 1195-1207Article in journal (Refereed)
    Abstract [en]

    In this article a Switching Model Predictive Attitude Controller for an Unmanned quadrotor Helicopter subject to atmospheric disturbances is presented. The proposed control scheme is computed based on a Piecewise Affine (PWA) model of the quadrotor’s attitude dynamics, where the effects of the atmospheric turbulence are taken into consideration as additive disturbances. The switchings among the PWA models are ruled by the rate of the rotation angles and for each PWA system a corresponding model predictive controller is computed. The suggested algorithm is verified in experimental studies in the execution of sudden maneuvers subject to forcible wind disturbances. The quadrotor rejects the induced wind–disturbances while performing accurate attitude tracking.

  • 4.
    Andrikopoulos, Georgios
    et al.
    Department of Electrical and Computer Science, University of Patras.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Manesis, Stamatis
    Department of Electrical and Computer Engineering, University of Patras.
    Pneumatic artificial muscles: a switching model predictive control approach2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 12, p. 1653-1664Article in journal (Refereed)
    Abstract [en]

    In this article, a switching Model Predictive Controller (sMPC) for a Pneumatic Artificial Muscle (PAM) is presented. The control scheme is based on a switching PieceWise Affine (PWA) system model approximation that is able to capture the high nonlinearities of the PAM, while improving the overall model accuracy, and is composed of: a) a feed-forward term regulating control input at specific reference set-points, and b) a switching Model Predictive Controller handling any deviations from the system’s equilibrium points. Extended experimental studies are being presented that prove the overall scheme’s efficiency.

  • 5.
    Axelsson, Patrik
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Karlsson, Rickard
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Norrlöf, Mikael
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Bayesian State Estimation of a Flexible Industrial Robot2012In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 20, no 11, p. 1220-1228Article in journal (Refereed)
    Abstract [en]

    A sensor fusion method for state estimation of a flexible industrial robot is developed. By measuring the acceleration at the end-effector, the accuracy of the arm angular position, as well as the estimated position of the end-effector are improved. The problem is formulated in a Bayesian estimation framework and two solutions are proposed; the extended Kalman filter and the particle filter. In a simulation study on a realistic flexible industrial robot, the angular position performance is shown to be close to the fundamental Cramér-Rao lower bound. The technique is also verified in experiments on an ABB robot, where the dynamic performance of the position for the end-effector is significantly improved.

  • 6. Berndtsson, Magnus
    et al.
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Design of a dynamic threshold generator for λ-tuned control loops2008In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 16, no 5, p. 623-631Article in journal (Refereed)
    Abstract [en]

    A dynamic threshold generator is employed for detecting faults in λ-tuned control loops. To this end, an optimizationalgorithm for dynamic threshold generators is proposed. The a priori-information from λ-tuning is used in designing astate estimator with integral action. A dynamic threshold generator for the residual of this state estimator is derived and the optimization algorithm is applied. Simulations with measurement data from an experimental water tank setup show that the method is capable of detecting a small fault without generating false alarms.

  • 7.
    Birk, Wolfgang
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Arvanitidis, Ioannis
    Medvedev, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Jönsson, Pär
    Kungliga tekniska högskolan, KTH.
    Foam level control in a water model of the LD converter process2003In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 11, no 1, p. 49-56Article in journal (Refereed)
    Abstract [en]

    This paper deals with estimation and control of foam level in dynamic foaming. An improved foam level estimation methodology from a microphone signal and its automatic calibration is presented. The dynamical reaction of the foam level on air lance movements is modelled using system identification. Based on the resulting mathematical model, a controller for foam level stabilisation is designed and applied to a water model, representing the LD converter process. It is shown that the foam level can be controlled using a microphone as the measurement device and air lance movement as the actuator.

  • 8.
    Birk, Wolfgang
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Castaño, Miguel
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering.
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    An Application Software For Visualization and Control Configuration Selection of Interconnected Processes2014In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 26, p. 188-200Article in journal (Refereed)
    Abstract [en]

    This paper presents a new application software for control conguration selection of interconnected industrial processes,called ProMoVis. Moreover, ProMoVis is able to visualize process models and process layout at the physical leveltogether with the control system dynamics. The software consists of a builder part where the visual representationof the interconnected process is created and an analyzer part where the process is analyzed using dierent controlconguration selection tools.The conceptual idea of the software is presented and the subsequent design and implementation of ProMoVis isdiscussed. The implemented analysis methods are briey described including their usage and implementation aspects.The use of ProMoVis is demonstrated by an application study on the stock preparation process at SCA Obbola AB,Sweden. The results of this study are compared with the currently used control strategy.The study indicates that ProMoVis introduces a systematic and comprehensive way to perform control congurationselection. ProMoVis has been released under the Apache Open Source license.

  • 9. Birk, Wolfgang
    et al.
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Johansson, Robert
    SSAB Tunnplåt AB.
    Medvedev, Alexander
    Implementation and industrial experiences of advanced control and monitoring in coal injection2000In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 8, no 3, p. 327-35Article in journal (Refereed)
    Abstract [en]

    This paper summarizes the implementation and industrial experiences of a model-based control and gas-leakage detection system in a coal injection plant. It describes how advanced control and monitoring can be implemented in an industrial environment while taking human–machine interface aspects into consideration. The operation of the advanced and the conventional concept are compared regarding evaluation data, experiences and observations of operators and maintenance personnel. It is shown that the advanced control and monitoring system improves plant performance without disturbing routines in plant operation and, moreover, is positively accepted by the plant operators.

  • 10. Brus, Linda
    et al.
    Zambrano, Darine
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Black-box identification of solar collector dynamics with variant time delay2010In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 18, no 10, p. 1133-1146Article in journal (Refereed)
  • 11. Düstegör, Dilek
    et al.
    Frisk, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Coquempot, Vincent
    Krysander, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Staroswiecki, Marcel
    Structural Analysis of Fault Isolability in the DAMADICS benchmark2006In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 14, no 6, p. 597-608Article in journal (Refereed)
    Abstract [en]

    Structural analysis is a powerful tool for early determination of fault detectability/fault 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 modelling to get desired isolability properties of the diagnosis system.

  • 12.
    Eidehall, Andreas
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Pohl, Jochen
    Volvo Car Corporation, Sweden.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Joint Road Geometry Estimation and Vehicle Tracking2007In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 15, no 12, p. 1484-1494Article in journal (Refereed)
    Abstract [en]

    Detection and tracking of other vehicles and estimation of lane geometry will be required for many intelligent driver assistance systems in the future. By combining the processing of these two features into a single filter, better utilisation of the available information can be achieved. For instance, it is demonstrated that it is possible to improve the road shape estimate by including information about the lateral movement of leading vehicles. Statistical evaluation is done by comparing the estimated parameters to true values in varying road and weather conditions. The performance is also related to typical requirements of active safety applications such as adaptive cruise control and a new safety function called emergency lane assist.

  • 13.
    Ekvall, Jenny
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Hägglund, Tore
    Improved web break strategy using a new approach for steam pressure control in paper machines2008In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 16, no 10, p. 1151-1160Article in journal (Refereed)
    Abstract [en]

    This paper presents a new strategy for steam pressure control during web breaks in the paper machine. The aim was to restart paper production with the same drying properties of the cylinder as before the break. A detailed physical dynamic model of the drying cylinder has been developed. The accuracy of the model has been verified through experiments made at the M-real paper mill in Husum, Sweden. Verifications are made both during normal operation and during web breaks. The dynamic model has been reduced in order to derive simple transfer functions which were used to find the optimal steam pressure trajectory during web breaks. The resulting strategy has been tested on a paper machine with good results and it has been well received at the mill.

  • 14.
    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.

  • 15.
    Eriksson, Lars
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, Faculty of Science & Engineering.
    Rizzo, Gianfranco
    University of Salerno, Italy.
    Chamaillard, Yann
    University of Orleans, France.
    Editorial Material: Editorial: Special Issue Section on Automotive Control in CONTROL ENGINEERING PRACTICE, vol 61, issue , pp 183-1852017In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 61, p. 183-185Article in journal (Other academic)
    Abstract [en]

    n/a

  • 16.
    Evestedt, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Medvedev, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Wigren, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Windup properties of recursive parameter estimation algorithms in acoustic echo cancellation2008In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 16, no 11, p. 1372-1378Article in journal (Refereed)
  • 17. Falck, Tillmann
    et al.
    Dreesen, Philippe
    De Brabanter, Kris
    Pelckmans, Kristiaan
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    De Moor, Bart
    Suykens, Johan A. K.
    Least-Squares Support Vector Machines for the identification of Wiener-Hammerstein systems2012In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 20, no 11, p. 1165-1174Article in journal (Refereed)
    Abstract [en]

    This paper considers the identification of Wiener-Hammerstein systems using Least-Squares Support Vector Machines based models. The power of fully black-box NARX-type models is evaluated and compared with models incorporating information about the structure of the systems. For the NARX models it is shown how to extend the kernel-based estimator to large data sets. For the structured model the emphasis is on preserving the convexity of the estimation problem through a suitable relaxation of the original problem. To develop an empirical understanding of the implications of the different model design choices, all considered models are compared on an artificial system under a number of different experimental conditions. The obtained results are then validated on the Wiener-Hammerstein benchmark data set and the final models are presented. It is illustrated that black-box models are a suitable technique for the identification of Wiener-Hammerstein systems. The incorporation of structural information results in significant improvements in modeling performance.

  • 18. Falkman, Petter
    et al.
    Lennartson, Bengt
    Tittus, Michael
    University of Borås, School of Engineering.
    Specification of a batch plant using process algebra and petri nets2009In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, no 9, p. 1004-1015Article in journal (Refereed)
    Abstract [en]

    The focus of the present paper is on the specification of routing and resource allocation systems. Such systems can be described as a set of shared resources and a set of products. The products utilize the resources in order to be manipulated according to a certain specification. This product specification consists of a set of operations that are to be executed in a certain order by specific resources. This results in a desired product route through the resource system, and hence the product specification is also called a routing specification. The process algebra petri net (PPN) formalism, i.e. a combination of petri nets and process algebra, implies efficient and less complex models for routing specifications compared to PNs and automata descriptions. The aim of this paper is to show how the PPN language can be used in order to simplify the specification of desired routes of the chemical batch process.

  • 19.
    Flärdh, Oscar
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Mårtensson, Jonas
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Exhaust pressure modeling and control on an si engine with vgt2014In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 25, no 1, p. 26-35Article in journal (Refereed)
    Abstract [en]

    For a turbocharged si engine, the exhaust pressure is of high importance for the gas exchange process as well as for the turbine power. It is therefore important to control the exhaust pressure accurately during load transients. This paper presents and evaluates a nonlinear controller for the exhaust pressure in an si engine equipped with a variable geometry turbine. A mapping from the states, inputs, and disturbances to future outputs is formed, and inverting the input/output relation in this mapping gives a control law. The controller, which can be tuned as a pi controller, utilizes a model for the turbine mass flow capturing the flow characteristics over the operating range. This controller is compared to a linear pi controller and a feedback linearization controller. Evaluation is performed using both simulations and measurements on a real engine, showing the superior behavior of the nonlinear controllers over the linear controller for this problem. Moreover, the presented controller achieves almost as good performance as a feedback linearization controller, but with easier tuning and implementation.

  • 20.
    Fridholm, Björn
    et al.
    RISE, Swedish ICT, Viktoria.
    Wik, T.
    Nilsson, Magnus
    RISE, Swedish ICT, Viktoria.
    Kalman filter for adaptive learning of look-up tables with application to automotive battery resistance estimation2016In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 48, p. 78-86Article in journal (Refereed)
    Abstract [en]

    In online automotive applications, look-up tables are often used to model nonlinearities in component models that are to be valid over large operating ranges. If the component characteristics change with ageing or wear, these look-up tables must be updated online. Here, a method is presented where a Kalman filter is used to update the entire look-up table based on local estimation at the current operating conditions. The method is based on the idea that the parameter changes observed as a component ages are caused by physical phenomena having effect over a larger part of the operating range that may have been excited. This means that ageing patterns at different operating points are correlated, and these correlations are used to drive a random walk process that models the parameter changes. To demonstrate properties of the method, it is applied to estimate the ohmic resistance of a lithium-ion battery. In simulations the complete look-up table is successfully updated without problems of drift, even in parts of the operating range that are almost never excited. The method is also robust to uncertainties, both in the ageing model and in initial parameter estimates.

  • 21.
    Garami, Attila
    et al.
    University of Miskolc, Hungary.
    Toth, Pal
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Csordas, Bernadett
    University of Miskolc, Hungary.
    Palotas, Arpad
    University of Miskolc, Hungary.
    Reaction zone monitoring in biomass combustion2018In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 74, p. 95-106Article in journal (Refereed)
    Abstract [en]

    In this work we demonstrate the utilization of a machine vision-based combustion monitoring system in biomass combustion. The proposed system monitored the location of the reaction zone in a 3 MW, grate-fired biomass boiler operated at varying loads and with fluctuating fuel quality. The system can help guarantee equal primary air supply to different regions of the grate and avoid the elutriation of fly ash by providing information on the location of the reaction zone. Strong correlation was found between the reaction zone boundary location and most process parameters, indicating that the location of the reaction zone can be a useful metric in monitoring and control by providing supplementary measurements to already existing monitoring to avoid over-emissions and improve economics.

  • 22.
    Garulli, Andrea
    et al.
    Dipartimento di Ingegneria dell'Informazione Universita' degli Studi di Siena, Italy.
    Hansson, Anders
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Khoshfetrat Pakazad, Sina
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Masi, Alfio
    Dipartimento di Ingegneria dell'Informazione Universita' degli Studi di Siena, Italy.
    Wallin, Ragnar
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Robust finite-frequency H2 analysis of uncertain systems with application to flight comfort analysis2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 6, p. 887-897Article in journal (Refereed)
    Abstract [en]

    In many applications, design or analysis is performed over a finite-frequency range of interest. The importance of the H2 norm highlights the necessity of computing this norm accordingly. This paper provides different methods for computing upper bounds of the robust finite-frequency H2 norm for systems with structured uncertainties. An application of the robust finite-frequency H2 norm for a comfort analysis problem of an aero-elastic model of an aircraft is also presented.

  • 23.
    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.

  • 24.
    Gunnarsson, Fredrik
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Control Theory Aspects of Power Control in UMTS2003In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 11, no 10, p. 1113-1125Article in journal (Refereed)
    Abstract [en]

    The global communication systems critically rely on control algorithms of various kinds. In universal mobile telephony system (UMTS)-the third generation mobile telephony system just being launched-power control algorithms play an important role for efficient resource utilization. This survey article describes and discusses relevant aspects of UMTS power control with emphasis on practical issues, using an automatic control framework. Generally, power control of each connection is distributedly implemented as cascade control, with an inner loop to compensate for fast variations and an outer loop focusing on longer term statistics. These control loops are interrelated via complex connections, which affect important issues such as capacity, load and stability. Therefore, both local and global properties are important. The concepts and algorithms are illustrated by simple examples and simulations.

  • 25.
    Gunnarsson, Svante
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Collignon, Vincent
    Université Catholique de Louvain, Belgium.
    Rousseaux, Olivier
    Université Catholique de Louvain, Belgium.
    Tuning of a Decoupling Controller for a 2×2 System using Iterative Feedback Tuning2003In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 11, no 9, p. 1035-1041Article in journal (Refereed)
    Abstract [en]

    Iterative feedback tuning is used to tune a decoupling controller for a 2 × 2 multivariable system. The tuning is carried out in two steps. In the first step the coefficients of two proportional decoupling controllers are tuned, and in the second step two PD-controllers are tuned. The approach is evaluated on a nonlinear simulation model of a two-link manipulator. The evaluation is carried out using two different reference trajectories and also in the presence of friction. The resulting closed loop systems show satisfactory behavior in all three cases.

  • 26.
    Hansson, Anders
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Servin, Martin
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Semi-autonomous shared control of large-scale manipulator arms2010In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 18, no 9, p. 1069-1076Article in journal (Refereed)
    Abstract [en]

    Semi-autonomous operation with shared control between the human operator and control computer has been developed and examinedfor a large-scalemanipulator for gripping and lifting heavy objects in unstructured dynamical environments. The technique hasbeen implemented on a electro-hydraulic actuated crane arm with redundant kinematic structure. Several modes of automation andinteraction were evaluated. Experiments show satisfactory smoothness in the transitions between autonomous, shared and manualcontrol, increased performance in log loading for inexperienced operators while experienced operators reported reduced workload.

  • 27.
    Hedlund, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Goncalves de Oliveira, Janaina
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Bernhoff, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Sliding Mode 4-Quadrant DCDC Converter for a Flywheel Application2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 4, p. 473-482Article in journal (Refereed)
    Abstract [en]

    A sliding mode control system for a 4-quadrant DCDC converter was designed and a low voltage prototype was constructed. The target application is a flywheel based all-electric driveline. Important qualities are current and voltage control, bidirectionality, and stability for a broad input voltage range, focusing on a smooth transition between operating quadrants. The control decisions were based entirely on the latest available measurements, implying that no memory needs reinitializing when changing quadrant. The boost control was based on a topology specific current source approximation. The control was found to be parameter invariant, regardless of high input/output dynamics variance.

  • 28.
    Hellström, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Ivarsson, Maria
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Look-ahead control for heavy trucks to minimize trip time and fuel consumption2009In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, no 2, p. 245-254Article in journal (Refereed)
    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.

  • 29.
    Hellström, Erik
    et al.
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Åslund, Jan
    Linköping University, Department of Electrical Engineering, Vehicular Systems. Linköping University, The Institute of Technology.
    Nielsen, Lars
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Design of an efficient algorithm for fuel-optimal look-ahead control2010In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 18, no 11, p. 1318-1327Article in journal (Refereed)
    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.

  • 30.
    Hjalmarsson, Håkan
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Gevers, Michel
    Université Catholique de Louvain.
    Special section on algorithms and applications of Iterative Feedback Tuning2003In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 11, no 9, p. 1021-1021Article in journal (Other academic)
  • 31.
    Hjalmarsson, Håkan
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Rojas, Cristian R.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Rivera, D. E.
    System identification: A Wiener-Hammerstein benchmark2012In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 20, no 11, p. 1095-1096Article in journal (Other academic)
  • 32.
    Holmberg, Ulf
    et al.
    Halmstad University, School of Information Technology, Halmstad Embedded and Intelligent Systems Research (EIS).
    Valentinotti, S.
    Institut d 'Automatique, Ecole Polytechnique Federale de Lausanne, Switzerland.
    Bonvin, D.
    Institut d 'Automatique, Ecole Polytechnique Federale de Lausanne, Switzerland.
    An identification-for-control procedure with robust performance2000In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 8, no 10, p. 1107-1117Article in journal (Refereed)
    Abstract [en]

    A data-driven controller design procedure is proposed in this paper. The controller is based on both an estimated plant model and its estimated uncertainty described by an ellipsoid in parameter space. Desired performance is specified by the speed and the damping of the modeled response. The unmodeled response is rejected by requiring robust performance with respect to a generalized stability region. Moreover, estimation of a disturbance model enables further rejection of the unmodeled response. The methodology is applied to a nonlinear and unstable magnetic suspension system. High performance is achieved for various specifications over a large operational range.

  • 33.
    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.

  • 34.
    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.
    EKF-Based Adaptation of Look-Up Tables with an Air Mass-Flow Sensor Application2011In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 19, no 5, p. 442-453Article in journal (Refereed)
    Abstract [en]

    A method for bias compensation and online map adaptation using extended Kalman filters isdeveloped. Key properties of the approach include the methods of handling component aging, varyingmeasurement quality including operating-point-dependent reliability and occasional outliers, andoperating-point-dependent model quality. Theoretical results about local and global observability,specifically adapted to the map adaptation problem, are proven. In addition, a method is presented tohandle covariance growth of locally unobservable modes, which is inherent in the map adaptationproblem. The approach is also applicable to the offline calibration of maps, in which case the onlyrequirement of the data is that the entire operating region of the system is covered, i.e., no specialcalibration cycles are required. The approach is applied to a truck engine in which an air mass-flowsensor adaptation map is estimated during a European transient cycle. It is demonstrated that themethod manages to find a map describing the sensor error in the presence of model errors on ameasurement sequence not specifically designed for adaptation. It is also demonstrated that themethod integrates well with traditional engineering tools, allowing prior knowledge about specificmodel errors to be incorporated and handled.

  • 35. Iannelli, Luigi
    et al.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Jönsson, Ulf T.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Vasca, Francesco
    Subtleties in the averaging of a class of hybrid systems with applications to power converters2008In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 16, no 8, p. 961-975Article in journal (Refereed)
    Abstract [en]

    High-frequency dither signals are commonly used to implement modulation schemes in power electronics converters. These systems represent an interesting class of hybrid systems with external excitation. They have a rich dynamical behavior, which cannot be easily understood intuitively. Despite the common use of averaging techniques in power electronics, it was only recently proved that a dithered hybrid system can be approximated by an averaged system under certain conditions on the dither signal. Averaging and averaged models for various types of power converters are analyzed in the paper. It is shown that the averaged nonlinearity depends on the dither shape and that dither signals with Lipschitz-continuous averaged nonlinearities can be used to adapt the equivalent gain of power converters. Practical stability of the original dithered system can be inferred by analyzing a simpler averaged system. The main contribution of the paper is to show that the averaged and the dithered systems may have drastically different behavior if the assumptions of the recently developed averaging theory for dithered hybrid systems are violated. Several practical experiments and simulation examples of power electronics converters are discussed. They indicate that the conditions on the dither signal imposed by the averaging theory are rather tight.

  • 36.
    Jarzebowicz, Leszel
    et al.
    Gdansk Univ. Technol., POL.
    Karwowski, Krzysztof
    Gdansk Univ. Technol., POL.
    Kulesza, Wlodek
    Blekinge Institute of Technology, Faculty of Engineering, Department of Applied Signal Processing.
    Sensorless algorithm for sustaining controllability of IPMSM drive in electric vehicle after resolver fault2017In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 58, p. 117-126Article in journal (Refereed)
    Abstract [en]

    This paper presents a sensorless algorithm designated for the emergency control of an interior permanent magnet synchronous motor (IPMSM) drive in electric or hybrid vehicle. Special requirements for emergency-activated sensorless algorithms are defined, and shortcomings of state-of-the-art methods in terms of the considered application are discussed. The proposed emergency-activated algorithm is based on analysing the derivatives of motor phase currents measured over the duration of particular inverter states. The method is computationally simple and does not require additional hardware since the derivatives are measured indirectly. A lag between activating the algorithm upon an emergency flying start and re-establishing the torque controllability is defined. The proposed algorithm was implemented in the controller of a laboratory IPMSM vehicle drive and tested under varying operational conditions, including the emergency activation. © 2016 Elsevier Ltd

  • 37.
    Jin, Junchen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Ma, Xiaoliang
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Kosonen, Iisakki
    An intelligent control system for traffic lights with simulation-based evaluation2017In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 58, p. 24-33Article in journal (Refereed)
    Abstract [en]

    This paper introduces an intelligent control system for traffic signal applications, called Fuzzy Intelligent Traffic Signal (FITS) control. It provides a convenient and economic approach to improve existing traffic light infrastructure. The control system is programmed on an intermediate hardware device capable of receiving messages from signal controller hardware as well as overriding traffic light indications during real-time operations. Signal control and optimization toolboxes are integrated into the embedded software in the FITS hardware device. A fuzzy logic based control has been implemented in FITS. In order to evaluate the effects of FITS system, this study attempts to develop a computational framework to evaluate FITS system using microscopic traffic simulation. A case study is carried out, comparing different commonly used signal control strategies with the FITS control approach. The simulation results show that the control system has the potential to improve traffic mobility, compared to all of the tested signal control strategies, due to its ability in generating flexible phase structures and making intelligent timing decisions. In addition, the effects of detector malfunction are also investigated in this study. The experiment results show that FITS exhibits superior performance than several other controllers when a few detectors are out-of-order due to its self-diagnostics feature.

  • 38.
    Jung, 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, Computer Engineering. Linköping University, The Institute of Technology.
    Development of misfire detection algorithm using quantitative FDI performance analysis2015In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 34, p. 49-60Article in journal (Refereed)
    Abstract [en]

    A model-based misfire detection algorithm is proposed. The algorithm is able to detect misfires and identify the failing cylinder during different conditions, such as cylinder-to-cylinder variations, cold starts, and different engine behavior in different operating points. Also, a method is proposed for automatic tuning of the algorithm based on training data. The misfire detection algorithm is evaluated using data from several vehicles on the road and the results show that a low misclassification rate is achieved even during difficult conditions. (C) 2014 Elsevier Ltd. All rights reserved.

  • 39.
    Jung, Daniel
    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.
    Krysander, Mattias
    Linköping University, Department of Electrical Engineering, Computer Engineering. Linköping University, The Institute of Technology.
    A flywheel manufacturing error compensation algorithm for engine misfire detection2016In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 47, p. 37-47Article in journal (Refereed)
    Abstract [en]

    A commonly used signal for engine misfire detection is the crankshaft angular velocity measured at the flywheel. However, flywheel manufacturing errors result in vehicle-to-vehicle variations in the measurements and have a negative impact on the misfire detection performance, where the negative impact is quantified for a number of vehicles. A misfire detection algorithm is proposed with flywheel error adaptation in order to increase robustness and reduce the number of mis-classifications. Since the available computational power is limited in a vehicle, a filter with low computational load, a Constant Gain Extended Kalman Filter, is proposed to estimate the flywheel errors. Evaluations using measurements from vehicles on the road show that the number of mis-classifications is significantly reduced when taking the estimated flywheel errors into consideration.

  • 40.
    Klein, Marcus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    Eriksson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Åslund, Jan
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering, Vehicular Systems.
    Compression ratio estimation based on cylinder pressure data2006In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 14, no 3 SPEC. ISS., p. 197-211Article in journal (Refereed)
    Abstract [en]

    Four methods for compression ratio estimation based on cylinder pressure traces are developed and evaluated for both simulated and experimental cycles. The first three methods rely upon a model of polytropic compression for the cylinder pressure. It is shown that they give a good estimate of the compression ratio at low compression ratios, although the estimates are biased. A method based on a variable projection algorithm with a logarithmic norm of the cylinder pressure yields the smallest confidence intervals and shortest computational time for these three methods. This method is recommended when computational time is an important issue. The polytropic pressure model lacks information about heat transfer and therefore the estimation bias increases with the compression ratio. The fourth method includes heat transfer, crevice effects, and a commonly used heat release model for firing cycles. This method is able to estimate the compression ratio more accurately in terms of bias and variance. The method is more computationally demanding and is therefore recommended when estimation accuracy is the most important property. © 2005 Elsevier Ltd. All rights reserved.

  • 41.
    Krysander, Mattias
    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.
    Leakage Detection In a Fuel Evaporative System2009In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 17, no 11, p. 1273-1279Article in journal (Refereed)
    Abstract [en]

    On-board diagnostic (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 the number of leakage checks is 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 a production engine and fuel system setup in a laboratory environment.

  • 42. Lequin, O.
    et al.
    Gevers, M.
    Mossberg, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Bosmans, E.
    Triest, L.
    Iterative Feedback Tuning of PID parameters: Comparison with classical tuning rules2003In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 11, no 9, p. 1023-1033Article in journal (Refereed)
  • 43.
    Leufvén, Oskar
    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.
    A surge and choke capable compressor flow model: Validation and extrapolation capability2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 12, p. 1871-1883Article in journal (Refereed)
    Abstract [en]

    Increasingly stringent emissions legislation combined with consumer performance demand, have created the need for complex automotive engines. The control of these complex system rely heavily on control oriented models. Models capable of describing all operating modes of the systems are beneficial, and the models should be easily parametrized and enable extrapolation. A large database of automotive compressor maps is characterized, and used to develop, validate and automatically parametrize a compressor flow model capable of describing reversed flow, normal operation and choke. Measurement data from both an engine test stand, and a surge test stand, is used to parametrize and validate the surge capability of the model. The model is shown to describe all modes of operation with good performance, and also to be able to extrapolate to small turbo speeds. The extrapolation capability is important, since compressor maps are shown to lack information for low speeds, even though they frequently operate there in an engine installation.

  • 44.
    Ma, Xiaoliang
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics. KTH, School of Architecture and the Built Environment (ABE), Centres, Centre for Traffic Research, CTR.
    Jansson, Magnus
    KTH, School of Electrical Engineering (EES), Signal Processing.
    A model identification scheme for driver-following dynamics in road traffic2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 6, p. 807-817Article in journal (Refereed)
    Abstract [en]

    The driver-following, or car-following, model is one of the most fundamental driver behavior models that are applied in intelligent transport applications. Its fidelity determines the applicability of microscopic traffic simulators, where the model is often implemented to mimic real traffic. Meanwhile, the behavioral model is fundamental to the development of advanced driving assistance systems (ADAS). This paper develops a dynamic model identification approach based on iterative usage of the extended Kalman Filtering (EKF) algorithm. Among other things, this allows to carry out model identification using a rather general optimization objective on the whole physical states of the following vehicle. In particular, the method is established on the basis of the equivalence between the Kalman filter and the recursive least squares (RLS) method in a specific context of parameter identification. To illustrate the method, two car-following models are studied in numerical experiments using real car-following data. The method has shown advantages in replication and prediction of vehicle dynamics in car-following over the conventional approaches. It has also the potential to be further extended for building tactical driving controllers in intelligent transportation applications.

  • 45.
    Mansouri, Sina Sharif
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kanellakis, Christoforos
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Fresk, Emil
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kominiak, Dariusz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Cooperative coverage path planning for visual inspection2018In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 74, p. 118-131Article in journal (Refereed)
    Abstract [en]

    This article addresses the inspection problem of a complex 3D infrastructure using multiple Unmanned Aerial Vehicles (UAVs). The main novelty of the proposed scheme stems from the establishment of a theoretical framework capable of providing a path for accomplishing a full coverage of the infrastructure, without any further simplifications (number of considered representation points), by slicing it by horizontal planes to identify branches and assign specific areas to each agent as a solution to an overall optimization problem. Furthermore, the image streams collected during the coverage task are post-processed using Structure from Motion, stereo SLAM and mesh reconstruction algorithms, while the resulting 3D mesh can be used for further visual inspection purposes. The performance of the proposed Collaborative-Coverage Path Planning (C-CPP) has been experimentally evaluated in multiple indoor and realistic outdoor infrastructure inspection experiments and as such it is also contributing significantly towards real life applications for UAVs.

    The full text will be freely available from 2020-05-01 11:28
  • 46.
    Mansouri, Sina Sharif
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kanellakis, Christoforos
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Georgoulas, Georgios
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kominiak, Dariusz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    2D visual area coverage and path planning coupled with camera footprints2018In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 75, p. 1-16Article in journal (Refereed)
    Abstract [en]

    Unmanned Aerial Vehicles (UAVs) equipped with visual sensors are widely used in area coverage missions. Guaranteeing full coverage coupled with camera footprint is one of the most challenging tasks, thus, in the presented novel approach a coverage path planner for the inspection of 2D areas is established, a 3 Degree of Freedom (DoF) camera movement is considered and the shortest path from the taking off to the landing station is generated, while covering the target area. The proposed scheme requires a priori information about the boundaries of the target area and generates the paths in an offline process. The efficacy and the overall performance of the proposed method has been experimentally evaluated in multiple indoor inspection experiments with convex and non convex areas. Furthermore, the image streams collected during the coverage tasks were post-processed using image stitching for obtaining a single overview of the covered scene.

    The full text will be freely available from 2020-06-01 11:15
  • 47.
    McKelvey, Tomas
    et al.
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Stenman, Anders
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Gustafsson, Fredrik
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    Rivera, Daniel E.
    Arizona State University, USA.
    Ljung, Lennart
    Linköping University, Department of Electrical Engineering, Automatic Control. Linköping University, The Institute of Technology.
    On Adaptive Smoothing of Empirical Transfer Function Estimates2000In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 8, no 11, p. 1309-1315Article in journal (Refereed)
    Abstract [en]

    The determination of the right resolution parameter when estimating frequency functions of linear systems is a trade-off between bias and variance. Traditional non-parametric approaches, like `window-closing' employ a global resolution parameter - the window width - that is tuned by ad hoc methods, usually visual inspection of the results. This paper suggests a method that tunes such parameters by an automatic procedure. A further benefit is that the tuning can be performed locally, i.e., that different resolutions can be used in different frequency bands. The ideas are based on local polynomial regression and a data-driven bandwidth selector. The advantages of the proposed method are illustrated in numerical examples.

  • 48. Millán, P.
    et al.
    Orihuela, L.
    Vivas, C.
    Rubio, F. R.
    Dimarogonas, Dimos V.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Sensor-network-based robust distributed control and estimation2013In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 21, no 9, p. 1238-1249Article in journal (Refereed)
    Abstract [en]

    This paper proposes a novel distributed estimation and control method for uncertain plants. It is of application in the case of large-scale systems, where each control unit is assumed to have access only to a subset of the plant outputs, and possibly controls a restricted subset of input channels. A constrained communication topology between nodes is considered so the units can benefit from estimates of neighboring nodes to build their own estimates. The paper proposes a methodology to design a distributed control structure so that the system is asymptotically driven to equilibrium with L2-gain disturbance rejection capabilities. A difficulty that arises is that the separation principle does not hold, as every single unit ignores the control action that other units might be applying. To overcome this, a two-stage design is proposed: firstly, the distributed controllers are obtained to robustly stabilize the plant despite the observation errors in the controlled output. At the second stage, the distributed observers are designed aiming to minimize the effects of the communication noise in the observation error. Both stages are formulated in terms of linear matrix inequalities. The performance is shown on a level-control real plant.

  • 49. Murgovski, N.
    et al.
    Egardt, B.
    Nilsson, Magnus
    RISE, Swedish ICT, Viktoria.
    Cooperative energy management of automated vehicles2016In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 57, p. 84-98Article in journal (Refereed)
    Abstract [en]

    This paper presents a cooperative adaptive cruise controller that controls vehicles along a planned route in a possibly hilly terrain, while keeping safe distances among the vehicles. The controller consists of two predictive layers that may operate with different update frequencies, horizon lengths and model abstractions. The top layer plans kinetic energy in a centralized manner by solving a quadratic program, whereas the bottom layer optimizes gear in a decentralized manner by solving a dynamic program. The efficiency of the proposed controller is shown through several case studies with different horizon lengths and number of vehicles in the platoon.

  • 50.
    Mustafa, Mohammed Obaid
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nikolakopoulos, George
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Kominiak, Dariusz
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    A Fault Detection Scheme Based on Minimum Uncertainty Bounds Violation for Broken Rotor Bars in Induction Motors2016In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 48, p. 63-77Article in journal (Refereed)
    Abstract [en]

    In this article, a novel method for broken bars fault detection in the case of three-phase induction motors and under different payloads will be presented and experimentally evaluated. In the presented approach, the cases of a partially or full broken rotor bars is being also considered, caused by: a) drilling 4mm and 8mm out of the $13$mm thickness of the same rotor bar, and b) fully drilled (13mm) one, two and three broken bars. The proposed fault detection method is based on the Set Membership Identification (SMI) technique and a novel proposed minimum boundary violation fault detection scheme, applied on the identified motor's parameters. The system identification procedure is being carried out on the simplified equivalent model of the induction motor, during the steady-state operation (non-fault case), while at the same time the proposed scheme is able to calculate on-line the corresponding safety bounds for the identified variables, based on a priori knowledge of the measuring corrupting noise (worst case encountered). The efficiency, the robustness and the overall performance of the established fault detection scheme is being extensively evaluated in multiple experimental studies and under various time instances of faults and load conditions.

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