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  • 1.
    Aidanpää, Jan-Olov
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Gustavsson, Rolf K.
    Vattenfall, VRD.
    Lundström, Niklas L. P.
    Umeå university.
    Karlsson, Martin
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Calleecharan, Yogeshwarsing
    Nässelqvist, Mattias
    Karlberg, Magnus
    Lundin, Urban
    Uppsala University.
    Developments in rotor dynamical modeling of hydropower units2009In: Proceedings of the IUTAM Symposium on Emerging Trends in Rotor Dynamics: held in New Delhi, India, March 23 - March 26, 2009 / [ed] Kshitij Gupta, Dordrecht: Encyclopedia of Global Archaeology/Springer Verlag, 2009Conference paper (Refereed)
  • 2.
    Alzghoul, Ahmad
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Data stream mining for increased functional product availability awareness2011In: Functional Thinking for Value Creation: Proceedings of the 3rd CIRP International Conference on Industrial Product Service Systems, Technische Universität Braunschweig, Braunschweig, Germany, May 5th - 6th, 2011 / [ed] Jürgen Hesselbach; Christoph Herrmann, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2011, p. 237-241Conference paper (Refereed)
    Abstract [en]

    Functional Products (FP) and Product Service Systems (PSS) may be seen as integrated systems comprising hardware and support services. For such offerings, availability is key. Little research has been done on integrating Data Stream Management Systems (DSMS) for monitoring (parts of) a FP to improve system availability. This paper introduces an approach for how data stream mining may be applied to monitor hardware being part of a Functional Product. The result shows that DSMS have the potential to significantly support continuous availability awareness of industrial systems, especially important when the supplier is to supply a function with certain availability.

  • 3.
    Arvidsson, Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Hjelm, Karin
    Southern Swedish Forest Research Centre, SLU, P.O. Box 190, Lomma. SE-234 22, Sweden.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Digital precision planning tool for autonomous forest regeneration of mixed tree species2023Conference paper (Refereed)
  • 4.
    Hansson, Linnea J.
    et al.
    Skogforsk, The Forestry Research Institute of Sweden, 751 83 Uppsala, Sweden.
    Sten, Gustav
    Department of Engineering Design, KTH-Swedish Royal Institute of Technology, 100 44 Stockholm, Sweden.
    Rossander, Morgan
    Skogforsk, The Forestry Research Institute of Sweden, 751 83 Uppsala, Sweden.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Manner, Jussi
    Skogforsk, The Forestry Research Institute of Sweden, 751 83 Uppsala, Sweden.
    van Westendorp, Ruben
    Bräcke Forest AB, 843 31 Bräcke, Sweden.
    Li, Songyu
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Eriksson, Anders
    Skogforsk, The Forestry Research Institute of Sweden, 751 83 Uppsala, Sweden.
    Wallner, Anna
    Södra, 351 89 Växjö, Sweden.
    Rönnqvist, Mikael
    Département de Génie Mécanique, Université Laval, Québec, QC G1V 0A6, Canada.
    Flisberg, Patrik
    Creative Optimization Sweden AB, 302 31 Halmstad, Sweden.
    Edlund, Björn
    Skogstekniska Klustret (The Swedish Cluster of Forest Technology), 907 29 Umeå, Sweden.
    Möller, Björn
    Department of Engineering Design, KTH-Swedish Royal Institute of Technology, 100 44 Stockholm, Sweden.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Autoplant—Autonomous Site Preparation and Tree Planting for a Sustainable Bioeconomy2024In: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 15, no 2, article id 263Article in journal (Refereed)
    Abstract [en]

    Sustainable forestry requires efficient regeneration methods to ensure that new forests are established quickly. In Sweden, 99% of the planting is manual, but finding labor for this arduous work is difficult. An autonomous scarifying and planting machine with high precision, low environmental impact, and a good work environment would meet the needs of the forest industry. For two years, a collaborative group of researchers, manufacturers, and users (forest companies) has worked together on developing and testing a new concept for autonomous forest regeneration (Autoplant). The concept comprises several subsystems, i.e., regeneration and route planning, autonomous driving (path planning), new technology for forest regeneration with minimal environmental impact, automatic plant management, crane motion planning, detection of planting spots, and follow-up. The subsystems were tested separately and integrated together during a field test at a clearcut. The concept shows great potential, especially from an environmental perspective, with significantly reduced soil disturbances, from approximately 50% (the area proportion of the area disturbed by disc trenching) to less than 3%. The Autoplant project highlights the challenges and opportunities related to future development, e.g., the relation between machine cost and operating speed, sensor robustness in response to vibrations and weather, and precision in detecting the size and type of obstacles during autonomous driving and planting.

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  • 5.
    Johnsson, Helena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Alerby, Eva
    Luleå University of Technology, Department of Arts, Communication and Education, Education, Language, and Teaching.
    Hyyppä, Kalevi
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Jonsson, Håkan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Computer Science.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Stenberg, Magnus
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Strömberg, Thomas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mathematical Science.
    En pedagogisk idé för ingenjörsutbildningarna vid Luleå tekniska universitet2009Conference paper (Refereed)
    Abstract [sv]

    Utmärkande för Luleå tekniska universitet (LTU) har länge varit närheten mellan studenterna och lärarna vilket har manifesterats genom klassrumsundervisning, lärartillgänglighet, mindre studiegrupper, koncentrerade campus etc. Undervisningsformerna har dock ändrats till att idag omfatta dels klassiska föreläsningar i stora studentgrupper, men också projektarbete i team där totalt sett 1/3 av all undervisning vid Luleå tekniska universitet sker i projektform. En fråga har ställts: Har Luleå tekniska universitet idag en gemensam pedagogisk idé för ingenjörsutbildningarna? I så fall är ytterligare en fråga hur denna pedagogiska idé tar sig uttryck i organisationen?Intervjuer med 40 aktiva lärare vid Luleå tekniska universitet har genomförts av projektgruppen (tillika författarna) varpå svaren har grupperats och analyserats i fjorton olika teman. Från dessa teman har sedan fyra hörnstenar i en definition av en pedagogisk idé aggregerats. Formuleringen av den pedagogiska idén lyder: Ett aktivt lärande för yrkeslivet – i branschnära projekt och med god vetenskaplig grund tränas förmågan att arbeta som ingenjör genom coachning från lärare i ett nära och öppet klimat. Idén har antagits av den tekniska fakultetsnämnden vid Luleå tekniska universitet och verifierats på institutionerna. Exempel på implementering och hur den pedagogiska idén aktivt verkar presenteras i artikeln.

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  • 6.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A noise reduction method for vibration measurement on rotating machineries2008In: ISROMAC-12: the Twelfth International Symposium on Transport Phenomena and Dynamics of Rotating Machinery ; Honolulu, Hawaii, February 17 - 22 nd, 2008, Honolulu, 2008Conference paper (Refereed)
    Abstract [en]

    In order to validate rotordynamical models vibration measurements in noisy environments leading to poor quality are in many cases necessary e.g. on-site measurements. For rotordynamical systems not only unwanted broad banded noise but also distinct frequencies are often present e.g. due to unbalance. The aim of this paper is therefore to suggest a noise reduction method in order to increase the quality of such vibration measurements. Both random noise and distinct frequency noise are applied on a finite element model of the rotor system. First, vibration data is stored when the system is running only with the noise as excitation source. Then a known input (i.e. a shaker) is added and the vibration data is stored again. Finally, the noisy signal is subtracted from the one with known input in the frequency domain. This noise reduction method significantly increased the coherence.

  • 7.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A simulation driven rotordynamical design method supporting functional product development2007Conference paper (Other academic)
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  • 8.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Approximated stiffness coefficients in rotor systems supported by bearings with clearance2010In: International Journal of Rotating Machinery, ISSN 1023-621X, E-ISSN 1542-3034, Vol. 2010, no Article ID 540101Article in journal (Refereed)
    Abstract [en]

    Many kinds of rotating machinery are supported by bearings with clearance, which are further clamped in a supporting structure. When designing such machinery it is important to be able to predict dynamics and hence valid models are needed. Due to gravity, the shaft often vibrates close to a static equilibrium position leading to a possibility to linearise the equation of motion. Although several studies on bearings with clearance exist, there are still no reports on how such clearances affects the stiffness coefficients close to a static equilibrium position. Therefore, analytical expressions for such approximated pedestal stiffness coefficients have been derived in this paper. By using such approximated pedestals in simple rotordynamical models, it was found that the eigenfrequencies decrease significantly with clearance. It is further shown that the approximated pedestal stiffness coefficients only will be valid for vibrations close to the static equilibrium position.

  • 9.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Concept evaluation and contact problems in simple rotordynamical systems2003Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Rotating machines serves an important role in many different applications. Extensive research has been made, manly during the last century, in order to develop these systems and understand the dynamics. The theory of rotordynamics differs in many fundamental aspects from structural dynamics and is therefore usually treated as an own research area. In rotordynamical applications there exist several qualitatively different concepts. For example super- and subcritical machines supported on different types of bearings like ball-, roller- or journal bearings etc. At the early stage of the product development, the problem is often to find a general tool which can be used for dynamical evaluation of these concepts. Many concepts also contain significant nonlinearities which need to be studied separately. One such nonlinearity is a clearance which arises between a fixed support and an axially movable bearing assembly. Another nonlinear effect is the loss of contact which can occur in preloaded spherical roller thrust bearings. The aim is hence to present a method to dynamically evaluate different rotordynamical concepts, describe nonlinear effects due to these contact problems and suggest suitable design parameters. For the concept evaluation a linear model which captured the gyroscopic effect is proposed, while the contact problems are handled with nonlinear models (usually piecewise linear). The governing equations of motion are solved analytically in the linear case but needs to be simulated in the nonlinear cases. However, in some special cases it is possible to find steady state solutions even for the contact problems. Simulations of design spaces, Poincaré maps, bifurcation diagrams, Lyapunov exponents, contact forces etc. have been used to study the systems. In order to evaluate different concept, design spaces spanned by a requirement variable and three design parameters are plotted. These are four dimensional plots where the variations of the requirement variables are visualised by colours. This is done both for the unbalance response and an impact in order to include both the homogenous and particular solution. In the clearance problem bifurcation diagrams and Poincaré maps indicates that multi-, quasi- or chaotic motions are possible which in many cases include impacts. When stabilising rods are applied the unstable areas (positive maximum Lyapunov exponent) are reduced. In the case with the spherical roller thrust bearings nonperiodic motions are found. The stability shows strong dependency on the amount of preload. A method to dynamically evaluate rotordynamical concepts is suggested. Some especially interesting ranges of the design parameters which give low vibrations are presented. It has further been shown that strong nonlinear dynamics which may lead to failure can be expected in systems with clearance between the stator and bearing assembly. One way to get rid of such unwanted vibrations is to apply stabilising rods. It is than important to choose the right parameters since otherwise worse conditions may occur. In systems supported by preloaded spherical roller thrust bearings it is important that the preloading is high enough. Otherwise jump phenomenon and nonperiodic motions can arise. An expression of the limit preload of going in or out of full contact has been derived which can be used to choose a suitable preloading.

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  • 10.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Investigation of a saddle node bifurcation due to loss of contact in preloaded spherical roller thrust bearings2009In: Chaos, Solitons & Fractals, ISSN 0960-0779, E-ISSN 1873-2887, Vol. 41, no 4, p. 1750-1759Article in journal (Refereed)
    Abstract [en]

    Spherical roller thrust bearings are used as supports in many rotating machineries. By applying an axial preload, clearance between the raceways and the rollers can be avoided. In order to increase the endurance, the preload shall be kept as low as possible. However, a bearing with low preload is sensitive of loosing full contact leading to nonlinear stiffness characteristics. The objective of this paper is to suggest a tool, which can be used to determine suitable preload and to show that a saddle node bifurcation can occur if the preload is too small.Studying the model in a rotating frame leads to an autonomous equation of motion from which stationary points and their stability can be analysed. Some set of parameters give a nonhyperbolic eigenvalue, and by investigating the corresponding central manifold it is found that a saddle node bifurcation occurs. Since explicit equations for the stationary points are derived, they can be used to choose a preload high enough to make sure that full contact always is a possible solution. It is however shown that if the preload becomes too small, the system enters an area of multiple solutions and a saddle node bifurcation can occur.

  • 11.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Rotordynamic effects of adding spherical roller thrust bearing stiffness components to fiber refiner models2008In: ISROMAC-12: the Twelfth International Symposium on Transport Phenomena and Dynamics of Rotating Machinery ; Honolulu, Hawaii, February 17 - 22 nd, 2008 / Pacific Center of Thermal-Fluids Engineering, Honolulu, 2008Conference paper (Refereed)
    Abstract [en]

    One key component in panelboard production is the fiber refiner which grinds cellulose woodchips into slender fibers. Current fiber refiners are rotating machines where the grinding takes place between a stator and a rotor. The rotor can be supported by preloaded spherical roller thrust bearings (SRTB) which for simplicity are often modeled as springs with radial stiffness. However, a more detailed analysis of these bearings shows that other stiffness components are also present. Thus, the aim of this paper is to show how dynamic properties change as such stiffness components are introduced.The SRTB stiffness matrix is derived from a simplified finite element model. This derived stiffness matrix is then used in another rotordynamic model. Campbell diagrams show that these additional stiffness components influence the eigenfrequencies in such a way that they should be considered when analyzing fiber refiners.

  • 12.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Rotordynamical concept evaluation of fibre refiners2005Doctoral thesis, comprehensive summary (Other academic)
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  • 13.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Aidanpää, Jan-Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Evaluation of rotordynamical concepts subjected to rotating unbalance and impulse2002In: Proceedings of the Sixth International Conference on Rotor Dynamics, IFT o MM: Sydney, Australia, September 30 to October 4, 2002 / [ed] Eric Hahn, Sydney: UNSW Printing Services, , 2002, p. 752-758Conference paper (Refereed)
  • 14.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Aidanpää, Jan-Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Investigation of an unbalanced rotor system with bearing clearance and stabilising rods2004In: Chaos, Solitons & Fractals, ISSN 0960-0779, E-ISSN 1873-2887, Vol. 20, no 2, p. 363-374Article in journal (Refereed)
    Abstract [en]

    The nonlinear vibrations of a rotor system with bearing clearance and stabilising rods are considered. In this paper the main objective is to evaluate effects of applying stabilising rods and from a dynamical point of view find preferable parameter ranges. A piecewise linear two degrees-of-freedom model is proposed. The system is studied and evaluated by analysis of steady state, bifurcation diagrams, Lyapunov exponents and contact force. It is shown how transition lines (which separate different categories of motion), periodicity and sensitivity to small perturbation are affected by the parameters defining the stability rods. By applying specific stabilising rods the periodicity is changed for some parameter ranges, unstable areas are reduced, the total maximum normal contact force is increased while the dynamical part is mainly reduced. The analytical expressions for the transition limits can be used as a design tool to choose suitable parameters. It is concluded that the stability rods should be applied vertically and that high preloading and stiffness prevents the system from impact motion. The stabilising rods are effective tools to avoid nonlinear behaviors but it is necessary to carefully analyse the specific application

  • 15.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Aidanpää, Jan-Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Nonlinear dynamics due to loss of contact in preloaded spherical roller thrust bearings2004In: Extended Abstracts + Proceedings (CD-ROM) of the 10th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery - ISROMAC-10: Honolulu, Hawaii, USA March 07-11, 2004 / [ed] Dieter Bohn, Aachen: Inst. of steam and gas turbines, RWTH , 2004Conference paper (Refereed)
    Abstract [en]

    Extended Abstracts + Proceedings (CD-ROM) of the 10th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery - ISROMAC-10 (Honolulu, Hawaii, USA March 07-11, 2004)

  • 16.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Aidanpää, Jan-Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Numerical investigation of an unbalanced rotor system with bearing clearance2003In: Chaos, Solitons & Fractals, ISSN 0960-0779, E-ISSN 1873-2887, Vol. 18, no 4, p. 653-664Article in journal (Refereed)
    Abstract [en]

    The nonlinear vibrations of a rotor system with bearing clearance are considered. The model consists of an unbalanced shaft with two d.o.f connected to a nonrotating massless housing by linear springs and dashpots. The clearance occurs when the housing (modelled as a ring) has a radius less than the stator. The behaviour of this system has been investigated with the use of time histories, Poincare maps, bifurcation diagrams, Lyapunov exponents, phase portraits, cell mapping and design space. Numerical simulations have achieved these results. The main objective was to find possible causes of failure in machines containing this type of clearance. The existence of subharmonic, quasi-periodic or even possible chaotic motion has been found. It is shown that these motions may give raise to bouncing modes, which results in high bearing forces and hence can be a possible cause of failure

  • 17.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Aidanpää, Jan-Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Rotordynamical modelling of a fibre refiner during production2007In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 303, no 3-5, p. 440-454Article in journal (Refereed)
    Abstract [en]

    A key component in panel board production is the fibre refiner, whose task is to break cellulose wood chips into slender fibres. This refining process takes place between a rotor and a stator, where a gap of around 0.5 mm is found. In the development of these refiners predicting the dynamics is important; hence, mathematical models are needed. For refiners and other applications like brakes, turbines, and compressors, the interaction between the rotor and the surrounding medium can in many situations be significant. In addition to external load, this interaction can also change the characteristics of the system, which should be considered in the design process. Today, there exists no validated load model for fibre refiner process. Hence, the aim of this paper is to suggest one.Measured axial force data were divided into a constant part and a superimposed oscillating part with different frequencies. For both parts a linear dependence on the gap between the stator and the rotor was assumed. Finally, a four degrees of freedom (dof) model was used to fit a pressure distribution to the axial force model.This process load model led to stiffness and external loads that can be both time dependant. If the pressure distribution only shows a radial variation along the refining zone, all the external loads except the axial one will vanish. The number of functions describing the stiffness parameters also decrease from eight to four. In one case, four stiffness coefficients vanish, whereas the remaining coefficients become constant. This occurs if the process load does not follow the angular vibrations and there is no gap dependence on the oscillating parts of the process load. Numerical simulations showed that by applying a specific process load model, the vibration orbit changed from the unbalance response by means of shape and vibration origin. The unstable domain was further increased when the process load model was applied.Measurements are necessary to select a realistic process model for a specific application. The derived model can be used in product development to choose suitable system parameters and thus to avoid dynamical problems.

  • 18.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Aidanpää, Jan-Olov
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
    Rotordynamical simulations of a fibre refiner during production2011In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 330, no 18/19, p. 4460-4473Article in journal (Refereed)
    Abstract [en]

    A key component in panel board production is the refiner, whose task is to break raw cellulose wood chips into slender fibres, done by a relative angular motion between stator and rotor. The main problem in predicting the dynamics of these machines is to model the complicated fibre breaking process, since the refining process leads to a three-phase flow (solid wood, water and steam) between the stator and rotor. By modelling the rotor as a rigid body, the process can only contribute by a resulting force and a resulting moment. Through this approach and axial force measurements, it has been shown that the refining process can be treated as a time dependent stiffness matrix and external load. The objective for this paper is to predict and explain dynamical characteristics of fibre refiners during production in such a way that the results can be used already at early stages of the product development process. Two different pressure distribution cases are studied, i.e. one axisymmetric with only radial variations and one non-axisymmetric. It is found that the axisymmetric case only excited forward modes, while the non-axisymmetric case excited all modes. The time dependent stiffness matrix resulted in unstable domains, but also in stable domains with intermittent high amplitudes.

  • 19.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Applied Physics and Mechanical Engineering.
    Karlsson, Martin
    Lloyd’s Register ODS AB.
    Karlsson, Lennart
    Luleå University of Technology, Department of Applied Physics and Mechanical Engineering.
    Näsström, Mats
    Luleå University of Technology, Department of Applied Physics and Mechanical Engineering.
    Dynamics of rotor systems with clearance and weak pedestals in full contact2010In: 13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery 2010 (ISROMAC-13): Honolulu, Hawaii, USA, 4 - 7 April 2010, Red Hook, NY: Curran Associates, Inc., 2010, p. 531-536Conference paper (Refereed)
    Abstract [en]

    Many rotating machineries are supported by bearings with clearance, which are further clamped in, compared to the bearing stiffness, weak pedestals. As have been reported in several studies, it is essential to choose a proper clearance in order to avoid unwanted vibrations. When rotating machineries supported by bearings with clearance are subjected to stationary loads (gravity, magnetic pull etc.), it may not loose contact between the shaft and the bearing (i.e. full contact). However, even in full contact unwanted dynamics can occur which is of interest in this paper. It is found that the clearance give raise to anisotropic pedestal stiffness. It is further shown that some of the resonance frequencies decrease with the clearance.

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  • 20.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Marjavaara, Daniel
    LKAB, Kiruna, Sweden.
    Lundström, T. Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Simulation driven processing function development, offering and operation2012In: Proceedings of the ASME 2012 International Mechanical Engineering Congress & Exposition IMECE2012: November 9-15, 2012, Houston, Texas, USA, New York: American Society of Mechanical Engineers , 2012, Vol. 3, p. 1561-1572, article id IMECE2012-87548Conference paper (Refereed)
    Abstract [en]

    In today’s industry, functional provision is becoming more and more important, necessitating increased simulation support. In this paper, the objective is to present a modeling and simulation approach for simulation-driven design (SDD) to support function development. The scope of this paper is simulation support for developing hardware equipment used in processing industry. The research is founded on industrial needs identified through two parallel interview-based studies in the Swedish process industry. Both companies explore doing business with functional products rather than hardware, in scenarios where the responsibility for and availability of the functions may remain with the service provider. One as-is and one future (to-be) scenario are presented. A decomposition of a general processing function (applicable to both companies) describes how the companies transfer machine input to output specifications. The decomposition includes customer and provider value and the paper demonstrates, as part of the results and based on the SDD approach, how that value may be increased through evaluation and prioritization. Additionally, the SDD approach shows that it is possible to identify a set of solutions which meet the specified requirements, supporting evaluation and prioritization of business offers and activities.

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  • 21.
    Karlberg, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Sandberg, Stefan
    PM/PD Press Hardening Tech Centers, Tool CAE Analyst, GESTAMP HardTech AB, SE-971 25 Luleå, Sweden.
    Lundin, Michael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    State of the art in simulation-driven design2013In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 18, no 1, p. 68-87Article in journal (Refereed)
    Abstract [en]

    During the last few decades, and in order to increase product development efficiency, simulations strategies have been developed to guide designers towards better solutions rather than to verify suggested and basically unevaluated solutions. Such approaches are often called Simulation Driven Design (SDD), which is of interest in this review. The objective of this paper is to show the research evolution of SDD and identify the state of the art in SDD methodology. The literature review comprises several hundred references, of which 79 are included in this paper. The results comprise the state of the art in simulation driven design including the history, various definitions, criteria and effects of using SDD approaches.

  • 22.
    Karlsson, Lennart
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Editorial2013In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 18, no 1, p. 1-2Article in journal (Other academic)
  • 23.
    Karlsson, Lennart
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Pahkamaa, Andreas
    Luleå University of Technology.
    Karlberg, Magnus
    Luleå University of Technology.
    Löfstrand, Magnus
    Luleå University of Technology.
    Goldak, John
    Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, ON, K1S 5B6, Canada.
    Pavasson, Jonas
    Luleå University of Technology.
    Mechanics of materials and structures: a simulation-driven design approach2011In: Journal of Mechanics of Materials and Structures, ISSN 1559-3959, E-ISSN 2157-5428, Vol. 6, no 1-4, p. 277-301Article in journal (Refereed)
    Abstract [en]

    Engineering product development has developed considerably over the past decade. In order for industry to keep up with continuously changing requirements, it is necessary to develop new and innovative simulation methods. However, few tools and methods for simulation-driven design have been applied in industrial settings and proven to actually drive the development and selection of the ideal solution. Such tools, based on fundamental equations, are the focus of this paper. In this paper the work is based on two cases of mechanics of materials and structures: welding and rotor dynamical simulations. These two examples of simulation-driven design indicate that a larger design space can be explored and that more possible solutions can be evaluated. Therefore, the approach improves the probability of innovations and finding optimal solutions. A calibrated block dumping approach can be used to increase the efficiency of welding simulations when many simulations are required.

  • 24.
    Karlsson, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Samuelsson, Henrik
    Lloyd's Register ODS.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Co-variance driven stochastic subspace identification approach for rotordynamics2010In: 13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery 2010 (ISROMAC-13), 2010Conference paper (Refereed)
  • 25.
    Karlsson, Martin
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Samuelsson, Henrik
    Lloyd's Register ODS.
    Karlberg, Magnus
    Using operational modal analysis to determine rotordynamic modes2010In: 13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery 2010 (ISROMAC-13): Honolulu, Hawaii, USA, 4 - 7 April 2010, Red Hook, NY: Curran Associates, Inc., 2010, p. 527-530Conference paper (Refereed)
    Abstract [en]

    Operational Modal Analysis (OMA) has lately been a more and more common tool in structural dynamics. The benefits compared to Experimental Modal Analysis (EMA) are that one does not need any artificial excitation and that the structure does not have to be at rest, which is a requirement of EMA. So far, OMA has won terrain for modal analysis of large structures such as buildings and bridges, and for vehicles such as helicopters and ships. For rotating equipment, OMA has not yet been widely used or evaluated. Rotordynamic modes depend on the operating condition of the rotating equipment (e.g. speed). Hence the fundamental requirement of EMA that the testing object should be at rest is not fulfilled. Mapping of critical speeds during start-up and coursing down gives some important operating information, but it will not give all modal information needed to validate a theoretical model or to verify the requirements of damping. The aim of this paper is to evaluate OMA for rotordynamical modal analysis. A numerical model of rotor is used as test object. The response is analyzed with various SSI methods. The results are presented in a Campbell diagram, showing the frequency dependent rotor modes as well as the structural modes. Values for the damping are presented in a root locus plot. These results agree well when comparing the results with a direct naturalvalue solver for the numerical model. It is concluded that OMA can be applied to rotordynamical applications. However, identifying corresponding modes at different speeds can be difficult at field measurements; hence the authors suggest further research and development of Operational Modal Analysis in this specific area.

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  • 26.
    Källström, Elisabeth
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindström, John
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Håkansson, Lars
    Department of Applied Signal Processing, Blekinge Institute of Technology.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Bellgran, David
    Volvo Construction Equipment, Eskilstuna.
    Frenne, Nicklas
    Volvo Construction Equipment, Eskilstuna.
    Renderstedt, Reza
    Volvo Construction Equipment, Eskilstuna.
    Lundin, Joakim
    Volvo Construction Equipment.
    Larsson, Jonas
    Volvo Construction Equipment, Eskilstuna.
    Analysis of automatic transmission vibration for clutch slippage detection2015In: 22nd International Congress on Sound and Vibration: ICSV 2015, Florence, Italy, 12-16 July 2015, Florence: International Institute of Acoustics and Vibrations , 2015Conference paper (Refereed)
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  • 27.
    Källström, Elisabeth
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Volvo Construction Equipment, Eskilstuna, Sweden.
    Lindström, John
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Digital Services and Systems.
    Håkansson, Lars
    Linnaeus University, Växjö, Sweden.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lin, Jing
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Vibration-based Condition Monitoring of Heavy Duty Machine Driveline Parts: Torque Converter, Gearbox, Axles and Bearings2019In: International Journal of Prognostics and Health Management, E-ISSN 2153-2648, Vol. 10, article id 014Article in journal (Refereed)
    Abstract [en]

    As more features are added to the heavy duty construction equipment, its complexity increases and early fault detection of certain components becomes more challenging due to too many fault codes generated when a failure occurs. Hence, the need to complement the present onboard diagnostic methods with more sophisticated diagnostic methods for adequate condition monitoring of the heavy duty construction equipment in order to improve uptime. Major components of the driveline (such as the gearbox, torque converter, bearings and axles) are such components. Failure of these major components of the driveline may results in the machine standing still until a repair is scheduled. In this paper, vibration based condition monitoring methods are presented with the purpose to provide a diagnostic framework possible to implement onboard for monitoring of critical driveline parts in order to reduce service cost and improve uptime. For the development of this diagnostic framework, sensor data from the gearbox, torque converter, bearings and axles are considered. Further, the feature extraction of the data collected has been carried out using adequate signal processing methods, which includes, Adaptive Line Enhancer, Order Power Spectrum respectively. In addition, Bayesian learning was utilized for adaptively learning of the extracted features for deviation detection. Bayesian learning is a powerful prediction method as it combines the prior information with knowlegde measured to make update. The results indicate that the vibration properties of the gearbox, torque converter, bearings and axle are relevant for early fault detection of the driveline. Furthermore, vibration provide information about the internal features of these components for detecting deviations from normal behavior.

    In this way, the developed methods may be implemented onboard for the continuous monitoring of these critical driveline parts of the heavy duty construction equipment so that if their health starts to degrade a service and/or repair may be scheduled well in advance of a potential failure and in that way the downtime of a machine may be reduced and costly replacements and repairs avoided.

  • 28.
    Källström, Elisabeth
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindström, John
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Håkansson, Lars
    Department of Applied Signal Processing, Blekinge Institute of Technology.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Renderstedt, Reza
    Volvo Construction Equipment.
    Larsson, Jonas
    Volvo Construction Equipment.
    Identification of vibration properties of heavy duty machine driveline parts as a base for adequate condition monitoring: Axle2016In: ICSV 2016 - 23rd International Congress on Sound and Vibration: From Ancient to Modern Acoustics / [ed] Vogiatzis, K; Kouroussis, G; Crocker, M; Pawelczyk, M, 2016Conference paper (Refereed)
    Abstract [en]

    With increasing complexities in the heavy duty construction equipment, early fault detection of certain components in the machine becomes more and more challenging due to too many fault code generated when a failure occurs. The axle is one of such component. The axle transfers driving torque from the transmission to the wheels and axle failure may result in costly downtime of construction equipment. To reduce service cost and to improve uptime, adequate condition monitoring based on sensor data from the axle is considered. Vibration is measured on the axle. Analysis of the data has been carried out using adequate signal processing methods. The results indicate that the vibration properties of the axle are relevant for early fault detection of the axle. In this way; the health of the axle may be continuously monitored on-board using the vibration information and if the axle health starts to degrade a service and/or repair may be scheduled well in advance of a potential axle failure and in that way the downtime of a machine may be reduced.

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  • 29.
    Källström, Elisabeth
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Volvo Construction Equipment, Eskilstuna, Sweden.
    Lindström, John
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Håkansson, Lars
    Linnaeus University, Växjö, Sweden.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Öberg, Olof
    Volvo Construction Equipment, Eskilstuna, Sweden.
    Identification of Vibration Properties of Wheel Loader Driveline Parts as a Base for Adequate Condition Monitoring: Bearings2017In: / [ed] Gibbs B., International Institute of Acoustics and Vibration , 2017Conference paper (Refereed)
    Abstract [en]

    In order to reduce costly downtime, adequate condition monitoring of the automatic transmission components in heavy duty construction equipment is necessary. The transmission in such equipment enables to change the gear ratio automatically. Further, the bearings in an automatic transmission provide low friction support to its rotating parts and act as an interface separating stationary from rotating components. Wear or other bearing faults may lead to an increase in energy consumption as well as failure of other related components in the automatic transmission, and thus costly downtime. In this study, different sensor data (particularly vibration) was collected on the automatic transmission during controlled test cycles in an automatic transmission test rig to enable adequate condition monitoring.

    An analysis of the measured vibration data was carried out using signal processing methods. The results indicate that predictive maintenance information related to the automatic transmission bearings may be extracted from vibrations measured on an automatic transmission. This information may be used for early fault detection, thus improving uptime and availability of heavy duty construction equipment.

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  • 30.
    Källström, Elisabeth
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development. Volvo Construction Equipment, Eskilstuna, SE-63185, Sweden.
    Lindström, John
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems. Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, ProcessIT Innovations R&D Centre.
    Håkansson, Lars
    Department of Applied Signal Processing, Blekinge Institute of Technology, Karlskrona, 371 79, Sweden.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Öberg, Olof
    Volvo Construction Equipment, Eskilstuna, SE-63185, Sweden.
    Renderstedt, Reza
    Volvo Construction Equipment, Eskilstuna, SE-63185, Sweden.
    Larsson, Jonas
    Volvo Construction Equipment, Eskilstuna, SE-63185, Sweden.
    Identification of vibration properties of heavy duty machine driveline parts as a base for adequate condition monitoring: Torque converter2016In: ICSV 2016 - 23rd International Congress on Sound and Vibration: From Ancient to Modern Acoustics / [ed] Vogiatzis, K; Kouroussis, G; Crocker, M; Pawelczyk, M, 2016Conference paper (Refereed)
    Abstract [en]

    Improving uptime is paramount in the heavy duty construction equipment business. Failure ofcritical components in the heavy duty machine may lead to unnecessary stops and expensive downtime. The torque converter, a complex omponent of the driveline, transmits and multiplies torque from the engine to the gearbox, and its failure may not only lead to the machine standing still but may also lead to damage of other parts of the automatic transmission. For adequate condition monitoring of the torque converter, different sensor data are measured on a construction equipment machine during controlled driving sessions. Vibration has been measured on the torque converter. An initial investigation of the vibration measured on the torque converter has been carried out to identify its vibration properties in order to enable its health monitoring to prevent failure. Initial signal analysis of the data have been carried out using Order Power Spectrum and Order Modulation Spectrum methods. The results indicate that the torque converter vibration properties contain information relevant for early fault detection.

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  • 31.
    La Hera, Pedro
    et al.
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences Umeå Campus Umeå Sweden.
    Mendoza-Trejo, Omar
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå Campus, Umeå, Sweden.
    Lindroos, Ola
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå Campus, Umeå, Sweden.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindbäck, Torbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Latif, Saira
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Li, Songyu
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Exploring the feasibility of autonomous forestry operations: Results from the first experimental unmanned machine2024In: Journal of Field Robotics, ISSN 1556-4959, E-ISSN 1556-4967Article in journal (Refereed)
    Abstract [en]

    This article presents a study on the world's first unmanned machine designed for autonomous forestry operations. In response to the challenges associated with traditional forestry operations, we developed a platform equipped with essential hardware components necessary for performing autonomous forwarding tasks. Through the use of computer vision, autonomous navigation, and manipulator control algorithms, the machine is able to pick up logs from the ground and manoeuvre through a range of forest terrains without the need for human intervention. Our initial results demonstrate the potential for safe and efficient autonomous extraction of logs in the cut-to-length harvesting process. We achieved a high level of accuracy in our computer vision system, and our autonomous navigation system proved to be highly efficient. This research represents a significant milestone in the field of autonomous outdoor robotics, with far-reaching implications for the future of forestry operations. By reducing the need for human labor, autonomous machines have the potential to increase productivity and reduce labor costs, while also minimizing the environmental impact of timber harvesting. The success of our study highlights the potential for further development and optimization of autonomous machines in the forestry industry.

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  • 32.
    La Hera, Pedro
    et al.
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå Campus, Sweden.
    Trejo, Omar Mendoza
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå Campus, Sweden.
    Lindroos, Ola
    Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences, Umeå Campus, Sweden.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindbäck, Torbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Latif, Saira
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Li, Songyu
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Exploring the Feasibility of Autonomous Forestry Operations: Results from the First Experimental Unmanned MachineManuscript (preprint) (Other academic)
  • 33.
    Latif, Saira
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindbäck, Torbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Evaluation of Autonomous Navigational Accuracy for Different Reference Points in PurePursuit Algorithm for Center-Steered Articulated Vehicles2023In: Robot Intelligence Technology and Applications 7: Results from the 10th International Conference on Robot Intelligence Technology and Applications / [ed] Jo, J.; Helbig, M.; Stantic, B.; Choi, H-L.; Oh, H.; Hwangbo, J.; Lee, C-H., Springer Nature, 2023, p. 201-212Conference paper (Refereed)
    Abstract [en]

    Accurate autonomous navigation for off-terrain utility vehicles with no human intervention is an essential requirement to achieve full automation. Within several applications, though higher autonomous navigational accuracy (almost ±2.5 cm) has been achieved in some commercially available vehicles yet requirements for human intervention is still very much required in several situations. This study investigates autonomous navigational accuracy of PurePursuit algorithm for different reference points for a non-steerable-wheels center-steered articulated vehicle. PurePursuit algorithm is preferable choice for path tracking for its simplicity and for vehicles where high speed is not a requirement. Evaluation of PurePursuit algorithm for utility vehicles of type studied in this paper is somewhat less explored area. We have compared the autonomous navigational accuracy of PurePursuit algorithm for different reference points for a set of different path complexities that also includes vehicles kinematic constraints in simulation environment. Average lateral and heading deviations were calculated for a set of different path complexities, and it was found that in general proposed reference point for PurePursuit algorithm for center-steer articulated vehicle shows better lateral and heading autonomous navigational accuracy than the traditional PurePursuit algorithm.

  • 34.
    Latif, Saira
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindbäck, Torbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Wallsten, Johanna
    Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden.
    Bale Collection Path Planning Using an Autonomous Vehicle with Neighborhood Collection Capabilities2022In: Agriculture, E-ISSN 2077-0472, Vol. 12, no 12, article id 1977Article in journal (Refereed)
    Abstract [en]

    This research was mainly focused on the evaluation of path planning approaches as a prerequisite for the automation of bale collection operations. A comparison between a traditional bale collection path planning approach using traditional vehicles such as tractors, and loaders with an optimized path planning approach using a new autonomous articulated concept vehicle with neighborhood reach capabilities (AVN) was carried out. Furthermore, the effects of carrying capacity on reduction in the working distance of the bale collection operation was also studied. It was concluded that the optimized path planning approach using AVN with increased carrying capacity significantly reduced the working distance for the bale collection operation and can thus improve agricultural sustainability, particularly within forage handling.

  • 35.
    Latif, Saira
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindbäck, Torbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Outdoor tests of autonomous navigation system based on two different reference points of PurePursuit algorithm for 10-ton articulated vehicle.2024In: IEEE Access, E-ISSN 2169-3536, Vol. 12, p. 8413-8421Article in journal (Refereed)
    Abstract [en]

    This work presents outdoor test results of autonomous navigation system based on two different reference points of PurePursuit algorithm for a 10-ton articulated research platform. PurePursit is commonly used simplified tracking algorithm based on geometric calculation of desired steering angle by pursuing certain number of points/distance ahead on given path from a fixed reference point of vehicle. Choice of fixed reference point effects the tracking accuracy particularly for articulated/center-steered vehicles. In this experimental work, PurePursuit algorithm with a virtual reference point(PPV) and commonly used front-axle reference point(PPF) is evaluated for heavy duty articulated vehicles in outdoor experiments. Experimental data shows that choice of reference point in PurePursuit algorithm for articulated vehicle has impact on tracking accuracy in terms of crosstrack errors and heading errors. Navigation tests were performed on a flat asphalt surface for paths of sharp complexities i-e a path with continuous curvature (circular path) and a path with sharp turns (zigzag path) with different initial conditions i-e initial position of vehicle. In general, it can be concluded that PurePursuit algorithm with front reference point (PPF) produced fewer crosstrack errors while PurePursuit algorithm with virtual midpoint reference (PPV) produced fewer heading errors.

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  • 36.
    Latif, Saira
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindbäck, Torbjörn
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Wallsten, Johanna
    Swedish University of Agricultural Sciences (SLU), Sweden.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Challenges and Opportunities for Automation of Agricultural Vehicles in Sweden2021In: Proceedings of the 20th International Conference of the International Society for Terrain-Vehicle Systems and 9th Americas Conference of the International Society for Terrain-Vehicle Systems (ISTVS 2021) / [ed] Martelli M., Kovecses J., Shenvi M., Dixon J., International Society for Terrain-Vehicle Systems , 2021, p. 313-324Conference paper (Refereed)
    Abstract [en]

    Swedish agriculture has gone through many changes over past years in terms of production, working methods, technology and use of natural resources. To achieve its vision of 2030, Swedish agricultural is rapidly transforming into more and more digitized and automated alternatives and the objective for the research presented in this paper was to identify challenges and opportunities by using automated agricultural vehicles. Data was collected through a survey and review of scientific literature and official reports. The current use and level of automation in Swedish agriculture was studied as well as aspects of productivity, profitability, ergonomics and sustainability by use of regular agricultural vehicles and farming practices. Furthermore, key challenges and opportunities related to automation of agricultural vehicles were further identified. It was found that farmers foresee several areas where automated agricultural vehicles could add value in their production (improved productivity, work environment, environmental impact etc.). However, to utilize these values, there are several challenges identified including technology readiness levels, security, responsibility distribution etc. By overcoming these challenges, it is plausible that the sustainability of agricultural operations with vehicles involved could be significantly improved through automation.

  • 37.
    Li, Songyu
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lideskog, Håkan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    van Westendorp, Ruben
    Bracke Forest AB, Bräcke, Sweden.
    Obstacle detection vision system enabling autonomous mounding on clearcuts2023In: Proceedings of the 16th European-African Regional Conference of the ISTVS, International Society for Terrain-Vehicle Systems , 2023Conference paper (Refereed)
  • 38.
    Lideskog, Håkan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Ersson, Back Tomas
    Sveriges Lantbruksuniversitet.
    Bergsten, Urban
    Sveriges Lantbruksuniversitet.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Determining boreal clearcut object properties and characteristics for identification purposes2014In: Silva Fennica, ISSN 0037-5330, E-ISSN 2242-4075, Vol. 48, no 3, article id 1136Article in journal (Refereed)
    Abstract [en]

    After clearcutting, machines traffic the clearcut conducting different silvicultural activities. Many objects on a forest clearcut (slash residues, stones, stumps and roots) may disturb e.g. site preparation and planting. This paper describes properties and characteristics of these objects. A flowchart was developed that describes a possible computer-aided system that identifies the objects, and ultimately, makes a machine avoid or target them. A system for obstacle identification creates conditions for further technical development and (semi)automation of e.g., site preparation, mechanized planting, and stump removal.

  • 39.
    Lideskog, Håkan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Automatic clearcut obstacle identification using a time-of-flight camera2014Conference paper (Refereed)
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  • 40.
    Lideskog, Håkan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Automatic obstacle identification using a time-of-flight camera2014Conference paper (Refereed)
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  • 41.
    Lideskog, Håkan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Simulated continuous mounding improvements through ideal machine vision and control2016In: Silva Fennica, ISSN 0037-5330, E-ISSN 2242-4075, Vol. 50, no 2, article id 1386Article in journal (Refereed)
    Abstract [en]

    To promote the growth and survival of regenerated forests, site preparation prior to tree planting on clearcuts is necessary. This is often performed with scarifiers, either through trenching or mounding. Mounding is generally considered better in a plant survival perspective but is inefficient on obstacle-rich clearcuts. By utilising machine vision through e.g. remote sensing methods, new strategies can enable efficient mound positioning. In this paper, three realistic strategies utilizing ideal clearcut object identification through machine vision have been developed that can be used for more efficient mounding. The results show that mounding efficiency can be significantly improved with a new mound positioning strategy that employs ideal object identification, especially on obstacle-rich clearcuts.

  • 42.
    Lideskog, Håkan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Bergsten, Urban
    Swedish University of Agricultural Sciences, Department of Silviculture, Sveriges Lantbruksuniversitet, Swedish University of Agricultural Sciences, Svartberget.
    Development of a research vehicle platform to improve productivity and value-extraction in forestry2015In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 38, p. 68-73Article in journal (Refereed)
    Abstract [en]

    In spite of the high level of mechanization in most forestry operations there is a continuedneed for improvements in productivity and cost effectiveness. Automation of mechanised operations isone possible solution to achieve such improvements but new techniques that can acquire informationfrom the surroundings and make proper analyses rendering in streamlined or new work proceduresare prerequisites. Furthermore, product producers buying forest biomaterials often have certainquality wishes. As an addition to automatic work procedures, new technology can further be used toretrieve information for identification and selection of certain tree assortments with differentbiomaterial properties. In this way, performance-based delivery of tree biomaterial extracted withhighly automated work procedures has the possibility to be an enabler to continue the productivitydevelopment progress in the forest sector. The objective for this paper is therefore to summarizepossible technical needs for and to design an experimental research vehicle platform for academia andmachine developers to test and validate new solutions that could improve cost effectiveness inforestry. The platform is designed specifically to test and validate various control systems forautonomy and robotics and also to enable tests and validation of attachments, e.g. to enable betterplanting procedures or identification of trees with certain properties. Sensors are embedded in theplatform to register angles, rotation speed, etc., thus actualising machine automation as an enabler forperformance-based delivery of planting or of tree biomaterial assortments.

  • 43.
    Lideskog, Håkan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Lindström, John
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Bergsten, Urban
    Sveriges Lantbruksuniversitet.
    Ersson, Back Tomas
    Sveriges Lantbruksuniversitet.
    Functional products in forestry: challenges and opportunities2012In: Proceedings of the 1st International Conference on Through-life Engineering Services, Cranfield University Press , 2012Conference paper (Refereed)
  • 44.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Dagman, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Functional Products lifecycle: Governed by sustainable win-win situations2014In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 22, p. 163-168Article in journal (Refereed)
    Abstract [en]

    The paper proposes a Functional Products (FP) lifecycle viewed from economic, ecologic and societal perspectives. The overall FP lifecycle is further discussed from the viewpoint of its technical and economic lifecycles. The paper suggests that the overall FP lifecycle is governed by a sustainable win-win situation between the provider and customer sides, and thus that there needs to be a balance regarding the perceived value for both parties

  • 45.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Dagman, Andreas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    The Functional Products technical lifecycle and its four sub-lifecycles2015In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 38, p. 222-227Article in journal (Refereed)
    Abstract [en]

    The paper provides a further verification of the Functional Products (FP) technical lifecycle and additional details regarding its four sub-lifecycles concerning: hardware, software, service-support system and management of operation. Outlined, in a novel way, is how the four sub-lifecycles may be embodied in order to manage and keep the FP technical lifecycle running at an agreed-upon level of availability. The FP technical lifecycle is further analyzed from the viewpoint of its supporting role to the FP economic lifecycle, as well as compliance, regulatory and commercial aspects.

  • 46.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Outlining an overall Functional Product lifecycle: combining and coordinating its economic and technical perspectives2017In: CIRP - Journal of Manufacturing Science and Technology, ISSN 1755-5817, E-ISSN 1878-0016, Vol. 17, p. 1-9Article in journal (Refereed)
    Abstract [en]

    Currently, industry is showing increasing interest in performance-based business models. Functional Products is one such business model, where the provider offers a function to customers at an agreed-upon level of availability, productivity or efficiency, etc. A Functional Product comprises the following four main constituents: hardware, software, service support system and management of operation, which together deliver value to customers on a long-term basis. This paper, based on empirical data, provides an outline and starts the verification of a proposed overall Functional Product lifecycle combining and coordinating its economic- and technical perspectives. The perspectives are combined and the key aspects of the necessary coordination between and within the perspectives, i.e., sustainable win-win situations and coordination of sub-lifecycles for the economic perspective, and the need for coordination between the Functional Products’ technical perspective's four sub-lifecycles (hardware, software, service-support system and management of operation), are elaborated and discussed. Further, addition of new functionality, contract management, and long-term management of operation are discussed in the light of managing fleets/individual customers, assets and availability. The proposed overall Functional Product lifecycle is further analyzed from a number of views and aspects.

  • 47.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    A development process for Functional Products: hardware, software, service support system and management of operation2012In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 16, no 3/4, p. 284-303Article in journal (Refereed)
    Abstract [en]

    The development process for a Functional Product (FP) is complex and there is a need to coordinate, monitor, control and share information as well as to communicate properly among the parties involved in the process. This paper proposes a conceptual development process to manage the FP development, including development of hardware, software, service support system, and how to manage the operation of an FP. Further, challenges related to the integrated development of FPs are also discussed.

  • 48.
    Lindström, John
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Löfstrand, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Functional product development: what information should be shared during the development process?2012In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 16, no 2, p. 95-111Article in journal (Refereed)
    Abstract [en]

    The development process for a Functional Product (FP) is complex and there is a need to share information as well as to communicate it among the parties involved in the process. The paper concerns shared information that is of specific interest when developing FPs, in contrast to information that must be shared during a general product or service development process. The findings are compiled in a conceptual table comprising such specific information items pertaining to both the initial development as well as post development parts of an FPs lifecycle. This table can be used as an aid to any development process or method, as it points out information items that must necessarily be shared, but not how they to be shared.

  • 49.
    Löfstrand, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Andrews, John
    Nottingham Transportation Engineering Centre, Faculty of Engineering, University of Nottingham.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Functional product system availability: simulation driven design and operation through coupled multi-objective optimisation2011In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 13, no 2, p. 119-131Article in journal (Refereed)
    Abstract [en]

    This paper describes on a conceptual level how the availability of functional products (consisting of hardware (HW) and a support system) may be simulated. The main objective of this paper is to present a simulation-driven methodology for predicting and optimising the availability and cost of functional products in both development and operation. The proposed simulation and optimisation methodology includes both HW and support system models, which coupled form a simulation model of a system (functional product) delivering the function. Two different simulation-driven methodologies are suggested in the paper: one for development and another for operation of functional products

  • 50.
    Löfstrand, Magnus
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Reed, Sean
    University of Notttingham.
    Karlberg, Magnus
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Andrews, John
    University of Notttingham.
    Karlsson, Lennart
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Dunnett, Sarah
    Loughborough University.
    Modelling and simulation of functional product system availability and support costs2012In: International Journal of Product Development, ISSN 1477-9056, E-ISSN 1741-8178, Vol. 16, no 3-4, p. 304-325Article in journal (Refereed)
    Abstract [en]

    Functional products (FP), total offers or product service systems, that comprise of both hardware (HW) and support services (SS) sold as an integrated offering under an availability guarantee, are becoming increasing popular in industry. This paper addresses, through modelling and simulation, the challenge faced by suppliers in developing an integrated HW and SS design to produce an FP which meets contracted availability. A recently published framework specified how an integrated model hardware and service support system model could be used to obtain functional availability predictions and perform simulation driven functional product development. This paper presents the first example of an integrated functional product model. It uses fault tree, Petri net and discrete event simulation techniques to enable the prediction of functional product availability and support costs. Such predictions are used here to evaluate and compare different service support system designs.

12 1 - 50 of 68
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