liu.seSearch for publications in DiVA
Change search
Refine search result
1234 1 - 50 of 179
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Jouannet, Christopher
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems . Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    A Framework for Aerodynamic and Structural Optimization in Conceptual Design2007In: 25th AIAA Applied Aerodynamics Conference, 25-28 June, Miami, FL, USA, AIAA , 2007, p. 4061-Conference paper (Other academic)
    Abstract [en]

    Aircraft design is an inherently multidisciplinary activity that requires different models and tools for various aspects of the design. At Linköping University a novel design framework is being developed to support the initial conceptual design phase of a new aircraft. In this work main attention has been paid to wing design, with respect to aerodynamic efficiency and loads, and to structural analysis. By linking together various modules via a user-friendly interface based on a spreadsheet, the framework allows multidisciplinary analysis and optimizations to be carried out. This paper will present the framework, give an overview of its development status and give an indication on the future work.

  • 2.
    Amadori, Kristian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Machine Design.
    Jouannet, Christopher
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems.
    Krus, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Machine Design.
    Aircraft Conceptual Design Optimization2008In: International Congress of the Aeronautical Sciences ICAS,2008, Stockholm, Sweden: ICAS , 2008Conference paper (Refereed)
    Abstract [en]

    Aircraft design is an inherently multidisciplinary activity that requires different models and tools for various aspects of the design. At Linköping University a novel design framework is being developed to support the initial conceptual design phase of new aircraft. By linking together various modules via a userfriendly spreadsheet interface, the framework allows multidisciplinary analysis and optimizations to be carried out. The geometrical model created with a high-end CAD system, contains all the available information on the product and thus it plays a central role in the framework. In this work great attention has been paid to techniques that allow creating robust yet highly flexible CAD models. Two different case studies are presented. The first one is a hypothetic wing-box design that is studied with respect to aerodynamic efficiency and loads, and to structural analysis. In this study two approaches were compared. In one case the wing-box design was optimized with a fixed number of structural elements, where only dimensions and position were allowed to change. Then the same wing-box was analyzed allowing also the number of structural elements to vary. Thus only the parts that are required are left and a more efficient design can be obtained. In the second case study a mission simulation is performed on a UAV-type aircraft. Required data for the simulation are gathered from the CAD model and from aerodynamic analysis carried out with PANAIR, a high order panel code. The obtained data are then used as inputs parameters for flight simulation in order to determined hydraulic systems characteristics.  

  • 3.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Jouannet, Christopher
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Use of Panel Code Modeling in a Framework for Aircraft Concept Optimization2006In: 11th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, 6-8 September, Portsmouth, Virginia, USA, 2006, p. 7084-Conference paper (Other academic)
    Abstract [en]

     

     

    In this study the use of a high-order panel code within a framework for aircraft concept design is discussed. The framework is intended to be a multidisciplinary optimization tool to be adopted from the very beginning of the conceptual design phase in order to define and refine the aircraft design, with respect to its aerodynamic, stability and control, structure and basic aircraft systems. The presented work is aimed at developing a module for aerodynamic analysis of concepts as a basis for a direct search optimization of the concept layout. The design criterion, used in the example presented here, is to minimize the maximum take-off weight required to fulfil the mission. Classic and simple equations are used together with the data generated by the panel code solver to calculate the aircraft’s performances. Weights are calculated by means of statistical group weight equations, but the weight could also be calculated from a CAD-model. The design of an Unmanned Combat Air Vehicle is used as test case for three different optimization algorithms: one gradient method based (Fmincon), one non-gradient based (Complex) and one Genetic Algorithm (GA). Comparison of results and performances shows that the Genetic Algorithm is best fitted for the specific problem, having the by far best hit rate, even if it is at a cost of longer computing time. The Complex algorithm requires less iterations and is also able to find the optimum solution, but with a worse hit rate, while Fmincon can not reach to a global optimum. The suggested optimized configuration for the aircraft is very similar to the Boeing X-45C and Northrop Grumman X-47B.

  • 4.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Lundström, David
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Automated Design and Fabrication of Micro Air Vehicles2011In: Journal of Aerospace Engineering, ISSN 0893-1321, E-ISSN 1943-5525, Vol. 226, no 10, p. 1271-1282Article in journal (Refereed)
    Abstract [en]

    A methodology for an automated design and fabrication of micro-air vehicles (MAVs) is presented. A design optimization framework has been developed that interfaces several software systems to generate MAVs to optimally fulfil specific mission requirements. By means of amulti-objective genetic algorithm, families of MAVs are tailored with respect to objectives such as weight and endurance. The framework takes into consideration the airframe and aerodynamic design as well as the selection and positioning of internal components. The selection of propulsion system components is made from a database of off-the-shelf components. In combination with a three-dimensional printer, physical prototypes can be quickly manufactured. A validation of the framework results from flight tests of a real MAV is also presented.

  • 5.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Lundström, David
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Evaluation of Automatically Designed Micro Air Vehicles and Flight Testing2010Conference paper (Refereed)
    Abstract [en]

    The presented work is centered on the evaluation of Micro or Mini Air Vehicles (MAV) that have been automatically designed and manufactured. An in-house developed design framework uses several coupled computer software’s to generate the geometric design in CAD, a well as list of off the shelf components for the propulsion system, and computer code for autonomous flight ready to upload in the intended autopilot. The paper describes the experiences made so far regarding automation of the design process and of manufacturing. Furthermore, it presents results from evaluation and analysis of the optimization algorithm and flight testing, and from continuing work with the framework to achieve deeper understanding of the process and to fine-tune the design automation performance. The flight data is correlated to the predicted performances to validate the models and design process.

  • 6.
    Amadori, Kristian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Machine Design .
    Lundén, Björn
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Krus, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Using CAD-Tools and Aerodynamic Codes in a Distributed Conceptual Design Framework2007In: Aerospace Sciences Meeting and Exhibit,2007, USA: AIAA , 2007Conference paper (Refereed)
    Abstract [en]

    Aircraft design is an inherently multi-disciplinary activity that requires different models and tools for various aspects of the design. At Linköping University a novel design framework is being developed to support the initial conceptual design phase of a new aircraft. Different modules are included, each one addressed to analyze and evaluate different aspects of the airplane, such as its aerodynamics, its weight and structure, its sub systems and its performances. All modules are easily accessible from a user-friendly interface based on an Excel spreadsheet. The link between all modules is based on Service Oriented Architecture (SOA) and allows both distribution and integration of all functions. This paper will present the framework, give an overview of its development status and give an indication on the future work.

  • 7.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Melin, Tomas
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Staack, Ingo
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Multidisciplinary Optimization of Wing Structure Using Parametric Models2013Conference paper (Other academic)
    Abstract [en]

    Aircraft design is an inherently multidisciplinary activity that requires integrating different models and tools to reach a well-balanced and optimized product. At Linköping University a design framework is being developed to support the initial design space exploration and the conceptual design phase. Main characteristics of the framework are its flexible database in XML format, together with close integration of automated CAD and other tools, which allows the developed geometry to be directly used in the subsequent preliminary design phase. In particular, the aim of the proposed work is to test the framework by designing, optimizing and studying a transport aircraft wing with respect to aerodynamic, geometry, structural and accessability constraints. The project will provide an initial assessment of the capability of the framework, both in terms of processing speed and accuracy of the results.

  • 8.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Tarkian, Mehdi
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Ölvander, Johan
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Flexible and Robust CAD Models for Design Automation2012In: Advanced Engineering Informatics, ISSN 1474-0346, E-ISSN 1873-5320, Vol. 26, no 2, p. 180-195Article in journal (Refereed)
    Abstract [en]

    This paper explores novel methodologies for enabling Multidisciplinary Design Optimization (MDO) of complex engineering products. To realize MDO, Knowledge Based Engineering (KBE) is adopted with the aim of achieving design reuse and automation. The aim of the on-going research at Linköping University is to shift from manual modelling of disposable geometries to Computer Aided Design (CAD) automation by introducing generic high-level geometry templates. Instead of repeatedly modelling similar instances of objects, engineers should be able to create more general models that can represent entire classes of objects. The proposed methodology enables utilization of commercial design tools, hence taking industrial feasibility into consideration. High Level CAD templates (HLCt) will be proposed and discussed as the building blocks of flexible and robust CAD models, which in turn enables high-fidelity geometry in the MDO loop. Quantification of the terms flexibility and robustness is also presented, providing a means to measure the quality of the geometry models. Finally, application examples are presented in which the outlined framework is evaluated. The applications have been chosen from three ongoing research projects aimed at automating the design of transport aircraft, industrial robots, and micro air vehicles.

  • 9. Andersson, J.
    et al.
    Krus, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Wallace, D.
    Multiobjective Optimization of Hydraulic Actuation Systems2000In: ASME Design automation conference,2000, 2000Conference paper (Other academic)
    Abstract [en]

       

  • 10.
    Andersson, Johan
    et al.
    Maskinkonstruktion Tekniska fakultetet i Linköping.
    Krus, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    A multi-objective optimization approach to aircraft preliminary design2003In: World Aviation Congress,2003, Montreal, Canada: SEA , 2003Conference paper (Refereed)
  • 11.
    Andersson, Johan
    et al.
    Maskinkonstruktion Tekniska fakulteten.
    Krus, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Metamodel Representations for Robustness Assessment in Multiobjective Optimization2001In: The International Conference on Engineering Design ICED 01,2001, Glasgow, UK: ICED 01 , 2001Conference paper (Refereed)
    Abstract [en]

      

  • 12.
    Andersson, Johan
    et al.
    Linköping University, Department of Mechanical Engineering, Machine Design. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Multiobjective optimization of mixed variable design problems2001In: Evolutionary Multi-Criterion Optimization First International Conference, EMO 2001 Zurich, Switzerland, March 7–9, 2001 Proceedings / [ed] Eckart Zitzler, Lothar Thiele, Kalyanmoy Deb, Carlos Artemio Coello Coello and David Corne, Springer Berlin/Heidelberg, 2001, Vol. 1993, p. 624-638Chapter in book (Refereed)
    Abstract [en]

    In this paper, a new multiobjective genetic algorithm is employed to support the design of a hydraulic actuation system. First, the proposed method is tested using benchmarks problems gathered from the literature. The method performs well and it is capable of identifying multiple Pareto frontiers in multimodal function spaces. Secondly, the method is applied to a mixed variable design problem where a hydraulic actuation system is analyzed using simulation models. The design problem constitutes of a mixture of determining continuous variables as well as selecting components from catalogs. The multi-objective optimization results in a discrete Pareto front, which illustrate the trade-off between system cost and system performance.

  • 13.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Braun, Robert
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Dell'Amico, Alessandro
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Nordin, Peter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Pettersson, Karl
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Staack, Ingo
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Next Generation Simulation Software using Transmission Line Elements2010In: Fluid Power and Motion Control / [ed] Dr D N Johnston and Professor A R Plummer, Centre for Power Transmission and Motion Control , 2010, p. 265-276Conference paper (Refereed)
    Abstract [en]

    A suitable method for simulating large complex dynamic systems is represented by distributed modelling using transmission line elements. The method is applicable to all physical systems, such as mechanical, electrical and pneumatics, but is particularly well suited to simulate systems where wave propagation is an important issue, for instance hydraulic systems. By using this method, components can be numerically isolated from each other, which provide highly robust numerical properties. It also enables the use of multi-core architecture since a system model can be composed by distributed simulations of subsystems on different processor cores.

    Technologies based on transmission lines has successfully been implemented in the HOPSAN simulation package, develop at Linköping University. Currently, the next generation of HOPSAN is developed using an object-oriented approach. The work is focused on compatibility, execution speed and real-time simulation in order to facilitate hardware-in-the-loop applications. This paper presents the work progress and some possible features in the new version of the HOPSAN simulation package.

  • 14.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Parker Hannifin, Borås, Sweden.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    A Flexible Working Hydraulic System for Mobile Machines2016In: International Journal of Fluid Power, ISSN 1439-9776, Vol. 17, no 2, p. 79-89Article in journal (Other academic)
    Abstract [en]

    This paper proposes a novel working hydraulic system architecture for mobile machines. Load sensing, flow control and open-centre are merged into a generalized system description. The proposed system is configurable and the operator can realize the characteristics of any of the standard systems without compromising energy efficiency. This can be done non-discretely on-the-fly. One electrically controlled variable displacement pump supplies the system and conventional closed-centre spool valves are used. The pump control strategies are explained in detail. Experimental results demonstrate one solution to the flow matching problem and the static and dynamic differences between different control modes.

  • 15.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    A Hybrid of Pressure and Flow Control in Mobile Hydraulic Systems2014In: 9th InternationalFluid Power Conference (IFK). Vol. 1. Aachen, Germany, 24-26 March 2014 / [ed] Hubertus Murrenhoff, 2014, p. 190-201Conference paper (Refereed)
    Abstract [en]

    This paper presents a hybrid pump controller approach for mobile hydraulic systems, influenced by both pressure and flow. The controller is tuneable to be able to set the order of importance of the pressure and flow controller, respectively. It is thus possible to realize a load sensing system, a flow control system or a mix of the two. Using a low load pressure feedback gain and a high flow control gain, a system emerges with high energy efficiency, fast system response, high stability margins and no flow matching issues. In this paper, both theoretical studies and practical implementations demonstrate the capability of a hybrid pump control approach.

  • 16.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Energy Efficient Fluid Power System for Mobile Machines with Open-centre Characteristics2014In: 9th JFPS International Symposium on Fluid Power. Matsue, Japan, 28-31 October 2014, The Japan Fluid Power System Society , 2014, p. 452-459Conference paper (Other academic)
    Abstract [en]

    This paper presents a flexible and energy efficient system solution which mimics the behaviour of an open-centre system. An electro-hydraulic variable displacement pump and closed-centre valves are used. Instead of having a flow in the open-centre gallery, that flow is calculated using a pressure sensor and a valve model. The variable pump is then controlled in order to only deliver the flow that would go to the actual loads. It is also possible for the operator to decide how much load dependency there should be. The extreme case is not having any load dependency at all, resulting in a system where the pump displacement setting is controlled according to the sum of all requested load flows. It is thus possible to realize a system design with open-centre characteristics, a flow control system or something in between. Each operator can thereby get their optimal control characteristic while having high energy efficiency.

  • 17.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Flow versus pressure control of pumps in mobile hydraulic systems2014In: Proceedings of the Institution of mechanical engineers. Part I, journal of systems and control engineering, ISSN 0959-6518, E-ISSN 2041-3041, Vol. 228, no 4, p. 245-256Article in journal (Refereed)
    Abstract [en]

    This work studies an innovative working hydraulic system design for mobile applications, referred to as flow control. The fundamental difference compared to load-sensing systems is that the pump is controlled based on the operator’s command signals rather than feedback signals from the loads. This control approach enables higher energy efficiency since the pressure difference between pump and load is given by the system resistance rather than a prescribed pump pressure margin. Furthermore, load-sensing systems suffer from poor dynamic characteristics since the pump is operated in a closed-loop control mode. This might result in an oscillatory behaviour. Flow control systems have no stability issues attached to the load pressure feedback since there is none. This allows the pump to be designed to meet the response requirements without considering system stability. Pressure compensators are key components in flow control systems. This study addresses the flow matching problem which occurs when using traditional compensators in combination with a flow-controlled pump. Flow sharing pressure compensators solve this problem since the pump flow will be distributed between all active functions. Simulation results and measurements on a wheel loader application demonstrate the energy-saving potentials and the dynamic improvements for the flow control system.

  • 18.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Dynamic Analysis of Single Pump, Flow Controlled Mobile Systems2011In: The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11: Volume 2 / [ed] Harri Sairiala & Kari T. Koskinen, 2011, p. 223-238Conference paper (Refereed)
    Abstract [en]

    Interest has increased in flow controlled systems in the field of mobile fluid power. The capital distinction between traditional load-sensing (LS) systems and flow controlled systems is that the pump is controlled based on the operator’s total flow demand rather than maintaining a certain pressure margin over the maximum load pressure. One of the main advantages of flow controlled systems is the absence of the feedback of the highest load pressure to the pump controller. In this paper, a dynamic analysis is performed where flow controlled and LS systems are compared. It is shown how instability can occur in LS systems due to the pump controller and proven that no such instability properties are present in flow controlled systems. A drawback with one type of flow controlled system is that the highest load dynamically will disturb the lighter loads. This paper shows a novel way to optimize the damping in such systems by controlling the opening position of the directional valve independently of the flow. The mentioned disturbance between the highest load to the others can thereby be reduced.

  • 19.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Design Rules for High Damping in Mobile Hydraulic Systems2013In: 13th Scandinavian International Conference on Fluid Power, Linköping University Electronic Press, 2013, p. 13-20Conference paper (Refereed)
    Abstract [en]

    This paper analyses the damping in pressure compensated closed centre mobile working hydraulic systems. Both rotational and linear loads are covered and the analysis applies to any type of pump controller. Only the outlet orifice in the directional valve will provide damping to a pressure compensated system. Design rules are proposed for how the system should be dimensioned in order to obtain a high damping. The volumes on each side of the load have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension for maximized damping; both smaller and larger orifice areas give lower damping independently of the volumes. This paper presents a method to dimension the outlet orifice area and the load volumes in order to obtain a desired system damping. Experimental results, which confirm the theoretical expectations, are also presented. The conclusions are that it is possible to obtain a high damping contribution from the outlet orifice if the system is dimensioned correctly. However, the energy efficiency needs to be considered while improving the damping

  • 20.
    Axin, Mikael
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Optimized Damping in Cylinder Drives Using the Meter-out Orifice: Design and Experimental Verification2012In: 8th International Fluid Power Conference Dresden: "Fluid Power Drives!", 2012, Vol. 1, p. 579-591Conference paper (Other academic)
    Abstract [en]

    This paper analyses the damping of a flow controlled cylinder with a mass load and an outlet orifice. By using linear models, a mathematical expression for the damping is derived. It is shown that the volumes on each side of the piston have a high impact on the damping. In case of a small volume on the inlet side, the damping becomes low. However, the most important thing is to design the outlet orifice area properly. There exists an optimal orifice dimension; both smaller and larger orifice areas give low damping independently of the size of the volumes. In this paper a design is proposed of the outlet orifice area that optimizes the damping of the system. Experimental results which confirm the theoretical expectations are also presented. The conclusions are that without an outlet orifice, the hydraulic system will not contribute with any damping at all. Furthermore, large dead volumes in the cylinder will increase the damping, but at the expense of the system’s efficiency.

  • 21.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Aspects of Parameter Sensitivity for Series Hydraulic Hybrid Light-Weight Duty Vehicle Design2016In: Proceedings of the 9th FPNI Ph.D. Symposium on Fluid Power (FPNI2016), American Society of Mechanical Engineers , 2016, article id V001T01A041Conference paper (Refereed)
    Abstract [en]

    Hybridization of a vehicle’s drivetrain can in principle help to improve its energy efficiency by allowing for recuperation of kinetic energy and modulating the engine’s load. How well this can be realized depends on appropriate sizing and control of the additional components. The system is typically designed sequentially, with the hardware setup preceding the development and tuning of advanced controller architectures. Taking an alternative approach, component sizing and controller tuning can be addressed simultaneously through simulation-based optimization.

    The results of such optimizations, especially with standard algorithms with continuous design variable ranges, can however be difficult to realize, considering for example limitations in available components. Furthermore, drive-cycle based optimizations are prone to cycle-beating. This paper examines the results of such simulation-based optimization for a series hydraulic hybrid vehicle in terms of sensitivity to variations in design parameters, system parameters and drive cycle variations. Additional relevant aspects concerning the definition of the optimization problem are pointed out.

  • 22.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Component Sizing Study for a Light-Duty Series Hydraulic Hybrid Vehicle in Urban Drive Cycles2013Conference paper (Refereed)
    Abstract [en]

    With the focus on energy efficiency for many different kinds of vehicle applications,hybridization is considered a possible solution to reduce fuel consumption. While hybrid electric concepts are already available for passenger vehicles, and also considered for heavier applications, hybrid hydraulic alternatives have been mainly limited to the latter, which benefit most from the higher power density available. To study the different hybrid architectures and applications, a modeling framework for the system design is developed using the simulation tool Hopsan from Linköping University.  Previously,  the  model  of  a  series  hydraulic  hybrid  vehicle  was introduced, a light-duty vehicle simulated over two standard urban drive cycles, and its potential for further work established. In this paper, the model is extended by including a simple combustion engine power management to provide for more realistic propulsion of the hydraulic drivetrain, showing the potential to operate a series hydraulic hybrid vehicle’s engine in more efficient regions. Additionally, the design is studied concerning the effects of a variation of key component sizes on the accuracy and energy efficiency objectives. Instead of subjecting the system to (multi- objective) optimization, at this stage the individual component’s influence is studied, and the objectives are dealt with separately from each other to eliminate the need for compromise   between   them,   both   to   gain a better understanding of the interdependencies.

  • 23.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Design Study and Parameter Optimization for a Light-Weight Series Hydraulic Hybrid Vehicle2015Conference paper (Refereed)
    Abstract [en]

    Hydraulic hybrid drives are one potential way of improving the fuel efficiency of vehicles, including the possi-bility of recuperating braking energy in a hydraulic accumulator. The high power density of fluid power is mainly advantageous for heavy vehicles, or duty cycles characterized with frequent braking and acceleration. For smaller vehicles, hydraulic hybrid drives are thus most interesting under urban and suburban driving conditions. Amongst the existing architectures, the series hydraulic hybrid offers the advantage of operating the internal combustion engine independently of the vehicle speed, at the cost of a less efficient transmission path than a purely mechanical one. Previously, a series hydraulics hybrid light-duty vehicle was modelled in the transmission-line modelling (TLM)-based simulation software Hopsan from the division of Fluid and Mechatronic Systems (Flumes) at Linköping University. This paper studies through simulation-based optimi-zation how the fuel-optimal vehicle design is affected by various mixes of urban and suburban driving requirements. Both the system’s hardware and the parameters of a basic control strategy are considered. The results show quite similar designs for most performance requirements combinations, and can be the base for further studies addressing additional requirements, conditions and objectives.

  • 24.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Modeling of a Series Hybrid Hydraulic Drivetrain for a Light-Duty Vehicle in Hopsan2013In: Conference proceedings: 13th Scandinavian International Conference on Fluid Power / [ed] Petter Krus, Magnus Sethson, Liselott Ericson, Linköping, Sweden: Linköping University Electronic Press, 2013, p. 107-112Conference paper (Refereed)
    Abstract [en]

    Hydraulic hybrids continue to receive attention as a possible solution in the search for improved fuel economy for different vehicle types. This paper presents a model for a series hydraulic hybrid light-duty vehicle, developed in the Hopsan simulation tool of Linköping University’s Division of Fluid and Mechatronic Systems (Flumes). Focusing on the hydraulic transmission which employs a pump control based on the hydraulic accumulator’s state-of-charge (SoC), several simplifications were made, especially concerning mechanical components. Simulation over two urban standard cycles shows promising results concerning dynamic performance and energy recuperation potential, provided sufficient component sizing to compensate for the mechanical limitations. This paper lays the foundation for both a further refined model - suitable for optimizing the full drivetrain, including component sizing and controller parameterization - and the development of comparable models for parallel and power-split hybrid architectures.

  • 25.
    Baer, Katharina
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    System Parameter Study for a Light-Weight Series Hydraulic Hybrid Vehicle2014In: PROCEEDINGS OF THE 8TH FPNI PH.D SYMPOSIUM ON FLUID POWER, 2014, ASME Press, 2014, p. V001T03A004-Conference paper (Refereed)
    Abstract [en]

    Amongst the hybrid vehicle propulsion solutions aiming to improve fuel efficiency, hybrid electric solutions currently receive most attention, especially on the market. However, hydraulic hybrids are an interesting alternative, especially for heavier vehicles due to higher power density which is beneficial if higher masses are moved. As a step towards a comprehensive design framework to compare several possible hydraulic hybrid architectures for a specified application and usage profile, the model of a series hydraulic hybrid vehicle was previously introduced and initially studied concerning component sizing for an exemplary light-duty vehicle in urban traffic. The vehicle is modeled in the Hopsan simulation tool. A comparably straight-forward engine management is used for the vehicle control; both pump and engine controls are based on the hydraulic accumulator’s state-of-charge. The model is developed further with respect to the accumulator component model. Based on that, the influence of several system and component parameters, such as maximum system pressure and engine characteristics, as well as controller parameters on the vehicle’s performance is analyzed. The goal is to allow for more understanding of the system’s characteristics to facilitate future optimization of the system.

  • 26.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Full Vehicle Simulation of Forwarder with Semi Active Suspension using Co-simulation2016Conference paper (Refereed)
    Abstract [en]

    A major concern in the forest industry is impact on the soil caused by forest machines during harvesting. A six-wheel pendulum arm forwarder is being developed. The new forwarder aims at reducing soil damage by an even pressure distribution and smooth torque control and thereby also improving the working environment. The suspension contains pendulum arms on each wheel controlled by a hydraulic load sensing system in combination with accumulator.

    A natural approach is to model each part of a system in the bestsuited software. In this case, the hydraulic system is modelled in the Hopsan simulation tool, while the vehicle mechanics is modelled in Adams. To understand the whole system it is necessary to simulate all subsystems together. An open standard for this is the Functional Mock-up Interface. This makes it possible to investigate the interaction between the hydraulic system and the multi-body mechanic model.

    This paper describes how different simulation tools can be combined to support the development process. The technique is applied to the forwarder’s pendulum suspension. Controllers for height and soil force are optimized to minimize soil damage and maximize comfort for the operator.

  • 27.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    An Explicit Method for Decoupled Distributed Solvers in an Equation-Based Modelling Language2014In: Proceedings of the 6th International Workshop on Equation-Based Object-Oriented Modeling Languages and Tools / [ed] David Broman & Peter Pepper, New York: Association for Computing Machinery (ACM), 2014, p. 57-64Conference paper (Refereed)
    Abstract [en]

    The Modelica language offers an intuitive way to create object-oriented models. This makes it natural also to use an object-oriented solver, where each sub-model solves its own equations. Doing so is possible only if sub-models can be made independent from the rest of the model. One way to achieve this is to use distributed solvers by separating sub-models with transmission line elements. This offers robust and predictable simulations, simplified model debugging and natural parallelism. It also makes it possible to use different time steps and solver algorithms in different parts of the model to achieve an optimal trade-off between performance and accuracy. The suggested method has been implemented in the Hopsan simulation environment. Different modelling techniques for taking advantage of the distributed solver approach are explained. Finally, three example models are used to demonstrate the method.

  • 28.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Multi-Threaded Distributed System Simulations Using the Transmission Line Element Method2016In: Simulation (San Diego, Calif.), ISSN 0037-5497, E-ISSN 1741-3133, Vol. 92, no 10, p. 921-930Article in journal (Other academic)
    Abstract [en]

    By introducing physically motivated time delays, simulation models can be partitioned into decoupled independent sub-models. This enables parallel simulations on multi-core processors. An automatic algorithm is used for partitioning and running distributed system simulations. Methods for sorting and distributing components for good load balancing have been developed. Mathematical correctness during simulation is maintained by a busy-waiting thread synchronization algorithm. Independence between sub-models is achieved by using the transmission line element method. In contrast to the more commonly used centralized solvers, this method uses distributed solvers with physically motivated time delays, making simulations inherently parallel. Results show that simulation speed increases almost proportionally to the number of processor cores in the case of large models. However, overhead time costs mean that models need to be over a certain size to benefit from parallelization.

  • 29.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Multi-Threaded Real-Time Simulations of Fluid Power Systems Using Transmission Line Elements2012Conference paper (Refereed)
    Abstract [en]

    The demand for large-scale real-time simulations of fluid power systems is in-creasing, due to growing demands for added functionality. Real-time simulationscan be used in for example hardware-in-the-loop experiments and embeddedcontrol systems. In order to achieve real-time performance, it is often necessaryto use small or simplified models, reducing the usefulness and accuracy of theresults. This article proposes the use of transmission line modelling (TLM) forexploiting multi-core hardware in real-time and embedded systems. The charac-teristics of the TLM method are analysed to identify difficulties and possibilities.A method for how to parallelise TLM models is then presented. Subsequently, aprogramming interface for implementing the parallel models in the target systemsis introduced. Practical experiments show that the approach works and that themethod is applicable. So far, however, it has required great effort on the part ofthe engineer, both when it comes to programming, compiling and importing themodel into the target environments, although some attempts to automate the pro-cedure have been successful, reducing the level of complexity.

  • 30.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Parallel Implementations of the Complex-RF Algorithm2017In: Engineering optimization (Print), ISSN 0305-215X, E-ISSN 1029-0273, Vol. 49, no 9, p. 1558-1572Article in journal (Refereed)
    Abstract [en]

    Even though direct-search optimization methods are more difficult to parallelize than population-based methods, there are many unexploited opportunities. Five methods for parallelizing the Complex-RF methods have been implemented and evaluated. Three methods are based on the unchanged original algorithm, while two require modifications. The methods have been tested on two test function and one real simulation model. An analysis of the algorithm has been performed. This provides a basis for parametrization of the parallel methods. Without changing the original algorithm, speed-up of 2.5-3 is achieved. With allowing modifications, a speed-up of up to 5 is obtained without significantly reducing the probability of finding the global minimum. Speed-up does not scale linear to the number of threads. When more threads are added, parallelization efficiency decreases. However, a comparison with a particle swarm method shows that Complex-RF performs better regardless of the number of threads, due to its fast convergence rate.

  • 31.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Tool-Independent Distributed Simulations Using Transmission Line Elements And The Functional Mock-up Interface2013Conference paper (Refereed)
    Abstract [en]

    This paper describes how models from different simulation tools can be connected and simulated on different processors by using the Functional Mockup Interface (FMI) and the transmission line element method (TLM). Interconnectivity between programs makes it possible to model each part of a complex system with the best suited tool, which will shorten the modelling time and increase the accuracy of the results. Because the system will be naturally partitioned, it is possible to identify weak links and replace them with transmission line elements, thereby introducing a controlled time delay. This makes the different parts of the system naturally independent, making it possible to simulate large aggregated system models with good performance on multi-core processors. The proposed method is demonstrated on an example model. A suggestion of an XML extension to the FMI standard for describing TLM ports is also presented.

  • 32.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Towards A Parallel Distributed Equation-Based Simulation Environment2012In: 53rd SIMS Conference on Simulation and Modelling, 2012Conference paper (Refereed)
    Abstract [en]

    Distributed solvers provide several benefits, such as linear scalability and good numerical robustness. By separating components with transmission line elements, simulations can be run in parallel on multi-core processors. At the same time, equation-based modelling offers an intuitive way of writing models. This paper presents an algorithm for generating distributed models from Modelica code using bilinear transform. This also enables hard limitations on variables and their derivatives. The generated Jacobian is linearised and solved using LU-decomposition. The algorithm is implemented in the Hopsan simulation tool. Equations are transformed and differentiated by using the SymPy package for symbolic mathematics. An example model is created andverified against a reference model. Simulation results are similar, but the equation-based model is four to five times slower. Further optimisation of the algorithm is thus required. The future aim is to develop a distributed simulation environment with integrated support for equation-based modelling.

  • 33.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Nordin, Peter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    High Performance System Simulation Using Multiple Processor Cores2011In: The Twelfth Scandinavian International Conference on Fluid Power, SICFP'11 / [ed] Harri Sairiala & Kari T. Koskinen, 2011Conference paper (Refereed)
    Abstract [en]

    Future research and development will depend on high-speed simulations, especially for large and complex systems. Rapid prototyping, optimization and real-time simulations require  simulation tools that can take full advantage of  computer hardware.  Recent developments  in the computer market indicate  a change in focus from increasing the speed of processor cores towards increasing the number of cores in each processor. HOPSAN is a simulation tool for fluid power and mechatronics, developed at Linköping University. It  is based upon the transmission line  modeling  (TLM)  technique. This method is very suitable for taking advantage of multi-core  processors.  This paper presents  the  implementation  of multi-core support in the next generation of HOPSAN. The concept is to divide the  model  into equally sized  groups of  independent components,  to make it possible to  simulate  them  in separate threads. Reducing overhead costs and finding an effective sorting algorithm constitute  critical steps for maximizing the benefits.  Experimental results show  a significant reduction in simulation time. Improvement of algorithms in combination with a continuous increase in the number of processor cores can potentially  lead to further  increases  in simulation performance. 

  • 34.
    Braun, Robert
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Nordin, Peter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Improved Scheduling Techniques for Parallel Distributed-Solver System SimulationManuscript (preprint) (Other academic)
    Abstract [en]

    Shortening simulation time is an important step towards efficient simulation-based product development. A long-used method is to exploit physically motivated time delays to split up the model into distributed solvers. In this way, the use of a centralized sequential solver can be circumvented. For maximum simulation performance, however, an efficient scheduling technique is also required. Four task scheduling methods for distributed-solver simulations has been implemented and evaluated. Experiments indicate that the best choice largely depend on model size, load distribution and granularity. Lock-based barrier synchronization provides the highest speed-up for small models. A fork-join implementation, with implicit synchronization and work-stealing scheduling, works better for models with a large total workload. It is common that workload and load distribution of a simulation model varies during execution depending on the current state of the simulation. Three of the implemented schedulers support dynamic load balancing during execution. Results show that task-stealing is the most efficient method for the specific test model. A possible continuation of this work is an automatic selection of the best scheduling technique based on knowledge about model properties and available computer resources.

  • 35.
    Dell' Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Ericson, Liselott
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Henriksen, Fredrik
    Skogforsk, the Swedish Forestry Research Institute of Sweden.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Modelling and experimental verification of a secondary controlled six-wheel pendulum arm forwarder2015In: the 13th European Conference of ISTVS / [ed] Roberto Paoluzzi, 2015, p. 1-10Conference paper (Refereed)
    Abstract [en]

    One of the major concerns in the forest industry is the impact on the soil caused by the forest machines duringharvesting, where damages can have a negative impact on e.g. further growth. One of the main reasons is wheel slip.Another concern is the working environment of the operator due to the harsh ground in the forest. Both these issueshave a negative impact on productivity. An attempt to overcome these challenges is made within a collaborative researchproject, which among others also includes Linköping University, where a new six-wheel pendulum arm forwarder isbeing developed. The new forwarder aims at reducing the soil damage by an even pressure distribution and smooth torquecontrol, as well as increased damping of the complete chassis, and thereby improving the working environment. This ispossible since each wheel, driven by its own hydraulic motor, is attached to a pendulum arm allowing to control the heightof each wheel independently of each other. The forwarder has a total maximum weight of 31 tonnes, including 14 tonnesmaximum load. It consists of two steerable joints and is driven by a 360 bhp diesel engine. The transmission consists oftwo hydraulic pumps and six hydraulic motors.This paper deals with the development of the driveline and presents the first experimental tests of the implementedcontrol strategies, where a secondary control approach is chosen for its ability to individually control the torque on eachwheel. The control strategies, presented in the paper, include pressure control, velocity control of the vehicle and ananti-slip controller. To support the development of the control strategies, models of the vehicle and hydraulic subsystemsare derived. The aim with this paper is to verify the concepts on the actual vehicle. The initial results are promising,indicating that the suggested concept is feasible.

  • 36.
    Dell'Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    A Test Rig for Hydraulic Power Steering System Concept Evaluation using Hardware-in-the-Loop Simulation2013In: ICFP 2013, 2013Conference paper (Refereed)
    Abstract [en]

    This paper derives a test rig of a power steering system with purpose to investigate the performance of closed-centre valves as actuators in the steering system loop using hardware-in-the-loop simulation. Servo valves are used for independent control of each chamber pressure. The approach is to use a static model of the reference actuator and control the pressures with the servo valves accordingly. A simulation model of the system is used to verify the approach. Results from the test rig are presented from on-centre driving which show how the pressure is controlled satisfyingly.

  • 37.
    Dell'Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Closed-Centre Hydraulic Power Steering by Direct Pressure Control2014In: The 9th JFPS International Symposium on Fluid Power : Matsue 2014 : Oct. 28-31, 2014, The Japan Fluid Power System Society , 2014, p. 332-339Conference paper (Other academic)
    Abstract [en]

    An ongoing trend in the vehicle industry is the development of steering related active safety functions for increased road safety. For this to be a reality there must exist a steering system that allows to either change the road wheel angle or torque by means of an external signal, called active steering. Due to heavy vehicles’ high axle load, hydraulic power is needed to assist the driver in turning the wheels. This paper looks into a solution where self-regulated pressure control valves are used for electronic control of the assistance pressure in order to realise active steering. The valve has closed-centre for a high potential to reduce the energy consumption. A model based approach is used to analyse the system. A non-linear simulation environment is developed to compare the closed-centre system with the original system. A linear analysis is also performed to discover the influence of valve properties on steering system performance. Results have shown that a feasible solution exists and that there exists a relation between valve dynamics, boost gain and steering system loop stability.

  • 38.
    Dell'Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Modeling, Simulation, and Experimental Investigation of an Electrohydraulic Closed-Center Power Steering System2015In: IEEE/ASME transactions on mechatronics, ISSN 1083-4435, E-ISSN 1941-014X, Vol. 20, no 5, p. 2452-2462Article in journal (Refereed)
    Abstract [en]

    In steering-related active safety systems, active steering is a key component. Active steering refers to the possibility to control the road wheel angle or the required torque to turn the wheels by means of an electronic signal. Due to the high axle loads in heavy vehicles, hydraulic power is needed to assist the driver in turning the wheels. One solution to realize active steering is, then, to use electronically controlled valves that are of closed-center type. This means that the assistance pressure, or force, can  be set to any feasible value and still benefit from the high power density of fluid power systems. A closed-center solution also implies that a significant reduction in fuel consumption is possible. This paper investigates such an electrohydraulic power steering system, and a comparison with the original system is also made. The findings have shown that while a high response of the pressure control loop is desired for a good steering feel, instability might occur at higher steering wheel torque levels. This has effectively been shown and explained by simulation and hardware-in-the-loop simulation, together with linear analysis. For any desired boost curve, the response of the pressure control loop must be designed to preserve stability over the entire working range.

  • 39.
    Dell'Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Modelling and experimental validation of a nonlinear proportional solenoid pressure control valve2016In: International Journal of Fluid Power, ISSN 1439-9776, Vol. 17, no 2, p. 90-101Article in journal (Refereed)
    Abstract [en]

    This paper investigates the static and dynamic behaviour of a pressure control valve with nonlinear negative characteristics. The pressure control valve has both reducing and relieving capability and is actuated by a solenoid. The static characteristics have been measured over the entire working range, covering the dynamic response of the solenoid, as well as the complete valve. A model is proposed that considers the flow as a mix of laminar and turbulent flow and flow forces with a flow angle that varies with the stroke of the spool. The model shows good agreement with measurements. The investigations show that the flow forces decrease with higher flow rates as a result of a flow angle that tends to go towards a vertical angle. This results in an increase in pressure with flow during pressure reducing mode. A linear analysis is also presented, explaining this as a negative spring constant in the low frequency range. Stability is, however, maintained.

  • 40.
    Dell'Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Pohl, Jochen
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Conceptual Evaluation of Closed-Centre Steering Gears in Road Vehicles2012In: Proceedings of the 7th FPNI PhD Symposium on Fluid Power, 2012 / [ed] Massimo Milani, Luca Montorsi, Fabrizio Paltrinieri, 2012, p. 433-452Conference paper (Refereed)
    Abstract [en]

    This paper is a study into the possibility to use a self-regulated pressure control valve as a way of realizing active steering into road vehicles by hydraulic means. From an actuator point of view, active steering refers to the possibility to control the assistance pressure via an external signal. From the steering system control loop, it is seen that the task of the steering system is to control the assistance pressure in each chamber of the assistance cylinder. A methodology is also derived for investigating the concept and finding a set of design parameters based on system requirements. This is based on a linear approach and later a simulation of the complete steering system with vehicle and driver. In order to assure good control accuracy during fast actuation of the valve a high gain is required. This would require an over damped valve with large proportions. This design was tested to verify the design methodology. A feasible design based on maximum available spool force was also tested. This design showed to large deviation in steering wheel torque compared to the original system.

  • 41.
    Dell'Amico, Alessandro
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Pohl, Jochen
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Modeling and Simulation for Requirement Generation of Heavy Vehicles Steering Gears2010In: Fluid Power and Motion Control (FPMC 2010) / [ed] D N Johnston and A R Plummer, Centre for Power Transmission and Motion Control , 2010, p. 475-490Conference paper (Refereed)
    Abstract [en]

    Today’s passenger vehicles are becoming more and more safe as more steering related active safety functions are being introduced. As an example, lane keeping assist functions or even electronic vehicle stability with steering intervention can be mentioned. However, the same trend can yet not be witnessed for heavy vehicles, which is, among others, due to a lesser degree of controllability of the steering system. While electric power assisted steering has been introduced in passenger cars in recent years on a broader basis, electric power assisted steering is yet not suitable for heavy vehicles due to heavier loads on the steering rack. Heavy vehicles thus lack a freely programmable steering system.The purpose of this paper is to generate and evaluate the requirements of future hydraulic actuation concepts for heavy vehicles, where emphasis is put on the required steering actuator linearity and bandwidth. Both actuator response and linearity are decisive for transmitting a proper steering feel to the driver. In this study we provide a structured approach to derive the required bandwidth as a function of the system sizing and provide a simulation supported method for deriving the requirements of linearity and accuracy.

  • 42.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Dell' Amico, Alessandro
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, Faculty of Science & Engineering.
    MODELLING OF A SECONDARY CONTROLLED SIX-WHEEL PENDULUM ARM FORWARDER2015Conference paper (Refereed)
    Abstract [en]

    One of the major concerns in the forest industry is the impact on the soil caused by the forest machines during harvesting, where damage can have a negative impact on growth at replanting for example. Another concern is the working environment of the operator. Both these issues have a negative impact on productivity. A new six-wheel pendulum arm forwarder is being developed within a collaborative research project. The new forwarder aims to reduce soil damage by means of an even pressure distribution and smooth torque control. This paper presents the first step in the development of the driveline, where a secondary control approach is chosen for its ability to control the motion of each wheel individually. Simulation models of both vehicle and driveline have been constructed developed, partly for the development of the control strategy, and partly for evaluation. A speed control concept and a torque control concept have both been evaluated for different scenarios with regard to their ability to reduce wheel slip. Results have shown that a velocity control approach is more sensitive to kinematic model accuracy while wheel slip is handled automatically. A torque control approach is more robust towards model accuracy while the reduction of slip is dependent on an accurate model.

  • 43.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Eriksson, Björn
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Dell'Amico, Alessandro
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    An Electric Hydraulic Hybrid Light Vehicle with Energy Recovery2011In: 52nd National Conference on Fluid Power, Las, 2011, p. 741-749Conference paper (Refereed)
    Abstract [en]

    A three wheeled electric hydraulic hybrid vehicle with tiltingbody was built and tested at Linköping University as a partof a student project. The goal of the student project wasto design and fabricate an environmentally friendly vehicleto enter the Formula ATA Electric & Hybrid Italy 2009 competition.The design of the vehicle was based on the rulesand requirements of the competition. The vehicle was alsoprepared for a hydraulic recovery system which was laterimplemented on the vehicle. Hydraulic motor/pump unitsare used to brake and recover energy and to provide additionalboost during acceleration. The energy recovery storageis hydraulic gas accumulators, while the primary propulsionsystem is electrical with Li-Fe batteries. Gas accumulatorshave very high power density superior to electricalbatteries.In this paper, the design of the hydraulic recovery system isdescribed along with simulation and experimental results.The concept shows high potential and the tests show a20 % recovery of the kinetic energy by the hydraulic systemfor a given cycle.

  • 44.
    Eriksson, Björn
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Nordin, Peter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Hopsan NG, A C++ Implementation using the TLM Simulation Technique2010In: SIMS 2010 Proceedings, The 51st Conference on Simulation and Modelling, 14-15 October 2010 Oulu, Finland / [ed] sko Juuso, Oulu, Finland, 2010Conference paper (Refereed)
    Abstract [en]

    The Hopsan simulation package, used primarily for hydro-mechanical simulation, was first released in 1977. Modeling in Hopsan is based on a method using transmission line modeling, TLM. In TLM, component models are decoupled from each other through time delays. As components are decoupled and use distributed solvers, the simulation environment is suitable for distributed simulations. No numerical errors are introduced at simulation time when using TLM; all errors are related to modeling errors. This yields robust and fast simulations where the size of the time step does not have to be adjusted to achieve a numerically stable simulation. The distributive nature of TLM makes it convenient for use in multi-core approaches and high speed simulations. The latest version of Hopsan was released in August 2002, but now the next generation of this simulation package is being developed. This paper presents the development version of Hopsan NG and discusses some of its features and possible uses.

  • 45.
    Gavel, Hampus
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Andersson, Johan
    Linköping University, Department of Mechanical Engineering, Machine Design. Linköping University, The Institute of Technology.
    Quantification of the Elements in the Relationship matrix: A conceptual study of Aircraft Fuel System2004In: 42nd AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA, paper AIAA-2004-0538, 2004, no AIAA-2004-0538, p. 5244-5252Conference paper (Refereed)
    Abstract [en]

    This paper describes how the framework of thc house of quality and design structure matrices are used to visualizee dependencies between top level requirements and engineering design properties. It is also discussed how quantification of the matrix elements may increase the understanding of how the top-level requirements impacts the low-level design parameters. lndeed, history has shown that overlooking combinatory effects between subsystems and night conditions may become expensive. Not only in terms of not goning getting the sizing right but more so if an entirely wrong concept is chosen.

    This paper shows a matrix technique that has successfully been used at Saab and how this technique may facilitate the cconcept evaluation process of early fuel system design.

    The matrix method aids the designer to take alk the relevant aspects into account when evaluating a design. Use of the method will also increase the understanding of what top-level requirement or combination thereof, which drives the choice of one particular concept rather than the other. The understanding of how the top-level requiremEnts impacts low level design parameters such as pump size or pipe diameter will also increse.

  • 46.
    Gavel, Hampus
    et al.
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Andersson (Ölvander), Johan
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Johansson (Lundén), Björn
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Probabilistic design in the conceptual phase of an aircraft fuel system2005In: 7th AIAA Non-Deterministic Design Forum, Austin, USA, 2005, no AIAA-2005-2219Conference paper (Refereed)
  • 47.
    Gavel, Hampus
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology. Saab Aerospace, Sweden.
    Lantto, Birgitta
    Saab Aerospace, Sweden.
    Ellström, Hans
    Saab Aerospace, Sweden.
    Jareland, Martin
    Saab Aerospace, Sweden.
    Steinkellner, Sören
    Linköping University, Department of Management and Engineering. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Andersson (Ölvander), Johan
    Linköping University, Department of Management and Engineering. Linköping University, The Institute of Technology.
    Strategy for Modeling of large A/C fluid systems2004In: World Aviation Congress and Display, WAC-04, SAE Technical Paper 2004-01-3093, 2004, p. 1495-1506Conference paper (Refereed)
    Abstract [en]

    There is an ongoing trend in the European Military a/c industry towards cooperation between nations when purchasing and between manufacturers when developing and producing a/c. Different manufacturers at different locations develop different parts or sub-systems. When using this approach a vital part of a fast and precise system evaluation is the use of simulation models. In order to stay competitive it is not only sufficient to be able to build large simulation models but also to do it fast.

    This paper describes the conclusions regarding a modelling strategy of large fluid systems drawn from the building of a simulation model of the JAS 39 Gripen fuel system. An overall process is suggested into which the activities of building a model are fitted. This is however not the main objective; it is more important to identify the different issues and activities at the engineering level. If these are properly dealt with, the model development time will be reduced, if not, the wrong model may be designed. "Wrong" here means a model that does not do the job, or solves a problem other than the one intended by the stakeholder.

  • 48.
    Gavel, Hampus
    et al.
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Ölvander Andersson, Johan
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Johansson Lundén, Björn
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Aircraft fuel system synthesis aided by interactive morphology and optimization2007In: 45th AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA, Reno,USA: AIAA , 2007, no AIAA-2007-0653Conference paper (Refereed)
  • 49.
    Gavel, Hampus
    et al.
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Ölvander (Andersson), Johan
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Machine Design . Linköping University, The Institute of Technology.
    Optimal Conceptual Design of Aircraft Fuel Transfer Systems2006In: Journal of Aircraft, ISSN 0021-8669, Vol. 43, no 5, p. 1334-1340Article in journal (Refereed)
    Abstract [en]

     

    This paper describes early considerations that have to be made when designing an aircraft fuel system. Emphasis is placed on illustrating the impact of top-level aircraft requirements on low-level practicalities such as fuel system design. Choosing between concepts is one of the most critical parts of any design process. Different concepts have different advantages, and the concept that is the best choice is often dependent on the top-level requirements. This paper shows how optimization has been used successfully at Saab Aerospace as a tool that supports concept selection. The example studied is the design of a fuel transfer system for a ventral drop tank and the optimization results in different conceptual designs depending on the top-level requirements.

     

  • 50.
    Gavel, Hampus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Machine Design .
    Ölvander, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Machine Design .
    Krus, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Machine Design .
    A quantified relationship matrix aided by optimization and probabilistic design2008In: 26th Congress of the International Council of the Aeronautical Sciences,2008, Anchorage: ICAS , 2008Conference paper (Refereed)
1234 1 - 50 of 179
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf