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  • 1.
    Andersson, Bo
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Hydraulisk riktningsventil2005Patent (Other (popular science, discussion, etc.))
    Abstract [sv]

    En hydraulisk riktningsventil av "öppet-centrum"-typ med ett ventilhus och en i detta rörlig vetilslid för reglering av flöde av hydraulfluid genom ventilen har en tryckkompenseringsventil anordnad i minst en för anslutning till en driven anordning avsedd arbetport för att tryckkompensera flödet från arbetsporten till den drivna anordningen.

  • 2.
    Andersson, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Open-center ventiler för framtidens mobila applikationer2004In: Fluid Scandinavia : specialtidningen för hydraulik och pneumatik, ISSN 1402-5590, Vol. 2, no 1Article in journal (Other academic)
  • 3.
    Andersson, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Over-centervenilers svängningsbenägenhet2004In: Hydraulikdagarna 2003,2003, Linköping, Sweden: Linköpings universitet , 2004Conference paper (Refereed)
  • 4.
    Andersson, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Variabla pumpar i mobila system2007In: Hydraulikdagar 07,2007, Linköping: Linköpings universitet , 2007Conference paper (Other academic)
    Abstract [sv]

    Det här föredraget behandlar olika systemprinciper för att styra en variabel pump i en mobil applikation. Variabla pumpar med elektrisk styrning ger möjlighet till nya intressanta systemprinciper.

  • 5.
    Andersson, Johan
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Multiobjective optimization in engineering design: applications to fluid power systems2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on how to improve design and development of complex engineering systems by employing simulation and optimization techniques. Within the thesis, methods are developed and applied to systems that combine mechanical, hydraulical and electrical subsystems, so-called multi-domain systems. Studied systems include a landing gear system for a civil aircraft, electrohydrostatic actuation systems for aircraft applications as well as hydraulic actuation systems.

    The usage of simulation and optimization in engineering design is gaining wider acceptance in all fields of industry as the computational capabilities of computers increase. Therefore, the applications for numerical optimization have increased dramatically. A great part of the design process is and will always be intuitive. Analytical techniques as well as numerical optimization could however be of great value and can permit vast improvements in design.

    Within the thesis, a framework is presented in which modeling and simulation are employed to predict the performance of a design. Additionally, non-gradient optimization techniques are coupled to the simulation models to automate the search for the best design.

    Engineering design problems often consist of several conflicting objectives. In many cases, the multiple objectives are aggregated into one single objective function. Optimization is then conducted with one optimal design as the result. The result is then strongly dependent on how the objectives are aggregated. Here a method is presented in which the Design Structure Matrix and the relationship matrix from the House of Quality method are applied to support the formulation of the objective function.

    Another approach to tackle multiobjective design problems is to employ the concept of Pareto optimality. Within this thesis a new multiobjective genetic algorithm is proposed and applied to support the design of a hydraulic actuation system. The outcome from such a multiobjective optimization is a set of Pareto optimal solutions that visualize the trade-off between the competing objectives. The proposed method is capable of handling a mix of continuous design variables and discrete selections of individual components from catalogs or databases.

    In real-world situations, system parameters will always include variations to some extent, and this fact is likely to influence the performance of the system. Therefore we need to answer not only the question "What is best?", but also "What is sufficiently robust?" Within this thesis, several approaches to handle these two different questions are presented.

  • 6.
    Andersson, Johan
    et al.
    Maskinkonstruktion Tekniska fakultetet i Linköping.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    The Evolve Project - a Mechatronic project for final year students2003In: International Conference in Engineering Design ICED03,2003, Stockholm, Sweden: ICED'03 , 2003Conference paper (Refereed)
  • 7.
    Andersson, Lars
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Information sharing in mobile robot teams: deployment with uncertainty consideration2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work presented in this thesis deals with information sharing within mobile robot teams. Main focus is on information related to team positioning and localization. The goal of this research is to find models for how to best deploy a group of robots.

    The motion platforms covered are well adapted. although very important for the results. Motion models are crucial when calculating the dead reckoning of each platform. Results in the appended work show that the motion model has heavy impact on the possibility to affect the uncertainty of a robot team as new ground is deployed.

    The sensor models discussed may not necessarily be what is commonly used in the research field. Instead good approximations are used, that describe the main features of the sensor type. The focus is to present different sensor types and describe how the characteristics affect the uncertainty of the robot team, not to create new sensor models. A general model for sensors with polar measurement coordinates is derived. This can be used with different sensors with the same characteristics.

    A framework for sharing information within the robot team is derived. This is based on earlier work presented as "The Stochastic Map". However, the framework is tailored to suite the purpose of this work. Different estimation methods are also discussed, with main focus is on Kalman filtering techniques.

    The resulting part of this work present different ideas of what should be considered when deploying a group of robots. Results show how different dist ribution of sensors will affect the localization uncertainty of the group. It is also shown how different deployment formations affect the uncertainty within the team.

    List of papers
    1. On Sensor Fusion Between a Pair Of Heterogeneous Robots
    Open this publication in new window or tab >>On Sensor Fusion Between a Pair Of Heterogeneous Robots
    2003 (English)In: Proceedings of the 6th International Conference on Information Fusion, Cairns, Australia, 8th–11th July, 2003, 2003, p. 1287-1294Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    This paper present work in progress, aiming to find models that can be used as guidelines in how to best deploy a team of heterogeneous robots to solve a given task. That is, this research is focusing on how much each robot can increase the certainty about its own position and orientation in a global perspective as well as relative to other team members. It also, in some extent investigate what happens too the uncertainty and correlation within the group. The motive is to provide an insight into the utility of fusing position information communicated within the team, in aspect of increased accuracy. It also investigates in what way different usage of sensors will effect the results. Since the goal of the paper is insight, the minimum configuration of two robots and two landmarks is studied although the results are scalable to larger robot teams. The results show that by placing a camera on the moving robot measuring the bearing of a stationary robot gives better estimation of the moving robots orientation, which can be crucial for the solution of the association problem.

    Keywords
    Cooperative, Robot, Navigation, Distributed, Fusion, SLAM, CLAM
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-15106 (URN)0-9721844-4-9 (ISBN)
    Available from: 2008-10-16 Created: 2008-10-16 Last updated: 2013-11-04Bibliographically approved
    2. On utilizing geometric formations for minimizing uncertainty in 3 robot teams
    Open this publication in new window or tab >>On utilizing geometric formations for minimizing uncertainty in 3 robot teams
    2004 (English)In: Proceedings of The 8th Conference on Intelligent Autonomous Systems, IAS-8, Amsterdam, Netherlands, 10th–12th March, 2004, , p. 100-110p. 100-110Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper presents work in progress, aiming to find models that can be used as guidelines in how to best deploy a team of robots to solve given tasks. The motive is to provide an insight into the utility in fusing position information communicated within the team, in aspect of increased accuracy in position and orientation estimate. The minimum configuration of three robots is studied. The robots are equipped with camera-like sensors that make omni directional bearing measurements to eachother. To reduce the free variables the formations are restricted so that two subordinate robots are located at the same distance to a master robot. For this configuration the information matrix is explored. A few formations are chosen and studied further, through simulations. The simulations show that there exists a breakpoint in traveled distance, where the formation minimizing orientation uncertainty for the master robot, changes from a column-formation to a line formation. The simulations also show that a line or column formations are not a good choice when balansed position uncertainty is required. In the case of balansing position uncertainty, a triangular formation is better.

    Publisher
    p. 100-110
    Keywords
    Geometric formations, minimize uncertainty
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-15319 (URN)9781586034146 (ISBN)
    Available from: 2008-10-31 Created: 2008-10-31 Last updated: 2013-11-04Bibliographically approved
    3. Effects on Uncertainty Utilizing Formation-Planning in Robot Teams
    Open this publication in new window or tab >>Effects on Uncertainty Utilizing Formation-Planning in Robot Teams
    2004 (English)In: Proceedings of The 5th Symposium on Intelligent Autonomous Vehicles, IAV 2004, Lisbon, Portugal, 5th–7th July 2004, 2004Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper presents work in progress, aiming to find models that can be used as guidelines in how to best deploy a team of robots to solve given tasks. The motive is to provide an insight into the utility in fusing position information communicated within the team, in aspect of increased accuracy in position and orientation estimate. The minimum configuration of three robots moving over a flat surface is studied. The robots are equipped with omni-directional cameralike sensors that make bearing measurements to each other. To reduce the free variables the formations are restricted so that two subordinate robots are located at the same distance to a master robot. For this configuration the information matrix is derived and studied. There are numerical results presented that indicate how the uncertainty of the master robot changes depending of the bearing to the subordinate robots and the distance traveled.

    Keywords
    Multi-Robot, Cooperative, Formation, Localization
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-15320 (URN)
    Available from: 2008-10-31 Created: 2008-10-31 Last updated: 2013-11-04Bibliographically approved
  • 8.
    Andersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    On Group-Centric Topology Representation for Mobile Robot Teams2004Report (Other academic)
    Abstract [en]

    When dealing with robot localization and simultaneous map building one of the greates problem is to keep the created map consistent. Due to linearization, simplifications and other errors in models resent work has shown that the map created will, eventually, diverge. One way of dealing with these problems is to present the map in robot coordinates and thereby increase the consistency of the map. In the case many robots are used to create a map collectively this consistency problem often arises even sooner. This work propose a new method of dealing with the consistency problem when doing collaborative mapping by presenting the map in a groupcentric coordinate frame that continuously moves together with the robot team as new areas are explored.

  • 9.
    Andersson, Lars
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Berglund, Marcus
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Production Engineering.
    Camera Based Concept for Enhancement of IRB Accuracy using Fixed Features and SLAM2006In: 8th Biennal ASME Conference on Engineering Systems Design and Analysis,2006, Torino: ESDA , 2006Conference paper (Refereed)
    Abstract [en]

    A standard IRB (Industrial Robot) of today is not capable of positioning itsels to within better than 2-5mm relative to a given structure or object. In order to be able to perform high precision manufacturing, the requirement is less than 0,5mm. Existing solutions for 6DOF measurements to enhance the accuracy are not only expensive but also lacks flexibility. An affordable, accurate concept for IRB closed loop position feedback is presented here. This article proposes a method for using a camera together with fixed features to enhance the accuracy of an IRB in industrial manufacturing processes. The method is based on SLAM (Simultaneous Localization and Mapping), used to structure collected information about the features (mapping), and for the IRB to locate itself among the features (localization). The concept covers a scenario in which a set of features are placed within the working area. A camera is mounted on the IRB to observe (measure) the relative pose of the feature set. When the system is running observation of only one feature increases accuracy. However, in normal operation more features are observed which will increase accuracy further. The system setup is a standard IRB, ABB4400, on which a single camera with IR flash is mounted and used as sensor. The features are made out of reflectors that are placed in the production cell. The camera is also equipped with an IRfilter to improve the signal to noise ratio, simplifying image processing and accelerating execution. The execution time is critical since the goal is to sample at such rate that as to cover the dynamics of the robot. 

  • 10.
    Andersson, Lars
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Degerman, Pär
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Zachrison, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    PILZ -- Personal Indoor Localization Zone, Extended System Analysis and Design2006Report (Other academic)
  • 11.
    Asplund, Anders
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    How a continuously changing B2B environment influences the selection of suppliers: introducing a model and process approach2004Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Creation of a supply base is perhaps the most important task of the purchasing function. In this creation process, potential suppliers must be identified, analysed and decisions made. Decisions that, in most cases, have direct effects on the company's "bottom line". The tools to support and aid this process are often one-dimensional and assume to a high degree that, in all cases, there is a valid description of the best possible supplier. This research suggests that this is not the case. Which is the best possible supplier is situation specific. This is a fact acknowledged in the literature and by the empirical material. What is missing is a tool to support the supplier selection process from a starting point that each sourcing situation is unique. This research proposes such a process approach and, at the same time, a model for supplier selection.

    The purpose of this study is to analyse and develop the process of, and the criteria for, supplier selection in a sub-tier, business to business context. The research has been initiated by, and had its starting point in, one company (Volvo Aero Corporation) acting in the specific and very demanding environment of the aero-engine industry. The main aim of this research is to give managerial implications for purchasing professionals.

    To be able to ensure that the best possible supplier for a specific situation is selected, the situation has to be analysed. This research proposes a model and process that starts by defining the minimum requirement which a supplier has to fulfil for a purchaser to be convinced that the intended relationship will be successful for the intended period of time. This minimum requirement is called the supplier profile. The business environment, network and market conditions, the.purchasing company 's strategies and the characteristics of the product, service or function to be sourced are identified as influential factors when creating the supplier profile. The results also highlight the need to work cross-functionally when creating the supplier profile and the need to combine different theoretical bases to get a complete picture of the requirements to put on a potential supplier.

  • 12. Berefelt, F
    et al.
    Boberg, B
    Nygårds, Jonas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Strömbäck, P
    Collaborative GPS/INS Navigation in Urban Environment2004In: ION National Technical Meeting 2003,2004, 2004Conference paper (Other academic)
  • 13.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Aircraft conceptual design methods2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Generally aircraft conceptual design is defined as the starting point for concept sketcing and evaluation, but before that work can start an even earlier stage has to be covered.

    This is the stage where different scenarios are being worked through in which the aircraft as a platform is supposed to work. The scenarios will differ between civil and military use of course. but will have to fit well inside both customers and manufacturers strategic plans for the future.

    In planning for the future it's vital to think and plan in broader terms, i.e. not only creating single products but rather create families of aircraft. This way of thinking and planning is usual amongst civil manufacturers. Creating a family based product line means better economics, better market coverage and of course lesser risk taking if and when the market changes. On the military side this way of thinking and planning is still quite unusual, mainly because customers are governments which usually only ask for single products.

    The manufacturer from his point of view must think differently, he needs to spread his risk taking, especially as orders from the govemment are becoming scarcer. Therefore a modular product line would be of economic interest and would probably interest more customers.

    The basic idea behind Saab Gripen (three roles merged into one single platform), or the US Joint Strike Fighter (JSF) idea of a modular aircraft, could be seen as the start of some kind of new family planning, but family planning on the military side could reach further than that. Probably military manufacturers can learn a lot from their civil counterparts.

    Conceptual design might be a one man job in the early stages, but will very soon develop into team work. This development is only natural since the conceptual designer can't be expected to have detailed knowledge or experience which will cover every item. Conceptual design introduces a holistic viewpoint into the aircraft design process and it's vital to keep this viewpoint as long as possible. This becomes even more important over time, since the more detailed the project gets, the overall goal tends to drown into details.

    Conceptual design phase offers the only occasion when design changes still can be made quite easily. Design freeze is not only a simple freeze of aircraft layout and geometry, it also sets the fmal prize tag on the aircraft. So in a way it is what you did (and what you forgot to do) in the conceptual design phase which fmally decides the faith of the end product. Hence conceptual design needs all the time it takes to be able to develop successful future products.

    Generally there are two sides to conceptual design: either you develop a brand new design or make changes to an already existing one. Either way has its own needs and can't be run in the same manner, since different tools are needed in both cases. A new design needs a good conceptual design program, while in the latter case only minor parts of it might be used. A new design starts off fresh; everything is possible and nothing is sacred, but changing on an existing design means working with hands tied, you do not change things that easily.

    Aircraft Conceptual Design takes long time to learn. It requires more than just being able to run a conceptual design program. Previous experience in a number of different aircraft design disciplines is a must; so is the ability to be able to humbly listen to experienced people's knowledge and advice.

    This paper describes methods for aircraft conceptual design at two basic levels. At the top level there's a method described for conceptual design of civil jet transport aircraft.

    On the second level different methods for conceptual design of core aircraft systems such as landing gear, environmental control and hydraulic are presented.

    List of papers
    1. The Sunriser - A Design Study in Solar Powered Flight
    Open this publication in new window or tab >>The Sunriser - A Design Study in Solar Powered Flight
    2000 (English)In: SAE Technical Paper 2000-01-5507, 2000Conference paper, Published paper (Other academic)
    Abstract [en]

    The design task for last year students in Aircraft Design at Linköping University was to design a manned solar-powered aircraft. The mission was to survey the U.S./Mexican borderline in search for possible intruders. The Sunriser began as a sole paper project, but quite soon we felt a need to prove that solar-powered flight really was feasible. Thus the decision was made to design and build a solar powered demonstrator of our own design.

    The demonstrator aircraft, a radio controlled model aircraft named "the Sunrazor," was designed, built and flown with good result.

    This paper deals with the basic theory of sun-powered flight and describes the basic thoughts and design considerations which finally led to the configurations chosen.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-35265 (URN)10.4271/2000-01-5507 (DOI)26023 (Local ID)26023 (Archive number)26023 (OAI)
    Conference
    2000 World aviation Congress, San Diego, California, October, 2000
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-11-07
    2. Landing Gear Design in the Conceptual Design Phase
    Open this publication in new window or tab >>Landing Gear Design in the Conceptual Design Phase
    1999 (English)In: SAE Technical Paper 1999-01-5523, 1999Conference paper, Published paper (Other academic)
    Abstract [en]

    A well-designed landing gear and a proper integration is of utmost importance for the success of any aircraft design. This should never be neglected but often is, especially in the conceptual design stage. This paper reflects the author''s own experience in landing gear design of the Saab Gripen aircraft as well as experience gained on aircraft conceptual designs of later dates. The aim of the paper is to underline the importance of spending more time on landing gear design and integration in conceptual design. The paper reflects the importance of proper interaction between landing gear design and other disciplines and above all underlines the fact that landing gear design should be treated as an equally important design parameter, just as any other, in the final choice of aircraft configuration.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-100442 (URN)10.4271/1999-01-5523 (DOI)
    Conference
    1999 World aviation Congress, San Fransisco, California, October, 1999
    Available from: 2013-11-07 Created: 2013-11-07 Last updated: 2013-11-07
    3. Sizing the Landing Gear in the Conceptual Design Phase
    Open this publication in new window or tab >>Sizing the Landing Gear in the Conceptual Design Phase
    2000 (English)In: SAE Technical Paper 2000-01-5601, 2000Conference paper, Published paper (Other academic)
    Abstract [en]

       

    A tool has been developed in order to design or evaluate a proposed landing gear layout and to determine its size and weight. The methodology has been developed primarily for landing gears of the telescopic suspension type.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-35273 (URN)10.4271/2000-01-5601 (DOI)26049 (Local ID)26049 (Archive number)26049 (OAI)
    Conference
    2000 World aviation Congress, San Diego, California, October, 2000
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-11-07
    4. Conceptual Design of a New Generation JAS 39 Gripen Aircraft
    Open this publication in new window or tab >>Conceptual Design of a New Generation JAS 39 Gripen Aircraft
    2006 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes the conceptual phase of a modification proposal for Saab Gripen, which aims to create the best possible basis for future aircraft development. One of the main tasks in this respect is to investigate different means to extend range. This paper describes the technical outcome from the concept generation, concept selection, and concept refinement at system and airframe level. The chosen concept involves relocation and redesign of the main landing gear. The original main landing gear bay is converted into fuel tanks. The relocation of the main gear enables a new ventral twin store carriage with supersonic jettison capability to be introduced. The concept proposal yields the following improvements:

    · Increased range due to increased fuel capability

    · Increased maximum allowed takeoff weight due to beefe d-up main gear

    · Increased weapon flexibility and capability due to introduction of two new ventral store

    · Introducing supersonic jettison capability

    The paper also includes a description of how the work is related to the overall design process in general and the conceptual phase in particular, as described in design methodology literature.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-12980 (URN)10.2514/6.2006-31 (DOI)
    Conference
    44th AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2013-11-07
  • 14.
    Berry, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Aircraft Desígn at LiU2004In: EWADE 2004,2004, 2004Conference paper (Other academic)
  • 15.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Landing Gear Design in the Conceptual Design Phase1999In: SAE Technical Paper 1999-01-5523, 1999Conference paper (Other academic)
    Abstract [en]

    A well-designed landing gear and a proper integration is of utmost importance for the success of any aircraft design. This should never be neglected but often is, especially in the conceptual design stage. This paper reflects the author''s own experience in landing gear design of the Saab Gripen aircraft as well as experience gained on aircraft conceptual designs of later dates. The aim of the paper is to underline the importance of spending more time on landing gear design and integration in conceptual design. The paper reflects the importance of proper interaction between landing gear design and other disciplines and above all underlines the fact that landing gear design should be treated as an equally important design parameter, just as any other, in the final choice of aircraft configuration.

  • 16.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Sizing the Landing Gear in the Conceptual Design Phase2000In: SAE Technical Paper 2000-01-5601, 2000Conference paper (Other academic)
    Abstract [en]

       

    A tool has been developed in order to design or evaluate a proposed landing gear layout and to determine its size and weight. The methodology has been developed primarily for landing gears of the telescopic suspension type.

  • 17.
    Berry, Patrick
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    The Sunriser - A Design Study in Solar Powered Flight2000In: SAE Technical Paper 2000-01-5507, 2000Conference paper (Other academic)
    Abstract [en]

    The design task for last year students in Aircraft Design at Linköping University was to design a manned solar-powered aircraft. The mission was to survey the U.S./Mexican borderline in search for possible intruders. The Sunriser began as a sole paper project, but quite soon we felt a need to prove that solar-powered flight really was feasible. Thus the decision was made to design and build a solar powered demonstrator of our own design.

    The demonstrator aircraft, a radio controlled model aircraft named "the Sunrazor," was designed, built and flown with good result.

    This paper deals with the basic theory of sun-powered flight and describes the basic thoughts and design considerations which finally led to the configurations chosen.

  • 18.
    Caldenfors, Dag
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    A method for modelling and simulation of joint driver-vehicle performance at vehicle handling limits2004In: International Conference on Engineering Design,2003, Stockholm, Sweden: ICED'03 , 2004Conference paper (Refereed)
  • 19.
    Caldenfors, Dag
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Identification of joint driver-vehicle performance in car skidding recovery tasks2004In: Symposium on Automated Systems based on Human Skill and Knolwdge,2003, Gothenburg, Sweden: IFAC2003 , 2004Conference paper (Refereed)
    Abstract [en]

         

  • 20.
    Caldenfors, Dag
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Dekker, Sidney
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Industrial Ergonomics.
    Smith, Christian Skinner
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Industrial Ergonomics.
    An Initial Model of Driver-Vehicle Performance in Recovery from Skids on Icy Roads2006In: 50th Annual Meeting of the Human Factor and Ergonomics Society,2006, San Fransisco: Human Factors and Ergonomic Society , 2006Conference paper (Refereed)
    Abstract [en]

     Closed-loop instability caused by excess phase lag has been studied widely in aviation. Here we develop and test a model of its counterpart in vehicle-driver-coupling, where participants were asked to recover from a skid on a slippery road. We model the damping effect of sucessful recovery as viscoelastic behavior. Oscillation number is the predictor variable; steering wheel angle is the response variable. 

  • 21.
    Degerman, Pär
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Automatic parallel parking: park assist systems for passenger vehicles2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis discusses how the problem of parking a passenger car can be solved. There ane numerous obstacles when creating a fully or semi automated system for assisting the parking maneuver. The obstacles range from unobtrusive Man Machine Interface issues to robust algorithms for finding features in sensor data.

    Such a system will also have to cope with ever changing environments, most of which will not be discovered during the design phase. Misuse will also be common, since the function is aimed at a mass market - the car buyers. These interesting problem areas is also coupled with the customer value. A car buying customer today aims at feature content and comfort. So for a parking system to survive it needs to be extremely intuitive; the customer value must be discovered during a short test drive with the vehicle. A learning period before the user can operate the system is not feasible.

    The work presented here proposes an interesting algorithm for finding parking space features in sensor data collected using ultrasonics. The algorithm, which is based on the well known Hough transform have been proved to be robust in real world experiments.

    Furthermore it is also investigated how critical the mount ing of the environment sensing subsystem is. Where should the sensors be placed and where should they be facing to maximize the performance.

    Emphasis have also been put on designing a functional architecture that fits in the car development process of today. The implementation of a system in a car must fit in the platform and component reuse is critical to keep cost down.

    To test theories developed during the work a prototype car has been used. The prototype is essential to analyze the robustness of algorithms in different parking scenarios. It has also been an invaluable tool when conducting customer surveys to find where the customer value of these kind of systems is.

    List of papers
    1. A semi-automated parallel parking system for passenger cars
    Open this publication in new window or tab >>A semi-automated parallel parking system for passenger cars
    2006 (English)In: Proceedings of the Institution of mechanical engineers. Part D, journal of automobile engineering, ISSN 0954-4070, E-ISSN 2041-2991, Vol. 220, no 1, p. 53-65Article in journal (Refereed) Published
    Abstract [en]

    Car parking has been, and still is, a growing problem, with increasing vehicle sizes in the luxury segment as well as sport-utility vehicles. This is especially true when bearing in mind the confined parking spaces in parking lots and cities. While damage during parking generally does not cause any injury to the passengers, it is costly and annoying. Park assist systems are by no means new on the market, since passive systems which provide longitudinal guidance using ultrasonic distance sensors have been available on the market for a number of years.

    The system presented is a semi-automated approach to parallel parking problems, as they frequently occur in European and Asian cities. The challenge during the development of this system was to have as few components as possible added to a standard vehicle, seeking reuse of many of the already built-in functionalities. The result is a system that leaves the longitudinal control of the vehicle to the driver but automates the steering process, and even stops the vehicle when the final parking position is reached.

    Keywords
    electric steering gear, ultrasonic distance sensors, functional architecture
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-36019 (URN)10.1243/095440705X69650 (DOI)000234903900005 ()29425 (Local ID)29425 (Archive number)29425 (OAI)
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-20
    2. Hough Transform for Parking Space Estimation Using Long Range Ultrasonic Sensors
    Open this publication in new window or tab >>Hough Transform for Parking Space Estimation Using Long Range Ultrasonic Sensors
    2006 (English)In: SAE Technical Paper, Detroit: SAE , 2006, p. 2006-01-0810-Conference paper, Published paper (Refereed)
    Abstract [en]

    This paper describes a system for supporting the driver of a passenger car in different parking situations. Todays cars are getting larger in size and the drivers view in both forward and rearward direction is becoming more limited. This fact calls for a system of sensors and algorithms capable of supporting the driver through the parking maneuvre in a safe and smooth way.

    The paper presents the development of some of the subsystems in a fully automatic parallel parking system, utilizing ultrasonic ranging sensors for environment mapping. In contrast to existing passive parking aid systems, the ultrasonic range sensors need to have a narrower aperture to be able to map the surroundings properly. This can be accomplished by either increased sensor size or by a higher number of sensors.

    The emphasis of the paper is the signal conditioning in the parking system. The Hough-transform along with a statistical CUSUM test are used to find the properties of the target parking space.

    The system makes use of hardware components already available in modern cars and a small number of added components. The resulting system is automated, from finding a suitable parking space to maneuvering the car into the parking space, while keeping the driver in authority since the longitudinal control, i.e. throttle and brakes, are still the drivers responsibilities.

    The prototype system is implemented in a Volvo S60 which has been modified with an electric power steering unit and an ultrasonic sensor array consisting of a total of six sensors spread out around the vehicle. The electric power steering unit is used for steering wheel angle control when the system is active by adding an external torque to the assist torque normally applied.

    Place, publisher, year, edition, pages
    Detroit: SAE, 2006
    Keywords
    automatic parking systems, ultrasonic sensing
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-36020 (URN)10.4271/2006-01-0810 (DOI)29427 (Local ID)29427 (Archive number)29427 (OAI)
    Conference
    SAE 2006 World Congress & Exhibition. Detroit, USA. April 3-6, 2006
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-20
    3. A Full Four-Quadrant Hydraulic Steering Actuator Applied to a Fully Automatic Passenger Vehicle Parking System
    Open this publication in new window or tab >>A Full Four-Quadrant Hydraulic Steering Actuator Applied to a Fully Automatic Passenger Vehicle Parking System
    2006 (English)In: Proceedings of the 4th FPNI-PhD Symposium, Lafayettem, IN, USA: FPNI Fluid Power Net Publications , 2006, p. 387-396Conference paper, Published paper (Refereed)
    Abstract [en]

    This project describes how the Active Pinion hydraulic steering system can be used to replace a electric power steering actuator in the Parking Pilot automatic parking system.

    Customer demand for fully or semi automatic parking systems in passenger cars, are getting higher with increased cost of parking related body damage repair coupled with restricted rearward sight and the larger dimensions of modern cars. This, however, puts new demands on the steering actuator. An automatic parking system requires full control of the steering servo, which is not possible with current hydraulic actuators. Instead these systems have to rely on electric servos which allow for the needed controllability.

    All current electric steering servos have the drawback that it is impossible to use them on anything but small or medium sized cars. Since a parking system can be seen as a premium accessory, which is more likely to attract customers who buy larger cars, this is a major hindrance for the success of automatic parking systems.

    A solution to the problem is to construct a controllable variant of the hydraulic steering servo, the Active Pinion. In this concept a small electric pilot motor is added to the traditional hydraulic valve, which adds one additional degree of freedom to the servo, accomplishing full four-quadrant operations.

    The project discusses how the Active Pinion concept is introduced in the Parking Pilot parking system and how different demands on the parking system relates to the performance of the actuator. The parking system is installed in a prototype car and simulation of the Active Pinion concept is accomplished with HWIL simulation in a load simulator.

    Place, publisher, year, edition, pages
    Lafayettem, IN, USA: FPNI Fluid Power Net Publications, 2006
    Keywords
    hpas, epas, automotive, power steering, automatic parkin, active pinion, parking plot
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-35816 (URN)28628 (Local ID)1-4243-0499-7 (ISBN)28628 (Archive number)28628 (OAI)
    Conference
    4th FPNI-PhD Symposium. Sarasota, FL, USA, 2006.
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-12-12
    4. Ultrasonic Sensor Modeling for Automatic Parallel Parking Systems in Passenger Cars
    Open this publication in new window or tab >>Ultrasonic Sensor Modeling for Automatic Parallel Parking Systems in Passenger Cars
    2007 (English)In: SAE Technical Paper, 2007, p. 2007-01-1103-Conference paper, Published paper (Refereed)
    Abstract [en]

    The performance of a parking system is dependent on many factors. One is the placement of the sensors. In this paper a system which uses ultrasonic ranging sensors is considered. The mounting of a ultrasonic sensor on a passenger vehicle is restricted by, among other factors, design, assembly process, enclosure cost and reliability. All of which must be considered when choosing optimal mounting locations.

    The basis of this work includes a ray-trace based simulation environment which is used to capture the physical properties of sound traveling through air. The simulation environment together with sensor models, is used to evaluate the effect of different mounting positions on the accuracy of the detection of the parking space. The Hough transform is used here, as well as in the real system, in order to extract the confining lines of the parking space from the sensor measurements. The strength of these lines are then used to compare different sensor mounting locations.

    The created simulation environment differs from other work in this area since it tries to capture the physical properties of the sound waves as opposed to the geometric-only approach. The emitted sound pulse is divided into a large number of rays, each with sound properties tied to them. These rays are then traced through a model of the parking space environment, reflections are calculated and finally the summarized echo into the listening sensor is calculated.

    The simulation is implemented in 3D Studio MAX which make it relatively easy to create various realistic parking scenarios. An important factor for choosing 3D Studio MAX as the basis of the simulation environment was that it allowed for a new way of modeling ultrasonics using ray-tracing, and at the same time - using the same ray-tracing technology - excellent visualization capabilities.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-102488 (URN)10.4271/2007-01-1103 (DOI)
    Conference
    SAE 2007 World Congress & Exhibition, Detroit, MI, U.S.A., 16th–19th April, 2007
    Available from: 2013-12-12 Created: 2013-12-12 Last updated: 2017-12-20
  • 22.
    Degerman, Pär
    et al.
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Pohl, Jochen
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Sethson, Magnus
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Hough Transform for Parking Space Estimation Using Long Range Ultrasonic Sensors2006In: SAE Technical Paper, Detroit: SAE , 2006, p. 2006-01-0810-Conference paper (Refereed)
    Abstract [en]

    This paper describes a system for supporting the driver of a passenger car in different parking situations. Todays cars are getting larger in size and the drivers view in both forward and rearward direction is becoming more limited. This fact calls for a system of sensors and algorithms capable of supporting the driver through the parking maneuvre in a safe and smooth way.

    The paper presents the development of some of the subsystems in a fully automatic parallel parking system, utilizing ultrasonic ranging sensors for environment mapping. In contrast to existing passive parking aid systems, the ultrasonic range sensors need to have a narrower aperture to be able to map the surroundings properly. This can be accomplished by either increased sensor size or by a higher number of sensors.

    The emphasis of the paper is the signal conditioning in the parking system. The Hough-transform along with a statistical CUSUM test are used to find the properties of the target parking space.

    The system makes use of hardware components already available in modern cars and a small number of added components. The resulting system is automated, from finding a suitable parking space to maneuvering the car into the parking space, while keeping the driver in authority since the longitudinal control, i.e. throttle and brakes, are still the drivers responsibilities.

    The prototype system is implemented in a Volvo S60 which has been modified with an electric power steering unit and an ultrasonic sensor array consisting of a total of six sensors spread out around the vehicle. The electric power steering unit is used for steering wheel angle control when the system is active by adding an external torque to the assist torque normally applied.

  • 23.
    Degerman, Pär
    et al.
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Rösth, Marcus
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    A Full Four-Quadrant Hydraulic Steering Actuator Applied to a Fully Automatic Passenger Vehicle Parking System2006In: Proceedings of the 4th FPNI-PhD Symposium, Lafayettem, IN, USA: FPNI Fluid Power Net Publications , 2006, p. 387-396Conference paper (Refereed)
    Abstract [en]

    This project describes how the Active Pinion hydraulic steering system can be used to replace a electric power steering actuator in the Parking Pilot automatic parking system.

    Customer demand for fully or semi automatic parking systems in passenger cars, are getting higher with increased cost of parking related body damage repair coupled with restricted rearward sight and the larger dimensions of modern cars. This, however, puts new demands on the steering actuator. An automatic parking system requires full control of the steering servo, which is not possible with current hydraulic actuators. Instead these systems have to rely on electric servos which allow for the needed controllability.

    All current electric steering servos have the drawback that it is impossible to use them on anything but small or medium sized cars. Since a parking system can be seen as a premium accessory, which is more likely to attract customers who buy larger cars, this is a major hindrance for the success of automatic parking systems.

    A solution to the problem is to construct a controllable variant of the hydraulic steering servo, the Active Pinion. In this concept a small electric pilot motor is added to the traditional hydraulic valve, which adds one additional degree of freedom to the servo, accomplishing full four-quadrant operations.

    The project discusses how the Active Pinion concept is introduced in the Parking Pilot parking system and how different demands on the parking system relates to the performance of the actuator. The parking system is installed in a prototype car and simulation of the Active Pinion concept is accomplished with HWIL simulation in a load simulator.

  • 24.
    Edvardsson, Jon
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Contributions to program- and specification-based test data generation2002Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Software testing is complex and time consuming. One way to reduce testing effort is to automatically generate test data. In the first part of this thesis we consider a framework by Gupta et al. for generating tests from programs. In short, their approach consists of a branch predicate collector, which derives a system of linear inequalities representing an approximation of the branch predicates for a given path in the program. This system is solved using their constraint solver called the Unified Numerical Approach (UNA). In this thesis we show that in contrast to traditional optimization methods the UNA is not bounded by the size of the solved system. Instead it depends on how input is composed. That is, even for very simple systems consisting of one variable we can easily get more than a thousand iterations. We will also give a formal proof that UNA does not always find a mixed integer solution when there is one. Finally, we suggest using some traditional optimization method instead, like the simplex method in combination with branch-and-bound and/or a cutting-plane algorithm as a constraint solver.

    In the second part we study a specification-based approach for generation of software tests developed by Meudec. Briefly, tests are generated by an automatic partitioning strategy based on partition rules. An important step in the process is to reduce the number of generated subdomains and find a minimal partition. However, we have found that Meudec-s algorithm does not always produce a minimal partition. In this work we present an alternative solution to the minimal partition problem by formulating it as an integer programming problem. By doing so, we can use well known optimization methods to solve this problem.

    A more efficient way to derive a minimal partition would be using Meudec's conjectured two-step reduction approach: vertex merging and minimal path coverage. Failing to find a general solution to either of the steps, Meudec abandoned this approach. How-ever, in this work we present an algorithm based on partial expansion of the partition graph for solving the first step. Furthermore, our work in partial expansion has led to new results: we have determined an upper bound on the size of a minimal partition. In turn, this has led to a stronger definition of our current minimal partition algorithm. In some special cases we can also determine lower bounds. 

  • 25.
    Ericson, Liselott
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Johansson, Andreas
    Parker Hannifin AB.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    The source admittance method A new measurement method for hydrostatic pump flow pulsation2006In: Proc. of the 4th FPNI - PhD Symposium Sarasota, Vol 1, Sarasota: Coastal Printing , 2006, p. 297-309Conference paper (Refereed)
    Abstract [en]

    Two main drawbacks with hydraulic systems are noise and vibrations, mainly created from flow pulsations in positive displacement pumps. The flow ripple can be divided in two parts; kinematic and compressible. Kinematic flow ripple is created due to the limited number of pumping elements. Compressible flow ripple is created due to cornpressibility effects in the pumping chambers and is the dominating effect at high pressures. There are well proven methods to decrease noise in specific operation conditions, but there is an urgent need for new techniques in machines working under varying operation conditions. There is also a need for improved measurement methods to be used in product development and to judge new inventions to decrease noise.

    Simulation techniques are useful in the early stages of the development process. There are useful and accurate simulation models capable of predicting source flow ripple in hydrostatic pumps and thereby useful for optimisation purposes. Simulation results are, however, of less practical use before they are experimentally verified . The experimental methods must be simple and straightforward if they are to be accepted in industry.

    This paper describes a new method to measure source flow. It is called the source admittance method. Compared to earlier methods such as the two-microphone method, the main benefit is that there is no need for a model of the outlet channel - the source flow is measured through an additional pressure transducer inside the pump. The method works very well with a tested fixed bent-axis pump with a rather simple outlet channel. Experiments have also been performed with a variable in-line pump with added complexity to the out let channel. Although the overall impression is positive, these experiments show that the method needs to be further to be used for such machines. In both cases, the new method is compared with earlier verified simulation models and with measurements based on the two-microphone method. Apart from the mentioned discrepancies in a narrow frequency range, agreement is very good.

  • 26.
    Ericson, Liselott
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems .
    Ölvander, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    En effektiv metod för att reducera flödespulsationer från variabla hydraulmaskiner2007In: Hydraulikdagar 07,2007, Linköping: Linköpings universitet , 2007Conference paper (Other academic)
    Abstract [sv]

     Den här presentationen behandlar en metod som effektivt reducerar flödespulsationer i variabla hydraulmaskiner, genom att förskjuta dödpunktens läge. Det realiseras genom att införa en fast inklinationsvinkel vinkelrätt mot den normala deplacementsvinkeln. Genom att förskjutningsvinkeln ändrar kolvarnas dödpunkt kommer förkompressionen och efterexpansionen att variera när deplacementet ändras. Tidigare arbeten visar, både teoretiskt och experimentellt, fördelarna med förskjutningsvinkeln för pumpar men inga utförligare utredningar för maskiner som arbetar både som motor och pump.

  • 27.
    Eriksson, Björn
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Andersson, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    The Dynamic Performance of a Pilot Stage in the Poppet Type Hydraulic Flow Amplifier2008In: The 51st NCFP Technical Conference,2008, Proceedings of the 51st NCFP Technical Conference: Omnipress , 2008, p. 659-Conference paper (Refereed)
    Abstract [en]

    This paper examines the dynamic properties of the pilot stage in a poppet type two-stage flow control valve of the -Valvistor- type. The particular valve studied is a screw-in Valvistor valve of NG16 size. There are several benefits to this valve type: it has a high closed loop bandwidth and the design allows big flow capacities. An attractive feature of this two-stage valve is that the pilot flow contributes to the total flow giving higher steady state flow efficiency. The dynamic characteristics of the main stage were discussed in an earlier paper. In this paper the aim is to study the influence of the pilot stage of the valve. The bandwidth of this type of valve is often unexpected low. Due to the high bandwidth of the Valvistor element the pilot dynamics is often dominating. In this paper it is shown by measurements the influence of different parts in the pilot valve that limits its bandwidth. Flow forces are used in this valve to compensate the pressure dependency in the flow. It is a common way of design in so called pressure compensated valves. It is discussed in the paper how this flow forces influences the dynamic properties of the pilot valve. The mentioned flow forces interact together with the mechanical spring in the pilot valve. Although the studied valve is just one of many variants of the Valvistor principle, we will investigate it closely due to the interest for this valve among other researchers. One important conclusion is that the inductance of the pilot solenoid is often limiting the bandwidth of the valve as a whole. 

  • 28.
    Eriksson, Björn
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Larsson, Jonas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    A Novel Valve Concept Including the Valvistor Poppet Valve2008In: Ventil : revija za fluidno tehniko in avtomatizacijo, ISSN 1318-7279, Vol. 14, no 5, p. 433-442Article in journal (Other academic)
    Abstract [en]

    These days, energy efficient mobile fluid power systems are of great interest. A mobile system containing several different cylinder drives supplied with a single load sensing pump (LS-pump) has a number of advantages as well as disadvantages. One of the main advantages is the need of only one system pump. This makes the fluid power system compact and cost-effective. A challenge is to keep the hydraulic losses at low level, especially losses at smaller loads. This paper introduces a fail-safe proportional valve element that is based on the Valvistor poppet valve. Due to the demands of flexibility the poppet valve is bi-directional. The valve has an innovative hydro-mechanical layout that makes it fail-safe, unwanted lowering loads, for example, never occur. The new valve includes simple sensors that are suitable for identification of mode switches, e g between normal, differential and regenerative modes. It is also possible to maneuver the system with maintainted velocity control in the case of sensor failure. In a less complex system the concept has benefits as well. For example in systems where fail-safe-bi-directional on/off valves are needed, then without mode sensing capabilities.

  • 29.
    Eriksson, Björn
    et al.
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Palmberg, Jan-Ove
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Individual Metering Fluid Power Systems: Challenges and Opportunities2011In: Proceedings of the Institution of mechanical engineers. Part I, journal of systems and control engineering, ISSN 0959-6518, E-ISSN 2041-3041, Vol. 225, no 12, p. 196-211Article in journal (Refereed)
    Abstract [en]

    A review of recent and current research on individual metering fluid power systems is presented. An overview of different systems and their pros and cons is given. General challenges related to independent metering fluid power systems are discussed. The major choices in the design of these systems are the hardware layout and the control strategy. The evolution of existing independent metering fluid power systems from the 1970s until the present day is also presented.

  • 30.
    Eriksson, Björn
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Modellering och design av Valvistorn2007In: Hydraulikdagar 07,2007, Linköping: Linköpings universitet , 2007Conference paper (Other academic)
    Abstract [sv]

     Detta paper presenterar en modellering av den kända Valvistorventilen samt en ny utvidgning av denna ventil som ger den proportionalegenskaper i två flödesriktningar på ett fail-safe sätt.

  • 31.
    Eriksson, Björn
    et al.
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Rösth, Marcus
    MCD Parker Hannifin AB.
    Palmberg, Jan-Ove
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    A High Energy Efficient Mobile Fluid Power System: Novel System Layout and Measurements2008Conference paper (Other academic)
    Abstract [en]

    This is one of the earliest publications of the proposed energy efficient individual metering system shown in chapter 5, section 5.3.3. This paper introduces the novel system design, which utilizes independent meter-in and meter-out valves. This system design has the potential to increase energy efficiency considerably in a system that consists of a pump  connected to more than one fluid power actuator. The system proposed here is not dependent on pressure transducers for either flow control or mode selection. The main difference between the work presented in this paper and earlier work is the control strategy. The output signal choices in the closed loops are new. Some functionality is kept in hardware to avoid  critical sensor dependency. The presented system uses pressure compensators to achieve desired flows.

  • 32.
    Eriksson, Ola
    et al.
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    Wren, Joakim
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Loyd, Dan
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering. Linköping University, The Institute of Technology.
    A comparison between in vitro studies of protein lesions generated by brain electrodes and finite element model simulations1999In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 37, no 6, p. 737-741Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to develop a finite element model for simulation of the thermal characteristics of brain electrodes and to compare its performances with an in vitro experimental albumin model. Ten lesions were created in albumin using a monopolar electrode connected to a Leksell Neuro Generator and a computer-assisted video system was used to determine the size of the generated lesions. A finite element model was set up of the in vitro experiments using the same thermal properties. With a very simple heat source applied to the finite element model in the proximity of the upper part of the tip, a good agreement (no deviations in width and distance from tip but a deviation in length of −1.6 mm) with the in vitro experiments (width 4.6±0.1 mm and length 7.4±0.1 mm) was achieved when comparing the outline of the lesion. In addition, a gelatinous albumin-model was set up and compared to computer simulations resulting in deviations in width of −0.4 mm, length of −2.2 mm and distance from the tip of −0.1 mm. Hence, the utilisation of finite element model simulations may be a useful complement to in-vitro experiments.

  • 33.
    Filla, Reno
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Alternative system solutions for wheel loaders and other construction equipment2008Conference paper (Other academic)
    Abstract [en]

    Within the Volvo Group there exist long-ranging experiences regarding hybrid propulsions systems for heavy commercial vehicles of the brands Volvo Trucks, Renalt Trucks, Mack Trucks, Nissan Diesel and Volvo Bus. For commercial vehicles like these, hybrid technology is to be regarded seriously and a business case is often given. The search for energy efficient solutions goes on also for construction equipment, and hybrids are everyone's topic. Within Volvo Construction Equipment there is a tradition of researching and developing energy efficient solutions, an example of which was the presentation of a first prototype of a hybrid wheel loader in the beginning of 2008. In this paper the wheel loader will be used as an example for other types of construction machinery. Using a systematic design approach, several more principle design solutions can be found. Reduced fuel consumption by 50% while keeping the performance and productivity at the same level is only possible by considering the complete machine as one system using a holistic approach. 

  • 34.
    Filla, Reno
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Effektivare hjullastare: Hybrider?2007In: Hydraulikdagar 07,2007, Linköping: Linköpings universitet , 2007Conference paper (Other academic)
    Abstract [sv]

    Med allt högre bränslepriser och den tilltagande samhällsdebatten om växthusgaser och klimatförändringar förvånar det inte att även företag utanför personbilsbranschen undersöker alternativa systemlösningar för att minska avgasutsläppen och oljeberoendet. Detta föredrag presenterar Volvo CEs satsning på elhybrider med fokus på hjullastare.

  • 35.
    Garcia-Padron, Ricardo
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology. Univ.,.
    Heat and water transfer for lacquer drying and thermal signatures: modelling, simulation and experiment2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The coupled phenomenon of heat and water transfer is essential in many scientific and industrial problems. This thesis focuses this phenomenon on two areas; lacquer drying and thermal signatures. Simulations of physical phenomena may in some cases replace extensive experimental investigations, which may be complicated and expensive. In other cases simulations may provide means to reduce the number of experiments necessary to perform. In the thesis models, as simple as possible, are used to simulate heat and water transfer. Experiments were made and are compared with the simulations in order to verify the validity of the simplified models.

    In the first part of the thesis the drying of a waterborne lacquer coating used in wood manufacturing industry is investigated. Problems concerning upward water transfer resulting in a specified drying period, and downward water transfer resulting in fibre swelling are addressed. Experiments were made in a full-scale drying plant.

    In the second part of this thesis heat and water transfer in solar radiated sand is investigated. The main purpose of these investigations is to improve the predictions of thermal signatures related to detection of buried objects, e.g. buried land mines. Among several factors, influencing the thermal signatures received by optical systems, water movement in the soil and water evaporation from the surface have been found to be of particular interest. Experiments were made in an indoor test landscape.

    In two related papers two other methods for investigating problems connected to lacquer drying are presented. In the first paper two-way factorial design is used to optimise the drying process of waterborne lacquer coating in a full-scale drying oven. In the second paper the inverse heat conduction problem is used to predict the surface temperature of a particleboard based on measurements inside the board.

  • 36.
    Grante, Christian
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    On design of complex safety critical automotive systems: a semi-automated approach for balancing profit and safety2004Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Design processes for complex safety-critical systems in the automotive industry need to evolve in order to address increasing demands for integration of car functions over common networked infrastructures. New processes must address cost and safety concerns, and at the same time maximize profit. Automation provides a possibility to address these problems in design of complex systems and should thus be utilised. Automation is possibly the only option for handling the increasing technological complexity while still preserving the iterative design procedure that both reduces cost and gives room for design innovations. This thesis proposes a design process supported by novel techniques for semi-automatic safety and reliability analysis. System models are combined with multi-objective optimisation techniques to assist the gradual development of designs that can meet reliability and safety requirements as well as maximise profit within pragmatic development cost constraints. The proposed process relies on tools to automate some aspects of the design that can be automated and thus simplified without loss of the creative input brought to the process by designers. This thesis also presents the background and the necessity for this technical evolution towards network-embedded systems using open distributed architectures for future cars.

  • 37.
    Grante, Christian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Anderson, Johan
    Maskinkonstruktion Tekniska fakuleten i Linköping.
    Safety considerations in optimisation of design specification content2003In: International Conference in Engineering Design ICED03,2003, Stockholm, Sweden: ICED'03 , 2003Conference paper (Refereed)
  • 38.
    Grante, Christian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Andersson, Johan
    Maskinkonstruktion Tekniska fakulteten.
    A method for evaluating functional content in mechatronic systems using optimisation2003In: Research in Engineering Design, ISSN 0934-9839, E-ISSN 1435-6066, Vol. 14, no 4, p. 224-235Article in journal (Other academic)
    Abstract [en]

    This paper presents a method to support designers and product planners in determining the functionalities that should be implemented in a product and those that should not. The proposed method identifies the set of customer functions and technical implementations that maximise the potential product profit. The customer functions represent the functionality of the product, and the technical implementations are the hardware and software components needed to realise these functions. For industrial applications, the numbers of possible combinations of customer functions and technical implementations are extremely large. We present a mathematical framework that handles this problem. Furthermore, optimisation is employed to find the set of customer functions that will maximise profit when subjected to a restricted development budget in order to find the best possible business case. The method was evaluated on an industrial case study of active safety systems performed at Volvo Cars. Based on this case study, the proposed method shows a substantial potential compared to the methods presently used.

  • 39.
    Grante, Christian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Papadopoulos, Y
    Evolving car designs using model-based automated safety analysis and optimisation techniques2004In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. x, no xArticle in journal (Refereed)
  • 40.
    Grante, Christian
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Papadopoulos, Y.
    Techniques and Tools for Automated Safety Analysis & Decision Support for Redundancy Allocation in Automative Systems2003In: International Conference on Computer Software and Applications,2003, Dallas, Texas: IEEE , 2003Conference paper (Other academic)
  • 41.
    Hallander, Ingrid
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    A broad perspective on life cycle considerations in product development2004Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    For products with long life cycles, operational and support costs represent a significant part of the total cost for the product. Moreover, such products frequently tend to be complex and contain a mixture of both mature. stable technology with bng life cycles and new technology with short life cycles. lt is therefore of great interest to industry to determine how to take these factors into consideration in an efficient way during product development.

    Another factor that affects product development for these and other kinds of products with shorter life cycles is interest in taking a wider view of the end-user or customer scenario, for instance by offering support and after sales services for the products. All these interests drive the demand to consider life cycle related issues in product development, not just life cycle cost. This also makes a life cycle perspective interesting for fums that produce products with shorter life cycles than the ones studied here through the opportunity for after market sales and services.

    This research has been explorative, aiming to understand how firms manage to take life cycle related demands into consideration during product development. The aim was to expand from a cost oriented focus to a wider focus, a value oriented focus, here called life cycle value. The dominant question has been "how" life cycle related demands are considered, focusing on barriers to and enablers for this. Equally important has been to determine the implication of life cycle value for different firms and industries and to find out where value is added in product development. A combination of a quantitative and qualitative research approach has been used to collect empirical data.

    One important finding was that there is an interest to deliver a solution to the customer rather than just a product, to consider customer revenue. This adds a new perspective to the implication of life cycle value, moving from a life cycle cost scenario to a life cycle cost versus revenue scenario. The results fom cases were categorized into six main attributes. These attributes were considered to be very influential and important for the ability to take life cycle perspective into account during product development.

    • Holistic Perspective
    • Requirements & Metrics
    • Leadership & Management/Knowledge management
    • Tools & Methods
    • Organizational Factors
    • Enterprise Relationships

    Within each of these attributes, several practices and lessons learned were identified. Some of the results are also worth investigating further in continued research:

    • Requirements formulation and management is considered to be critical. Well defined and clearly stated demands are key to taking life cycle issues into account due to the difficulty of incorporating life cycle related demands into the product. Nonetheless, balancing these demands against others is perceived to be difficult, and there is a clear need for tools, methods or models to support decision-making in this context.
    • The incorporation of new technology and services is another field of interest to industry. Organizational support and planning for technology insertion and new innovations and services into existing products and product lines are needed.
    • The organizational support to balance specialization and integration in a product development context, with a long-term focus
    • The effect of a transfer from delivering a product to delivering product and support services to the organization.
    List of papers
    1. Life cycle value in product development: a case study in the transportation industry
    Open this publication in new window or tab >>Life cycle value in product development: a case study in the transportation industry
    2003 (English)In: DS 31: Proceedings of ICED 03, the 14th International Conference on Engineering Design, Stockholm, Stockholm, Sweden: ICED'03 , 2003, p. 417-418Conference paper, Published paper (Other academic)
    Abstract [en]

    Several factors prevent enterprises from having a holistic perspective during product development. Important aspects include increased product complexity and significant uncertainty with regard to technology. For products with a long life cycle this is extremely important since development and life cycle costs are high. The combination of complexity of system design and the limits of individual human comprehension typically make it difficult to envision a best value solution.

    In an attempt to encircle a more holistic perspective of value, the concept of Life Cycle Value has evolved within the Lean Aerospace Initiative, LAI. The implication of this is development of products incorporating life cycle and long-term focus including cost and performance and reliability factors. A similar perspective has evolved within the Lean Aircraft Research Program, LARP, in Sweden.

    This paper contributes a new study of how life cycle aspects are taken into consideration in a large corporation in the transportation industry. The purpose of the research was to examine relative contributions to product development and determine factors that significantly promote the ability to consider the life cycle perspective. The results will be discussed with respect to tools, methods, requirements, metrics, leadership and other organizational factors, innovation, and enterprise relationships.

    Place, publisher, year, edition, pages
    Stockholm, Sweden: ICED'03, 2003
    Keywords
    Life cycle, value, product development, transportation industry
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-36398 (URN)31246 (Local ID)1-904670-00-8 (ISBN)31246 (Archive number)31246 (OAI)
    Conference
    ICED 03, the 14th International Conference on Engineering Design, Stockholm
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-12-03
    2. Lifecycle value framework for tactical aircraft product development
    Open this publication in new window or tab >>Lifecycle value framework for tactical aircraft product development
    2001 (English)Conference paper, Published paper (Other academic)
    Abstract [en]

    Due to a dramatic reduction in defense procurement, the benchmark for developing new defense systems today is performance at an affordable cost. In an attempt to encircle a more holistic perspective of value, lifecycle value has evolved as a concept within the Lean Aerospace Initiative, LAI. The implication of this is development of products incorporating lifecycle and long-term focus instead of a shortsighted cost cutting focus. The interest to reduce total cost of ownership while still improving performance, availability, and sustainability, other dimensions taken into account within the lifecycle value approach, falls well within this context. Several factors prevent enterprises from having a holistic perspective during product development. Some important aspects are increased complexity of the products and significant technological uncertainty. The combination of complexity in system design and the limits of individual human comprehension typically prevent a best value solution to be envisioned. The purpose of this research was to examine relative contributions in product development and determine factors that significantly promote abilities to consider and achieve lifecycle value. This paper contributes a maturity matrix based on important practices and lessons learned through extensive interview based case studies of three tactical aircraft programs, including experiences from more than 100 interviews.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-102199 (URN)
    Conference
    2001 Eleventh Annual International Symposium, Melbourne, Australia, 1-5 July 2001
    Available from: 2013-12-03 Created: 2013-12-03 Last updated: 2013-12-03
  • 42.
    Hallander, Ingrid
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Life cycle value in product development: a case study in the transportation industry2003In: DS 31: Proceedings of ICED 03, the 14th International Conference on Engineering Design, Stockholm, Stockholm, Sweden: ICED'03 , 2003, p. 417-418Conference paper (Other academic)
    Abstract [en]

    Several factors prevent enterprises from having a holistic perspective during product development. Important aspects include increased product complexity and significant uncertainty with regard to technology. For products with a long life cycle this is extremely important since development and life cycle costs are high. The combination of complexity of system design and the limits of individual human comprehension typically make it difficult to envision a best value solution.

    In an attempt to encircle a more holistic perspective of value, the concept of Life Cycle Value has evolved within the Lean Aerospace Initiative, LAI. The implication of this is development of products incorporating life cycle and long-term focus including cost and performance and reliability factors. A similar perspective has evolved within the Lean Aircraft Research Program, LARP, in Sweden.

    This paper contributes a new study of how life cycle aspects are taken into consideration in a large corporation in the transportation industry. The purpose of the research was to examine relative contributions to product development and determine factors that significantly promote the ability to consider the life cycle perspective. The results will be discussed with respect to tools, methods, requirements, metrics, leadership and other organizational factors, innovation, and enterprise relationships.

  • 43.
    Heybroek, Kim
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Pumpstyrd arbetshydraulik i hjullastare2007Conference paper (Other academic)
  • 44.
    Heybroek, Kim
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Larsson, Jonas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Open Circuit Solution for Pump Controlled Actuators2006In: 4th FPNI - PhD Symposium Sarasota 2006, Sarasota: Coastal Printing , 2006, Vol. 1, p. 27-40Conference paper (Refereed)
    Abstract [en]

    Mobile machines of today often contain hydraulic valve controlled actuator loads in an open loop circuit. For the purpose of saving energy, the constant pressure pumps have in the past often been replaced by load sensing pumps and valves. In mobile applications, they have significantly reduced the energy consumption. Stricter environmental demands and rapidly increased fuel cost require an even lower consumption. By analyzing a typical working cycle of a construction machine, the possibility of energy recovery has been identified. The analyse confirms the importance of minimizing the metering losses. In a load-sensing valve solution these losses arise as a result of the unequal drive pressure levels. By adopting a displacement controlled regenerative solution, a significantly higher level of efficiancy can be obtained. 

  • 45.
    Johansson, Andreas
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Design principles for noise reduction in hydraulic piston pumps: simulation, optimisation and experimental verification2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Noise reduction in hydmulic systems has been an important research topic for several decades. In recent years, industry's interest in the area has grown dramatically. The reason is new national and international requirements and legislation governing working conditions. As a consequence of this, considerable reduction of noise from machinery in general has been achieved. The reduction of noise in hydraulic systems, however, has not gained from the same considerable progress, which implies that hydraulic noise has become perceptible through the surrounding machinery noise. Not only has noise reduction of hydraulic systems become increasingly important, it has also become more difficult because of the ever-increasing working pressure level, which is highly correlated to noise and vibration.

    Noise in hydraulic systems is created mainly by the hydrostatic pump and motor, working with large pressure differences in the suction and delivery ports. Being exclusively of displacement type, the hydrostatic machine creates substantial flow pulsations in both the discharge and suction ports. The flow pulsations give rise to system pressure pulsations, which in turn transform into vibration and audible noise. Excessive pulsating piston forces and bending moments due to the large pressure difference between the machine's discharge and suction ports also contribute to noise and vibration.

    To obtain satisfactory noise reduction, there is a need for effective and reliable design tools and design methods. This thesis concerns simulation, optimisation and experimental verification of axial piston pump design for noise reduction. Much of the work relates to the different origins of noise and how to formulate objective functions that simultaneously reflects different aspects of noise reduction. New and conventional design features are examined both theoretically and experimentally. One novel and promising design feature thoroughly investigated in this thesis is the so-called crossangle that aims to provide low noise in variable displacement machines. Different measurement approaches are employed for experimental verification. It is shown that conventional methods are often inadequate for measuring source flow in variable displacement units due to the complex outlet channel. A new method, referred to as the Source admittance method, is proposed.

    List of papers
    1. Dynamic analysis of shuttle technique performance applied on hydraulic transformer
    Open this publication in new window or tab >>Dynamic analysis of shuttle technique performance applied on hydraulic transformer
    2002 (English)In: Proc. of the 3rd International Fluid Power Conference (IFK'3): Volume 2, Fluid Power Focused on Applications, 2002, p. 249-261Conference paper, Published paper (Refereed)
    Abstract [en]

    As an alternative to traditional valve coutrol, hydraulic transformation has proved to be an attactive approach from an efficiency point of view. According to the Innas1 concept, hydraulic transformation is achicved using a modified displacement machine design. In order to realise the transformation using only one displacement machine, it is necessary to use a valve plate containing three kidney slots for the three supply lines: supply, load and tank. By displacing the valve plate, pressure/flow ratio can be transformed, ideally with preserved efficiency. When using three kidney slots together with a traditional displacement machine with two dead centres, the commutation between two subsequent kidneys will occur while the piston is moving. This will result in pre-compression or decompression of the cylinder fiuid, with severe pressure peaks as a consequence. Besides noise and vibration, these pressure peaks will decrease the total efficiency considerably. Also driving shaft torque variations will appear, which will affect the rotational movement by speed fluctuations. In order to minimise the pressure peaks during valving land passages. small pistons between pairs of cylinders in the barrel are introduced. This is referred to as shuttle technique. Using these shuttles, excess of cylinder fluid during commutation can be transferred to adjacent cylinders, and thus prevent cylinder pressure peaks from appearing.

    It is very difficult to measure the internal states of the shuttle in an operating transformer. By using computer simulation techniques, detailed analyses of the internal workings of the shuttle can be performed. In this work, a detailed description of the dynamic behaviour of the shuttle is given. Advantages and disadvantages of the technique are discussed.

    1 Innas BV, Netherlands

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-85958 (URN)978-3-82-659900-2 (ISBN)
    Conference
    3rd International Fluid Power Conference (IFK '3), March 5th and 6th 2002, Aachen, Germany
    Available from: 2012-12-05 Created: 2012-12-05 Last updated: 2012-12-05
    2. The importance of suction port timing in axial piston pumps
    Open this publication in new window or tab >>The importance of suction port timing in axial piston pumps
    2005 (English)In: Proc. of the 9th Scandinavian International Conference on Fluid Power, (SICFP '05) / [ed] Palmberg, Jan-Ove, Linköping: Linköping Universitet, Institute of Technology , 2005, p. 32-Conference paper, Published paper (Refereed)
    Abstract [en]

    Hydraulic pumps give rise to flow ripples in both discharge and suction lines. The flow pulsations transform into pressure ripples which in turn create vibration and audible noise. With a careful design of the valve plate timing, flow ripple can be minimised. Much research is dedicated to the design of discharge port commutation, i.e. the pre-compression dynamics. This work, however, focuses on the suction port timing.

    Besides controlling flow ripple in the tank line, suction port timing influences fluid air-release which in turn has substantial impact on the effective system bulk modulus. lncreased air-release implies reduced cylinder filling performance, reduced volumetric efficiency and increased flow pulsations. In addition, the cylinder decompression at suction port commutation directly affects the resulting piston force profile and internal bending moments which largely contributes to pump housing vibration and noise emissions. Thus. the design of the suction port timing is crucial for flow ripples, air-release, pump housing vibrations and direct noise emissions from the pump. Also. the risk for cavitation is controlled.

    This paper also investigates the efficiency of an Air Drain Groove, ADC, as an alternative to conventional pressure relief grooves at suction port commutation. Correctly designed, the ADG reduces the cylinder pressure at piston top dead centre by bleeding off a very small amount of cylinder fluid to the housing drain. The air-release hereby obtained is directed into the pump casing instead of into the suction port and should thereby give rise to a higher system bulk modulus. Experiments reveal, however, that the efficiency of the ADC is not preferable to a conventional pressure relief groove, neither regarding air-release, nor noise emissions.

    Place, publisher, year, edition, pages
    Linköping: Linköping Universitet, Institute of Technology, 2005
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-31417 (URN)17195 (Local ID)9185457965 (ISBN)9789185457960 (ISBN)17195 (Archive number)17195 (OAI)
    Conference
    The 9th International Conference on Fluid Powers, SICFP'05, July 1-3, Linköping, Sweden
    Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-12-05
    3. Optimal design of the cross-angle for pulsation reduction in variable displacement pumps
    Open this publication in new window or tab >>Optimal design of the cross-angle for pulsation reduction in variable displacement pumps
    2002 (English)In: Power Transmission and Motion Control: PTMC 2002 / [ed] Burrows, C. R. and Edge, K. A, Wiley-Blackwell, 2002, p. 319-333Conference paper, Published paper (Refereed)
    Abstract [en]

    The cross-angle, illustrated in this paper, is a fixed displacement angle around the axis perpendicular to the normal trunnion axis. With the cross-angle, the traditional piston dead centres will change as the normal displacement angle is varied. The result is a behaviour similar to thal of the revolving valve plate technique. but without any movable parts. When the cross-angle is used in a constant pressure system with a variable pump, the desired dead centre for optimal pro-compression coincides with the obtained dead centre for a wide range of displacement angles. This implies that when the cross-angle is used, the flow ripple becomes less sensitive to changes in displacement angles. The cross-angle does not constitute an alternative to the different design features developed, but rather as complement for preserved effective flow ripple reduction over a wide range of displacement angles.

    ln this study. simulation-based optimisations, employing non-gradient optimisation techniques such as genetic algorithms and the Complex method, are used in order to find the optimal cross-angle for a variable displacement pump. Furthermore. with the help of optimisation, the trade-offs between attributes such as low flow ripples, avoidance of large cylinder pressure-peaks, and cavitation have been studied. Increased insight is thereby gained into what possibilities the cross-angle offers regarding reduction of pump ripple for a variable displacement pump.

    Place, publisher, year, edition, pages
    Wiley-Blackwell, 2002
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-36697 (URN)32178 (Local ID)1860583792 (ISBN)978-1860583797 (ISBN)32178 (Archive number)32178 (OAI)
    Conference
    Bath Workshop on Power Transmission and Motion Control (PTMC 2002), September 2002, Bath, UK
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2012-12-05
    4. Influence from the cross-angle on piston forces and bending moments in variable hydraulic piston pumps
    Open this publication in new window or tab >>Influence from the cross-angle on piston forces and bending moments in variable hydraulic piston pumps
    2003 (English)Report (Other academic)
    Abstract [en]

    By implementing an additional incline (cross-angle) of the swash plate of an axial piston pump, in the direction perpendicular to the traditional displacement direction, the piston dead-centre points will move as the displacement angle varies. The cross-angle is fixed and normally very small (1-4°). If designed correctly, the movement of the dead-centre points achieved by using a cross-angle coincides with the dead centres desired for optimal cylinder pre-compression and decompression for all displacement angles. It has in earlier works been described how the cross-angle enables minimisation of discharge and inlet peak-to-peak flow ripple for all displacement angles simultaneously. In this paper, it is also investigated how the piston forces and the bending moments are influenced.

    The cross-angle is designed using simulation-based multi-objective optimisation. It is investigated how objective functions can be made up from peak-to-peak values as well as from frequency spectrum of signals. The trade-offs between the conflicting objectives considered are elucidated by using the concept of Pareto optimality. The result from such a Pareto optimisation is not one optimal solution, but a set of optimal solutions. With the technique presented, it is thus possible to investigate an optimal value for the cross-angle that the most beneficial impact on all factors that influence the noise level of the pump.

    Series
    LITH-IKP-R, ISSN 0281-5001 ; 1391
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-85981 (URN)
    Available from: 2012-12-05 Created: 2012-12-05 Last updated: 2012-12-05
    5. Experimental verification of cross-angle for noise reduction in hydraulic piston pumps
    Open this publication in new window or tab >>Experimental verification of cross-angle for noise reduction in hydraulic piston pumps
    2007 (English)In: Proceedings of the Institution of mechanical engineers. Part I, journal of systems and control engineering, ISSN 0959-6518, E-ISSN 2041-3041, Vol. 221, no 3, p. 321-330Article in journal (Refereed) Published
    Abstract [en]

    One of the most important drawbacks with hydraulic systems is noise and vibration, which mainly originate from the hydrostatic pump. A great number of noise-reducing design features have been developed, but they are all, to a greater or lesser extent, sensitive to variations in operational conditions. The present paper is concerned with optimal design and experimental verification of the cross-angle in an axial piston pump. The cross-angle is a small fixed incline of the swash plate in the direction that is perpendicular to the traditional displacement direction. It enables effective noise reduction throughout the whole range of displacement angles.

    Simulation-based optimization is used to design a pump with optimal cross-angle and a matching valve plate. The design is manufactured and experimentally evaluated. Source flow measurements using the two-microphone method show good agreement between simulation and experiments, which verifies the applicability of the simulation model used. The benefits from using the cross-angle are then verified by comparing it with a pump with a traditional swash plate design, i.e. without the cross-angle. Both source flow measurements and sound level measurements in an anechoic chamber show good improvements from using the cross-angle.

    Keywords
    Cross-angle, Noise, Optimization, Simulation, Source flow
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-49333 (URN)10.1243/09596518JSCE208 (DOI)
    Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
  • 46.
    Johansson, Andreas
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Reduktion av pulsationer vid pumpkonstruktion2004In: Hydraulikdagarna,2003, Linköping, Sweden: Linköpings universitet , 2004Conference paper (Refereed)
  • 47.
    Johansson, Andreas
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Blackman, B.
    Prediction of Pump Dynamics Utilizing Computer Simulation Model - with Special Reference to Noise Reduction2000In: SAE International Off Highway Conference,2000, 2000Conference paper (Other academic)
  • 48.
    Johansson, Björn
    Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems. Linköping University, The Institute of Technology.
    Model management for computational system design2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Computational system design is as an area within engineering design that to a large extent is based on simulation models together with tools and methods for analysis and design. This area is becoming increasingly important for providing information to designers and decision makers early in the design process, and enabling qualitative decisions to be made.

    Engineering design in general is today carried out in a collaborative, distributed, and at the same time competitive fashion where complex products are to a large extent assemblies of subsystems developed by several suppliers. It is important that models and computational design methods can be managed efficiently in such design projects, where models can be exchanged and integrated, design data managed, and proprietary information protected.

    In this thesis, a framework is presented which facilitates management of simulation models, design data, and computational processes. The framework emphasizes a model-centric view, which means that models are represented on a high level of abstraction, without tool-specific information.

    By defining models using the extensible Markup Language, XML, it is a straightforward matter to apply generic operators to the model and transform the model to several tool-specific implementations.

    The framework also enables integration of distributed computational resources. By implementing standards for so-called web service technology, simulation modules are published as remote model services, enabling partners in a project to deploy and invoke simulation models as black boxes. By publishing an interface to the model in a standardized format, and keeping the model at its original location, the model can be accessed and integrated without revealing proprietary information about the model. This approach also facilitates integration of existing so-called legacy tools and models.

    A data management approach is also presented where design data and the computational processes are handled. Variability measures for the design data are included, enabling probabilistic methodologies and design optimization to be applied in a straight-forward way. The computational

    design process is formalized by representing the process as an executable process description enabling direct implementation, modification, and exchange of processes.

    In the last part of the thesis, a number of evaluation examples are presented where some of the tools and concepts of this thesis are illustrated. These examples are mainly from the area of aircraft system design.

  • 49.
    Johansson, Björn
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Jouannet, Christopher
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Krus, Petter
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Machine Design.
    Distributed aircraft analysis using web service technology2004In: The World Aviation Congress,2003, Montreal, Canada: World Aviation Congress , 2004Conference paper (Refereed)
  • 50.
    Johansson, Björn
    et al.
    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.
    Palmberg, Jan-Ove
    Linköping University, The Institute of Technology. Linköping University, Department of Mechanical Engineering, Fluid and Mechanical Engineering Systems.
    Distrubuted Modelling: Object Oriented Implementation with Modelica and Transmission Lines2000In: Bath Workshop on Power Transmission and Motion Control, PTMC 2000,2000, 2000Conference paper (Other academic)
    Abstract [en]

      

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