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  • 1.
    Casselgren, Johan
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Engström, Niclas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Rosendahl, Sara
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Investigation of ice surface change during vehicle testing2014In: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 9, no 2, p. 137-150Article in journal (Refereed)
    Abstract [en]

    Today, there are a lot of vehicles and tyre testing carried out on lake ice surfaces. Thus, it is important to have knowledge about parameters that affect roadgrip. The thesis within this paper is that the liquid like layer which appears due to increasing temperature can be reduced by manipulating the ice roughness. This in turn should decrease the temperature dependence of the roadgrip in temperatures around 0°C. In order to investigate this, measurements of temperature, surface roughness and hardness and roadgrip were performed on three outdoor ice surfaces using an IR thermometer, an optical sensor with three IR-diodes, a steel ball drop indentation test and an RT3 curve, respectively. Additional ice roughness measurements were also made on two tempered ice surfaces in an ice hall. Results show a clear connection between ice temperature and roadgrip, unfortunately the created ice roughness was too small to influence the change in roadgrip

  • 2. Engström, Niclas
    Activity: Transportforum 20092009Conference paper (Other (popular science, discussion, etc.))
  • 3.
    Engström, Niclas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Andrén, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Direct low lateral slip roadgrip measurement compared with surface reflection of three laser beams2011Conference paper (Other academic)
  • 4.
    Engström, Niclas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Andrén, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Larsson, Roland
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Discrepancies between longitudinal high slip and lateral low slip friction measurements on prepared ice surfaces: Paper and poster2009In: Compendium of papers DVD, TRB 88th annual meeting: January 11 - 15, 2009, Washington, D.C, Washington, DC: TRB , 2009, p. 1-13Conference paper (Refereed)
    Abstract [en]

    The Swedish road administration requested that an independent organization facilitate friction tests with several types of friction measuring devices. These tests were done on the following three surfaces: macro rough and micro smooth ice, macro- and micro smooth ice and macroand micro rough ice. The objective was to evaluate lateral low slip measuring devices against traditional longitudinal high slip devices. This was done by evaluating how they measure road grip, i.e. friction differences between road surfaces and the measuring tire. Tests were performed on Lake Kakel near Arjeplog, northern Sweden on March 18th, 2008. Weather conditions were stable with ice temperatures between -4°C (24.8°F) and -3°C (26.6°F). Tests showed that changes on the ice surfaces were readily detected with all four of the lateral low slip friction measurement devices and the two longitudinal high slip devices. Friction resolutions were higher with low lateral slip devices compared to high longitudinal slip devices. The tires on the devices were of different types and are the main reason for the difference in friction resolution. One major difference was detected; the lateral low slip method measured higher friction between its regular winter tire and the macro rough, micro smooth surfacecompared to the friction on the macro- and micro rough ice. Longitudinal high slip devices measured higher friction between its industrial friction tire and macro- and micro rough ice. Capacity to measure friction in curves was only displayed by the high longitudinal slip devices.

  • 5.
    Engström, Niclas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Andrén, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Stop distances for ten studless winter tires2009Report (Other academic)
    Abstract [sv]

    Denna rapport innehåller stoppsträckor för tio omgångar dubbfria vinterdäck. Arbetets huvudmål är att kunna skapa en grund för vinterdäcksklassificering. Så småning om skall traffikanter kunna få relevant information om olika däckens förmåga att skapa tillräckligt väggrepp på farliga vinterväglag. Vägverket ser ett ökat behov av kunskap då dubbdäcksanvändandet kommer att minskas i framtiden.

  • 6.
    Engström, Niclas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Andrén, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Nybacka, Mikael
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Road grip test in Arjeplog2008Report (Other academic)
    Abstract [en]

    The Swedish road administration sees a need to improve the road grip estimation capacity for the Swedish road system. The challenge is to find methods to measure road grip fast and reliable. There where six different system types at the tests in Arjeplog, three continuous, two system measuring road grip through deceleration and one system based on GPS and accelerometers. Two system types used air craft runway tires. The other systems used either studded winter tires or friction winter tires. Test runs where performed and road grip where recorded for three different surface types, old system 2000 ice, polished ice and new system 2000 ice. Weather data was collected during the three days. It is clear that all systems can detect changes in road grip. It is clear that continuous systems hold an information advantage over the sequence oriented systems. For measurements of road grip on winter roads, we recommend that rubber compounds adapted for cold conditions are used, as the resolution of the road grip measurement where better. In extreme condition like on polished ice, studded winter tires increase the road grip significantly.

  • 7.
    Engström, Niclas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.
    Larsson, Roland
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Andrén, Henrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Fransson, Lennart
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Direct low lateral slip roadgrip measurement compared with surface reflection of three laser beams2010Conference paper (Refereed)
    Abstract [en]

    Road grip on roads depend on many factors and different techniques are available to estimate available road grip. To ensure that entrepreneurs have successfully restored the road grip to an acceptable level both entrepreneurs and road keepers need tools to evaluate present road grip. Information about road grip can also be utilized directly in a vehicle if available, for systems such as ABS, traction control, etc. To evaluate a non-contact method based on three laser beams with different frequency this equipment was mounted on a car equipped with a fifth wheel behind the car. The wheel is angled about 1.5 degrees compared with the centreline of travel. A force sensor in the hub measures forces acting on a standard winter tire also mounted to the hub, this is considered to be one measurement of road grip. The main reason is to see how well one can estimate road grip with a low cost non contact device made with Laser beams in combination with a photodiode.

  • 8.
    Fredriksson, Håkan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Engström, Niclas
    Ash, Jeremy
    Anthony Best Dynamics Ltd.
    Winter test of ABD steering robot2013Report (Other academic)
    Abstract [en]

    This report highlights the use of a steering robot with path-following for car testing in winter conditions. The steering robot was provided from Anthony Best Dynamics. Experiments have been made with a couple of commonly used test sequences (lane change, dual lane change, constant radius circle, handling), the result from these test are shown and discussed. The path-following algorithm gives steering commands to the car (replace the human driver), these commands affect how the car will move; hence, the car performance is affected by the behaviour of the path-following algorithm. The settings of the path-following algorithm greatly affect the car response in different situations. This is especially noticeable when the car starts to slide, a situation common when driving on a slippery winter road. The main focus for this report is to describe what happens when you push the path-following system to, and beyond, the physical limitations concerning road grip and vehicle speed. A theoretical analysis of the path-following algorithm and how it reacts on large lateral errors and high sideslip angles was done. As shown in the results, the evaluated path-following test sequences in general did work out well. Some characteristics of the algorithm, especially noticeable when driving in winter condition, were found and discussed. The overall impression is that the ABD steering robot with path-following can indeed be useful for repetitive test in winter conditions with bad road grip.

  • 9.
    Fredriksson, Håkan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    van Deventer, Jan
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Engström, Niclas
    Ash, Jeremy
    Anthony Best Dynamics Ltd.
    Automotive winter testing with path-following steering robot2015In: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 10, no 1, p. 29-52Article in journal (Refereed)
    Abstract [en]

    When testing modern active safety systems on cars, it is essential to test vehicle response to steering inputs. This paper highlights the use of a path-following steering robot for repetitive car testing in winter conditions. Experiments have been made with commonly used test sequences, e.g., lane-change, double lane-change, constant radius circle, and handling circuit. The steering input from the human driver is replaced by a steering robot and a path-following algorithm. The main focus for this paper is to describe what happens when one pushes the path-following system to, and beyond, the physical limitations of road grip when cornering at high vehicle speed. It shows that, with an appropriate tuning of the path-following parameters, the system performs predictably and satisfactorily. The overall conclusion is that a path-following steering robot is indeed useful for repetitive test in winter conditions with poor road grip.

  • 10. Nybacka, Mikael
    et al.
    Larsson, Tobias
    Jeppsson, Peter
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Product and Production Development.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Karlsson, Lennart
    Rantatalo, Matti
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Lindgren, Per
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Andren, Henrik
    Engström, Niclas
    Larsson, Roland
    Fransson, Lennart
    Hyyppä, Kalevi
    Fredriksson, Håkan
    Eriksson, Johan
    van Deventer, Jan
    Tingvall, Bror
    Project: CASTT - Centre for Automotive Systems Technologies and Testing2007Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Through the Centre for Automotive Systems Technologies and Testing, Luleå University of Technology aims to first of all support automotive winter testing in Northern Sweden. This means to support the local automotive test entrepreneurs and through them their customers: the car manufacturers and their suppliers. To succeed in this task, the center relies on the university's areas of leading research and most importantly on the cooperation between those areas.

1 - 10 of 10
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