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  • 51.
    Sikström, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Ericsson, Mikael
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Niklasson, Kjell
    University West, Department of Engineering Science, Division of Process and Product Development.
    Tools for simulation based fixture design to reduce deformation in advanced fusion welding2008In: Intelligent Robotics and ApplicationsLecture Notes in Computer Science Volume 5315,  2008: First International Conference, ICIRA 2008 Wuhan, China, October 15-17, 2008 Proceedings, Part II / [ed] Youlun Xioun, Springer, 2008, Vol. 5315 LNAI, no PART 2, p. 398-407Conference paper (Refereed)
    Abstract [en]

    The traditional fusion welding and fixture simulations are performed using advanced finite element simulation tools, commonly used are e.g. MSC.Marc, ANSYS, ABACUS and COMSOL Multiphysics. These simulations are made one at a time and separately due to heavy calculation load for each case. Such an approach does not give a full description of the integrated work piece and fixture behaviour. We propose a strategy to decrease the computational time and solve the problem accurately enough for industrial needs. Focus of the simulation result is on residual deformation. The work piece is a simplified component composed by metal sheets, and rigid and loose clamping was investigated. Simulation results give the size of forces and deformations in the clamped edge. Deformation measurements are performed using 3D-scanning of the work piece after cooling and released from fixture, same situation as in the FE-simulations. The proposed strategy has shown to be useful and is industrially competitive due to reduced engineering manpower, computation time, and need for practical experiments. The strategy is to use full off-line programming where computer aided robotics for weld sequencies is integrated with finite element modelling in order to obtain weld parameters and fixture design.

  • 52.
    Sikström, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Nilsen, Morgan
    University West, Department of Engineering Science, Division of Automation Systems.
    Eriksson, Ingemar
    GKN Aerospace, Trollhättan, Sweden.
    Optical Methods for In-Process Monitoring of Laser Beam Welding2014In: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-9Conference paper (Refereed)
    Abstract [en]

    This paper addresses the issue of evaluating and selecting optical sensors to be integrated with a 1μm laser beam welding system. The method used for this evaluation is mainly a survey of relevant research litterature. The result of this work is a matrix showing the different methods and distinct features related to relevant process conditions that can be estimated or detected with respective methods. This evaluation also includes considerations on the required sensor bandwidth in relation to inertia and time constants in the physical process.

  • 53.
    Soron, Mikael
    et al.
    ESAB Welding AB .
    De Backer, Jeroen
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Process and Product Development.
    Ilar, Torbjörn
    University West, Department of Engineering Science, Division of Production Engineering.
    A local model for online path corrections in friction stir welding2010In: INTERNATIONAL CONFERENCE ON SCIENTIFIC AND TECHNICAL ADVANCES ON FRICTION STIR WELDING AND PROCESSING. Program.http://www.polytech-lille.fr/IMG/pdf/program.pdf, 2010Conference paper (Refereed)
    Abstract [en]

    Friction stir welding (FSW) has always been associated with high forces and rigid machines Today’s trends towards joining of more complex structures in e.g. the automotive and aerospace industry, the applications require machinery with increased dexterity and flexibility, which cannot be achieved with the traditional FSW systems. But the introduction of more flexible machines, with more complex workspace capacity, will lead to undesired tool path deviations and in worst case a weld seam with inferior quality. In this study an industrial robot system is used to emphasise the need to compensate for the deviations caused by the high lateral forces resulting from the FSW process. A local model to compensate for such deviations is implemented, evaluated and compared to uncompensate welds in terms of quality and reliability.

  • 54.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    A Simulation-Based Optimisation Method for PLC Systems2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Tuning of process parameters such as time constants, cam values, velocities and robot paths, in order to increase capacity utilisation, is today a challenging manual on-line task in many automated manufacturing systems. On-line methods interfere with production and will cause unwanted downtime, which indeed reduces capacity utilisation. The literature offers virtual manufacturing and simulation-based optimisation as an approach, but without handling time-synchronised control functions, e.g. motion and feedback control.

    This thesis presents a simulation-based optimisation method for PLC systems, able to handle time-synchronised control functions. A programmable logic controller (PLC) is a commonly used type of industrial control system that is capable of handling all control functions in a manufacturing system. The approach presented in this thesis is, however, independent of the type of control systems used. Hence, PLC is used as a general name for all control systems, managing all discrete event, continuous feedback, motion, supervisory, as well as safety control functions.

    A generic simulation-based method for tuning of process parameters has been formulated.  Various goals are attainable by a multi-criteria optimisation approach. The idea is to use a time-synchronised hardware-in-the-loop simulation including real PLCs. By this approach, the method provides a distinct advantage as it involves all complex control functions by using the real PLC code. An additional benefit is that all tuned process parameters can be directly transferred to the PLCs in the manufacturing plant.

    To achieve a feasible simulation-based optimisation method for PLC systems, a new Combined Lipschitzian and Simplex (CoLiS) optimisation algorithm has been established. Complex control functions in industrial manufacturing systems cause conditions such as highly non-linear functions with multiple local optima, a considerable number of parameters and long evaluation times. All these conditions are managed by the non-gradient global CoLiS algorithm. The CoLiS algorithm starts with a global search and then switches over to local convergence. Additionally, all local optima determined during the global search are selected and then constitute starting points in separate local optimisation instances.

    To verify the formulated method’s suitability in industrial applications, and the effectiveness of the new CoLiS algorithm, an optimisation case study has been performed. Improved production performance, both in terms of increased production rate and smoother robot motions, was reached in an automotive sheet-metal press line.

  • 55.
    Svensson, Bo
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Optimisation of Manufacturing Systems Using Time Synchronised Simulation2010Licentiate thesis, comprehensive summary (Other academic)
  • 56.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Off-Line Parameter Tuning of a Sheet-Metal Press Line2011In: The 4th International Swedish Production Symposium, Lund: Swedish Production Academy , 2011, p. 459-466Conference paper (Refereed)
    Abstract [en]

    Anautomotive sheet-metal press line is an excellent example of an automatedmanufacturing system with time dependent complex control functions. The PLCcontrol functions include not only discrete events and supervisory control, butalso analogue feedback and motion control. Furthermore, most press line tuningmethods today are on-line and highly empirical, depending on individualoperators. Thus, there is a need of an objective off-line parameter tuningmethod. This paper presents an off-line parameter tuning of an automotivesheet-metal press line. Improved production performances have been reached,both in terms of increased production rate and smoother robot motions, comparedto today’s industrial on-line method. Two suitable optimisation algorithms havebeen implemented and evaluated. The challenge is to handle highly non-linearfunctions, considerable number of parameters, and long evaluation times in thesimulation. The utilised off-line method is a combination of simulation basedoptimisation and time synchronised hardware-in-the-loop simulation, i.e. avirtual manufacturing system including real PLCs. This method provides adistinct advantage, since it describes all complex control functions byexecuting the same PLC control code used in the manufacturing plant. A furtherbenefit is that all tuned process parameters can be directly transferred to themanufacturing plant.

  • 57.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    A Virtual Real-Time Model for Control Software Development: applied on a Sheet-Metal Press Line2005In: Industrial Simulation Conference 2005 / [ed] Jörg Kruger, Alexei Lisounkin, Gerhard Schreck, 2005, p. 119-123Conference paper (Refereed)
  • 58.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering. University West, Department of Engineering Science, Division of Production Systems.
    Off-Line Optimisation of Complex Automated Production Lines: Applied on a Sheet-Metal Press Line2007In: Proceedings of the 2007 IEEE International Symposium on Assembly and Manufacturing, IEEE , 2007, p. 82-87Conference paper (Refereed)
    Abstract [en]

    This paper presents a successful off-line

    optimisation case study of a sheet-metal press line for the

    automotive industry. The proposed off-line optimisation

    method results not only in increased production rate but also in

    obtaining smoother material handling motions. The off-line

    optimisation method contains two parts. The first part is a

    parameter study, combining factorial design with production

    line simulation including emulated control systems and

    resulting in a simplified performance model based on multiple

    linear regression. The second part is an optimisation on the

    simplified performance model using the Nelder Mead simplex

    method aiming at production optimisation. Due to the

    complexity in a modern production line, it is not possible to

    create a useful model representation of the entire control

    system code/function. Therefore, the proposed optimisation

    method is based on using production line simulation including

    emulated control systems with the real IEC 61131-3 control

    code. Our approach in this work is a parameter variation

    strategy for optimisation, i.e. adjusting the control system

    parameters in the same way as the line operators do, and not

    changing any control strategy.

  • 59.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering. University West, Department of Engineering Science, Division of Production Systems.
    Simulation based optimization of a sheet-metal press line2009In: IEEE Conference on Emerging Technologies & Factory Automation, ETFA 2009, 2009, p. 1-8Conference paper (Refereed)
    Abstract [en]

    An off-line optimization of a sheet-metal press line is performed with improved production performances, both in terms of increased production rate and smoother robot motions. Smooth motions prevent the sheet-metal to slide out of position or even fall out, thereby causing lengthy down times. The simulation based method use a process optimizer connected to a time synchronized virtual manufacturing model including real industrial control systems, e.g. PLC. The key benefit herein is that all tuned control system parameters can be directly downloaded to the real press line without any post-processing or transformations. The challenge to find suitable optimization algorithms for a press line that handle highly nonlinear, discontinuous functions; considerable number of parameters; and long evaluation times is reached.

  • 60.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering. University West, Department of Engineering Science, Division of Production Systems.
    Time-synchronised hardware-in-the-loop simulation - Applied to sheet-metal press optimisation2012In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 20, no 8, p. 792-804Article in journal (Refereed)
    Abstract [en]

    This paper presents an off-line process parameter tuning method, focussing on complex control functions for automated manufacturing systems. The proposed method is based on a combination of simulation-based optimisation and time-synchronised hardware-in-the-loop simulation. Real indus- trial control systems, e.g., PLCs, are included in the simulation, executing the unchanged control code from the manufacturing plant. This approach allows all plant control functions to be included, even time-critical feedback loops and vendor secret blocks such as motion control. Consequently, the method suggested manages the problems identified in previously presented simulation-based approaches. Furthermore, a case study of an automotive sheet-metal press line has been performed to verify the proposed method, with successful results.

  • 61.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Virtual Real-Time Model: a Tool for Increased Production2005In: Mekatronikmöte 2005, 2005Conference paper (Other academic)
    Abstract [en]

    Increasing the total number of produced components in a pre-existing production line, which is a large-scale mechatronic system, is a continuous and never-ending story in industry. There is a need for tools and methods to develop the control software off-line, i.e. to manage programming, verification, validation, optimisation, training new operators, etc. without using the real production line. Therefore a general Virtual Real-Time Model, VRTM, for simulating industrial production lines is proposed. The VRTM is intended to be used for off-line control software development and is aimed at increase the throughput in highly automated production lines. The main features of the VRTM are that the same control software is used as in the real production line and that virtual real-time is used, implying that everything is time-synchronised and works in the same way as in the real production line (including security functions). An applied VRTM simulating a sheet-metal press line is implemented and validated. A comparison test with the press line at Volvo Car Manufacturing in Göteborg is performed with a satisfactory agreement. This shows that the VRTM can be used for off-line control software development.

  • 62.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Nia, Nima K.
    Volvo Cars, VCIT, Olofström, Sweden.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Sheet-Metal Press Line Parameter Tuning using a Combined DIRECT and Nelder-Mead Algorithm2011In: The 16th IEEE International Conference on Emerging Technologies and Factory Automation: Toulouse, France, September 5-9, 2011, 2011, p. 1-8Conference paper (Refereed)
    Abstract [en]

    It is a great challenge to obtain an efficient algorithm for global optimisation of nonlinear, nonconvex and high dimensional objective functions. This paper shows how the combination of DIRECT and Nelder-Mead algorithms can improve the efficiency in the parameter tuning of a sheet-metal press line. A combined optimisation algorithm is proposed that determines and utilises all local optimal points from DIRECT algorithm as Nelder-Mead starting points. To reduce the total optimisation time, all Nelder-Mead optimisations can be executed in parallel. Additionally, a Collision Inspection Method is implemented in the simulation model to reduce the evaluation time. Altogether, this results in an industrially useful parameter tuning method. Improvements of an increased production rate of 7% and 40% smoother robot motions have been achieved.

12 51 - 62 of 62
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