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  • 51.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    A new Combined Optimisation Algorithm for Sheet-Metal Press Line Tuning2012In: Proceedings of the 5th International Swedish Production Symposium, SPS12: 6th-8th of November 2012 Linköping, Sweden / [ed] Mats Björkman, Linköping: Produktionsakademien, The Swedish Production Academy , 2012, p. 479-485Conference paper (Refereed)
    Abstract [en]

    This paper shows how a new combined optimisation algorithm can improve the efficiency in simulation-based parameter tuning of sheet-metal press lines. In automotive tandem sheet-metal press lines there are a number of critical interactions between moving parts to consider during the loading and unloading motions. All these interactions, both within each station and between the stations, are time-critical and must be synchronised to reach high production rates and avoid collisions. This cause conditions such as a highly non-linear objective functions with multiple local optima, considerable number of parameters, and long evaluation times. It is a great challenge to obtain an efficient direct search algorithm for global multi-criteria optimisation fulfilling all these conditions.

    The new combined algorithm starts with the Lipschitzian algorithm DIRECT as global search and then switches over to the Nelder-Mead simplex algorithm for local convergence. Furthermore, during the switch over, the algorithm determines all local candidates of the set of points evaluated by DIRECT, and starts multiple Nelder-Mead local searches in each of these.

  • 52.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Improving Performance in Flexible Manufacturing by a P-sop Approach2014In: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-8Conference paper (Refereed)
    Abstract [en]

    This paper present a Part oriented Sequence of Operation (P-SOP) approach that address flexibility, robustness and deployment in manufacturing cells up to plant level. A P-SOP description language has been formulated where the control strategy based on actual circumstances easily can be defined. Furthermore, a P-SOP multi-agent generator has been created that compiles the strategy description to multi-agents that control the manufacturing. Deadlock free IEC 61131-3 PLC code are directly generated from the description language. The code is not optimised for a specific scenario since the general description contains all possible routing paths and all resources available.

  • 53.
    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.

  • 54.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Automation Systems.
    P-SOP -€“ A multi-agent based control approach for flexible and robust manufacturing2015In: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 36, p. 109-118, article id 1301Article in journal (Refereed)
    Abstract [en]

    In a truly flexible manufacturing system the description of the control strategy must be updated every day. Hence, a new way to handle changes in the environment down to control system deployment and production is required. This paper presents a novel approach, based on P-SOP, to handle multi-agent based control and verification. The P-SOP approach addresses flexibility, robustness and deployment in the best possible manner with the least waste of time and effort. P-SOP includes a description language where the control strategy based on actual circumstances easily can be defined. Based on the description multi-agents, to control the manufacturing, are automatically generated. An industrial advantage is that the multi-agent generator creates IEC 61131-3 PLC code that can be executed on standard PLC’s. This feature eliminates the need for experts in PLC programming and reduce deployment time to become more efficient. Hence, this flexibility enables small series down to one off production in a competitive way. With multi-agent control it is also possible to handle rebalancing due to market changes, scheduling of available humans, introduction of new part types, and rerouting due to a machine break down or planned service. The generated agents are not optimised for a final solution with specific timings. All decisions are made on-line and the generated solution adapts to the circumstances that arise. With the P-SOP multi-agents it is easy to manually remove or introduce parts to the manufacturing cell without disturbing the system, e.g. for manually random inspections, removal of parts due to restart. The formulated description language and the multi-agent generator has been successfully tested and evaluated in an industrial environment.

  • 55.
    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)
  • 56.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Lennartson, Bengt
    University West, Department of Engineering Science, Division of Automation and Computer Engineering. University West, Department of Engineering Science, Division of Production Systems.
    An efficient algorithm for press line optimisation2013In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 68, no 5, p. 1627-1638Article in journal (Refereed)
    Abstract [en]

    Automated manufacturing processes such as automotive tandem press lines include time dependent complex control functions. All motions and critical interactions between moving parts must be synchronised to avoid collisions and reach high production rate. It is even for a skilled operator hard to optimise these processes on-line. Therefore, a hardware-in-the-loop simulation including real industrial control systems and its control code establish an essential tool for optimisation. Additionally, an efficient optimisation algorithm is required to reach a useful simulation-based optimisation method. This paper proposes a new optimisation algorithm starting with the Lipschitzian algorithm DIRECT as global search and then switches over to the Nelder-Mead simplex algorithm for local convergence. During the switch over, the new algorithm determines all local candidates of the set of points evaluated by DIRECT and starts multiple Nelder-Mead local searches in each of these. An optimisation study for an automotive press line shows that the proposed algorithm combines the benefits of the Lipschitzian and the simplex algorithms in an efficient way. The importance of multiple local searches from all local candidates found is also shown in the study. Based on the same number of function evaluations, it is also shown that this algorithm reaches improved press line performances compared to the stochastic differential evolution algorithm.

  • 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. 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.

  • 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.
    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.

  • 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.
    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.

  • 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.
    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.

  • 61.
    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.

  • 62.
    Svensson, Bo
    et al.
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Nilsson, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Danielsson, Fredrik
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    P-SOP Agent Generator for Flexible Manufacturing2013In: Lecture Notes in Mechanical Engineering, ISSN 2195-4356, E-ISSN 2195-4364, Vol. 7, p. 341-353Article in journal (Refereed)
    Abstract [en]

    In a flexible manufacturing industry the production planner may need to make an updated description of the control strategy every day. The description contains all possible routing paths and is based on actual circumstances. It varies depending on, e.g., rebalancing due to market changes, scheduling of available operators, introduction of new parts, and rerouting due to a machine break down or planned service. A Part oriented Sequence of Operation (P-SOP) description language has been formulated to assist the production planner to be able to handle these flexible manufacturing scenarios. Multi-agents to control the manufacturing are automatically generated from the P-SOP description language. The P-SOP agent generator creates IEC 61131-3 PLC code that can be executed on standard PLC’s. An agent consists of a head, a communicator and a body. The head and the communicator are the automatically generated part with a predefined interface against the physical body, e.g., the mechanical/electrical structure of a robot. This feature eliminates the need for an external expert in PLC programming. The head contains many small sub-sequences for all operations that are defined for the specific body. The purpose of the communicator is to communicate with surrounding neighbour agents to form a multi-agent system. The formulated language and the P-SOP agent generator has been successfully tested and evaluated in an industrial environment.

12 51 - 62 of 62
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