| 1. |
- Carlsson, Henrik, 1979-, et al.
(author)
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Automated Generation of Discrete Event System Simulation Models for Flexible Automation
- 2011
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In: The 21st International Conference on Flexible Automation and Intelligent Manufacturing. - 9789868729100 ; , s. 825-832, s. 825-832
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Conference paper (peer-reviewed)abstract
- Flexible automation cells with rapid product changes are an important competitive advantage for industries today. These cells can increase a company’s productivity and thereby increase their profits. A flexible cell shall be able to handle different products with none or minimal changes to the cell itself. A powerful tool, which can be used to analyse and verify such cells, is discrete event system simulation. Problems such as potential bottlenecks, deadlocks, answers to "what-if" questions and the level of resource utilisation can be gathered. The drawback of discrete event system simulation is that the modelling task is both time consuming and difficult to accomplish. Furthermore, state-of-the-art discrete event system simulation tools that are used in the industry today are not suitable for flexible automation. If the production scenario is changed, e.g. introduction of a new product, the simulation and modelling has to be redone and this is both time consuming and tedious. In this paper a new approach will be presented that enables discrete event simulation models to be generated automatically. The models are generated from information retrieved from a PLM/PDM database system, which is shared among other engineering tools such as robot simulation, CAD and process planning. Hence, when the cell and the database are updated a new model can easily be generated. The database is also connected to the real cell so up-to-date data can be retrieved from the real cell. The model generator described in this paper was implemented and tested in a discrete event system simulation tool and showed promising results. With this approach it is possible to handle flexible automation cells more effectively in a process planning stage.
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| 2. |
- Carlsson, Henric, 1979-, et al.
(author)
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General Time Synchronisation Method for PLC Programs Aiming at Virtual Verification and Development
- 2008
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In: 17th IFAC World. - 9783902661005 ; , s. 4440-4445
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Conference paper (other academic/artistic)abstract
- The latest state-of-the-art Computer Aided Production Engineering (CAPE) simulation technology offers OPC integration for PLC verification. A critical drawback with this technology has been identified and described within this paper. A new time synchronisation method and a simulation architecture are therefore presented and proposed. The time synchronisation method together with the architecture can be used when verifying and developing real-time dependent control logic for industrial control system, e.g. PLC with CAPE tools. The method described in this paper is general and should work on any PLCs that are compatible with the IEC 61131-3 standard. A test case was also carried out, showing that by disregarding time synchronisation it is impossible to verify real-time dependent PLC functions together with CAPE tools in a reliable way. However, the test case also shows that by applying the proposed time synchronisation method together with the described simulation architecture a successful industrial verification method is achieved
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| 3. |
- Glorieux, Emile, et al.
(author)
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Improved Constructive Cooperative Coevolutionary Differential Evolution for Large-Scale Optimisation
- 2016
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In: Computational Intelligence, 2015 IEEE Symposium Series on. - : IEEE. - 9781479975600 ; , s. 1703-1710
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Conference paper (peer-reviewed)abstract
- The Differential Evolution (DE) algorithm is widely used for real-world global optimisation problems in many different domains. To improve DE's performance on large-scale optimisation problems, it has been combined with the Cooperative Coevolution (CCDE) algorithm. CCDE adopts a divide-and-conquer strategy to optimise smaller subcomponents separately instead of tackling the large-scale problem at once. DE then evolves a separate subpopulation for each subcomponent but there is cooperation between the subpopulations to co-adapt the individuals of the subpopulations with each other. The Constructive Cooperative Coevolution (C3DE) algorithm, previously proposed by the authors, is an extended version of CCDE that has a better performance on large-scale problems, interestingly also on non-separable problems. This paper proposes a new version, called the Improved Constructive Cooperative Coevolutionary Differential Evolution (C3iDE), which removes several limitations with the previous version. A novel element of C3iDE is the advanced initialisation of the subpopulations. C3iDE initially optimises the subpopulations in a partially co-adaptive fashion. During the initial optimisation of a subpopulation, only a subset of the other subcomponents is considered for the co-adaptation. This subset increases stepwise until all subcomponents are considered. The experimental evaluation of C3iDE on 36 high-dimensional benchmark functions (up to 1000 dimensions) shows an improved solution quality on large-scale global optimisation problems compared to CCDE and DE. The greediness of the co-adaptation with C3iDE is also investigated in this paper.
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| 4. |
- Glorieux, Emile, et al.
(author)
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Optimisation of Interacting Production Stations using a Constructive Cooperative Coevolutionary Approach
- 2014
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In: Proceedings of 2014 IEEE International Conference on Automation Science and Engineering (CASE). - : IEEE conference proceedings. - 2161-8070 .- 2161-8089. - 9781479952830 - 9781479952823 ; , s. 322-327
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Conference paper (peer-reviewed)abstract
- Simulation-based optimisation carries the burden of computationally expensive fitness calculations. It is very often used to tackle large-scale optimisation problems with a relatively high level of complexity. Therefore, it is of interest to have optimisation techniques dedicated to simulation-based optimisation. This paper proposes a simulation-based optimisation approach, called Constructive Cooperative Coevolutionary (C3) search procedure, to optimise the control of interacting production stations. An optimisation algorithm is embedded in the C3 search procedure to optimise subproblems separately. It includes a novel constructive heuristic that creates a feasible solution for the considered problem efficiently. It also incorporates an extended version of the existing cooperative coevolutionary method that can handle large-scale optimisation problems. Furthermore, this paper presents a case study considering a sheet metal press line as an example of interacting production stations. In this case study, the performance of the proposedC3 search procedure is evaluated and compared with other optimisation algorithms. This shows that the C3 search procedure is able to successfully optimise the press line within a given number of fitness calculations, outperforming existing algorithms. Also, it is shown that C3 can be embedded with either stochastic or deterministic optimisation algorithms, without sacrificing performance.
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| 5. |
- Glorieux, Emile, et al.
(author)
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Simulation-based Time and Jerk Optimisation for Robotic Press Tending
- 2015
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In: Modellling and Simulation. - Ostende : ESM. - 9789077381908 ; , s. 377-384
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Conference paper (peer-reviewed)abstract
- Increased production rate and robot motion smoothness in a sheet metal press line are essential. Smooth robot motions avoid unplanned production interruptions and excessive wear of the robots. Reaching high production rate and smooth motions requires tuning of the tending press robot control to minimise the cycle time and jerk. Doing this for a press line with multiple robots is a complex large-scale problem. To model such problems for the optimisation process, computer simulations become almost essential. This work presents simulation-based optimisation of the time and jerk of robotic press tending operations and investigates the importance of including the robot motion’s smoothness. An optimiser works in concert with a simulation model of a sheet metal press line and its parametrised control system. The effect of including jerk minimisation in the objective function is tested on a real-world problem concerning a sheetmetal press line. The results illustrate the importance of including jerk-minimisation as an objective in the optimisation.Furthermore, the performance of this approach is compared with manual tuning by experienced operators. The results show that the proposed simulation-based optimisation approach outperforms manual tuning.
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| 6. |
- Nia, Nima, 1975, et al.
(author)
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Efficient geometrical simulation and virtual commissioning performed in stamping
- 2012
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In: Proceedings of 2012 IEEE 17th International Conference on Emerging Technologies & Factory Automation (ETFA 2012). - Polen : IEEE. - 9781467347372 - 9781467347365 - 9781467347358 ; , s. 1-8
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Conference paper (peer-reviewed)abstract
- In order to perform efficient geometrical simulation and virtual commissioning in stamping, three fields are investigated namely: simulation building time, collision detection time and optimization time. Hence, reducing time is the main theme of this paper. To reduce simulation building time and optimization time, an efficient stamping simulation model is built and tested. Collision detection time is examined by a relative motion method based on 3D to 2D geometrical collision detection. The presented results mean that simulation and virtual commissioning can be performed at least ten times faster compared to standard approaches.
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| 7. |
- Nia, Nima K., et al.
(author)
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A faster collision detection method applied on a sheet metal press line
- 2011
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In: The 4th International Swedish Production Symposium. - Lund : Swedish Production Academy. ; , s. 467-472, s. 833-840, s. 833-840
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Conference paper (peer-reviewed)abstract
- Geometrical collision detection is a time and resource consuming simulation task. In order to decrease time and resources, a general method applicable for 2D motions has been developed. The method is useful in simulation cases where 3D CAD data is part of an iterative method, e.g. optimization. The method is based on a transformation of a general 3D problem to a 2D problem, eliminating the need of 3D CAD models. Press Line simulations during the last decade have been accepted as a quality improvement method. Today simulations of automated press lines are done for internal collision checks in dies and external collision checks against dies and material handling equipment. If these collisions are not detected in simulations, they result in delays, in introduction of a new product in the line, so called line tryout or later when the line is ramped up to decide rate. The results of these collisions are used for pre-die design, design of grippers, maintenance and production planning. In this paper a new method, based on 2D simplifications, is developed and tested successfully in a virtual model of a press line at Volvo Car Manufacturing. Die Uppers 2 917 708 triangles and Die Lowers 602 686 triangles where reduced to 58 and 90 points. The result of the method shows substantial reduction of geometry data and considerable improvement in collision detection evaluation time over general 3D algorithms in the tested case.
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| 8. |
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| 9. |
- Svensson, Bo, 1959-, et al.
(author)
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Off-Line Optimisation of Complex Automated Production Lines : Applied on a Sheet-Metal Press Line
- 2007
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In: Proceedings of the 2007 IEEE International Symposium on Assembly and Manufacturing. - : IEEE. - 1424405637 ; , s. 82-87
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Conference paper (peer-reviewed)abstract
- This paper presents a successful off-lineoptimisation case study of a sheet-metal press line for theautomotive industry. The proposed off-line optimisationmethod results not only in increased production rate but also inobtaining smoother material handling motions. The off-lineoptimisation method contains two parts. The first part is aparameter study, combining factorial design with productionline simulation including emulated control systems andresulting in a simplified performance model based on multiplelinear regression. The second part is an optimisation on thesimplified performance model using the Nelder Mead simplexmethod aiming at production optimisation. Due to thecomplexity in a modern production line, it is not possible tocreate a useful model representation of the entire controlsystem code/function. Therefore, the proposed optimisationmethod is based on using production line simulation includingemulated control systems with the real IEC 61131-3 controlcode. Our approach in this work is a parameter variationstrategy for optimisation, i.e. adjusting the control systemparameters in the same way as the line operators do, and notchanging any control strategy.
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| 10. |
- Svensson, Bo, 1959-, et al.
(author)
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Sheet-Metal Press Line Parameter Tuning using a Combined DIRECT and Nelder-Mead Algorithm
- 2011
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In: The 16th IEEE International Conference on Emerging Technologies and Factory Automation. - 9781457700163 - 9781457700170 ; , s. 1-8
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Conference paper (peer-reviewed)abstract
- 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.
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