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A Simulation-Based Optimisation Method for PLC Systems
University West, Department of Engineering Science, Division of Electrical and Automation Engineering. (PTW)ORCID iD: 0000-0002-8878-2718
2012 (English)Doctoral 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.

Place, publisher, year, edition, pages
Göteborg: Chalmers , 2012. , p. 65
Series
Doktorsavhandlingar vid Chalmers tekniska högskola Ny serie, ISSN 0346-718X ; 3340
Keywords [en]
Simulation based optimisation, Virtual manufacturing, Industrial control system, PLC, Continuous simulation, Parameter tuning, Optimisation methods
National Category
Robotics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
URN: urn:nbn:se:hv:diva-4646ISBN: 978-91-7385-659-1 (print)OAI: oai:DiVA.org:hv-4646DiVA, id: diva2:555240
Public defence
2012-04-13, Lecture room C118, University West, Gustava Melins gata 2, Trollhättan, 10:15 (English)
Opponent
Supervisors
Available from: 2012-09-25 Created: 2012-09-19 Last updated: 2016-02-09Bibliographically approved
List of papers
1. Methods for Reliable Simulation-Based PLC Code Verification
Open this publication in new window or tab >>Methods for Reliable Simulation-Based PLC Code Verification
2012 (English)In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, ISSN 1551-3203, Vol. 8, no 2, p. 267-278Article in journal (Refereed) Published
Abstract [en]

Simulation based PLC code verification is a part of virtual commissioning, where the control code is verified against a virtual prototype of an application. With today’s general OPC interface it is easy to connect a PLC to a simulation tool for e.g. verification purposes. However, there are some problems with this approach that can lead to an unreliable verification result. In this paper, four major problems with the OPC interface are described, and two possible solutions to the problems are presented: a general IEC 61131-3 based software solution, and a new OPC standard solution

National Category
Robotics
Research subject
ENGINEERING, Mechatronics
Identifiers
urn:nbn:se:hv:diva-3154 (URN)10.1109/TII.2011.2182653 (DOI)000302720000007 ()2-s2.0-84859894562 (Scopus ID)
Available from: 2011-01-28 Created: 2011-01-28 Last updated: 2019-04-29Bibliographically approved
2. Time-synchronised hardware-in-the-loop simulation - Applied to sheet-metal press optimisation
Open this publication in new window or tab >>Time-synchronised hardware-in-the-loop simulation - Applied to sheet-metal press optimisation
2012 (English)In: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 20, no 8, p. 792-804Article in journal (Refereed) Published
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.

Keywords
Simulation based optimisation; Virtual manufacturing; PLC; Time synchronisation;
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-3155 (URN)10.1016/j.conengprac.2012.03.019 (DOI)000306032400006 ()2-s2.0-84861974437 (Scopus ID)
Available from: 2011-01-28 Created: 2011-01-28 Last updated: 2019-04-26Bibliographically approved
3. A Virtual Real-Time Model for Control Software Development: applied on a Sheet-Metal Press Line
Open this publication in new window or tab >>A Virtual Real-Time Model for Control Software Development: applied on a Sheet-Metal Press Line
2005 (English)In: Industrial Simulation Conference 2005 / [ed] Jörg Kruger, Alexei Lisounkin, Gerhard Schreck, 2005, p. 119-123Conference paper, Published paper (Refereed)
Keywords
virtual manufacturing
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-2296 (URN)90-77381-18-X (ISBN)
Conference
3rd International Industrial Simulation Conference, ISC'2005, June 9-11, Fraunhofer IPK, Berlin, Germany
Available from: 2010-03-17 Created: 2010-03-17 Last updated: 2018-07-25Bibliographically approved
4. Off-Line Optimisation of Complex Automated Production Lines: Applied on a Sheet-Metal Press Line
Open this publication in new window or tab >>Off-Line Optimisation of Complex Automated Production Lines: Applied on a Sheet-Metal Press Line
2007 (English)In: Proceedings of the 2007 IEEE International Symposium on Assembly and Manufacturing, IEEE , 2007, p. 82-87Conference paper, Published 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.

Place, publisher, year, edition, pages
IEEE, 2007
Keywords
virtual manufacturing
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-210 (URN)10.1109/ISAM.2007.4288453 (DOI)1-4244-0563-7 (ISBN)
Conference
IEEE International Symposium on Assembly and Manufacturing, ISAM 2007,Ann Arbor, Michigan, USA, July 22-25, 2007
Available from: 2009-04-23 Created: 2009-04-23 Last updated: 2014-05-08Bibliographically approved

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