This paper describes a general virtual manufacturing concept for industrial control systems. Our virtual manufacturing concept provides a distinct advantage; programming, verification and optimisation of complex real-time dependent control functions described by real control code, which can be directly transferred to the real manufacturing system. To achieve this distinct advantage, a time synchronised virtual manufacturing system is a necessity. The aim of this paper is thus to present and to describe in detail, our proposed virtual manufacturing concept. To the authors’ knowledge no such general virtual manufacturing concept, i.e. one that can correctly handle complex real-time dependent control functions, currently exists. To summarise previous work related to virtual manufacturing and industrial control systems, several critical issues have been identified. The virtual manufacturing concept proposed in this paper addresses these issues. To verify that our concept can manage these critical issues found and further is suitable in industrial applications a virtual manufacturing test case is also presented. The test case, that includes motion control (i.e. servo), complex control functions, real control systems etc., was carried out with success.

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.

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.