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Virtual Commissioning

Testing the components and behavior of a manufacturing plant project before actually constructing it constitutes an effective way of identifying in advance the kinds of critical difficulty that can cost so much time and money.

July 2014

Virtual Commissioning IMALab

The timeframe for manufacturing system engineering is progressively tightening, but at the same time the demands on planning accuracy and planning quality are growing.

The engineering process can be seen as a waterfall model: single steps in this model can only be executed one after the other. There is no iteration step back to previous steps. As a result, an integrated test of the planned manufacturing system cannot be carried out until it has actually been built. And consequently a considerable number of design problems and faults often remain undetected until the first system start-up.

Commissioning time consumes up to 25% of the time available for plant engineering and construction, and up to 15% is expended on correcting errors in the control software alone. The answer to this problem lies in virtual commissioning (VC).

During VC, a simulation model of the manufacturing system is used to allow commissioning through simulation, before building the system. The goal is the early detection and correction of errors generated during planning, design and programming.

The basic idea of Virtual Commissioning is to connect a digital plant model with a real plant.

Controlling System (e.g. PLC- Programmable Logic Controller or HMI-Human Machine Interface) so that engineers from different fields, such as design process and control, share a common model on which to they can work together.

Thus, for instance, the PLC program can be tested virtually before its physical implementation is finished. Furthermore, the general functionalities of the plant can be validated and tested in an earlier phase.

Thanks to precise simulation studies, the system’s full potential can be developed when this technology is used across the whole installation life cycle. In the planning phase, and then continuously during the engineering phase, important basic assumptions can be checked and concepts verified through simulation. This approach is known as simulation-based engineering.

What are the main components of Virtual Commissioning?

The virtualized plant, a mechatronic plant model, simulates the behavior of the real physical plant. It should respond correctly to PLC control signals in the same way as a real system would. Thus the whole process can be visualized for better human observation.

To fulfill these needs, the mechatronic model should include both a control oriented behavior model and a kinematic 3D-model.

The behavioral model simulates the uncontrolled behavior of the system. The behavioral states of production resources are modeled and calculated by means of logic and temporal components, whose operations are based on the control signals. In one PLC scan period, the behavior model should react to the control signals (output signals of PLC) according to the physical features of the plant and give the feedback signal (input signals of PLC) back to the PLC – just as must happen in the operation of a real system.

The kinematic 3D-model can be understood as a geometric model, which is based on the 3DCAD model and enriched with additional information e.g. the grouping of components which must move together and the definition of the DOF (degree of freedom) for every moving part. In contrast to today’s mechanical CAD models, the mechatronic components do not consist only of the 3D CAD model, but also of kinematic information (including end positions) and electrical information including the electrical name of the respective device. For the purpose of synchronization, a signal coupling system between the behavior model and kinematic 3D-model must be created.

The kinematic 3D-model is an important component in Virtual Commissioning, because it facilitates better understanding by visualizing movement behavior in 3D.

The potential benefits in reducing debugging and correction efforts required during real commissioning, however, can only be achieved if sufficiently detailed manufacturing system models are available for simulation. Up until now, the design of such models has required a high level of expertise and considerable effort, which makes virtual commissioning still unattractive for small and medium-sized enterprises (SME).

Investigating the feasibility of VC has been an important academic and industrial research objective for several years. In the present phase, an increasing number of models and tools for carrying out Virtual Commissioning are becoming available, making it possible to perform this activity in an increasingly rapid, precise and economic way, since it no longer has to involve a high level of expertise in model building and simulation.

This will enable more small and medium-sized enterprises to apply these techniques to optimize their engineering processes.

Virtual Commissioning is undoubtedly one of those critical innovations which promise to become increasingly important factors in industrial practice in coming years.

 

 

References:

Virtual commissioning of manufacturing systems

Peter Hoffmann, Talal M.A. Maksoud - University of Appl. Sc. and Arts, Hannover

Reimar Schumann, Giuliano C. Premier - Faculty of Advanced Technology, University of Glamorgan

 

Virtual commissioning of automated systems

Zheng Liu - Otto-von-Guericke University, Magdeburg,

Nico Suchold and Christian Diedrich - Institut für Automation und Kommunikation, Magdeburg