Under virtual commissioning (short: ViBN ) refers to the import, trying out and modifying planning data on a virtual machine before successfully tested programs on the real machine are transmitted. In this way, unforeseen errors can be identified and eliminated in the early development phases, before they actually lead to additional expenses and costs.
The basis for the virtual commissioning is the 3D simulation , which simulates the behavior of the machine. The simulation can be transferred to the entire factory as part of the digital factory . This enables not only individual robots and machine islands to be viewed, but also the complex relationships with regard to material flow and robot control to be mapped in order to optimize production planning. Virtual commissioning is becoming more and more important today. A comprehensive study has shown that an early VIBN enables a shortening of the commissioning time, lower development and implementation costs, the safeguarding of the process and product quality and thus the reduction of the production costs .
Control levels of virtual commissioning
During virtual commissioning, the previously generated sequence simulation is connected to the real controller. There are generally three levels available for this:
- The PLC level ( programmable logic controller )
- The material flow computer level (MFR) (Link)
- The production control level (link)
The simulation model always covers the level that is not part of the test setup. If the logic of the programmable logic controller (PLC) is to be checked, the model only covers the sensor - actuator level . If the MFR is to be tested, the model also contains the PLC logic . Mixed forms are also possible, whereby the PLC of individual plant areas is available, but other areas are adopted by the model. A holistic system test at the MFR level is possible, although individual areas at the PLC level have not yet been completed.
Virtual commissioning at the PLC level
Here the model is connected to the real PLC and controlled by it. In this way, the logic of the PLC can be tested before the system is actually operated. When testing the PLC software, the computer model behaves just like the real system. The actuator signals and control words coming from the PLC are interpreted and control the model. Examples of actuator signals are:
- Control signals for motors
- Opening / closing of valves
- Proportional controls of valves
The VIB model sends the sensor and feedback signals back to the PLC. Classic input signals are:
- Temperature sensors
- Pulse generator and encoder values
- Feedback signals from the motors
- Limit switch
Virtual commissioning at MFR level
With the virtual commissioning on the material flow computer (MFR) level, the communication between the MFR and the simulation model takes place on the telegram level. The logic of the PLC level is in the simulation model. The MFR sends transport orders to the system and queries status reports. The MFR (material flow computer) leads z. B. through individual transport orders for the warehouse management system, monitors conveyor systems and forwards the data to the PLC (the model). Here the simulation can display, check and, if necessary, improve the control of each individual automated operating, conveying and sorting element before commissioning.
Evaluation of the VIBN
It should be noted that the VIBN cannot completely replace the real commissioning or that it cannot exclude all sources of error, as the human factor cannot be adequately simulated (incorrect wiring, changed sensor positions). These points only become visible during actual commissioning.
The level of detail of the 3D simulation and the 3D model is initially offset by a higher level of effort, which is quickly amortized if the avoided costs for troubleshooting and the earlier reaching profitability are considered.
In addition, the VIBN has other advantages:
- The control technicians are more motivated, as they can test their software at an early stage in the project and also receive visual feedback
- Lower travel costs and family-friendly work thanks to shorter on-site commissioning
- Capacity tests easily possible
- Damage to the real system is avoided
- Unproductive waiting is avoided as the control can be tested independently of other areas
- Alternative control concepts can be tested safely on the model
- VDI / VDE guideline 3693: Virtual commissioning - Sheet 1: "Model types and glossary", 2016.
- Georg Wünsch: Methods for the virtual commissioning of automated production systems . IWB Research Reports, Volume 215. Munich 2008. ISBN 978-3-8316-0795-2
- Sascha Roeck: Real-time simulation of production plants with real control systems . Jost-Jetter Verlag, 2007, ISBN 3-939890-24-3 .