Virtual commissioning
The commissioning of control systems, the warehouse management system (WMS) and material flow computer (MFC) is usually only carried out with the help of the real hardware and therefore on the construction site. This means that the commissioning work is carried out sequentially after the hardware has been installed, even if functions and errors can already be tested in advance using software engineering methods. Real load tests are not possible with these systems in the necessary complexity. Virtual commissioning is used for this purpose.
Virtual commissioning with the help of a simulation model
In order to reduce or even avoid time-consuming and expensive troubleshooting on the real system when commissioning WMS and MFR, realistic tests can be carried out before the system is completed using an emulation model, also known as virtual commissioning.
During emulation, a simulation model of the system is connected to the real control software via an online link. The control software runs exactly as if it were already controlling the real system, but instead communicates with the simulation model of the hardware that is planned or under construction. The control software makes all scheduling decisions. The simulation model maps the system and movements and provides feedback to the control software via status telegrams, just as a “real” system would send them.
This means that the model can be used to simulate any workload conditions and critical situations in the system and the WMS and MFR can be tested thoroughly, even under high system loads. Situations can be reproduced as often as required in the simulation model for troubleshooting purposes. This saves a lot of time and effort, especially when small modifications to the specification need to be made for fine-tuning in order to optimize the performance of the overall system.
Commissioning can be shortened by weeks
This often shortens commissioning by weeks and avoids risks in the test phase. At the same time, despite the shorter commissioning time, emulation can be used to test far more scenarios and thus significantly improve the quality of the control system.
Furthermore, the emulation model can be used to train the system’s operating personnel before and during the implementation phase and to prepare them specifically for certain system states.
The emulation model can also be used later, during operation of a system, for example to expand the logistics system or to test new control versions and error corrections without having to intervene in the real system first. If changes are necessary, the parameterization of the control system and the load structure can also be tested in advance.
Technical requirements for virtual commissioning
The simulation software used to create the simulation model must above all be designed for the communication method of the control system. If the control system communicates via TCP/IP, the simulator requires so-called sockets, which enable data exchange via ASCII telegrams, for example. The telegrams now control the simulation model instead of its real components, as is the case after commissioning the system.
If, on the other hand, the control modules to be tested access a database, the simulator used must provide ODBC or SQL interfaces.
In addition, the level of detail and the system and communication architecture of the simulation model and the real system must be similarly structured in order to be coupled.
Further information can be found in the article Material flow simulation.
Image source: SimPlan AG