# Increasing Resilience of Production Systems by Integrated Design
## 3 Results
### Modular Manufacturing Cells for Problem-Independent Production  
Figure 13 shows a GUI for a robot cell to manipulate, measure, and stack up automotive parts. The cell consists of a KUKA robot and four stations, each realizing different process steps. The left part shows the parametrized job list followed by a specification for each job. A visualization in the right part provides an interaction with the operator and visualizes the abstract robot actions associated with the manufacturing layout and task. Here, the programming paradigm interacts with factory facility planning when the state-actual model is incorporated in the GUI. In the middle part, control buttons allow for the PLC to be connected to, the download of the program to the PLC, and the running of specific jobs. The new parametrization paradigm uses flexible robot jobs, parametrized by a GUI and subsequently downloaded into the PLC. The program, job/skill parameters, and the  
Figure 13: GUI of the skill-based automation for a flexible robot cell. chronology of skills can be controlled, adapted, and reorganized through a GUI. After basic commissioning of the complete skillset, no automation specialist is needed anymore. Job and process flow adaption and testing can be realized within a few minutes. Users without PLC or robot programming knowledge can implement changes, and the risk of errors in programming is reduced. Besides the aforementioned robot cell for manipulating automotive parts, another robot cell for the highly flexible loading and unloading of machine tools was automated based on the new parametrization paradigm. For the test of control functions and the evaluation of methods to increase the resilience of production systems, a model, shown in Figure 14, of a small production cell for additive manufacturing with machining finishing was created. The material flow within the cell is realized by different handling robots and a conveyor belt that transports the produced semi-finished products between the processing stations. For the finishing of the products, two machines for milling are modeled. One is a conventional cutting machine tool, and the other one is a robot with a milling spindle as tool. The coordinate transformation of the robot enables cartesian machining in three axes. Both machines are controlled by a NC controller so that the same NC code can be executed. While the machines perform the same machining task, they have different characteristics, e.g., movement accuracy, stiffness, damping or inertia, which lead to different machining results, as shown in Figure 15. The conventional milling machine has a higher stiffness so that the milling results on the part surface are of higher quality than the results reached with the robot. In the example shown, only the pure vibration behavior of the machines is depicted on the surface of the components. So far, no interactions between the material and the machining tool have been implemented in the model. Thus, the differences could only be evaluated qualitatively until now. Modelling the interactions between process and machine will be part of future work to increase the mapping accuracy in virtual commissioning. Figure 14: Production cell for additive manufacturing with redundant machines for machining finishing. The virtual commissioning in combination with physically based models of machines and components allows for the virtual evaluation of reconfiguration strategies before the real production system is redesigned. The individual components of the production system are stored in a library so that a completely free composition of production cells is possible. An example for a matrix production cell is shown in Figure 16. For this model, components from the model depicted in Figure 14 are reused, and a new cell structure is built. In combination with the capability-based system control methods, a fast restructuring of a production system is possible, including its evaluation by use of the digital twin.