# Increasing Resilience of Production Systems by Integrated Design
## 4 Discussion
### Matrix Production as Alternative Manufacturing Concept of the Future  
The growing diversity of product variants and the resulting decrease in batch sizes require the flexibility of production. Both internal and external events can lead to changed requirements or to disruptions in the production process that require an adjustment of production sequences and process chains.  
Modular production cells combine technologies with the necessary automation for their implementation to realize a defined process step. The matrix production concept allows for the free interlinking of such production cells and thus dissolves the limitations of today's established line production. A wide variety of product variants can be manufactured on one production structure. The sequence of the process steps to be performed is not predetermined by the structure of the manufacturing system. Each product follows its own path through the needed production cells and defines its own production structure. The duration of a single process step no longer determines the cycle of the entire production. Rather, the process steps are conducted independently of each other so that an infrastructure can be created that is oriented to processes and capacity requirements. However, the implementation of manufacturing cells requires control methods that enable a capability-based description of the machining processes. This is the basis for the rapid reconfiguration of the cell and the efficient adaptation to a new manufacturing task.  
The matrix production concept enables production to be quickly adjusted to changing requirements. Flexible reactions to customer demands, prioritization of rush orders, or parallel processing of different orders are possible with the same production technology. The robustness of the system increases when central process steps are available in multiple units. This makes production less susceptible to disruptions, as it is possible to switch to another cell if one fails. For this purpose, it is necessary to develop planning methods which, on the one hand, allow a statement about the most efficient processing of the current task, but also allow an evaluation of the planned process sequences with regard to other criteria such as the achievable accuracy during production or also the energy requirement of the production equipment. The methods of virtual commissioning provide the basic functions for the virtual analysis of the production process, considering the real control technology. In the future, it will be necessary to make the required extensions in order to be able to include the dynamic and energetic properties of the manufacturing systems as well as the interactions of machines and processes.  
With the methods presented, it is possible to achieve the necessary mutability of production systems, provide the corresponding planning methods, and thus increase the resilience of these systems.  
Conceptualization, M.S., A.H. and K.W.; methodology, M.S. and T.W.; formal analysis, M.S.; investigation, M.S. and T.W.; writing--original draft preparation, T.W., M.S., A.H., C.-C.S., K.W. and S.M.; writing--review and editing, S.I., T.W., M.S., A.H., C.-C.S., K.W. and S.M.; visualization, M.S., T.W. and C.-C.S.; funding acquisition, K.W.; supervision, S.I. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was partially funded by the German Federal Ministry of Education and Research (BMBF) under grant 01 IS18067 B (RESPOND) and the Federal Ministry for Economic Affairs and Energy (BMWI) under grant 20940 BG (SynLApp).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.