# Strategies and Methods for the Fault-Tolerant Function Development of Multi-Domain Systems +
## 7 Possible Applications of the Research  
The main aim of this paper is the exploration of approaches for system design on the functional level aimed at supporting the accommodation of faults in multi-domain systems. This research direction is especially important for technical systems whose functionality and safety is endangered by faults. Multi-domain systems at minimum utilise mechanical, electronic, and software function carriers (compare mechatronic products), but can also include hydraulic and pneumatic function carriers. Today, such complex systems are usually coordinated, controlled, and integrated by communication and computation systems--they are cyber-physical systems (CPS) [73]. A prominent trend has led to combined offerings--so-called product-service systems (PSS)--integrated products and services intended to fulfil customer needs; for PSS, the function domain especially requires close collaboration of experts from various domains [5]. The technical systems which can profit from the research results range from vehicles, aircrafts, and ships to prominent future products, such as space travel, transportation systems (e.g., in airports for luggage transport or the transportation of raw and unfinished parts within a production system), all kinds of autonomous machines, offshore wind farms, as well as decentralised energy supply and distribution. Another important area within which fault accommodation is crucial is the field of human enhancement, e.g., by means of wearable robots [74]. For application of the research, both the knowledge of prominent causes for the emergence of faults (Section 4) and skills for the conscious application of countermeasures (Section 5) are important prerequisites. Today, the necessity of processes, methods, and tools to support product development has been acknowledged and it is agreed that companies need to be enabled to identify new engineering practices and to foster the adoption of innovative concepts and techniques [75]. The enabling of design engineers includes the areas of the distribution of knowledge, teaching of skills, and ensuring reflection; case studies and detailed best practice explanations (see Section 6) can be a significant means to this end. It is important to note that the early conceptual stages of the development of technical systems can be crucial [5]; function development teams need to be involved in the early stages, which are often led by product management in order to avoid unintended early solution fixation. This could be caused by early concept decisions made by persons who are not familiar with more fault-tolerant solution alternatives. It is also crucial to note that all around the globe an increasing shortage of engineers has led to the need for the use of more efficient methods. Both the knowledge concerning causes for the emergence of faults and skills to apply appropriate countermeasures for the accommodation of faults can lead to more effective processes for designing functional and safe multi-domain systems. It is extremely necessary to integrate new approaches in digital design processes. Function models need to be integrated in the MBSE framework of industrial companies. The interconnection of function models with other system models \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Technical System** & **Fault** & **Health Risk** & \begin{tabular}{c} **Functional** \\ **Accommodation** \\ \end{tabular} & **Implementation Success** \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Gear System for \\ Race Car \\ \end{tabular} } & Incomplete & No acceleration &
\begin{tabular}{c} Redundancy/physical \\ diversity/analytical \\ repetitiveness \\ \end{tabular} & Safe engagement of gears \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Accommodation of the fault “incomplete engagement of gear”—summary. (computer-aided design (CAD), computer-aided manufacturing (CAM), product data management (PDM), assembly process models, etc.)