## 5 Exemplary Application of the Combined Model
An assessment is made of how reliable the actors--the function carriers--are; this assessment is initially described as actor failure probability on a continuous scale from 0 (the probability of this actor to fail is infinitely low) to 1 (the actor will definitely fail); this assessment can then be automatically transferred to a process occurrence (O) on a continuous scale from 0 (the probability of this process to be affected by actor failure is infinitely low) to 10 (this process will definitely be affected by actor failure). It is important to note that two of the entities use the core of a function--the process--for the assessment and only one entity uses the actors. Figure 18 shows an exemplary assessment for the multicopter example. The assessments in Figure 18 were carried out by the development engineers based on their experience and on the reliability information available for some of the components. The assessment of process severity (**A**) and process detectability (**A**) result from the experience of the involved engineers. For instance, the high process severity (**A**) for process 2 \"distribute energy according to need\" is a result of the fact that the operation of the multicopter is impossible without this process. The assessment of the actor failure probabilities (**C**) is based on a combination of general engineering experience and information concerning a certain actor (e.g., vendor reliability information); for instance, the high actor failure probability of actor 11 \"rotor\" is a result of the damage possibilities during the flight. From this assessment, the process SOD (severity, occurrence, detection) values can be calculated (Figure 19). From the results in Figure 19, it is obvious that the processes _Process 2 \"distribute energy according to need\"_, _Process 5 \"Calculate flightpath and motor engagement\"_ and _Process 13 \"distribute forces\"_ have the highest SODs (in the given example, a SOD of 125 was considered to be critical). If one intends to improve the overall functionality of the multicopter, these processes, as well as the functions they are part of and the actors (function carriers) that realize these processes, are a good place to start. Figure 19: Process severity, occurrence, detection (SOD) values for the multicopter. Figure 18: Assessment in a function path analysis. Visible are process severity values (**A**), the process detectability values (**B**), the actor failure probabilities (**C**) and the process occurrence values (**D**). During the exemplary application, the specific working style when applying an engineering framework based on GBDLs was obvious. A paradigm shift can be observed as the product is not designed in a conventional manner--instead, a family of products is \"programmed\". Earlier research has found a certain reluctance of the main stakeholder--the designers--to describe products based on UML or SysML [18; 19; 20]. The designers in this project were younger engineers trained in the engineering framework and were open to this kind of change. The integration of the IFM Framework did not impair their product development processes. The main aspects that are specific to the presented example are the connection of two different engineering frameworks, leading to a rich and integrated knowledge representation of an abstract function model in an engineering framework, and the utilization of this integrated function model for a function path analysis, which allows the identification of critical processes and functions. As mentioned above, a multicopter is a fairly complex technical system that requires a control system for realizing its central functions. Consequently, a relatively high level of functional interconnection is present in a multicopter. Integrated function modeling enables the capture of those interconnections and an integration in an engineering framework allows further functional analyses and the generation of functionally diverse system topologies and configurations.