## 4 Results and Discussion
The motor and its vibration signal represent an aggregate that, by its operation, fundamentally affects the vibration signals and symptoms of the other units, such as the pump and hydrogenerator. The presentation of symptoms for the operation of the pump and the hydrogenerator are similar to those for the pump and the hydrogenerator in their separate operation. Most symptoms have low values, and there are few differences (Figure 12a,b). Figure 10: Motor and pump as aggregates: (**a**) symptom values \(s_{1}\)–\(s_{6}\); (**b**) symptom values \(s_{9}\)–\(s_{16}\). Figure 9: Hydrogenerator as aggregate: (**a**) symptom values \(s_{1}\)–\(s_{8}\); (**b**) symptom values \(s_{9}\)–\(s_{16}\). From Figure 13a,b, it can be concluded that individual symptom differences are good if all aggregates are active. A strong fluctuation is only observed for \(s_{3}\). Figure 11: Motor and hydrogenerator as aggregates: (**a**) symptom values \(s_{1}\)–\(s_{2}\); (**b**) symptom values \(s_{9}\)–\(s_{16}\). Figure 12: Pump and hydrogenerator as aggregates: (**a**) symptom values \(s_{1}\)–\(s_{2}\); (**b**) symptom values \(s_{9}\)–\(s_{16}\). From Figure 14a,b, it is possible to see that the difference in symptoms is very good in the operation of all aggregates if the drill bit is installed. There is a strong fluctuation at \(s_{3}\) and partly at \(s_{1}\). Overall, it is possible to draw a partial conclusion that the designed symptoms and the created symptom vectors are suitable criteria for classifying the objects of the drill stand. It was assumed that it will be possible to create clusters based on the analysis, description, and visualization. Figure 15 shows the positions of the symptom vectors of the objects in the two-dimensional symptom plane that form individual clusters. Clusters of objects form calculated symptoms from \(N\) = 30 realizations of the vibration signal of all aggregates. Individual aggregates as objects (i.e., \(\mathbf{O}\equiv\mathbf{C}\)) of the drilling stand have their own defined part of the symptom space. However, the border between them is not sharp, and there is mutual overlap and the emergence of penetrations between clusters. When viewed in a two-dimensional symptom plane with symptoms \(s_{1}\) and \(s_{2}\), five clusters can be formed (see Figure 15a). Relatively good differentiability of clusters is possible for aggregates such as the motor (C\({}_{1}\)), the motor and hydrogenerator (C\({}_{5}\)), the drilling stand without a drill bit (C\({}_{7}\)), and the drilling stand with a drill bit (C\({}_{8}\)). The cluster (C\({}_{x}\)) represents a group of pump aggregates, the hydrogenerator, and their joint activity. Creating their separate clusters is not quite possible. Creating a cluster for the motor and pump unit together as an object is impossible because its symptoms are extensive. Symptom values were found in multiple clusters. Figure 15b shows the symptoms \(s_{1}\) and \(s_{4}\) in the symptom plane. The significance of the partial results is that it is possible to create clusters from the objects of the pump (C\({}_{2}\)), hydrogenerator (C\({}_{3}\)), and their joint activity (C\({}_{6}\)). Partial recognizability of objects through the clusters was noted for the motor and hydrogenerator (C\({}_{5}\)), the drill stand without a drill bit (C\({}_{7}\)), and the drill stand with a drill bit (C\({}_{8}\)). The motor and the motor and pump together were hard to recognize. Similar results were obtained for symptoms \(s_{1}\) and \(s_{5}\) shown in the plane in Figure 15c and for symptoms \(s_{2}\), \(s_{4}\) (see Figure 15d). Common features represent the possibility of creating a cluster (C\({}_{x}\)) and further clusters (C\({}_{1}\), C\({}_{5}\), C\({}_{7}\),C\({}_{8}\)). Another feature is a different distribution in the symptom plane. Figure 14: All stand aggregates with drill bit: (**a**) symptom values \(s_{1}\)–\(s_{6}\); (**b**) symptom values \(s_{9}\)–\(s_{16}\).