## 4 Experimental Results and Discussion
### Cobotic Preliminary Experiments
#### 4.3.1 Spraying Test  
The Franka Hand end effector was adapted to include a sampler of a spray per-time filled with water so that the functionality could be proven without incurring additional research and development costs to purchase professional chemical dispensers as end effectors. In detail, the spraying process encompasses several phases, from the home pose towards moves for searching (see Figures 10a and 11a), the decision making by the orchestrator component to devise both the cluster to spray and the pose estimation, the spray \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**State-of-the-Art** & **Model** & **Acc. (\%)** & **AP (\%)** & **mAP (\%)** & **F1-Score (\%)** \\ \hline [PERSON] et al. [34] & YOLOv4 & 48.90 & — & — & — \\ [PERSON] et al. [35] & SSD MobileNet v1 & — & — & 66.96 & — \\ [PERSON] et al. [27] & YOLOv5x & — & — & 79.60 & — \\ [PERSON] et al. [26] & Mask R-CNN & — & — & — & 84.00 \\ [PERSON] et al. [25] & Mask R-CNN & — & 89.53 & — & — \\ [PERSON] et al. [36] & YOLO-Grape & — & — & — & 90.47 \\ [PERSON] et al. [37] & Mask R-CNN & — & — & 92.78 & — \\ [PERSON] et al. [33] & YOLOv7 & — & — & 77.00 & 94.00 \\ Proposed (best) & YOLOv2 & 58.43 & 80.00 & 77.00 & 74.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison between the proposed model and the state-of-the-art DL for grapevine bunch detection, based on accuracy (Acc. ), average precision (AP), medium average precision (mAP) and F1-score (results taken from [33]). position (see Figures 9(c) and 9(c)), the actual spraying (Figures 9(d) and 9(d)) and the return to the home pose. Spraying Test in Indoor Controlled Environment  
The experimental laboratory tests were carried out by recreating a vineyard environment, using branches to hang fake vine leaves and the aforementioned plastic grape cluster replicas. In the tests performed, the synthetic grape clusters with the highest recognition percentage were the light red ones (82% on average) followed by dark red (77%) and finally white grape clusters, recognized with an average confidence of 66%. This is probably due to the laboratory lighting conditions, as well as the fact that the used dataset actually contains different degrees of ripeness and grape types. It could also depend on the non-typical background colors used in the laboratory tests: the background was, in fact, set by a white cloth, while in the training datasets, the back of the vines is typically made up of other vines, brown earth and green leaves. Spraying Test in Vineyard  
The developed CNN was able to recognize grape clusters even in a state of buds/_veraison_; that is, the phenological state that precedes the complete ripening of the bunch. It was therefore possible to use the robot directly on these, rather than adopting the plastic grape cluster used in the laboratory. This behaviour is supported by the results obtained in the exploratory study of Section 4.2.4 for the GBDDv2 and the OIDv7. Figure 12 depicts how the **608@VOC+WA-WGISD** behaves on the sample buds/_veraison_ images extracted from the GBDDv2 test set. A dedicated numerical analysis over both datasets showed that the performance metrics restricted to just the buds/_veraison_ are aligned with the overall scores reported in Table 5. This is the reason why the accuracy percentages in the field are comparable to those observed in the controlled environment. The developed procedure  
Figure 10: Cobotic preliminary experiment: spraying test in indoor controlled environment. seamlessly operates in the vineyard, since the adverse weather conditions (in particular, the high brightness in that area) did not bring any particular problem to the recognition of the adolescent stage of the bunch (Figure 11). Spraying Performance: Preliminary Considerations  
A quantitative study to evaluate the robotic performances in chemical administration is currently on-going and shall be the subject of a dedicated publication. Nevertheless, here follows some preliminary observations and guidelines to get a glimpse of the rationale in the matter.