# A Parcel Transportation and Delivery Mechanism for an Indoor Omnidirectional Robot
## 5 Results
### Experiments on Parcel Transportation and Delivery  
The operability of the mechanism was assessed in a first set of complete parcel transportation and delivery experiments developed in a multi-story building. This first set of delivery experiments was performed only with small parcels (SPs). This section is focused on the evaluation of the experiments from the point of view of the mechanism for parcel transportation and delivery. The procedures used to control the mobile robot and implement all the steps required to complete a parcel transportation and delivery task will be explained in a separate work that will be published elsewhere.  
Each parcel delivery experiment consisted of the following steps: (1) a parcel is received in the reception of the building; (2) the delivery robot is called so that it goes from its charging station to a predefined specific position at the reception; (3) the parcel is manually loaded onto the robot; (4) a delivery destination inside the building is selected by using the tactile screen of the robot; (5) the robot performs path planning [55] and starts the delivery; (6) if the navigation is successful, the robot arrives at the delivery destination, with its back oriented to the delivery zone; (7) then, the robot unloads the parcel; and (8) the robot waits some time in case the cardboard of the package needs to be returned back for recycling. After completing the delivery, (9) the robot performs path planning to return to the charging station, and (10) if the navigation is successful, the robot arrives at the charging station or at the reception of the building in the case of receiving another call to deliver a new package. In the cases in which the navigation to reach the destination is unsuccessful, the mobile robot is configured to return the parcel to the reception. Specifically, Table 5 reports the experimental results obtained in steps (3) in which a parcel is manually loaded onto the delivery robot, and (7) in which the delivery robot unloads the parcel at the delivery zone.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Mobile Robot** & **Action** & **Parcel** & **Experiments Success** \\ \hline \multirow{6}{*}{Stationary (placed in the delivery destination)} & & SE & 25 & 100\% \\  & & LE & 25 & 100\% \\ \cline{1-1}  & Automatic & VSP & 25 & 100\% \\ \cline{1-1}  & unload & SP & 25 & 100\% \\ \cline{1-1}  & & MP-H, horizontal & 25 & 68\% \\ \cline{1-1}  & & MP-V, vertical & 25 & 72\% \\ \hline \hline \end{tabular}
\end{table}
Table 4: Results of the experiments on automatic parcel unloading.  
Figure 8: Sequence of experiments on automatic parcel unloading: (**a**) with SE; (**b**) with LE transported horizontally (LE-H) and (**c**) vertically (LE-V); (**d**) with SP transported horizontally (SP-H) and (**e**) vertically (SP-V); (**f**) with MP transported horizontally (MP-H) and (**g**) vertically (MP-V).  
Table 5 shows the results of step (3) and step (7) evaluated in 25 complete transportation and delivery tasks. Figure 9 shows some images of the robot completing step (7): entering an office, arriving at the delivery destination with its back oriented to the delivery zone, automatically unloading the parcel, waiting some time to collect any waste from the parcel, and returning to the charging station or the reception of the building.  
In all the delivery tasks, the manual loading of the parcel was always successful, while the automatic unloading of the parcel was successful in 22 experiments in which the robot arrived at its delivery destination. However, in three of the delivery experiments, the robot was not able to arrive at the delivery destination because of a navigation problem, so the parcel was kept loaded in the robot and returned to the reception of the building. These unsuccessful deliveries were not caused by a failure of the parcel transportation and delivery mechanism, so they have not been considered as a failure from the point of view of automatic unloading at the delivery destination (see Table 5).