# Testing Procedure of Unmanned Aerial Vehicles (UAVs) Trajectory in Automatic Missions
## 4 Discussion  
The first part of the discussion should reflect on the interpretation of the result data that were obtained with the use of the new set of tests. The differences between the design values and the ones measured by the MS50 surveying instrument, as a reference data, can be used to assess the accuracy of the UAV mission, e.g., in the case of separation from infrastructure, obstacles [31; 32; 36], ensuring appropriate shooting distances, etc. The differences between the design values and those that were derived from the data stored in the LOG files of the UAV on-board computers allow for determining the internal accuracy of the on-board computer, i.e., the permissible values at which the planned tasks are considered to be fulfilled by its software. On the other hand, the differences between the values that were measured by the MS50 surveying instrument, as a reference data, and those that were captured from the data stored in the LOG files of the UAV on-board computers should be interpreted as helpful in determining the accuracy of the UAV on-board devices. The results of tasks 1-3 allow for stating that the stabilisation of the device in the horizontal plane, in most cases, does not exceed \(\pm 1.50\) m Tables 1 and 3. The results are not affected by the duration of the mission. Momentary changes in the position of the device with small values result from the adjustments that were introduced by the on-board computer based on the readings of gyroscopes and inclinometers installed in the IMU Figure 5. However, the time drift in the horizontal plane has mostly occurred during the strong wind tests and it has resulted from the wind pressure on the device, Table 2. In the paper on control of a UAV with a RTS 3D position, quality has been measured for the complete flight path [46]. In this case, the working space was also limited to a very small space, in a cube of a size of not more than 15 m. The stabilisation accuracy of the device in the vertical plane is much lower than in the horizontal plane, as in the tests presented in this paper. The main reason for the occurrence of differences is the scale error and the barometric sensor drift, Tables 2 and 6. During short hovers, it is unnoticeable, Figure 5b. However, taking into account the entire mission lasting several minutes, the barometer readings relative to the reference system significantly differ, Figure 5a. From the results of the performed measurements, it can be concluded that errors in the barometer scales and the drift of the sensor are a specificity of individual on-board computers and are dependent on the weather conditions, Table 6. It is worth adding that, for the confirmation of this conclusion, it would be necessary to conduct research on a larger set of such devices. Taking into account the results of the \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**LIGHT WIND**} & \multicolumn{4}{c}{**STRONG WIND**} \\  & & **PROJ-MS** & **PROJ-LOG** & **MS-LOG** & **PROJ-MS** & **PROJ-LOG** & **MS-LOG** \\  & & **[m]** & **[m]** & **[m]** & **[m]** & **[m]** & **[m]** \\ \hline \multirow{4}{*}{COM-1} & MAX & 10.07 & 10.18 & 0.61 & 10.19 & 10.22 & 0.76 \\  & MIN & 8.44 & 8.97 & 0.27 & 8.56 & 9.08 & 0.41 \\  & MAX-MIN & 1.64 & 1.21 & 0.34 & 1.63 & 1.14 & 0.35 \\  & \(\overline{X}\) & 9.33 & 9.68 & 0.44 & 9.37 & 9.54 & 0.58 \\  & \(\sigma\) & 0.50 & 0.37 & 0.10 & 0.81 & 0.61 & 0.18 \\ \hline \multirow{4}{*}{COM-2} & MAX & 9.77 & 10.30 & 0.61 & 10.47 & 10.46 & 0.98 \\  & MIN & 8.66 & 9.09 & 0.46 & 8.67 & 9.04 & 0.11 \\ \cline{1-1}  & MAX-MIN & 1.11 & 1.21 & 0.15 & 1.80 & 1.42 & 0.87 \\ \cline{1-1}  & \(\overline{X}\) & 9.14 & 9.64 & 0.54 & 9.48 & 9.64 & 0.51 \\ \cline{1-1}  & \(\sigma\) & 0.41 & 0.42 & 0.06 & 0.91 & 0.57 & 0.44 \\ \hline \hline \end{tabular}
\end{table}